2. government accession no. fhwatx77-225-1...(4 ft height x 6 ft width) single box, and 4 ft x 6 ft...
TRANSCRIPT
TECHNICAL REPORT STANDARD TITLE PAGE
1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FHWATX77-225-1 4. Title and Subtitle 5. Report Date
"Safety Treatment of Roadside Culverts on Low Volume March 1978 Roads" 6. Performing Organization Code
7. Author(s} 8. Performing Organization Report No.
T. L. Kohutek and H. E. Ross, Jr. Research Report 225-1
9. Performing Organization Name and Address 10. Work Unit No.
Texas Transportation Institute Texas A&M University 11. Contract or Grant No.
College Station, Texas 77843 Research Study 2-8-77-225 13. Type of Report ,and Period Covered
12. Sponsoring Agency Nome and Address Final Report Texas State Department of Highways and Public Transportation January 1977 - March 1978
Transportation Planning Division 14. Sponsoring Agency Code
P.O. Box 5051 Austin, Texas 78763 15. Supplementary Notes
Research performed in cooperation with DOT, FHWA. Research Study Title: "Economics of Highway Design Alternatives ll
• SDHPT Contact Man: Harold Cooner, FHWA Contact Man: C. P. Damon
16. Abstract
Current American Association of State Transportation and Highway Officials (AASHTO) criteria for safety-treating fixed roadside hazards suggest that all culverts within a certain clear distance of the edge of the traveled way be shielded by a roadside barrier. This is not necessarily a cost-effective solution for low volume highways.
Using a cost-effectiveness model currently recommended by AASHTO. guidelines for safety-treating culverts have been developed for 36 in. diameter pipe, 4 ft x 6 ft (4 ft height x 6 ft width) single box, and 4 ft x 6 ft multi-box (double box) culverts located on low volume, rural highways (average daily traffic less than 20,000). Each culvert design was evaluated on fill section embankments with 2~:1 and 6: 1 slopes and for end offsets of 12, 18, and 24 ft. The treatments considered for each culvert design and embankment slope were: 1) do nothing (i.e., leave the culvert unprotected); 2) extend the culvert end 30 ft from the edge of the traveled way; 3) provide guardrail protection; and 4) provide grate protection.
17. Key Words 18. Distribution Statement
Cost-Effectiveness, Culvert, Grates, No restrictions. This document is Guardrail, Roadside Barriers, Safety available to the public through the Treatment, Severity Index National Technical Information Service,
Springfield, Virginia 22161
19. Security Clossil. (of this report) 20. Security Clossif. (of this page) 21. No. of Pages 22. Price
Unclassified Unc 1 ass ifi ed 111 N/A
Form DOT F 1700.7 (B.6.' i
SAFETY TREATMENT
OF ROADSIDE CULVERTS
ON LOW VOLUME ROADS
by T. L. Kohutek
Engineering Research Associate
and
H. E. Ross, Jr. Research Engineer
Research RepoY't 225-1 Economics of Highway Design Alternatives
Research Study 2-8-77-225
Sponsored by The Texas State Department of Highways and Public Transportation
in cooperation with The United States Department of Transportation
Federal Highway Administration
March 1978
Texas Transportation Institute Texas A&M University
College Station, Texas
i i
FOREWORD
The information contained herein was developed on Research Study
2-8-77-225 entitled "Economics of Highway Design Alternatives. II It
is a cooperative research study sponsored jointly by the Texas State
Department of Highways and Public Transportation and the u. S. Depart
ment of Transportation, Federal Highway Administration.
The objective of the study is to develop guidelines for installing,
upgrading, and safety-treating various types of culvert designs. Empha
sis is placed primarily on culverts located on low volume roads (3,000
average daily traffic and less) although some work is done with inter
mediate volumes (20,000 average daily traffic).
A cost-effectiveness model was taken from the American Association
of Highway and Transportation Officials (AASHTO) guide for the selecting,
locating, and designing of highway traffic barriers (l). This model
provides the present value of the total cost of each alternative as
computed over a given period of time taking into consideration initial
construction costs, maintenance costs, and accident costs. Accident
costs incurred by the motorist, including vehicle damage and personal
injury, are considered together with damage costs incurred by the
highway department.
A ranking factor for each alternative is also calculated to aid
the designer in establishing a priority system for reducing culvert
hazards within a given roadway system. This factor is a ratio of the
benefits (as measured in accident cost savings) received to direct costs
incurred by the highway department when selecting an alternative.
iii
The alternative with the highest ranking factor (or benefit to cost
ratio) is generally the most desirable.
The contents of this report reflect the views of the authors who
are responsible for the facts and the accuracy of the data presented
herein. The contents do not necessarily reflect the official views
or policies of the Federal Highway Administration. This report does
not constitute a standard, specification, or regulation.
iv
SUMMARY
Key Words: Cost-Effectiveness, Culverts, Grates, Guardrail, Roadside
Barriers, Safety Treatments, Severity Index.
Current American Association of State Transportation and Highway
Officials (AASHTO) criteria for safety-treating fixed roadside hazards
on high-speed facilities suggest that all culverts within a certain
distance of the edge of the traveled way be shielded by a roadside
barrier (1). In a restricted highway funding environment, this is not
necessarily a cost-effective solution for low volume highways.
Using a cost-effectiveness model currently recommended by AASHTO (1),
warrants for safety-treating culverts have been developed for 36 in.
diameter pipe, 4 ft x 6 ft (4 ft height x 6 ft width) single box, and
4 ft x 6 ft multi-box (double box) culverts located on low volume, rural
highways (average daily traffic less than 20,000). Each culvert design
was evaluated on fill section embankments with 2~:1 and 6:1 slopes and
for end offsets of 12, 18, and 24 ft. The treatments cons i dered for
each culvert design and embankment slope were: 1) do nothing (i.e.,
leave the culvert unprotected); 2) extend the culvert end 30 ft from the
edge of the traveled way; 3) provide guardrail protection; and 4) provide
grate protection.
Figures are given to identify cost-effective treatments for the
range of variables (ADT, embankment slope, offset, culvert design and
safety treatment, etc.) considered in this study. For traffic volumes
less than 750 and offset distances greater than 12 ft, the most cost
effective alternative is to leave the culvert unprotected. At higher
traffic volumes the most cost-effective safety treatments are extending
v
the culvert end to 30 ft or grating. Guardrail was found to be cost
effective only for larger culvert sizes and higher traffic volumes.
However, guardrail protection was not the most cost-effective alterna
tive for these situations.
All supporting data and a discussion of the cost-effectiveness
model used in the study are included in this report. Examples are
given to illustrate the use of the criteria developed and to show the
techniques used to develop these criteria. Other examples are included
to enable the user to develop warrants for situations other than those
considered in this study.
vi
IMPLEMENTATION
Generally, there are three alternatives to evaluate when con
sidering th~ safety treatment of any roadside hazard: 1) do nothing,
i.e., leave hazard unshielded; 2) remove or reduce hazard so that
shielding is unnecessary; or 3) install a barrier.
second alternative may be accomplished as follows:
For culverts, the
1) extend the ends
of the culvert a sufficient distance from the edge of the traveled way
to allow an errant vehicle time and space to return to the road; and/or
2) "reduce" the hazard by providing grate treatment.
Extensive research has been performed to develop guidelines for
safety-treating many types of roadside hazards, but little effort has
been made to develop objective criteria for safety-treating culverts.
This study provided objective criteria for the safety treatment of
36 in. diameter pipe, 4 ft x 6 ft single box, and 4 ft x 6 ft multi-box
(double) culvert designs on both flat and steep roadside slopes and low
volume highways. For each of these configurations, the alternatives
discussed previously were considered as possible treatments. The
criteria developed in this study will aid the highway designer in two
ways. He will be able to (1) determine the most cost-effective safety
treatment for existing culverts, or (2) design the most cost-effective
culvert installation for new roadways. The same basic procedure used
in this study may be used to develop objective criteria for other
culvert designs on higher volume highways.
vii
ACKNOWLEDGMENTS
This study was conducted under a cooperative program between
the Texas Transportation Institute and the Texas State Department of
Highways and Public Transportation (SDHPT). It was sponsored by SDHPT
in cooperation with the U.S. Department of Transportation, Federal
Highway Administration (FHWA).
The authors wish to thank Mr. Harold Cooner of SDHPT and Mr. C.
P. Damon of FHWA for their opinions, guidance, and technical assistance
throughout the study. Thanks should also be extended to Mr. Dan Williams
of SDHPT for providing cost estimates for the various types of culvert
designs and grate protection safety treatments. Special thanks go to
Mrs. Sheila Darsie for her typing skills and overall assistance in
preparing this report. Mrs. Sylvia Velasco also helped type the final
manuscript.
viii
TABLE OF CONTENTS
Page
I. INTRODUCTION 1
I I. CULVERT DESIGNS AND TREATMENTS 3
General 3 Range of Variables 3 Assumptions and Limitations 9
III. GUIDELINES FOR EXTENDING OR UPGRADING EXISTING UNPROTECTED CULVERTS 11
IV. CONCLUSIONS AND RECOMMENDATIONS 32
V. FUTURE CONSIDERATIONS 35
APPENDICES 36
APPENDIX A. A DISCUSSION OF THE COST-EFFECTIVENESS MODEL Al
APPENDIX B. APPLICATION OF MODEL Bl APPENDIX C. SUPPORTING DATA Cl APPENDIX D. SAMPLE CALCULATIONS 01 APPENDIX E. REFERENCES El
ix
LIST OF FIGURES
Figure Page
1 TYPICAL ROADWAY SECTION WITH THE VARIOUS CULVERT DESIGNS 4
2 CULVERT SAFETY TREATMENTS 6
3 WARRANTS FOR EXTENDING OR UPGRADING A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE 12
4 WARRANTS FOR EXTENDING OR UPGRADING A 36 INCH PIPE CULVERT ON A 6:1 SLOPE 13
5 WARRANTS FOR EXTENDING OR UPGRADING A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE 14
6 WARRANTS FOR EXTENDING OR UPGRADING A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE 15
7 WARRANTS FOR EXTENDING OR UPGRADING A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE 16
8 WARRANTS FOR EXTENDING OR UPGRADING A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE 17
9 SAMPLE ADT INTERPOLATION FOR UNITY RANKING FACTOR 20
10 COST-EFFECTIVENESS CURVES FOR TYPICAL CULVERT ENDS ON 2~:1 SLOPES 21
11 COST-EFFECTIVENESS CURVES FOR TYPICAL CULVERTS ON 6:1 SLOPES 22
12 POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6:1 SLOPES 23
13 POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6:1 SLOPES AND SMALL (36 11 DIA.) CULVERTS ON STEEP SLOPES 24
14 POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6: 1 SLOPES AND St~ALL (36" DIA.) CULVERTS ON STEEP SLOPES 25
15 POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6:1 SLOPES 26
16 POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERT ENDS ON STEEP SLOPES 27
x
Figure
17
18
A1
A2
A3
LIST OF FIGURES (continued)
POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERT ENDS ON STEEP SLOPES
POSSIBLE DESIGN GUIDELINES FOR ALL CULVERT ENDS ON STEEP SLOPES
HAZARD ENVELOPE FOR AN UNPROTECTED CULVERT AND DITCH
HAZARD ENVELOPE FOR GUARDRAIL PROTECTED CULVERT
HAZARD ENVELOPE FOR GRATE PROTECTED CULVERT
xi
28
29
A3
A4
A5
Table
1
Al
A2
Bl
B2
B3
B4
B5
B6
B7
B8
Cl
C2
C3
C4
C5
LIST OF TABLES
INTERPOLATED ADT VOLUMES FOR RANKING FACTOR = 1.0
VALUES FOR CALCULATING THE COLLISION FREQUENCY (CF)
SEVERITY INDEX AND ACCIDENT COST
SEVERITY INDICES AND ACCIDENT COSTS FOR THE UNPROTECTED CULVERT
COST OF WING WALLS (CWW)
COST OF EXTENDING THE CULVERT PIPE OR BOX TO 30 FT FINAL OFFSET (CEXT)
COST OF FILL FOR EXTENDING THE CULVERT TO 30 FT FINAL OFFSET (CFILL)
INITIAL COST OF GRATE PROTECTION
DIRECT COSTS FOR EXTENDING A CULVERT TO 30 FT FINAL OFFSET
DIRECT COSTS FOR GUARDRAIL PROTECTION OF 36 IN. PIPE, 4 FT X 6 FT SINGLE BOX, AND 4 FT X 6 FT MULTI-BOX (2) CULVERTS ON 2~:1 AND 6:1 SLOPES
DIRECT COSTS FOR GRATE PROTECTION
RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
RANKING FACTORS FOR A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
RANKING FACTORS FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE
RANKING FACTORS FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
xii
19
A7
A8
B2
B3
B4
B5
B7
B9
B10
B10
C2
C5
C8
Cll
C14
LIST OF TABLES (continued)
Table Page
C6 RANKING FACTORS FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE C17
C7 TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE C20
C8 TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE C24
C9 TOTAL COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE C28
Cl0 TOTAL COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE C32
Cll . TOTAL COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE C36
C12 TOTAL COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE C40
C13 DIRECT COST DATA FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE C44
C14 DIRECT COST DATA FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE C45
C15 DIRECT COST DATA FOR A41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE C46
C16 DIRECT COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE C47
C17 DIRECT COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE C48
C18 DIRECT COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE C49
xiii
I. INTRODUCTION
Vehicle collisions with roadside hazards are inherent to any
existing highway facility. As highway improvement plans are prepared
to minimize these hazards, it is essential in a restricted funding
environment that final designs and alternatives be cost-effective to
the highway department.
A common and dangerous roadside hazard is the open-ended culvert.
There is little question that a collision with such a hazard can result
in property damage and serious personal injury or possible fatalities.
Culvert ends merit systematic and objective evaluation so that the most
cost-effective safety treatment will be utilized.
Barrier warrants for fixed objects on high-speed facilities (1)
suggest that all culverts within a predetermined "clear zone" be shielded
by a roadside barrier. However, the guide (1) also encourages the
application of a cost-effective procedure to provide an objective method
of comparing alternate safety treatments for problem hazards such as the
culvert. The options of lido nothingll, i.e., leaving the hazard
unshielded, and reduce or remove the hazard become possible safety
treatments on low volume facilities where the probability of accidents
is low.
