Murray Boulevard and Farmington Road
Intersection
Sirisha Kothuri
Wei Feng
Ping Guo
Meead Saberi
CEE 550 Transportation Safety Analysis
Outline• Introduction
• Site Description
• Crash Data Analysis
• Literature Review
• Countermeasures
• Cost/Benefit Analysis
• Recommendations
Introduction
Map of Intersection
Murray Boulevard•2 lane undivided•Runs N-S
Farmington Road•2 lane undivided •Runs E-W
Intersection•City of Beaverton •4-leg signalized•Slight skew•High Volume
Aerial View of the Intersection
Site Description - I
Murray Blvd
Farmington Road
Apt7-Eleven
AptApt
Site Description - II
Signal at Intersection Illumination at Intersection
Barrier at Intersection Pavement Markings at Intersection
Site Description - III
Speed Limit Sign on Farmington Speed Limit Sign on Murray
Driveways near Intersection School Zone Signs
Site Description - IV
Heavy Vehicles
Queue Spillover to Adjacent Intersection
Volume
Source: City of Beaverton
Crash Data Analysis
• Oregon Transportation Safety Data Archive (ortsda)• Crash File
• Crashes for 4 Years (2003 -2006) at intersection
• Vehicle File• Information about vehicles involved in crashes at intersection
• Participant File• Information about drivers involved in crashes at intersection
• Crash Patterns at the Intersection • Time of Day• Type of Crash• Severity• Weather• Light Conditions
• Driver Characteristics
• Residence Status
• Gender• Age
0
2
0 0 0 0
4 4
6 6
2
6
4
67
9
14
76
0
2 21 1
2
0
2
4
6
8
10
12
14
16
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:0
0
11:0
0
12:0
0
13:0
0
14:0
0
15:0
0
16:0
0
17:0
0
18:0
0
19:0
0
20:0
0
21:0
0
22:0
0
23:0
0
UN
K
Time of the day
Nu
mb
ers
of
cras
hes
Time of Day
13
1
62
27 6
0
10
20
30
40
50
60
70
ANGL-OTH O-STRGHT S-1STOP S-1TURN S-OTHER S-STRGHT
Type of Crash
Nu
mb
er
of
Cra
sh
es
Type of Crash
1 14
30
55
0
10
20
30
40
50
60
FAT INJA INJB INJC PDO
Severity
Nu
mb
er o
f C
rash
esCrash Severity
1 2
8
46
9
14
38
18
0
5
10
15
20
25
30
35
40
CA
RE
LES
S
DIS
-RA
G
IMP
LN
C
IMP
-TU
RN
INA
TT
EN
T
NO
-YIE
LD
OT
HE
R
OT
HE
R-I
MP
TO
O-C
LOS
TO
O-F
AS
T
Crash Cause
Nu
mb
er o
f C
rash
es
Crash Cause
Collision Diagram
Murray Blvd
Farmington Rd
Literature Review
• Rear End Crashes– Most common type at signalized intersections– Account for one-third of all reported crashes in US– Mostly PDO, sometimes severe injuries and fatalities occur
• Causes– Driver Behavior – Inattentive driving, smaller headways– Driver Age and Gender– Heavy Traffic Volumes– Dilemma Zone
Dilemma (Indecision) Zone
Source: Heng Wei, Characterize Dynamic Dilemma Zone and Minimize its Effect at
Signalized Intersections, Ohio Transportation Consortium (OTC), 2008
Dilemma (Indecision) Zone
Countermeasures1. Reduce speed limit on
approaches• 35 mph on Murray Blvd• 30 on Farmington Road
• Pros• Reduction in all types of crashes
• Cons• Increase in delay• Diversion of vehicles to other streets
Countermeasures
2. Advance Signal Warning Signs
• Murray Blvd & Farmington Rd
• Pros• Reduction in Rear End Crashes• Low cost• Easy Implementation
• Cons
Countermeasures3. Improve Signal Timing
• Optimize to ITE Standards
• Pros• Reduces Rear End PDO crashes
• Cons• Increases Fatal and Injury crashes
Countermeasures
4. Coordinated Signals• Coordinate adjacent intersections
• Pros• Allows progression of vehicles• Reduces all types of crashes
• Cons• Hard to implement
Cost Benefit Analysis
• Select Countermeasures– For each countermeasure, extract CRF– Calculate reduction in crashes– Calculate annual benefits and costs– Assume discount rate of 4%– Calculate NPV = NPVB – NPVC– Rank countermeasures in decreasing order of NPV
Cost Benefit Analysis
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
PDO INJC INJB INJA FATAL
Crash Type
Co
st (
$)
Cost of All Crashes at Intersection
Cost Benefit Analysis
1. Reduce vehicle’s approach speed limit
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
PDO INJC INJB INJA FATAL
Crash Type
Co
st (
$)
Before
After
Cost Benefit Analysis
2. Advance Signal Warning Signs
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
1,600,000
PDO INJ FATAL
Crash Type
Cos
t ($
)
Before
After
Conclusions & Recommendations
• Rear-end crashes are common at signalized intersections.
• Typical causes• Driver Behavior• Driver Age & Gender• Heavy Traffic Volumes• Dilemma Zone
• Countermeasures Ranking Based on B/C Analysis1. Install Advance Signal Warning Signs2. Reduce vehicle’s approach speed limit3. Signal Coordination
Acknowledgements
• Dr. Chris Monsere, PSU
• Jabra Khasho, City of Beaverton
• Baotu Ho, City of Beaverton