There are many variables to consider in the safety treatment of
any culvert design. Among these variables are the traffic volume, cul
vert size, culvert end offset distance, and the various available safety
treatment designs. Chapter II discusses the range of those variables
considered, along with the assumptions and limitations made in this
1
study. Chapter III contains the safety treatment guidelines, and
Chapter IV contains the conclusions. DetaiZs of the cost-effective
methodoZogies used in deveZoping the guideZines are presented in the
Appendix.
2
II. CULVERT DESIGNS AND TREATMENTS
General
The culvert designs and treatments studied are those that would
typically exist along low volume (average daily traffic less than 5000),
high-speed, rural facilities. Figure 1 shows a typical rural roadway
section considered in the study.
Range of Variables
The range of variables considered are listed below.
1) Culvert Size. Three typical sizes of culverts shown in
Figure 1, namely, the 36 in. diameter pipe, the 4 ft x 6 ft single box,
and the 4 ft x 6 ft multi-box (or double box) were studied.
2) Culvert Safety Treatments. Four safety treatment alternatives
were considered. These were: do nothing (i.e., provide no shielding
for the culvert), extend the culvert end to 30 ft from the edge of the.
traveled way, install guardrail, and place a grate over the culvert end.
These safety treatments are shown in Figure 2. Note that added fill
material is required when the culvert end is extended as shown in
Figure 2. Cost of the added fill was included in the analysis.
3) Traffic Volumes. Average daily traffic (ADT) ranged from 750
to 20,000 with emphasis placed on ADT's below 3000.
4) Original Culvert End Offset. Three offset distances -- 12, 18
and 24 ft -- were studied.
5) Embankment Slope. Culverts located on fill sections with
slopes of 2~:1 and 6:1 were studied.
3
Original Culvert End Offset 1
~----+- 30' Hazard Zone----'
Traveled Way ------'1-.. Shoulder 100-.--
8'-~- 12' --.J-- 12' ---t-- 8'
FIGURE 1. TYPICAL ROADWAY SECTION WITH THE VARIOUS CULVERT DESIGNS
(J1
Fill- Section
--,---3'or 4' __ 1 __ _
VIEW A- A
Wj,ng Wall
B
B
1----. 6'-~
VIEW B-B 4' X 6' SINGLE BOX 'CULVERT
CULVERT DESIGN 2
VIEW B-B 36" PIPE CULVERT
CULVERT DESIGN I
..-.-- 6' ------I ~- 6' ---.-I
VIEW B-B
4' X6' MULTI- BOX CULVERT CULVERT DESIGN 3
FIGURE 1 (CONTINUED). TYPICAL ROADWAY SECTION WITH THE VARIOUS CULVERT DESIGNS
A, I
A I
2
ORIGINAL
2 1/2: I
ui OR a: ~ 6: I o· w W SLOPE
FILL ADDED
E.O.P. -EDGE OF PAVEMENT E.O.S. - EDGE OF SHOULDER
SAFETY TREATMENT, 1 - EXTEND TO 30ft.
}._-------, ,
- .. -------- -~- ---------------------------~-....-
GROUND
-SECTION A - A _ LINE -....=.=:...;..:..~~ 1 - 1,--
FIGURE 2. CULVERT SAFETY TREATMENTS. 6
12'
-- --
-- --
B
10'
-\
---=( ---
25' END TREATMENT
150' or
...-. ...... - - - ..... - .... ----.-.. 200'
VARIABLE
25' END TREATMENT
1
SAFETY TREATMENT 2 - GUARDRAIL PROTECTION
I
WAY SHOULDER NOTE: GUARDRAIL IS A NON-TRAVELEDLf
-.
. BLOCKED, 12GA. W-BEAM RAIL
ON A ?,'DIA. TIMBER POST. @ 6'-3" SPACING. END TREAT-
I MENT IS GEET I BY AASHTO - I .-
-- 2-2
or6 GUIDELINES ill ----------" - -
L_______ _ r-- ------------
SECTION B- B FIGURE 2 (CONTINUED). CULVERT SAFETY TREATMENTS
7
FLAT BAR
CHANNEL
SAFETY TREATMENT 3- GRATE PROTECTION
HEIGHT OF
CULVERT
....... " - TOP .. VIEW
SIDE VIEW
FIGURE 2 (CONTINUED). CULVERT SAFETY TREATMENTS
8
Assumptions and Limitations
A certain number of assumptions and limitations were essential in
the development of the cost-effectiveness model used in this study.
Discussion of the basic assumptions, including encroachment rates and
severity indices with their related accident costs, can be found in the
AASHTO guide (1). Listed below are assumptions that were made in
addition to those necessary to develop the model:
1) ADT would remain relatively constant for the highway design
life (20 years).
2) The ditch at the culvert end will have 2:1 sloping walls and
the depth of the ditch will be half the height of the culvert.
3) The wing walls of the culvert will be the same slope as the fill
section (2~:1 or 6:1).
4) Grates placed on any culvert end will be designed such that it
is traversable and can support a 4500 lb vehicle under anticipated
dynamic loads.
5) A vehicle leaving the traveled way would have redirection
capabilities on a 6:1 fill section but not on a 2~:1 fill
section.
6) For all culvert sizes with offsets of 12 ft, 200 ft of guardrail
plus two 25-ft end treatments would be necessary to protect the
culvert. Culverts with offsets of 18, 24, or 30 ft require
150 ft of guardrail plus two 25 ftend treatments.
7) The severity indices and resulting accident costs were deter
mined based on a survey sent to 15 personnel from the Texas
Transportation Institute, Texas State Department of Highways
and Rublic Transportation and the United States Department of
Transportation, Federal Highway Administration (~).
9
8) Severity indices for the three open-ended culvert sizes studied
on 2~:1 and 6:1 slopes were for perpendicular ditch crossings.
9) The encroachment data used in the study (~) limit the results
obtained to two-lane highways (using the total ADT) and to the
right side of divided highways using one-way ADT (half the total
ADT) .
10
III. GUIDELINES FOR EXTENDING OR UPGRADING
EXISTING UNPROTECTED CULVERTS
Historically, roadside barriers have been the primary safety
treatment for culverts. Only recently has there been the development
of other alternatives such as the grate safety treatment. Determination
of the type of treatment used (if any) has been based primarily on
engineering judgment and available highway funds. This is especially
true of low volume highways. Development of selection and priority
procedures based on cost-effectiveness has enabled highway officials to
make more objective decisions. It was through such procedures, described
in the Appendices, that the guidelines presented in this chapter were
developed.
Figures 3 through 8 contain guidelines for determining the most
cost-effective means of treating 36 in. diameter pipe, 4 ft x 6 ft single
box, and 4 ft x 6 ft double box culverts for various offset, traffic
volume, and side slope conditions. These figures indicate the circum
stances where ranking factors exceed unity (i.e., where benefits exceed
costs), and which alternative has the highest ranking factor for a given
culvert size, ADT, side slope, and original culvert offset. Where ranking
factors for two alternatives were approximately the same for given
conditions, both treatments are shown as acceptable. The alternate
chosen would rest with the designer. Tables Cl through C6, Appendix C,
show the ranking factors calculated through application of the cost
effectiveness model.
11
30 ~
t '-'
I-24 W DO NOTHING en
1L. 1L. 0 0 18 Z W
t---' 0: N W
> 12 :.J ::> U
...J <t Z -(!)
CE 0
0 0 750 1500 2250 3000 15000 20000-
AVERAGE DAILY TRAFFIC FIGURE 3. WARRANTS FOR EXTENDING OR UPGRADING A 36-INCH PIPE CULVERT ON A 2~:1 SLOPE
30 ~
~ .......,
r-24 W en DO NOTHING
l..L. l..L. 0
Cl 18 Z W
t---I 0: w w
:J 12
::> U
...J <1 Z -(!)
0: 0
o ~-----+----~~~--~~~~--~--~~--~~--~~~~~~ 15000 20000 o 750 1500 2250 3000
AVERAGE DAILY TRAFFIC FIGURE 4. l4ARRANTS FOR EXTENDING OR UPGRADING A 36-INCH PIPE CULVERT ON A 6:'- SLOPE
30 ,........
t '-'
..... 24 W en
DO LL LL NOTHING 0 0 18 Z W
t-~ 0::: .,J::::o W
>- 12 :.J :::> (J
--1 <t Z -(!)
a: 0
0 0 750 1500 2250 3000 ' 15000 20000
AVERAGE DAILY TRAFFIC FIGURE 5. WARRANTS FOR EXTENDING OR UPGRADING A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
30 ~
t-= I.J... '-'
..... 24 W
(J) lJ... DO NOTHING I.J... 0 0 18·· Z W
I-..... 0::: U1 W
> 12 :.J ::> U ....J <t Z -(!)
a:: 0
'0 0 750, 1500 2250 3000 15000 20000
AVERAGE DAILY TRAFFIC FIGURE 6. WARRANTS FOR EXTENDING OR UPGRADING A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE
30 ,......
t '-'
I-24 W
(f) DO LL LL NOTHING 0
0 18 Z W
I---' cr: 0"1 W
:J 12
::> U
...J <l Z -(!) CE 0 I 0 ~I--~--~--~~~~~~--~--~--~~~~--~~~--~~~
o 750 1500 2250 3000 15000 20000-
AVERAGE DAILY TRAFFIC
FIGURE 7. WARRANTS FOR EXTENDING OR UPGRADING A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
30 ,..... t-= IJ... '-'
r-24 W
en DO NOTHING IJ... IJ... 0 Cl 18 Z W
t---' '0:: --...,J W
?j 12
:J U
...J <1 Z -(!)
0: 0
o ~-----+----~~~--~~~~--~--~~--~~--~~~~~~ o 750 1500 2250 3000 15000 20000·
AVERAGE DAILY TRAFFIC FIGURE 8. WARRANTS FOR EXTENDING OR UPGRADING A 4' X 6' MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
To use the figures:
1) Select the figure with the appropriate culvert size and slope.
2) Enter that figure with the proper ADT and culvert end offset.
3) Determine the appropriate treatment.
Note that these figures consider only the hazards of the slope, culvert
and ditch. Other hazards near or around the culvert may warrant other
types of safety treatment based on current AASHTO guidelines (1). The
information presented in these figures should be used in conjunction
with sound evaluation of the facts and engineering judgment.
To more precisely define the conditions where treatment is cost
effective, the ranking factor data were processed one further step.
Table 1 shows interpolated values of ADT for ranking factors of 1.0.
Figure 9 shows sample calculations for the ADT interpolation.
The interpolated ADT values shown in Table 1 were plotted versus
offset distance as shown in Figures 10 and 11 for steep and flat slopes,
respectively. The curves represent a ranking factor (i.e., benefit/
cost ratio) of 1.0; thus the curves define the boundary conditions where
treatment becomes cost-effective.
These curves may be used directly to develop design guidelines for
upgrading existing facilities. Although new location projects would
involve the added cost of about 48 ft of culvert (under travel lane and
shoulder to provide 12-ft offset) construction, it may be rationalized
that larger projects usually result in lower unit prices and thus the
curves are a good starting point for developing design guidelines for
routes on new locations.
Figures 12 through 18 illustrate the potential for developing design
guidelines for these curves. Once a set of guidelines has been formulated,
18
Table 1. Interpolated AOT Volumes for Ranking Factor = 1.0
A 0 T
Culvert Size Side Slope A = 12' A = 18' A = 24'
36 11 dia. 2~:1 1110 (E)* 2020 (E) 1900
36 11 dia. 6:1 1310 (E) 1980 (E) **
1-4'x6' 2~:1 1130 (G) 1270 (G) 1300
1-4'x6' 6:1 1600 (E) 2090 (E) 2850***
2-4'x6' 2~: 1 800 (G) 880 (G) 990
2-4'x6' 6:1 1350 (E) 1600 (E) 2000
*Parenthesis include treatment, i.e., (E) = extend, (G) = grate, that becomes cost effective at lowest volume.
**RF = 1.0 for AOT = 15,000 or less; assume RF = 1.0 for A = 23' for 3000<AOT<15,000.
(G)
(ON)
(G)
(E)
(E)
(E)
***RF = 1.0 appears to level off at a slightly larger offset than 24 ft for ADT's up to 15,000.
19
llL..
... Iw (/) lL.. lL.. o
24
18 .- .............. --- •
2 --.. ----......... -...... -.-.-....... , . •
1 0.88 I I I
. I I I I
.... _---11.11
1.15
1.75
3000
ADT
Example: Single 41 x 61 box culvert, 6:1 slope; extension is the most cost effective solution for each set of traffic volumes and offsets.
Sample calculation: RF2 - 1.0
Interpolated ADTRF = 1.0 = ADT2 - (ADT2 - ADT1) ( RF2 - RF1
At offset = 121
Interpolated ADTRF = 1.0 = 2250 - (2250 - 1500)((1.75 - 1.0)/1.75 - 0.88))
= 2250 - 750 (0.75/0.87)
= 2250 - 650
Interpolated ADTRF = 1.0 = 1600
'FIGURE 9. . SAMPLE ADT INTERPOLATION FOR UNITY RANKING FACTOR
20
I
24
:: -I-l&J U) LL..
18 u.. 0
I-0:
N LLI ..... ~
V Ff36" dia. RF = 1.0
2-4 1 x6 1 MBC ~ 1-4 1 x6 1 SBC I RF = 1.DC-..
RF = 1.0 .; RF<l RF>l -. ~<l /. --RF<l
~>1 RF>l ,
•
::l 12 u .-
...J .. c:r: Z § 0: 0 6
2~:1 Slo~e
o 500 1000 1500 2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 1 O. COST-EFFECTIVENESS CURVES 'FOR TYPICAL cut VERT ENDS ON 2~! 1 SLOPES
24
:: .. I-l&J U) lI-
18 LL 0 2-4'x6 1
' r~BC t- 'RF = 1.0 a:
N LaJ N ~
::> 12 (.)
..J " <t 36"dia. Z RF = 1.0 S 0:: 0, 6
6:1 Slope
o 500 1000 1500 , ,2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 11 • COST-EFFECTIVENESS 'CURVES-rOR-TYPICAL--CULVERTS ON' 6: 1 SLOPES
c •
I-I&J en IL. &L 0 l-
N G: III w
~ :) U
i IE 0
12
" dia. RF = 1.0
6
6:1 Slope
o~--------~----------~----------~--------~----------~----------~------~ 500 1000 1500 2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 12. POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6:1 SLOPES
C •
t-III en IL &L 0 ....
N G: &II ~
~ :) U
i ii: 0
24
18
12
36" dia. RF = 1.0
6
6:1 Slope
o~--------~----------~--------~----------~--------~~--------~------~ ~OO 1000 1500 2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0 FIGURE 13. POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6:1 SLOPES
AND SMALL (36" DIA.) CULVERTS ON STEEP SLOPES
C • t-
III en IL. II. 0 ....
N~ (.J1111 ~ :,) U
I iE 0
24
18 2-4 x6 1 MBC
RF = 1.0
12
6
6:1 Slope·
o~--------~----------~----------~--------~----------~----------~------~ 500 .000 1500 2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 14. POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6:1 SLOPES AND S~1ALL (36 11 DIA. ) CULVERTS ON STEEP SLOPES
- ----~---~. ------- - -.-- -- ----...- .. -.. - ------ --- -- --.-----
24
C .. ~
! 18 II.
0 l-
N ~ 0'1 1&1
~ :)
12 U
I 36" dia. RF = 1.0
-a: 0 6
6:1 Slope
o 500 1000 1500 2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 15. POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERTS ON 6:1 SLOPES
N .......
tIE 1&1
~
1:"41x6 1 SBe RF = 1.0
36" dia. RF = 1.0
B 12~----~--~--~--~--+-~~----~----------4---------~~---------r------~
I G:. o 6~--------~----~----+----------+----------~--------~r---------~------~
2~:1 Slope
o 500 1000 1500 2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 16. POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERT ENDS ON STEEP SLOPES
36/1 dia. RF = 1.0
C 1-4 1 x6 1 SBC • RF = 1.0 f-
III (I) I&.
~ N
t-oo ~
&II
3 ::» 12 U
I -D:. 0 6
2~:1 Slo12e
O ~--------~----------~--------~~--------~--------~----------3000~------~ . 500 1000 1500 2000 2500
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 17. POSSIBLE DESIGN GUIDELINES FOR TYPICAL CULVERT ENDS ON STEEP SLOPES
.-----.'~--,
36 11 dia. 24 RF = 1.0
C 2-4.' x6' MBC RF = 1.0~ • ...
1&1 (I)
"- 18 '~
... N IE ~ III
~ :)
12 U
i -0:. 0 6
2~:1 Slope
o 500 1000 1500 2000 2500 3000
INTERPOLATED AVERAGE DAILY TRAFFIC VOLUMES FOR RANKING FACTOR = 1.0
FIGURE 18. POSSIBLE DESIGN GUIDELINES FOR ALL CULVERT ENDS ON STEEP SLOPES
Figures 3 through 8 provide the necessary information for selecting the
treatment means. Example design guidelines are as follows:
1. For flat (6:1 or flatter) slopes and culvert sizes ranging
from 36 in. diameter pipe to double 4 ft x 6 ft boxes:
a. Where traffic is 1300 ADT or less and offset is 12 ft or
more, treatment is not cost-effective, as shown in
Figure 12; or,
b. Where traffic is 1500 or less and offset is 16 ft or more,
treatment is not cost-effective as shown in Figure 13
(36 in. diameter pipe on steep slopes also fit the same
criteria); or,
c. Where traffic is 1750 or less and offset is 20 ft or more,
treatment is not cost-effective as shown in Figure 14 (36 in.
diameter pipe on steep slopes also fit the same criteria); or
d. The IIdo-nothing" area could be defined to be variable with
traffic and offset as shown in Figure 15.
2. For steep (steeper than 6:1) slopes:
a. Where traffic volumes are 800 ADT or less, double 4 ft x
6 ft boxes and smaller size culvert ends with 12 ft or more
offset cannot be cost-effectively treated as shown in
Figure 16; or,
b. Where traffic volumes are 1100 or less and offset is 12 ft
or more, .single 4 ft x 6 ft and smaller size culvert ends
cannot be cost-effectively treated as shown in Figure 17.
These curves, particularly for steep slopes, could be further
developed by estimating additional unity ranking factor curves for
various culvert end areas as shown in Figure 18. Although resultant
30
design guidelines would be more difficult to use, a designer could enter
the resultant figure with a design traffic volume and culvert size and
determine the cost-effective offset.
In summary, the cost-effectiveness approach can be used to determine
appropriate design guidelines which identify conditions meriting treat
ment plus identifying the most cost-effective alternative treatment.
31
IV. CONCLUSIONS AND RECOMMENDATIONS
1. Unprotected culvert ends located 27 ft or more from the pavement
edge cannot be cost-effectively extended to 30 ft or safety treated
for the volumes, hazard size, and slopes considered. Although not
specifically identified in this study, there may be combinations of
culvert size, slope rate, and traffic volume where an existing culvert
may be cost-effectively extended from 27 ft to more than 30 ft from
pavement edge.
2. AASHTO guidelines (1) suggest that steep (1:1 or steeper) drop-offs,
with or without permanent bodies of water, warrant protection only
if the drop-off is greater than 2 ft in depth. In this regard,
small (e.g., 18- or 24-in. diameter pipes) culverts with heights of
2 ft or less should not be considered as severe as larger culverts.
For these installations, ends should be sloped, preferably to match
side slopes, stabilized with flush riprap if necessary, and the
surrounding area should be smoothly contoured to decrease potential
impact severity and improve crashworthiness.
3. The provision of flat (6:1 or flatter) slopes allows for possible
driver action to avoid culvert-end collisions. Comparisons of
Figure 3 with Figure 4, Figure 5 with Figure 6, and Figure 7 with
Figure 8 reveal the impact of steep versus flat slopes in identifying
traffic and offset conditions which merit treatment of culvert ends.
32
4. Figures 3 through 8 identify cost-effective treatments for various
culvert conditions. The following general conclusions may be made
regarding particular treatment methods:
(a) For both flat and relatively steep side slopes, leaving the
culvert unprotected was the most cost-effective alternative
for traffic volumes less than 750 and culvert offset distances
greater than 12 ft.
(b) When culvert extension is cost-effective, it is desirable that
the culvert be extended 30 ft or more from the roadside. In
general, it was found that when safety treatment is warranted,
culvert extension is ~ cost-effective method -- although not
always the most cost-effective. However, special circumstances
not considered in this study, such as where needed right-of-way
is unavailable or costly, may preclude culvert extension.
(c) Grates for relatively flat sloped culvert ends were not found
to be cost-effective due to the large grate area and resultant
high cost. For steep slopes, however, grates were found either
to be competitive with culvert extension or clearly the most
cost-effective alternative as shown in Figures 3, 5, and 7.
Where possible, standardization of grate shape and structural
design may be expected to reduce "in-place ll costs and further
enhance its attractiveness as a safety treatment. Simple, shop
fabricated grates designed for heavy (4500 lbs) passenger car
loading have demonstrated field performance, both from hydraulic
and impact standpoints. Reportedly, such a design has been
accidently impacted by a loaded truck with successful results
although grate deformation did occur.
33
(d) For the traffic volumes, slopes, and hazard sizes and locations
studied, guardrail protection was found to be ~ cost-effective
safety treatment only for the double box culvert and moderate
traffic volumes (greater than 2000 ADT) and the single box
culvert and high traffic volumes (greater than 20,000 ADT).
However, even for these culvert sizes and traffic volumes,
guardrail protection was not found to be the most cost-effective
alternative. Generally, guardrail protection appears to be a
more competitive alternative as the slope becomes steeper and
as the hazard size increases. In this regard, for culverts
larger than the double 4 ft x 6 ft considered in this study,
shielding by guardrail might be the most cost-effective solution.
5. Figures 10 and 11 may be used to develop design guidelines for new
location or upgrading existing facilities as exemplified in Figures 12
through 18. When such guidelines are combined with the information
regarding the most effective means of treatment as shown in Figures 3
through 8, a comprehensive, sound design policy is possible.
6. Other observations and conclusions can be made from this study if the
information presented in Figures 3 through 10 and Appendices A, B,
and C is used in conjunction with cost information available to the
various highway departments or agencies. These conclusions mayor
may not occur with those presented in this report.
34
v. FUTURE CONSIDERATIONS
In view of the research findings, the authors suggest the following
items be considered in future studies:
1) apply the cost-effectiveness model to
different culvert designs, slope conditions, and higher
traffic volumes;
2) refine the model to include hazards beyond the 30 ft clear
distance for fill sections with slopes steeper than 6:1;
3) develop a computer program with simple input data such as
culvert size and type, fill section slope, culvert end offset,
safety treatment, costs and restrictions (e.g., in some cases
extending to 30 ft is not possible), traffic volume, etc., to
provide more flexibility in design alternatives and to reduce
the computations required. and
4) incorporate encroachment data for low volume roads as they
become ava-; lab le.
35
APPENDICES
36
APPENDIX A A DISCUSSION OF THE COST-EFFECTIVENESS MODEL
The cost-effectiveness model used in this study calculates the
present value of each alternative over a given period of time, taking
into account the initial costs, maintenance costs, and accident costs.
The model can be expressed by the equation:
where:
CT = total present worth associated with the alternative (present dollar),
CI = initial cost of the alternative (present dollar),
CD = average damage cost per accident incurred to the alternative (present dollar),
CM = average maintenance cost per year for the alternative (present dollar),
COVD = average occupant injury and vehicle damage cost per accident (present dollar),
Cs = estimated salvage value of the alternative (future dollar),
CF = collision frequency (accidents per year),
KT,KJ = economic factors for some current interest rate.
The model is structured around an accident prediction technique used
to estimate the frequency at which a roadside hazard will be struck
over a given period of time. This is introduced into the model by
Al
the variable CF• Mathematically, the collision frequency is given
by the expression:
C = EF [(L + 62.9) • P(Y~A) + 5.14 F 10,560
(A2) where:
A = distance from edge of the traveled way to the hazard (offset),
L = hazard length (dimension parallel to the traveled way),
W = hazard width (dimension perpendicular to the traveled way),
EF = encroachment frequency (encroachments per mile per year),
these values are taken from the literature (~),
Y = the lateral displacement in feet, of the encroaching vehicle, measured from the edge of the traveled way to the longitudinal face of the hazard, and
p[Y~ •• ]= probability of a vehicle lateral displacement greater than some value. The values are taken from the literature (~).
Equation (A2) may be implemented directly into Equation (AI),
however, it should be noted that computation of the collision frequency
for multiple objects requires special procedures. Reference should
be made to the literature (1) for illustrations of these procedures.
To calculate the collision frequencies for the hazards in the
alternatives considered in this study, it was necessary to make three
idealizations. These are shown in Figures AI, A2, and A3. Note that
these hazard zones apply to both 2~:1 and 6:1 slopes.
A2
* ~ a.. 0 w
.... .r; .2 u ... ~o-0"0 Q; c: > a c: _
LLI .... cu ... > u-o :::J
0.0 E
30'
Ditch Hazard Lc Hazard
y ~Iope Hazard
"* Edge of Shoulder
"*"* Edge of Pavement
FIGURE AI. HAZARD ENVELOPE FOR AN UNPROTECTED CULVERT AND DITCH A3
Traveled Way
(I) -&: QJ
E -L.. 0 -2 CIJ
~ CIJ 0."0 o &: Q;LLJ >"0 &: &:
LLJ 0 --o .-o 0 a. L..
E 'E o ::::J
C)
Cl.. o LLJ
T 251 End
• ·Treatment
Ditch Hazard
ISO', When offset is· 18, 24, or 30 ft.
200' When offset is 121.
NOTE: GUardrail is a non-blocked 12 GA. W- beam rail on a 7" diameter timber ·post, @ 6'-3" spacing. End treatment is GEET 1 by AASHTO guide lines ( I )
FIGURE A2. HAZARD ENVELOPE FOR GUARDRAIL PROTECTED CULVERT A4
Cl. en o ~ w
Q,J 0-o "Q),c > 0 c .~ wo ...... u 0 0 .... 0-E
30'-----------------------~·1
Offs et ---t~-:::::"-:::::"'-'-_--+-_-r~L--,-I I I I I I
I Lc
Ditch Hazard
__ I ---- I ----~~--------------~~~--~
Io4--Wc~
/- Slope Hazard
• NOTE: Culvert is assumed part of slope
FIGURE A3. HAZARD ENVELOPE FOR GRATE PROTECTED CULVERT !t'
AS
Table Al contains a summary of the variables that would be
substituted into Equation (A2) to obtain CF for the various hazards_
It should be noted for hazards located both inside and outside the
30 ft. zone, that only the length and width inside this zone is
considered when calculating CF-
As stated in Chapter II, it was assumed that no vehicle redirec
tion will occur on 2~:1 slopes. Since the model assumes a chance of
redirection in the zone from the edge of the traveled way (EOTW) and
the lateral face of the hazard, certain special procedures must be
followed. The basic procedure is to project all hazards to the edge
of the shoulder at an 110 angle. The length used in Equation (A2)
would be the projected length along the edge of the shoulder. These
variable values are also shown in Table AI.
To obtain the average occupant injury and vehicle damage cost
per accident (COVD )' the criteria in Table A2 was used (!). Severity
indices were assigned to each hazard based on a survey sent to fifteen
personnel from the Texas Transportation Institute, Texas State Department
of Highways and Public Transportation and the United States Department
of Transportation, Federal Highway Administration (~). Each person
was asked to evaluate the relative severity of each hazard considered
in the study based on the criteria in Table A2. The averages of the
responses received were then assigned to each hazard to obtain COVO .
See Appendix B for particular values of the severity index and COVD .
A6
TABLE AI. VALUES FOR CALCULATING THE COLLISION FREQUENCY (CF)
Variables for Calculating CF Alternative Description
Al L2 W2 with Hazards
Unprotected Cu1vert3 and Ditch on 2~:1 Slope:
1) Culvert 8 ft. LC + 5.14 Wc 0
2) Ditch 8 ft. 123 - 5.14(Wc + Offset) 0
3) Slope 10 ft. (15 or -35 ft.) - LC + 5.14(Offset) 1 ft.
r----------_-------------------------------Unprotected Cu1vert 3 and Ditch on 6:1 Slope:
1) Cu1 vert 2) Ditch 3) Slope
1----------- ----ISO ft. of Guardrail Protection on Any SlopeS:
1) Approach guardrail and end treatment
2) Departure guardrail and end treatment
Offset
Offset + Wc + 6 ft. __ 4
LC 1 ft.
__ 4
Wc 24 ft. - (Offset + WC)
__ 4
----------------------------
14 ft.
11 ft.
175 ft.
-6 ft.
1 ft. 1 ft.
--------------- ---------------_._---- -------200 ft. of Guardrail Protection on Any SlopeS:
1) Approach guardrail and end treatment 2) Departure guardrail and end treatment
14 ft.
12 ft.
175 ft.
44 ft. 1 ft. 1 ft.
---------------------- ------------f---------Grate Protection6 7 on 2~:1 Slope
1) Ditch 2) Slope
8 ft.
10 ft. LD + 154 ft. - 5.14(Offset + WC)
(-16 or -66 ft.) - LD + 5.14(Offset + Wc
o 1 ft.
1--------------------------------------- ---6 7
Grate Protection on 6:1 Slope
1) Ditch Offset + Wc 30 ft. - (Offset + Wc) 2) Slope
__ 4 __ 4
IFor values of A greater than 30 ft., cF = O. 20n1y the length and width within a 30 ft. clear zone is considered. 3Refer to Figure AI. 4This is done by first finding CF for the slope protected by either 150 or 200 ft. of guardrail. Next, subtract the CF for the culvert and the CF for the ditch from this value to obtain the CF for a 6:1 slope. 5Refer to Figure A2. 6Refer to Fig~re A3. 7Since the grate is assumed to be traversable, it is also assumed to be part of the slope, so that there are only two hazards, namely, the ditch and the slope.
TABLE A2. SEVERITY INDEX AND ACCIDENT COST
Severity % PDO % Injury % Fatal Total Accident Index Accidents Accidents Accidents Cost (COVD )
0 100 0 0 $ 700
1 85 15 0 2,095
2 70 30 0 3,490 3 55 45 0 4,885
4 40 59 1 8.180 5 30 65 5 16,710
6 20 68 12 30,940
7 10 60 30 66,070 8 0 40 60 124,000 9 0 21 79 160,000
10 0 5 95 190,000
A8
APPENDIX B APPLICATION OF MODEL
Input Data
This appendix presents the particular values assigned to each
variable in Equation (AI). Values of CF are not given since the tech
nique used to calculate these values is presented in Appendix A. A
summary of all costs is given by each alternative. A constant value
for KT = 8.514 is used for all alternatives based on a 10% rate of
return over a 20 -year term.
Alternative I - The Unprotected Culvert
A) Assumptions
B)
where:
1) C = 0 I (no initial costs)
2) C = 0 D (no damage to culvert upon impact)
3) C = 0 M (no maintenance costs)
4) C = 0 S (no salvage value after 20 years)
Revised form of equation (AI):
CT = 8.514 [( CFCOVD)SLOPE + (CFCOVD) CULVERT + (CFCOVD ) DITCH J (Bl)
(CFCOVn)SLOPE = collision frequency times the occupant and vehicle damage caused by the slope;
(CFCOVD}CULVERT = collision frequency times the occupant and vehicle damage caused by the culvert; and
B1
(CFCOVD)DITCH = collision frequency times the occupant and vehicle damage caused by the ditch.
C) Summary of other costs
1) See Table B1.
TABLE B1. SEVERITY INDICES AND ACCIDENT COSTS FOR THE UNPROTECTED CULVERT*
Culvert Type (COVD)SLOPE
36 in. pipe on 2~:1 slope $5900 (3.3)**
36 in. pipe on 6:1 slope $2500 (1.3)
41 x 61 single box on 2~:1 slope $5900 (3.3)
41 x 6 1 single box on 6:1 slope $2500 (1.3)
41 x 61 multi-box on 2~:1 slope $5900 (3.3)
41 x 61 multi-box on 6:1 slope $2500 (1.3)
*Based on the criteria in Table A2. **Severity index in parenthesis.
(COVD ) CULVERT
$16,710 (5.0)
$16,710 (5.0)
$28,100 (5.8)
$28,100 (5.8)
$42,500 (6.3)
$42,500 (6.3)
Alternative II - Extending Existing Culvert to 30 Ft
A) Assumptions
1) Wing wall must be replaced.
B2
(COVD)DITCH
$7400 (3.8)
$6000 (3.4)
$10,000 (4.2)
$6400 (3.5)
$7400 (3.8)
$4900 (3.0)
2) Fill must be added for smooth transition between slopes.
B) Revised form of equation (AI):
(B2)
where:
CT30 = total cost of unprotected culvert with 30 ft. original offset
Cww = cost of wing wall
CEXT = cost of extending the culvert pipe or box; and
CFILL = cost of fill material.
c) Summary of other costs
1) See Tables B2, B3, and B4
TABLE B2. COST OF WING WALLS (CWW )
Culvert Type CWW for 2~: 1 Slope CWW for 6:1 Slope
36 in. pipe $260 $620
4' x 61 single box $460 $1100
41 x 6' multi-box $450 $1100
B3
TABLE B3. COST OF EXTENDING THE CULVERT PIPE OR BOX TO 30 FT FINAL OFFSET (CEXT )
Culvert Type
36 in. pipe on 2~:1 and 6:1 slopes*
41 x 61 single box on 2~:1 and 6:1 slopes**
41 x6 1 multi-box on 2~:1 and 6:1 slopes***
*Based on $25/ft. **Based on $95/ft.
***Based on $165/ft.
Original Offset 12 ft. 18 ft.
$450 $300
$1710 $1140
$2970 $1980
B4
24 ft.
$150
$570
$990
TABLE B4. COST OF FILL FOR EXTENDING THE CULVERT TO 30 FT FINAL OFFSET (C FILL )*
Original Offset
Culvert Type 12 ft. 18 ft.
36 in. pipe on 2~:1 slope $820 $1100
36 in. pipe on 6:1 slope $470 $520
41 x 61 single box on 2~:1 slope $900 $1200
41 x 61 single box on 6:1 slope $540 $550
41 x 61 multi- box on 2~:1 slope $930 $1200
41 x 6 l multi-box on 6:1 slope $550 $560
*Based on $2.35/yd. 3
B5
24 ft.
$1300
$570
$1300
$580
$1400
$580
Alternative III - Guardrail Protection
A) Assumptions
1) CI = (Length)($13/ft.)
2) Co = $225
3) COVO = $5900 (S.I. = 3.3)
4) CM = (Length)($1.50/ft.)
B) Revised form of equation (AI):
CT = CI + 8.514 f(co + COVO) (CF + CF ) + CM]·. (B3) L AP OP
where:
CI = total initial cost of barrier proper and end treatments ($3250 or $2600);
CD = damage cost to barrier proper and end treatments after a collision ($225);
Covo = occupant and vehicle damage cost caused by barrier proper and end treatments ($5900);
CM = total maintenance cost of barrier proper and end treatments ($375 or $300);
C = collision frequency for the approach guardrail and end treat-FAP ment; and
CF = collision frequency for the departure guardrail and end treatBP mente
Alternative IV - Grate Protection
A) Assumptions
1) CD = 0 (no damage to grate upon impact)
B6
2) CM = $100
3) Cs = 0 (no salvage value after 20 years)
B) Revised form of equation (AI):
CT = C1 + 8.514 [ (CFCOVD) SLOPE + (CFCOVD)DITCH + CM] (B4)
where:
C) Summary of other costs
1) See Table Bl for (COVO)SLOPE and (COVO)OITCH·
2) See Table B5 for CI .
TABLE B5. INITIAL COST OF GRATE PROTECTION*
Culvert Type CI on 2~:1 Slope CI on 6:1 Slope
36 in. pipe $600 $6900
41 x 61 single box $1300 $13,800
41 x 6' multi-box $2000 $19,100
*Includes only the cost of the grate.
B7
Ranking Factor
The ranking factor is a ratio of the benefits received by using
a particular alternative to the costs incurred by the highway depart
ment or agency associated with the installation of that alternative.
The following formula may be used for determining a ranking factor, R:
where:
CT = total cost associated with the unprotected culvert; H
(B5)
CT = total cost associated with the selected alternative; and I
CTO = total cost to the highway department or agency associated I with selected alternative.
To obtain CTO for each alternative simply substitute Cavo = 0 into I
equations (B1), (B2), (83), and (84). This will then give for the
unprotected culvert:
CTO = 0 I
extending to 30 ft.:
guardrail protection:
CTO = C1 + 8.514 [(CO)(CF + CF ) + CM] I AP OP
88
(B6)
(B7)
(B8)
and for grate protection:
(B9)
where all variables are as previously defined.
Tables B6, B7 and B8 list the direct costs for each alternative
based on equations (B7), (B8), and (B9).
TABLE B6. DIRECT COSTS FOR EXTENDING A CULVERT TO 30 FT FINAL OFFSET
Original Offset Culvert Type 12 ft. 18 ft.
36 in. pipe on 2~:1 slope $1500 $1700
36 in. pipe on 6:1 slope $1500 $1400
41 x 61 single box on 2~:1 slope $3100 $2800
41 x 61 single box on 6:1 slope $3400 $2800
41 x 61 multi-box on 2~:1 slope $4300 $3600
41 x 61 multi-box on 6:1 slope $4600 $3600
B9
24 ft.
$1700
$1300
$2400
$2300
$2800
$2600
TABLE B7. DIRECT COSTS FOR GUARDRAIL PROTECTION OF 36 IN. PIPE, 4 FT x 6 FT SINGLE BOX, AND 4FT x 6 FT MULTI-BOX (2)
CULVERTS ON 2~:1 AND 6:1 SLOPES
ADT OFFSET = 12 FT. OFFSET = 18.24 or 30 FT.
750 $6500 $5200
1500 $6600 $5300
2250 $6700 $5300
3000 $6700 $5400
15000 $6700 $5400
20000 $6900 $5500
TABLE Ba. DIRECT COSTS FOR GRATE PROTECTION
CTD for 2~:1 Slope CTD for 6:1 Slope Culvert Type I I
36 in. pipe $1500 $7700
41 x 6' single box $2100 $14,600
41 x 61 multi-box $2900 $20,000
B10
Using this infonnation, ranking factors were calculated for each
alternative. The alternative with the highest ranking factor is the
most desirable since it returns the largest benefits for the lowest
total direct costs. Ranking factors for leaving a culvert unprotected
is theoretically 1.0 since CT = CTand CTO = O. Thus alternatives H I I
with ranking factors less than 1.0 are undesirable since an unprotected
culvert has a higher ranking factor.
Figur-es 3 through 8 are based on the alternative with the highest
ranking factor. The unprotected culvert was assumed to have a ranking
of 1.0 since it was one of the alternatives considered.
B11
APPENDIX C SUPPORTING DATA
This appendix contains all the data necessary to obtain Figures
3 through 8. These data can also be used in conjunction with the
information presented in Appendices A and B to obtain new criteria
for different direct costs. See Appendix 0 for further discussion.
Tables C1 through C6 present the ranking factors for each alter
native by each culvert design considered in the study. Tables C7
through C12 list the total costs for each alternative by each culvert
design. Tables C13 through C18 list the direct costs for extending
each of the culvert designs. Note that ranking factors, direct costs
and total costs are given in each table for extending culverts to 18,
24, and 30 ft. Although this study was concerned primarily with
extending to 30 ft, it may not be possible where there are limited
right of ways or other extenuating circumstances. Thus it may be
feasible to extend the culvert to 18 or 24 ft where other alternatives
are not possible. Again see Appendix 0 for further discussion.
C1
() N
F ui~ A .3t.> 1 i'·J.. U I hi'vii::.1 t:t< P 1 .... [ uN A 2-1/2. r u 1 SLLd-'t:
A=1L' t-=T. .4.=lti I-T.
Flj\jAL UrF~Ll 1\'='30 Fl.
u. £:.' j -0. 1 L ~) 0.':;0 -0 .9;";'
l~CO"O 1 .'4 ~ 0.7 C 1 .72 -0 .8 't
~ '. ,
.-.I~ 1 .4h 2.t.Jb -0 .ft.>
....:.uGu.lJ ...>. -, 7 £: • .3 3 4 .. ::)4 -0 .. t) C,
1~0Uv.U 3.(:L, £:'.40 4 .44 -0 .D I
LeVoU .... 1 -..I • I;';, ~"" '/0 C.!:=;4 -0 • 5.4
TABLE C1. RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
A=c4 f-1'.
A=.j.O Fl. A:...·.30 FT.
-0. L'q -0 .32
O.5£:: 0 .36
1 .2 1 0.98
1 • <;1 -{ I .bb
2 .03 1. . 11
3.20 2 .. 76
RANK 1 NG FAC TCr.tS FUR GUARDRI\. I L VS. UNP KOT f.:C TEO
F(Ji-:( A ::,6 IN. Dll\r"H~TLt~ PIPL UN 1-.2-1/2 TO 1 SLJPi~
AD T A =:.} 2'FT. A.. ==-1 8FT. A::,::?'4.FT . A =7:.: (jr or •
"7f>O .0 -c .. -/2- -0 • £.3 -0 .6:::'- - 1 · (;7
1500.0 -o.~) ( -0 .. b-' -0 .. -10 -1 ... 1 :~)
(J w 22~O • 0 -0 .. 38 -0 · t:2 -0 .~) 7 - 1 .-)
..... r •• 1
3000 • 0 -(J • IB -0 · :b -0 .. 4::". -. I • '".".J ,'- ....
IbOOO .. 0 -0 .. 1 7' -0 .. ::·.5 -0 .42 - 1 · ;~s
20000 .0 0 .. 14 -0 .. 1 1 -0 .20 - . 1 • .... :~ ti
TABLE Cl (CONTINUED). RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
rU\NKING fACTDhS FUP GR/\ll':: Pr~OlcCTION \IS. Ut\PRUTECTED
F {y~ A :) 6 It\l. D I At,i f: r f q PI f} L (i N A 2 - 1/ L: T u 1 SL OPE
AD -J A=-12FT. A= 1 eFT. A=2~FT. A ='3 OF T ..
"7 ~;o. 0 u.07 -0 .. 27 -0.19 -1. 00
1500.0 1.14 0.47 0_,62 -1.00
n ..p. ;';2~O.O 2- • 13 1 · IS 1 .36 -1.00
3000.0 J .. 19 1 • b8 2.17 -1.00
l::~oon.G 2~.~~H 1 · (A 2.23 -1.00
20000.0 if.92 3.ll? 3.4ts -:'1.00
TABLE C1 (CONTINUED). RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
n (J1
F U k J~. J tJ 1 h;. I) 1 ,1-\ i"i L I l. k f--' 1 f-J tUN A t: 1 U 1 !..J L G P t,
Uk 1 C 1 N A L. C 1- t,' ~; t~ -. J~.:". 1 L r·f. h:::' 1 L' t-J. A;:.: 1 L: r'l. A;;;;:,]b FT.
f,:":' 1 L f- I • A::..2 Lt I· T • A=...;.,G j-'I. A :..:..2. '" FT ..
-l.!.c.~:L -(j · (;-( 0. It -0 {;.. 7 . _.'
1 ~l:O • U i..i • <i t) o. b-{ 1 .. (:::(; -0. 1,)
1 · I 1 1 · -, :] 2. -; '" 0 .2-' • _'-.....J ""'C,, ::..,0 .. U
1 • t 4 £:: • be 3.::"0 0 .. 70
1 · LIS 2.. -r ~~ ...:) .. ~(" 0 .. -'3
...}.0 U 4. 1 -, /'" ,J.
.~ j;C .....;....;. 1 .40
TABLE C2. RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
A::,',lb FT. A=-24 Fr ..
A =.:50 Fl. A=30 Fl.
-0 .. 2;':, -0.51
o .5·q· -(,) .o.£:
1 .;;'L 0 .43
2 .. 03 0 .~ 1
2.0S o .. ~.'f tJ
3.2b 1.70
RANKING FACTORS FUR GUAhDRAIL VS. UNPhOTECTfO
FOR A 3 bIN. D I AM ElL R ? j P L lJ hl A 6 T 11 1 SL G P [
ADT ;\ = 1 ~'FT • h=l 8Fl . A=2t.FT .. 1\ =-3 Oi= T •
750.0 -O.qs -1 • 00 -1 . 09 - 1 . 2 ~~
1500 .0 -O.b9 -1 · (,U -1 .. 1 L~ - I e, 42
() ;':'2 :;Q .0 -0. bS -1 · eo -1 r; I' - 1 () t . .::.. -~ . O'a
JOOO .0 -0. -79 -1 · co -1 • :)3 -. 1 .. ~:qj
15000 .0 -·0. -fP, -1 a, ct -1 .35 .....;1 . 72.3
2uOOO .u _.(j • 12. -1 .. LO -} o.4t -2. t ~
TABLE C2 (CONTINUED). RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
· ~;;Ar'4r<.lNG F~.CTUF~~~ FU!~ GRATE PROTECTION VS. UNPf<UTECTED
F(i~{ l\ 36 IN. DIAt.J(CTFR PIPE UN A b TO 1 SLUPE
AUT A=12FT. A=lbFT. A=2!+FT. A=30FT.
{SO.O -0.7'1 -0. f6 -O.q? -1.00
1500.0 -(j.~b -0. II -O.B3 -1.00
n --..J ?2!:)O.O -(i.]K -0. t.B -0.75 -1., 00
~:iO 00.0 - (J. 17 -0.44 -0 • (::, 7' -1.00
15000.0 -(i. 16 -0. 4:-1- -0.66 -1.00
~~·OOOO .0 (). 1 -{ -0. £:"1 -0.5.:5 -1.00
TABLE C2 (CONTINUED). RANKING FACTORS FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
n co
Po. ~ 1 ~ r -, • /'. = 12 Fl. A=12 '-=1. A= 1 f, Fl. A=lb FT.
/,::.·1(, ~I. A =L, 4 FT. A:::. ':::·U t= 1 • /\.=30 FT.
f.,UI
- l.l • L. .:... -0 .,2;0 0 .. 2l..- -0 .. -I 1 0.07'
\} • tJ..:;, 0.40 1 .. b-' -0 .4~ 1 • 14-
1 . c'4 1 .. 0 ~j 2.76 -0 .. lS 2. 1 3
~ ..• ' u (; 1 .7::""· 4 .(;~ 0 .1 tJ .i.c'O
£- • lie 1 . L(; 4. 1:::- 0 .. 1 7 3 .. 2b
..).,...:. '4 2- .l';. t'.. l" .. 12 0 .6:::: 4.Y;';;
TABLE C3. RANKING FACTORS FOR A 41 X 6 1 SINGLE BOX CULVERT ON A 2~:1 SLOPE
A=24 Fl.
A ;;;..30 f -J •
0.03
I .07
2.02
,j.Ob
3 .. 14
4 .7~
RANK ING FACTuhS FrH< GUA.~DkA 1 L \is. UNfJr-:,uTLCll-.D
FO~~ A 4 X b FT. SINGLt:: BOX CULVEnT ari A 2-1/c TU 1 SLUPL
ADl A ='1 Lf T .. A:::1 PF--T. A =~2 4 F.T · f, =<5 Ot-= 1 ..
"/50.0 -0 .. !:>O -0. t:.! -0 .61 - 1 · r ~
\./1..)
1500.0 -O.Ul -0 • 03 -0.22 -:-1 .. 1 ",
n 22~~O.O 0.43 0 "to 0 .. I :-"\ -1
1.0 · · ;> 1
:)000.(; 0.01 0 .. 1:-6 0 .::..:,() - 1 · c·t";
150(j 0.0 G .. "}5 0 • f0 () • 5~: - 1 · 29
20000 .0 1 .64 1 · t~} 1 • () 0 - 1 • :~'}
TABLE C3 (CONTINUED). RANKING FACTORS FOR A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
1-< AN KING F J\C ror~s F 01-< c;ru:.. TL IJI-Hl1 L CT ION VS.. UI'IPR OTEC TED
F l j r< A 4 X L> F T.. S r !\i GL C (", () X C lJ L V li=-< T D ~ A 2 -1 /2 TO 1 S LOP E
A()T .A. :::: 1 :::'.F"T., A=lP-FT. A=24FT. A=30F 1 •
-,~) G • 0 O.'~ 6 o. 15 0.15 -1.00
1500.0 l.~l 1 . 36 1 .30 -1.00
n C_'£.:"t)O.o ___ oj .. 2. t) 2.4::' 2 .. 37 -1.00 ....... 0
.JOOO.U Lt.7"1 3. b3 3.52 -1.00
1'-)000.0 Il • t: 2: :3. -(2 3.61 -1.00
;':0000.0 f.OI ~ .. ::A 5.36 -1.00
TABLE C3 (CONTINUED). RANKING FACTORS FOR A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
U /" 1 (, I N A. L G t":' F :.... l_ I A~ 1 L Ft .. A.:;..·l£: Fl. A=lb Fl. A=c4 FT.
i, =-~ 4 Fr. A=-24 fT. A=-30 t-= 1 • A=~O t-=T.
h0J
-l·. '-I l' -(; • ~~ '-I -\..1 • 0b -0 .S7 -0.2.6 -O.4t.
ti.L 1 O.5C".: 0.86 -·0 . 14 0.4";- o .OI
Ci. f -, 1 .2. _., 1 • -f t- O .2 t- 1 . 1 r::: 0.57 " t::. . .L ~. 0 • (;
.;)0U0.U 1 .,:j ., 1 • '.:/ ~I L .t:Jy 0 .bb 1 .b':J 1 • 1 1
1 . qc. 2 .. O~ L- . '/e 0 .. -I ';;., 1 • 'J4 1 . It>
.1 3.~2 4 .~(; 1 .3b 3.vo 1 .Sb L-.• -.J ....., L:.U000.u
TABLE C4. RANKING FACTORS FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE
RANKll'-JG F AC TOI1.S r liFl CUA~D KA 1 L V S. UN P i;;OTL elE D
FOf-< A 4 X f. FT. S I NGLt:. tic/X CUL V:::RT (Jr-J A 6 lO ) 5L(JFlE
AD1 A::::} £.:'f T .. A:::.l eFT ..
750.0 -0.74 -0. [2 -0 • l)l)
1500 .. 0 --0 .. 4 7 -0 .. tA -0 • :)6
-(i.24 -0.4t.'.
0. (}2
l~OOO.O G.uS -0 .. ~l -(J • (:;:j
20(JOO.O u.41 -0 .. 04 -G.qu
TABLE C4 (CONTINUED). RANKING FACTORS FOR A 41 X 6' SINGLE BOX CULVERT ON A 6:1 SLOPE
RANKING Ft.CTU~S FOi~ ~1<A1E PRUTECTIDN \IS. UNPROTeCTED
FUR A 4 x 6 Fl. SINCLE AOX CULVERT ON A 6 TO 1 SLOPE
ADl A=12FT. A=18Fl. A=24FT. A=30FT.
750.0 -Ci.79 -O ... bb -0.92 -1 .. 00
1 t) 0 0 .. 0 -0.59 -0. -,2 -O.8~ -1.00
n 2;'->:')0.0 -0.40 -0. ~H -0.76 -1.00 ~ w
3000.0 -0.19 -0.45 -0.68 -1.00
1 ~) 00 (j .0 -0.17 -0. Ll4 -0.67 -1.00
2.0000.0 0.1::- -0 • ,~L:' -0.54 -1.00
TABLE C4 (CONTINUED). RANKING FACTORS FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE
A::.. 1 L t:': r • A=-le: FT. A=lb t-=T. A::.16 FT. A::-.24 FT ..
A =-£:.4 PI .. /-'=-::'0 Fl. A=-24 ~T. A=30 FT. A=-30 FT.
/-i LJ i
-0. ~) it -O.4t., 0.35 -0 .b() 0.41 O.~l
-G.Ve... o. 1 1 1 • -fO -u .20 1 .bL 2.03
v .. ~j::':, 0 • t~ £:. C .SS 0 . lb :::5. 1 £: j, .. 42
.j '.j (tV .. U V.0 J 1 • 1 -, 4.:.:lU 0 .50 4 .tJ~ 4 .. 93
1::;OL0.0 u. L~ 1 .2 I Lt .. ,~ 1 0 .. 6 1 4.6~ t>.05
i • ~-,L 2.0t; 0.49 1 .2.,:, b.bl 7.::)b
TABLE C5. RANKING FACTORS FOR A 4' X 6' MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
RANK ING FACTORS F OR GUARD F:':'A I L VS. UNPr:~OTECTLD
FOR A 4 X 6 FT. r..HJL 1 I-t:H))( CULV[~T ON A 2-1/2 TCJ 1 SLUP[
AOT A.::::.12FT. J\ = 1 6FT . A=24FT . A=:JOFT •
750 &0 -0.21 -0. 11 -0.2'/ -1 · {j ,: 1500.0 0.t>d u. 7b 0 4 f ... - 1 · 1 .. -' --
n 2£-.:50 .0 1 .26 1 • t.7 1 · 1 0 -] • c~ 1 J--1 (J1
3000 .0 .2.03· 2 · 41 1 • -/l., - 1 · C:. ;,
ItlOOO.O 2.09 ., c. 4t. 1 .8? - j · 2 ,:A
20000 .0 ..::. .. 1 () 3 · -('~ 2 · ~j ~~ - 1 • .j {J
TABLE C5 (CONTINUED). RANKING FACTORS FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
F<I\hIKING Ff,:CTCRS fUt':: GRATe PR01[Cll(j~.J \15. UNPROTECTED
F Cl F< A 4- X 6 FT. r ... , U L T I -t3 U X C U L V L RT 0 N A 2 - 1 /2 TO 1 S LOP C
ADT A.:.:.·l~'FT. A=18FT. A=24FT. A=30FT.
-(50.0 O.b7 0 .. 71 0.4B -1.00
It.>GO.O C:.75 t::.42 1 .96 -1.00
n 22!::,O .0 ['.4(3 4 • DO 3.33 -1.00 ........ Q)
3000.0 t .. 3S 5./2 4.81 -1.00
l~OOO.O C.~O t) .. t.!:> 4.92 -1.00
£~oooo.o '1.36 8.4b 7.20 -1.00
TABLE C5(CONTINUED). RANKING FACTORS FOR A 41 X 51 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
t-U~ A Li X L Fl. j·jUL Il-ldJX LULVlk" eN A b 10 1 SLUPt.
1-\ =- 12FT. ,4,=-1.2 FT. A:::. 1 b FT. A=lb FT. A =·24 FT.
~ 1 i-J 1\ L U t- t~ ::-- r.:1 A=-:50 FT. A=L:4 Fl. A=30 FT. A=30 ~l.
l'.U 1
I ::0 .. v -0.0'-. j • 1 1 -0 .41 -o.ot.> -0.23
1:"00.0 o .L~: l.~~ 0.1-'
i • £. C. 0.71 1.76 1 .. 24
1 ,,~, t: 1.30 2.01
1 ::, l; L lj t V .:..- • u .... 1 .3'-l 2.7b 2.07
4 .. 04· 4.2..:)
TABLE C6. RANKING FACTORS FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
f~ANKjl'Jl; Ft,CTOk~ FCi{ (,uARDh:AIL v:.:.. lnJP;""'OTE..CTCD
FCJF< A L~ X fJ ~·T. I"IULTI-HOX CULVI:.I~T ON I, 6 Tn 1 ~)L..UIJE
ADT A =1 ?F-' · A=l EFT · A=24FT .. A=:::,(lF T6'
7~O.O -0. 44- -0 · !..b -0. (~13 - 1 . ."~ ,") L. ~~
1 500 • 0 o. 1 2 -0 · l..i -() .. b :-} -1 .. if c~
n I-' 22S0 .0 u.t) 1 () · 2()- -0 e· ~:) \) -1 a· t, 1 CO
3000.0 1 • 14 0 · 66 -0. -';[ -~
~, -' -} .. bU
1 5000 .0 1 · 1 ,) 0 t-9 --0 . :1.:- - 1 c-:. • .. t...) .... J
20000.0 1 .97 1 · :'2 -0 .Ob -;,.:. 1 ;~.
TABLE C6 (CONTINUED). RANKING FACTORS FOR A 41 X 6 1 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
FUR /\ 4 X 6 F T .. ~Jl UL 1 I - H [) X C U L V F R TON A 6 TO 1 S LOP F
'j \' t., AD r A:::.lc-F I . A ='1 ~Fr. A=-24FT. A=30FT.
750.0 -0.7''J -0. t~3 -0.90 -1.00
lS(;O.O -0. :i0 -0 .. (6 -0.80 -1.00
() ......
2;~ ::,0 .0 -0.27 -0. to -0.70 -1 .00 I..D
;:)0 (j 0 • (} -f) • G3 -0. ~j -0 .60 -1.00
It-}OOO.O -(J.Ol -0. -- '> -'"'-- -0.5':1 -1 ~OO
20000.0 0 .. ~j~") -0 .. 05 -0.44 -1.00
TABLE C6 (CONTINUED). RANKING FACTORS FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
TnT f\L C(j~: T nF A r·, UhH:':UT C.C lCU CULVt:"F<T
~ U F< A :3 v I i',j.. D I .A. r.'! L T I::: ~< P I r.J 1-:- U r", A ;: -1 / c: TO 1 5 L UP E
AD 'r ,/)' ::: 1 2fT. A:::.IAFT. A==-24FT. A=3 OF T.
7C::,O .0 3400.GO 2"~OO. 00 2400.00 1 300. 00
1500.0 b 10 (} .. 00 5100.GO 4900.0'0 250 0.00
n N 22t:)O.O (jDOO.C0 0
7400. 00 7200.00 37'00. 00
3000.0 1:J200 .. 00 lOOOO.Ou 9600.00 S 00 0.00
1~50GO.O 1.5400.GO 10100 • 00 9AOO.00 ~")lOO.OO
20000.0 IbvOO.OO 14000. (/0 13600.00 7'100.00
TABLE C7. TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
() N ..........
lu·.I,L l.L.~.i rUlo( LXfLNUING A CULVt:..Rl
A:..··li.:.. Fl. A=18 FT.
f l1';I'.L LiFt- ~d:. I f,:": i t, r I • J\=24 1-1. A=30 FT.
f-.Ul
~j £:. (j l) .. C 0 ~i~)O(). U(I :'::bOO.{)O ..::j 00 .00 ~.YOO.OO
!J tCl;.U(., c..v 0 (}. 0 (I 't 100.00 GO 00.00 4200.0,)
cl00.ll () (-:'£:00.00 t.30G.OO L2GO .00 tAOO.OO
10Cvv.vv 10-{00.00 Lt:.CU.00 10 -lOO .. 0 0 biOO.OO
10LOu.l;( .. 1 C';;lOG.OO bt·('O .. DU 1 GSOO .00 6tjOO .. GO
1 '" ( 0 \., • (, \.J lLtLVO.UO aeOO.VO l'-l-t.vO.OU t;;l 00. () (}
TABLE C7 (CONTINUED). TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
A=24 r1.
A=30 f-l.
3000.00
4~OO.OO
t:,500 .. 0 0
t--"OO .00
ob00.00
bbOO .00
lOT tI.L COS 1 (JF A GUtd~Dr<A IL PRdTt- CTt::::D C l.LVC.f<T
ADT A :::::12f-1 .. A=lbFT · A=24FT. A=~~(jf"T.-
7!::.O. G eSOG.oo 6900. llJ 6900.00 f (),! O. .~") {j
1bOO.0 lO~OO.OO 6600 · LO b600.f'IO i~, t.,O (). 00
n ~2~,O.O 12400.00 10200 N • O(i 1 o;~ 00« 0 {) 1020 l,. GO
N
3000 .0 14400.00 1 1 900. LO 1 1900 .00 1 1 \j () () • Go
15000 .0 14500.00 12100 • C0 12100 .00 12 100.'JO
20000.0 1 -(' -f 0 0 • :)() 14700. u" u 1'-t'700.00 l'-!7'JU .. UG
TABLE C7 (CONTINUED). TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
r u r ~ A .3 bIN.. [J 1 A r·l F T L r( ,j 1 !.) L (J N A 2 - 1 / 2 T (j 1 5 L (I ~ L
ADT A=12FT. f..=lBFT. A=24FT. A=30F 1.
7~~C:.O ~~:H) Ct. 00 290() . 00 2700.00 270 Q. GO
lS00.0 5]00.00 4400. GO 4000.00 4000.00
n ? ~:i~) 0 .0 {)7UO.00 :~LOO • ClO 5200.00 ~)200.00 N W
:3000 • .) d~(j0.0u 7£:UC. ()O b500.00 6500. 00
1 ~)O 00.0 d -lOO. 00 7300 .. UO 6500 .00 6500.00
20000.0 1 l:;;(.,l.'.()O 9600. CO 6500.00 t',50 C. 00
TABLE C7 (CONTINUED). TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE·
I~~----~' ~-~-
AUT A=12FT. A:::18FT. A=-24FT. A::.,30FT.
7:=.0. G :.:' 3 (j (} .. (j 0 1 -"00 .. GO 1200.00 60 O. 00
l~-:'OO.() 4(,00 .. 00 3300. 00 2400.00 1 10 O. 00
() N £.:~t:)O.O t.)7CG.OO 4 bOO. OU 3500.00 1 60 O. 00 ..p.
3(;,00.0 '.)00 (;.00 () :.:.()O .. 00 4-rOO.Oo 220 C .. 00
1 ~,o 0 (j • (J '9 ;::'00 .. 00 6600 • CO 4800.00 2200.00
2000,).0 12i)(JC.OO 9200. 00 6600.00 3100.00
TABLE CB. TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE '
n N (J1
A = 1 (:: r=-,. A=12 rOt. A= 1 b FI ..
h=24 FT. A:..::.:".!.4 f-T.
itU. c L L (I (J. (j C c.4ljO.00 £.:100.00 &::'3LO .00 2000.00
}:.)\..,(. .U 4 L_ G l,. .. u l ..... vUU .·00 ~(""H;.U() ..J~OO.OO 2t,OO.OO
::.:, i li IJ • V II 4 "00 • 0 () .:JIOO.OO qoOO .00 3000.00
..)v0U.U '( Li li () • :,.; c ~~00.0U -.l-iQU. OCt SbOO .00 360U.00
It.GG(I.{) 'f:') lu. u \., L0UO.00 ~-(O(;. GC t.) S. 00 .00 "':'oGO.GO
:i. \) 1 U u. \..1 V 1bO(i. (; (J 4600.00 1700.00 4oUO.OO
TABLE C8 (CONTINUED). TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
A='24 FT.
A=.30 rT.
1900.00
c.400.00
2YOO.00
3~Ou.OO
3500.00
4400.00
TOT AL COS T DF A l~lJAHDt~A IL P~OT L (TCO C lL VeRT
FOR A 36 IN. DIAMt:T(~!~ PIPt.: ON A 6 10 1 SLOPE
ADT J\ :;:: 1 2Fl . t, ;;.....1 bFT • A=24FT .. f'l = ::-:1 Of" T ..
750.0 o~GO.00 6900. lJ -, u L900.00 c,,<)GO. {,O
It>OO.O 10 !':',o 0 .. GO ~~600 • Gu [)oOO .00 _fiC>O (I,. uo
CJ N 22~O,.0 124Gu.no 0)
10200 · (,0 I02l)t) • on 1 0 c'(j l'~ • ( ,)
3000.0 14400.00 11900 • fJO 1 1 ,} () c; .. 00 1 1 ':.ld c. l'U
15000.0 14 !:.;0 Uoo 00 12 100 · (,0 1.: 100 .00 1 ,', .- 10 () .. 00
20000.0 177~)n.oo 14700 Of" 00 14700 .. ,00 147u G. ()()
TABLE C8(CONTINUED). TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
Ten AL ellS T (jF A. but-.rE i--)Rl)lLC fel' CULVf hT
f,.Dl A=I?Fl. f,.:::.1 dF T • A=-24F r. A=30FT.
-/~O. 0 b400 .. 00 6300. LO 8300.00 8300.aO
It'.'JO(j.0 ':/100.00 6800. GO EH300.00 680 o. 00
n N ~~ 2 50 .. 0 i..lIOO.OO 9300 .. (to ':J300.00 93CiO.OO -......J
300(1 .. U lLJ400.Ul) '}YOO. GO 9900.00 9900.00
l~)OOO.O I 0 lj () 0 .. 00 9900. no 9900.00 990 0.00
20000.Q 11000.00 10bOO .. GO lO6UO.OO 10600.00
TABLE C8 (CONTINUED). TOTAL COST DATA FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
lDTAL CO~,T UF Ahl Ui'H-'R.JTCC1FD CULVCf<T
FUf< A 4 X L F T ~ S I f',,(.Lr:' HO X (UL VfRl ON A 2 -1/2 TO 1 SLOPE
A.DT A,~12FT • A=lbFT. A=24FT. A=30FT~
7~) 0 .0 ::,t-:00.00 4 £: 00.00 3700.00 1300.00
1500.0 lObOu .. OO 8400.00 7400 .. 00 2500.00
() 3700 .. 00 N 22~,O. C 1 ~) :i () 0 • G 0 12300. CO 1 0900.00 CO
.jOOO.O 20t.luO .. OO 16600 • CO 14600.00 t> 00 0.00
lSO()v.O ;:_O"~(!O.00 16400.00 14900.00 5100.00
ZOOOO.O ~gOOO.00 ~3400 .. CO 20600.00 7100.00
TABLE C9. TOTAL COST DATA FOR A 41 X 6' SINGLE BOX CULVERT ON A 2~:1 SLOPE
I L', /.L CL,~ I F (it', L.AI LI'~() 11"", A CLJL VL. kJ
I-LI' /-, 'i A (. I- I. ~I r..;eLl. uL).. ClJLVL~<T lJl\ A c-l/~ 'II.J 1 SLUJ-'E
j; =. 1 £: f- 1 .. A~12 FT. A;.:. 1 t, rT. A=lb rT. A=-24 t-l.
r:. J. f'u,\ L l ,I r ~ L T J",=-lt', Fl. A;;: c' 4 F". A=30 Fl. A=-24 f-T. A=30 Fl.
AD r
~;!:..')l.i.VL. ~':.JOO.O() 4.jOO. 00 t; '+ (iO .00 4000. 00 :if~ 00 • (j 0
~t()\.}.0U SbOU.O() !jouu.00 ~.::.:uO .00 t!300.00 4900.00
1 ~:, ( C l; _ l, L 1 ~O (10. \) 0 oouO.OO 1 ;::bOO .00 tj~OO.OO 0100.00
~,,{) '-i L • v 1 f'..J U ~j. Uu I GLU0.0G t>100.00 1 b..j00 .00 -(t) GO. 0 () (400 .00
i (- L L I.' • l) L 1 -(vOO .0 u t,~(;G • 00 1 L600 .00 1':J00.00 'It:CO.OO
L. ' .. luU.vU c...cl:) 00. () 0 lO luv .vO 2c::3uO .00 ~:/t-OO • 00 ~A00 .00
TABLE C9 (CONTINUED). TOTAL COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
TOTAL COST OF A (,UJ\!d)}<A IL PkCiTfCTED Cl.LVL:RT
ADT A:::l~~rl . /, =.:1 EFT . A=24FT. A="':.Or-T ..
7t:>O.O (3:)00.00 6900. CO 6~OO.OO 6 (.;; (; (I • C. 0
1500.0 10~OO.OO dbOO. O~) ,~bOD .GU c. b(J (! • () U
n w 2250.0 124(;0.00 10200.: a 00 10200.00 102.00 .. 00
3000.0 1440U.00 11 ':100 • LO 119UO.OO 1 1 \'(.i (;.,. ud
l::}OOO.O 14500.00 1 ~ 100 • 0,; 12100.00 12 1 [) () • CO
20000.0 1 "'" U 0.00 14 ((10 • (;C I If lCIO.O() 14lG{, .. uU
TABLE C9 (CONTINUED). TOTAL COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
FC1R A 4 X (; fT. SlhlhLE he)>'. CULVk:i<T 01'1 A 2-}/2 TO 1 SLOPt:::.
t.Dl A = 1 ;;f r • A=lt<FT. A="24t=T .. A=3GFT.
7t0.0 LJ3CO.OO 3 bOO .. 00 3400.00 3400.00
1500.0 0400.00 ~")bOO. 00 4700.00 4700.00
() w 2.2!:) 0 • (J b40U.lJl) 7 100. CO ~900.00 !..>90(l.OO .......
::'iOOO.O lO!:;!Oli.OO <..1. L 0 0 • (/0 7100.00 7100.00
It:.OOO.O 10700.00 9000. 00 7200.00 7200.00
20000.0 1.::5":100 .. 00 11600 • 00 9200.00 920 0.00
TABLE C9 (CONTINUED). TOTAL COST DATA FORA 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
n w N
· ,
lUTAL CCS"I UF At.,) lJh.i~"'ROTt-:CIED CULVt:RT
F(jr~ A 4 X 6 FT. SINGLE bClX CULVEf~T ON A 6 TO 1 SLOPE
1\ = 1 2F T. A=18FT. A=24FT.
750 .. 0 37()O.OO 2600.00 1800.00
1GOO.0 7400.00 S~OO. CiO ~500.00
22~O.O lUhOO.OO 7600.00 5100.00
3000.0 14!Juu.()O 102 00. 00 6900.00
1 ~)O 0 (). 0 14-bOO.OO 10400 • 00 -rooD. 00
20000.0 .£:..ut:iOli.OO 145(;0.00 9800.00
TABLE CIO. TOTAL COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE
A=3 OF 1.
60 0.00
1 10 O. 00
1600.00
2200.00
220 o. 00
3100.00
()
W W
'ILI'I-',L Lu~>l fL.k LAllhLJi'·'l. A CULVt-:RT
t, =:.·1 L rl. A=-12 f-l. A=.·lt: FT. A=:.:lb FT .. A::;24 Fl.
A ='2 '-t f'l. A='.,jO Fl. A:.::.:JO FI ..
... it CU. V l< ~:':"O().O(J :':;S(i0. (}O ..)(00 • () 0 3.)00.00 2bOO.00
, I,,; L l.' .. \J (; c10li.I.JU 4~0u.Uv ~J(JO .. 00 ..J~OO.,OO ;:)4 AU .00
~.'4 G l, • U U If (10 .. G G :';00U.OO -( 1 00 .. (j LJ 44-00.00 ~YOO.OO
..:suGv.u l.::u vI.,.,. vU '..>:J00.CO ~SO() .0(; b900.uO t,OOO.OO 4400.00
l~\J()C'.u 1 L~ J v. ()u ',(jOO .00 t.bOO.00 \J() GO .00 ~:OOO .. OO 4500.00
,UuuCI.0 1 L.:J Ul,. \.- U l~~(;(j.OO b4{)0.00 1 1 100.00 SbVO.OO 5;:)OO.UO
TABLE CI0 (CONTINUED). TOTAL COST DATA FOR A 4' X 6' SINGLE BOX CULVERT ON A 6:1 SLOPE
TDTAL COST OF A GUAkDRAIL ~RUTECTLO ClLV~kT
F (J t< A 4 X b F 1 ., S It \f b Lt:. Hex C U L V LR TON A 6 TO 1 ~; L u;::' ~~
ADl A = 1 ~Fl . A::: 1 eFT .. A =2/~ r- T • A =:.~:'" cr: T.
750.0 8~()O.OO 6900 • 00 6900.00 (, 'Jl) (,. CO
l~OO.O 1 ()!:;lCO. GO 6600. u,) (~·6 00. (.10 F,bf) L. CO
22t:.·O.O 1240(}.OO 1 () 20 0 • O{, 10200.0(; 1 (j ~ .. ;) (I. () ~.
3000.0 1440(~.00 11 ~oo .. OJ 1 }qoo.oo 1 1 ">fl o. ()d
1500(J.O 14~)no.ou I? 1 co. no I£.> 1 (; 0 • 00 1 ; Il,O.Cd
2.0000.0 1770(> .. 00 14 (00.00 14 -(00.00 14 l0 o. e(1
TABLE CI0 (CONTINUED). TOTAL COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE
()
w U1
TOTAL CU~~T ()F .A. GI~AIC PIHJ rEelED CULVEPT
FGf< A 4 X £:, FT. SlI'-....!CLr-. HUX CULVL1~T UN: A 6 TU 1 SLOPE
AD"f /-\=12FT. t>.=lfFT. A=24FT. A=30FT.
7!>O .0 1 ~) :. () 0 • 0 0 1S200.('0 15200.00 1~2'OO. 00
l~JOO.O 10000.00 1 ~~ 100. GO 15700.00 15700.00
22 SO .. 0 16600.00 16~! 00 • CO 16200.00 16200.00
::>000.0 17,::)(jO.OO Ib(300.UO 16800.00 16(:100.00
1:') 000.0 17:'-';(lO.OO 16bOO.00 IbROO.OO 16800.00
20000.0 10400 .. 00 ]7700.00 1-(700.00 17700.00
TABLE CIO (CONTINUED). TOTAL COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 6:1 SLOPE
(J w 0)
TOTAL CO~.T (JF ,l\N UNPF<UTFC1ED CULVERT
ror< A 4 X l) FT. f\1UL TI -8 ox CULVl:: f~T ON A 2-1/2 TO 1 SLOPE
ADT A=l:::-Fl. A:::.18FT. A =2'~Fl. A=-3 OF T.
7 t) (; • (} IIOO.OO 6400.(:0 5500.00 1 ::lO 0.00
1 t)O-O. 0 14200.00 1~700. 00 1 1000.00 2500.00
2?~O.O 2GS<OO.,OO lE600.00 16100.00 3700.00
3000.0 2800U.00 ~:4000. 00 21600.00 500 0.00
lSOOO.O 2iH>0 0.00 25400. CO 22000.00 5100.00
20()()O.U 3'J600.00 ~~200. 00 30400.00 7"100.00
TABLE ell. TOTAL COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
F L h h .... X c t-'. I"> U L I 1 - L lJ /, ( U L V L F< 1 LA"; A 2. - 1 / C. -, U I ~L L P L
uFo, 1 G I ;"Ji-. L Lrf-!.: 1:. I i, ~ 1 '- F -, . A=l t: Fl . t.=- 12 F r. A=IL. t-T . A::..lb ~1 • A=Ll.4 Fl.
F 1'Y.AL LA': ~ .. :'-L -I j.~ - 1 c· r: I . i\ ::;...:::: Lj t- -J . A =-:"0 ~1 . A=-i::..4 fT . A::.......;,O FT. A..:::.30 FT.
JD I
(:"v.0 4...,1 (;(,.00 t t, 0 () .. (J 0 5L0e ... 00 7600 .. 00 4900.00 4100.00
i::.-")0.~J l<-f'-iuli.uv l,-+I...OO.u() c.';I L IJ • 0 () 1 ~l 00 .00 t:.100.00 ~300.00
L i::..:...:.O .. (j .::C":':'l;'J.l;0 1 S1(;0.00 6100.UO 162 UO .. 00 7300.00 t:oOO.OO
_i.jvl,. v i::.. CI L 0 l; • l. (; 24~(jO .VL, S:300.00 2.5-(00 .00 b600.0U leOO.OO
1:': L-(Jv.() t... 11 \, (; • C (, t...t...GGO.C0 440C .. O(J £: 4 1 00 .00 b'lOO.00 7900.00
<.:.v00u .v .:)L'-....\...l.i.0lt ..;;; ~'+ 0 (j .00 11400.00 .:J-~000.00 10700.00 9600.00
TABLE CII (CONTINUED). TOTAL COST DATA FOR A 4' X 6' r~ULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
TOTAL COST OF A GUAf.:Di<AIL Pi~nTFCTE[) ClLVt:.f(T
F () I~ f.. 4 X 6 fT. ',1 U L r I -!j 0 X C U L V C F,r[ (\ N A .2 - 1 /2 TO 1 ~ L n p c
ADT A =1 ;'Fl . f\:::l t'Fl . A=?,!.FT. .A :::~-> Cl F- T •
7'1::J0.0 5t.~OO. 00 6900 . 00 6')(;0.00 69U O. C,('I
1500.0 10~O{).()O h6(;O. (, '\ ,. ,:)bOO • () e t:LO (.1. uu
n w 2~~tJO •. 0 12400.00 tOe'CO. CD 1 O?oc.oo lC2(iCi. i.; (~
0::>
21(,00.0 1440G.UO 11St00. LO 1 1 QOO .00 1 i '::;0 o. uG
15000.0 14=uO.00 12100. 00 1:::: 100.00 12 100._ C()
20000.0 17-' (10. ~o 14-lliO . Lt,: 14 10 (j .00 lq.rvu .. 00
TABLE CII (CONTINUED). TOTAL COST DATA FOR A 4' X 6' t1ULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
lOTAL COSf O~ A GRATE PRUrCCTEO CULVERT
FOR A 4 X 6 FT~ MULTI-3UX CULVeRT ON A 2-1/2 TO 1 SLope
ADl A=12fT. A='16FT'. A=24FT. A=3 OFT.
7t>O.O 4, -to 0.00 4300., 00 4100.00 410U.OO
ItJOO.O 6!:";'O0.00 5800 • LQ 5400.00 54UO.00
n 2~:50.0 blOO.OD 7100.GO 6600.00 660 0.00 w
~
300U .. u 9~00.00 8600.00 7900.00 '790 O. 00
lSOOO.O 10100.00 5700. 00 7900.00 7'900.00
20000.0 12800.00 11 GOO .. uO 9900.00 9<)0 0.00
TABLE C11 (CONTINUED). TOTAL COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:lSLOPE
TUl'l,L COS T Ut- !\N ln~Pi~lJT [C TtD C ULVt:"RT
FDR A 4 X 6 FT. r"iUL 1 I -dOX CULVL!-'';:T 01'1 A 6 TO 1 SLOPE
ADT I\=-j~>t-=T. A=lbFJ. A=24FT. A=:iOFT.
750.0 5000.00 4000 .. GO 2600.00 60 0.00
1500 .. 0 11:500 .. 00 79UO.00 5200.00 1 100.00
2.2~O.O It.:·(}O.OO 11 600 • ().) 7500.00 1600.00
300G.O 22100.00 15600. r,o 10100.00 2200.00
1500G.O 22500.00 lS":IOU. CO 10300.00 ?200.00
20000.0 ..51200.00 £:2000. GO 14300.00 3100.00
TABLE C12 .. TOTAL COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
CJb: lclNi\L lJ r- j- ~. 1:::.1 ;"'.::.-·1 L t-I A~l L: t-1 .. ~ -. M- 12 Fl • h=lb t=T .. A=l b FT. A=24 Fl . f ! [\u'L Uf f ~,~ I A~ 1 L' i- 'j' • A=-c.4 FJ . A='.::.O FT .. ;:""=~4 fT . A=.:.O Fl .. A='30 ~-r ..
Jl...u·1
, :.,.,(/ • v c,~ L \~ .. L L S~OO • C U ~ 100 .. OG 4,:->00 .Oli 4C:::00 .. ()O ~20() .00
l~ClJ. (j 1 ul Oll .. li0 (;,5G(i .. U(; 5-/00. UC (!JOO .00 4100 .00 3-100.00
...:,£~ ~ o .. (; I ..jL' (; \.1 .. V U ! lJ':)vG .0 G c.,2CJU. 00 S':-7GO .GO ::'cOO.OO 4300 .. 00
.....:t.f\...i(j .. L- 1 "Ie 0lJ .. 00 l,j~(;(j.Oli t,buL .va 1 £~~(jO .00 ~b00.00 4bGO.OU
1 ::.' lJ () ~; e, U 1 (, 1 Cl,; .. L (; 1 ~, to(j .0(; tb0u.UO 1 ~ 7uu .00 5bOO. 00 L.bOO .. 00
LV(jl;0 • v .24i:..'(il.L.I.; 1 -((.)u(;.O « -/000 .0(" 1 be. vO .00 0/00.00 5700 .. 0 {J
TABLE C12 (CONTINUED). TOTAL COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
TOT ALe 0 ~,T 0 FAG U I~ FD n A I L PRO T 1-= C TEn C LL VE i:( T
FOR A 4 X 6 FT. r,lUL l I -.H LJ( CUL V i:- RT (ji'4 t, 6 TO 1 SLOPL.
ADT A ~12FT .. A =1 EFT. A=;::24FT .. A =.<~ OF·T •
750 • 0 8500.00 6900 • CO 6()OO.0(J 690 (J .. reo
1 t:. () 0 .0 lOt,(;li.00 hbGO. 00 f..\~(IU .00 0t~~)(}. DU
CJ 2250.0 12400.00 10200. C,O lQ200.00 lO£.'\.iO.~~iu ..j::::. N
3000.U 1440u.00 11 900. 0\) 11(100.00 1 1 '-j'::l L • (I lJ
l~)OOO.O 14 ~,o 0.00 12 1 00. co 1 2100 .00 12 laC. \)0
20000.U I -I -, (, 0 • u 0 14 rUO ... (,i. 1 47(iO .0 l) 14 -to C .. UC;
TABLE C12 (CONTINUED). TOTAL COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
T CIT 1\ L C C) STU FAG ~ A T [ P 1-< () l LeT E D C U L V L ~T
'=01< A 4 X 6 Fl. f·1UL r ]-l-ilJX CULVERT ON A 6 TO 1 SLUPE
ADl A=12fT. A='lSFT. A=21~FT • A=30F 1.
206\'}O.O~) 20500.('.0 20500.00 2050 o. 00
1500.0 2.1300.00 21100.00 21100.00 .21100.00
21 ':400. 00 21600.00 21 60 o. 00
3000.0 .2:2000.00 22 I 00. 00 22100.00 22100.00
l~OOO.Q 22100.00 22200.00 22.200.00 2220 0.00
20000.0 23000. 00 23000.00 23000 .. 00
TABLE C12 (CONTINUED). TOTAL COST DATA FOR A 4' X 6' MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
iL;ip.L L'},,\LCi C(.J~' Fu« LX'Lf\lUINl. A CUL\lLr-<l
~Lt~ A ~.(j 1l". L:ll-',I·,L'Lh. t-"!i-'L uN A 2-1/e:: T0 1 ~Ll.JPt:.
A~·l.·_ Fl. /:-..=-1" Fl. 1'\=--121-'1. A=-lt:-, fT. A=-10 Fl. A=-24 Fl.
I ... :::: 1 ,--. t-'l. r=(:4 r-l. A::.:-24 1-'1'. A=..)V FT. A=-,jO FT.
AUf
" c L, • 0 L 110(/.(;0 It:Cl; .. OL 1 1 GO .0(; I ICO.u(j 1700.00
ivv.Uv 1100.00 lSOO.OU 1 1 CO .. 00 lIOO.OO 1700.00
/OU.0L 11OO.OU lSOJ.00 1100 .00 lIOO.OO 1700.0G
IlJu .. uU 1 100 .0(; 1~O0.00 1100 .. 00 lIOO.UO 1700.00
1 ~=.;u(,l' .. \,,.l Iu u. 0 II I 1(;(;.00 IS00.0lJ 1 1 GO .. 0 0 1700.00 17'00 .. 00
"Ov.00 110U.00 l!JOO.uO 1 100 .. U 0 1700.",0 1700.00
TABLE C13. DIRECT COST DATA FOR A 36 INCH PIPE CULVERT ON A 2~:1 SLOPE
----------------------------~----
j., ~ 1 c.' 1-1. A~ U-. Fl. A=lb Fl ..
/I.=-1 b F I .. A=~O Fl. A=30 FT. A ='30 FT.
':.- () l,. i.,u 1£:.00.00 1 ~) C. 0 • 0 c.' 1 100.00 1400.L(; 130{).OO
~vv.uu 1';:.00.00 1500.00 1100.00 1400.00 1300.00
Sl,.v.v\... li.:O(J.OG 150(;.00 1 100 .0 Ci 1400.00 1300.00
JuUU .. U ':;1 (1\ .. ,; • (; {J J.£::OO.\)(J 1500 .. 00 1 100 .00 1400.00 1300.00
~; ~j () .. () (, 1.:::-00.()O I ~,oc • DO 1 100 .00 1400.0G 1300 .00
£::uGuU.0 \lOv.uu 14::00.00 1500.00 1100 .0 U 1400.00 1300 .. 00
TABLE C14. DIRECT COST DATA FOR A 36 INCH PIPE CULVERT ON A 6:1 SLOPE
P=-lt: Fl. A=l::::: Fl. II = 1 L Fr. A=lf.: For. A .::.2.4 Fl.
A=3(J ~I .. A='..)O FT. A=':':iO fl.
h,DI
I::' C' \.i • li 0 £::.1(;0.(,(; .310(;.00 } 700 .00 £.-:bUO.GO ~400 .00
l-.:.>vv.vU t:~lOO.OO .:)100.00 1700.00 £:,:(:500.00 2400.00
i..:',LL.LC i.'100.GU .J1uu.()U I', uu .00 e:bOO.U0 2400.00
l..:>Cli.vl. £:'100.,0(; .3100.00 1 -/00 .00 £::000.00 2400.00
.1 ~,U \) • U l; L..l 00.00 .;.,lUU.OO 17UO .. 00 2bOO.OO 2400.00
L . .i()\.I.uu '-.iOO.()0 :':duu.00 1700 .00 2bOO.vC 2400.00
TABLE Cl~ DIRECT COST DATA FOR A 41 X 61 SINGLE BOX CULVERT ON A 2~:1 SLOPE
FL:h ;:... " " L Fl. ~ 1 r'~C.LL L,LX CULVt h1 LJi\i A. C> 1(; 1 !.:.LCll-'t:
f' . .::.:.le: fT. A=lc. fT. A=-lb FT. A=-i:.4 Fl.
~\-l<· Fl. A=-c'4 Fl. A=24 ~l. ;'.::.';;0 F1 '"'
I.U;
1 () lj C • Uli .. ~500. () G ':::'400 • () 0 t:: 000 .0 L ;::bOO.UO £:,300.00
ic,0v .vv ~~!::> 0 () . () (: ':';;4vL; aUO 4000 .00 ~bOO.OO ~300 .00
1 '.()u. Ll ~~:U(;.()O 340u .00 ;;:u(;() .Ou 2bGO. 00 L.'300 .00
.J ali () • 0 lI.Ju\J. lIL ,-t.00 .oe 341'..H,,: • UC £:: U \)() .00 L.buCi a 00 ~3u0.0(;
iG 0L . Llv £:SOU . o (j ;.:040(; .00 L.O GO . 00 2600.00 2300.00
levu.uti c.:!J00.0() ,)400 .00 cO 00 .00 ~bOO. 00 ~3uO.OO
TABLE C16. DIRECT COST DATA FOR A 41 X 6 1 SINGLE BOX CULVERT ON A 6:1 SLOPE
('") . +::> CD
A=-lc. Fl. ;:"'.=12 t-T. /,,::·10 f"T. A::lt.~ ~T.
h~·l(.' f--'. A:::c'4 fT. A=·.;:;,O t-T. A=£:'4 FT. A=..jO f'l.
7 ':.... (j • (; j 7 G v. 0(; :"00(1 • (j U 4300.00 Ll (..10 .00 '::'cOO.OO
i I()U.UO ..j0 (J (I • () (. 't~O(;.0U 21 00 .00 ;:;'600. 00
1 lUu. U (, ~iO 0 (J .00 4~Ol; .(;(; ~ 1vO .00 ,:,:,c.. () 0 .. 00
..:.. l' (; LJ • 1.., } /L.l).l.ll.o .J0CU .0 G 4..JOv .00 Ll (10 .00 :.:H., 0 U .. 0 (j
1 ( (; l,l .. l. L _/00 G .. () (, 4:::'00 .00 c' 1 \)0 .00 2,600 .. 00
1 (l!ll .. tH; ;,)000.00 4JOu.00 c. 1 00 .0 v ::'000.00
TABLE C17. DIRECT COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 2~:1 SLOPE
A=-£::4 f-T.
A=30 F·f.
cbOO.ClO
£>600.00
"_bOG.OO
LcOD.OO
£:.60U .. 00
cliOO.OO
I .. :;. 1 2 f- T • f, ::. 1 c' fl. A:....·lb ~1. A:=:16 Fl. A:=:24 F"'. t";il\J/\L Lf-r~t:..' A::'':':;O FT. A::.:Ctf Fl. A=..JO FT ..
I ... U I
LL·UO.l'll :)400 • (I 0 46(;U. 00 c4 uO .00 3bOO.00 2600.00
',;;\,;If.v ..... ~li Cu. u (I 460U.00 '=::400 .OU 3000.00 ~:bOO .00
L_ £~ 0 Li • U\'j :.~ Lt CO.OC 460u.UO ~400 .00 .,:H> 0 0 • 00 ~'bOO .00
:::,,£:.u0.vl. ~400 .00 4600. 00 24 vO .00 ~600.00 2000.00
1::' (; 0 U • 0 I.. L. 0 u. uU .... 400.0C 4r"uu .nu £:4 uO .00 ...::;(>00.00 £:.600.00
L:..u l, l.Jv • U ~_i.:.:O\,j.vll ~A 00 .OG 4t...00.00 .24-00 .00 3bOO.OO 2600.00
TABLE C18. DIRECT COST DATA FOR A 41 X 61 MULTI-BOX (2) CULVERT ON A 6:1 SLOPE
Example 1: Given:
APPENDIX D SAMPLE CALCULATIONS
A 4 ft x 6 ft double box culvert is located on a 2~ fill section rural highway with an average daily traffic of 2250. The end of the culvert is 24 ft from the edge of the traveled way and has no other hazards on the slope or around the culvert and ditch. There are no restrictions on the type of safety treatment which may be used.
Required: Determine the most cost-effective alternative. Solution: a) 1) Select Figure 10 (2~:1 slope).
Example 2: Given:
2) Enter with ADT = 2250 and Offset = 24 ft. 3) The point ADT = 2250 and A = 24 ft falls
to the right of the line for two 4 ft x 6 ft MBC. Therefore, safety treatment is recommended.
4) Select Figure 7 (4 ft x 6 ft multi-box (2) culvert on a 2~:1 slope).
5) Enter with ADT = 2250 and Offset = 24 ft. 6) Safest alternative is either extend to 30 ft or
grate protection.
A 36-in. diameter pipe culvert is located on a2~:1 fill section rural highway with an average daily traffic of 1500. The end of the culvert is 18 ft from the edge of the traveled way and has no other hazards on the slope or around the culvert and ditch. There are no restrictions on the type of safety treatment which may be used.
Required: Determine the total costs and ranking factors for a) the unprotected culvert; b) extending the culvert end to 30 ft; c) guardrail protection; and d) grate protection for the direct costs listed in Tables B6 through B8; e) repeat steps a) through d) for 30% decreased direct costs in extending and grate treatments; f) determine most cost~ effective alternative for no increase or decrease in direct costs and for 30% decreased direct costs.
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Solution: a) Unprotected Culvert From Table C7: CT = $5100 (ADT = 1500, A = 18 ft)
R = 1.0 (see Appendix B for discussion)
b) Extend Culvert End to 30 ft From Table C7: CT = $4200 (ADT = 1500, Ao = 18 ft, AF = 30 ft)
From Table Cl: R = 0.52 (ADT = 1500, Ao = 18 ft, AF = 30 ft)
c) Guardrail Protection: From Table C7: CT = $8600 (ADT = 1500, A = 18 ft)
From Tab'l e C1: R = -0.67
d) Grate Protection From Table C7: CT = $4400
From Table C1: R = 0.47
e) 1) Unprotected Culvert (no direct costs involved) CT = $5100
R = 1.0
2) Extend Culvert End to 30 ft (30% decrease in direct costs) From Table C13 or Table B6: CTO = $1700
To calculate the new total costs: CT = $4200 - (30%)($1700)
CT = $3690
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f)
Using Equation (B5) to calculate the ranking factor:
_ $5100 - $3690 R - (70%){$1700)
R = 1 .18
3) Guardrail Protection (no decrease in direct costs) CT = $8600
R = -0.67
4) Grate Protection (30% decrease in direct costs) From Table B8: CTO = $1500
CT = $4400 - (30%)($1500)
CT = $3900
_ $5100 - $3900 R - (70%)($1500)
R = 1.14
No increase or decrease in direct costs. From parts a) - d) : CT = $5100, R = 1.0 for unprotected culvert;
CT = $4200, R = 0.52 for extending to 30 ft;
CT = $8600, R = -0.67 for guardrail 'protection;
CT = $4400, R = 0.47 for grate protection.
and
Based entirely on total costs, extending appears to be the most cost-effective solution; however, it has a ranking factor less than 1.0. This means that more money must be spent than will be received in benefits by extending to 30 ft. Thus, the most cost-effective alternative is to leave the culvert unprotected. This can also be determined by entering Figure 3 with AOT = 1500 and Offset = 18 ft.
30% decrease in direct costs From part e): CT = $5100 R = 1.0 for unprotected culvert;
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Example 3: Given:
Required: Solution:
CT = $3960 R = 1.18 for extending to 30 ft;
CT = $8600 R = -0.67 for guardrail protection; and
CT = $3900 R = 1.14 for grate protection
Based on total costs and ranking factors, extending appears to be the best alternative. However, the total cost and ranking factor for grate protection is so near that of extending, that either alternative is considered the most cost-effective.
A 4 ft x 6 ft single box culvert is located on a 6:1 fill section rural highway with an average daily traffic of 3000. The end of the culvert is 12 ft from the edge of the traveled way and has no hazard on the slope or around the culvert and ditch. Right-of-way space is limited so that the culvert can be extended a maximum of 24 ft from the edge of the traveled way. Determine the most cost-effective alternative. 1) Select Figure 11 (6:1 slope). 2) Enter with ADT = 3000 and Offset = 12 ft. 3) The point ADT = 3000 and A =12 ft falls to the right
of the line for one 4 ft x 6 ft SBe. Therefore safety treatment is recommended.
4) Select Figure 6 (4 ft x 6 ft single box culvert on a 6:1 slope).
5) Enter with ADT = 3000 and Offset = 12 ft. 6) Safest alternative is to extend to 30 ft. This alternative is not possible due to limited right-ofway; thus, the alternative with the next highest ranking factor is the most desirable. Extending the culvert end to 18 or 24 ft might also be a possible treatment. From Table C4: R = 1.0 for unprotected culvert; R = 2.69 for extending culvert end to 30 ft (not a
possible alternative);
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Example 4: Given:
R = 1.99 R = 1.37
for extending culvert end to 24 ft; for extending culvert end to 18 ft;
R = 0.02 for guardrail protection; and R = -0.19 for grate protection. For this, extending to 24 ft clearly provirles the second highest ranking factor next to extending to 30 ft. Thus, the culvert end should be extended to a final offset of 24 ft to obtain the second most cost-effective solution. This same procedure can be applied to other situations in which the recommended alternatives in Figures 3 through 8 cannot be implemented.
A portion of highway has been designed for an average daily traffic of 20,000 and will be located on a 6:1 fill section. A 4 ft x 6 ft single box culvert is necessary for drainage under the roadway at Station 1+00. All hazards within 50 ft of the traveled way and 100 ft on either side of the culvert have been removed. The culvert end cannot be closer than 12 ft and no farther than 30 ft from the edge of the traveled way. Assuming no initial costs for an unprotected culvert with a 12 ft offset, it has been determined that the following additional costs are necessary: $3500 for an 18 ft offset, $7000 for a 24 ft offset, and $11,000 for a 30 ft offset. All costs include labor and material for extending the culvert and for the necessary fill to maintain a 6:1 slope.
Required: Determine the most cost-effective culvert end offset and/or safety treatment at Station 1+00.
Solution: The general procedure is to determine the total cost and ranking factor at each offset for the unprotected, guardrail protected, and grate protected culvert. The costs given above must be used in conjunction with the costs given in Appendices Band C.
D5
1) The Unprotected Culvert (see Table Cl0) 12ft Offset: CT = $20,500 (from Table Cl0)
CTO = $0
R = 1.0
18 ft Offset: CT = $3500 + $14,500 = $18,000
CTO = $3500
R - $20,500 - $18,000 = 0 71 - $3500 ·
24 ft Offset: CT = $7000 + $9800 = $16,800
CTO = $7000
R - $20,000 - $16,800 = 0 53 - $7000 ·
30 ft Offset: CT = $11,000 + $3100 = $14,100
Cro = $11,000
R = $20,500 - $14,100 = 0 58 $1',000 ·
2) The Guardrail Protected Culvert (see Tables 87 and Cl0) 12 ft Offset: CT = $17,700 (from Table Cl0)
CTO = $6900 (from Table 87)
R - $20,500 - $17,700 = 0 41 - $6900 .
18 ft Offset: CT = $14,700 + $5500 + $3500 = $23,700
CTO = $5500 + $3500 = $9000
R - $20,500 - $23,700 = -0.36 - $9000
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24 ft Offset: CT = $14,700 + $5500 + $7000 = $27,200
CTD = $5500 + $7000 = $12,500
R ~ $20,500 - $27,200 = -0.54 - $12,500
30 ft Offset: CT = $14,700 + $5500 + $11,000 = $31,200
CTD = $5500 + $11,000 = $16,500
R = $20,500 - $31,200 = 0 65 $16,500 - ·
3) Grate Protected Culvert (see Tables 88 and C10) 12 ft Offset: CT = $18,400 (from Table C10)
CTD = $14,600 (from Table 88)
R - $20,500 - $18,400 = 0.14 - $14,600
18 ft Offset: CT = $17,700 + $3500 = $21,200
Cro = $14,600 + $3500 = $18,100
R - $20,500 - $21,200 = -0.04 - $18,100
24 ft Offset: Cr = $17,700 + $7000 = $24,700
Cro = $14,600 + $7000 = $21,600
R - $20,500 - $24,700 = -0.19 - $21,600
30 ft Offset: CT = $17,700 + $11,000 = $28,700
CrD = $14,600 + $11,000 = $25,600
R - $20,500 - $28,700 = -0.32 - $25,600
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From these calculations, the most cost-effective alternative, based on ranking factor, is to leave the culvert unprotected at a 12 ft offset distance (CT = $20,500; R = 1.0). Based on total costs, the best alternative is to leave the culvert unprotected using a 30 ft offset (CT = $14,100; R = 0.58). Note that the additional initial costs used in this example greatly influence the final results since they are a large percentage of the total and direct costs. Care should be taken in estimating these costs in order to obtain correct results.
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APPENDIX E REFERENCES
1. Guide for Selecting, Locating, and Designing Traffic Barriers, Part I, American Association of State Highway and Transportation Officials, 1977, pp. 15-21, 156-186, 222.
2. Hutchinson, J.W. and Kennedy, T. W., IIMedians of Divided Highways -Frequency and Nature of Vehicle Encroachments," Bulletin 487, University of Illinois Engineering Experiment Station, 1966.
3. Glennon, J. C., "Roadside Safety Improvement Program on Freeways -A Cost-Effectiveness Priority Approach,1I National Cooperative Highway Research Program Report 148, 1974, 64 pp.
4. Weaver, G. D., Post, E. R., and French, D. D., "Cost-Effectiveness Program for Roadside Safety Improvements on Texas Highways - Volume 2: Computer Program Documentation Manual, 1.1 Research Report 15-1, Texas Transportation Institute and Texas Highway Department, February 1975.
5. Memorandum to T. J. Hirsch, R. M. Olson, E. L. Marquis, G. D. Weaver, C. E. Buth, D. L. Ivey, J. E. Martinez, M. E. James, D. L. Woods, and G. E. Hayes, Texas Transportation Institute; Harold Cooner, Ray Ratcliff, and Gerald Peck, Texas State Department of Highways and Public Transportation; and C. P. Damon, Federal Highway Administration, from Terry L. Kohutek of Texas Transportation Institute, Texas A&M University, April 5, 1977, concerning the severity index of various roadside hazards.
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