bim bridge inspection and maintenance technical standards branch class b bridge inspection course...

BIMBridge Inspection and Maintenance

Technical Standards BranchClass B Bridge Inspection Course

Culvert Inspection and Ratings

CulvertInspection and Rating




2

Introduction• Bridge -sized culvert has an equivalent

diameter of 1500mm or greater• Bridge site that requires a 1500 mm pipe due to

hydraulic discharge• Will routinely inspect smaller culverts if there

are several ( low level crossing)• May also inspect if multiple small culverts are

equivalent in capacity to bridge-sized• May inspect certain other non-bridge sized

culverts




3

Introduction

• Many different types of culverts - see BIS manual

• Vast majority are CSP or SPCSP in various shapes - round, arch pipe, horizontal ellipse

• Three culvert forms• Same forms used for all types of culverts• Timber pipe (TP) culverts exception

– Use TT form




4

Form Types

• CUL1– Single culvert or single culvert extended with same

material and size

• CULM– Two or more culverts (MP, SP or BP etc.)– Includes 1 Upstream & 1 Downstream End sections

per Barrel section as required – Includes 2 cell box extended with single steel

• CULE– Single culvert extended with different material

and/or size– One Upstream & Downstream section, Barrel

sections for all cells and/or pipes




5

N um ber of C ulverts

P ipe # TypeSpan C orr. P rofileBarre l LengthR ise (or D ia.) P l. Thickness Shape

1

2

3

4

Specia l Features

Specia l Features C om m ent

Bridge C ulvert Inspection

Inventory Information

• Extracted from BIS • Span/rise is original design shape• Span type see Sec. 13.2.3• Corr. Profile (76x25, 152x51, etc.)• Specific information is provided for all pipes

– a culvert extended with same material is considered to be one culvert




6

Numbering and Identification

• Where the culvert does not carry flow determine “upstream” and “downstream”– Look in direction of increasing chainage

• (to north or east)

– Left is “upstream” (end 1)– Right is “downstream” (end 2)– Keep same choice for each subsequent inspection




North or East

South or West

“Downstream” End 2

“Upstream” End 1

2

1

7





8


• Primary span is the largest span at the site• Secondary span is the smaller span• Where more than one culvert the same

number barrel sections 1, 2, 3, etc.• Culverts are numbered in order of increasing

chainage (to north or east)




9

Ends - General

• Individual rating sections for the upstream and downstream ends

• Single upstream and downstream end sections for the CUL1, CULE and CULM forms

• Upstream and Downstream sections are identical

• Items are inspected and rated the same way for both ends




10

Downstream End

Direction

W ingw alls

(Shape : )

End Treatm ent (Concrete, Steel, O thers, None)

Collar/C oncrete S lope P rotection

Headw all

Cutoff W all

Bevel End

Invert Above/Below Stream Bed

Scour P rotection

Scour/E rosion

Beavers (Y /N )

Heaving (m m )

Above/Below (m m )

(Type : )

(Avg. R ock S ize (m m ) : )

Ends - General




11

Downstream End

Direction

End Treatm ent (Concrete, Steel, O thers, None)

Ends - General

• Record direction of end in Explanation of Condition

• Record End Treatment type• Scour Protection is not End Treatment

N




12

Ends - End Treatment

• Purpose:– Improve aesthetics– Improve hydraulic performance– Prevent undermining due to scour– Prevent scour of the embankment– Reduce piping along or under the culvert– Resist uplift due to buoyancy forces– Shorten the culvert– Stiffen the ends




14

Downstream End

Headw all

End Treatment - Headwall

• Located over the crown• Usually attached to the barrel• Purpose:

– Aesthetics– Strengthen end– Resist buoyancy force– Retaining walls




15

End Treatment - Headwall

• Look for:– Signs of movement or tilting– Loose connections

• Rate according to condition of material and functionality of component

• Condition affecting functionality rate 4 or less




16

Downstream End

C ollar/C oncrete S lope P rotection

End Treatment - Collar / Slope Protection

• Located along the beveled slopes of flexible culverts between headwall and cutoff wall

• Usually constructed from concrete• Usually used with and connected to headwall

and cutoff walls– May be used alone




17


• Purpose:– Aesthetics– Stiffen the bevel– Resist buoyancy force– Improve hydraulic efficiency of end– Concrete slope protection

• protect against scour / erosion• reduces piping potential




18


• Look for:– Evidence of piping or scour / erosion– Loose connections– Voids underneath or settlement

• Rate according to condition of material and functionality of component

• If piping, rate 4 or less:– Also rated under bevel end and barrel




19

D ow nstream End

W ingw alls

(Shape : )

End Treatment - Wingwalls

• Generally found at culverts that do not have bevels

• Not solidly attached to the barrel• Usually constructed from concrete or steel• Purpose

– Improve hydraulic efficiency– Retain embankment fill




20


• May be parallel or flared– Parallel wingwall

• require less scour protection between them

– Flared wingwalls• more hydraulic efficient

• May have a reinforced concrete slab between– Prevents undermining of wingwalls due to scour– Act as struts for greater stability




21


• Indicate wingwall Shape– No Explanation of Condition required

• Look for:– Evidence of movement– Loose connections (gap at barrel)– Scour / erosion at toe or behind wingwall

• If wingwall is unstable rate 4 or less• Separation losing fill rate 4 or less• Includes rating of wingwall floor slab




22

Downstream End

C utoff W all

End Treatment - Cutoff Wall

• Located at the end of the culvert• Vertical wall extending down below the bottom

of the culvert• Depth exceeds the depth of the riprap or

concrete apron

• Usually constructed from concrete or steel• Purpose:

– Reduce potential for undermining of end of culvert– Minimize possibility of piping– Resist buoyancy force




23

End Treatment - Cutoff Wall

• Look for evidence of:– Undermining– Piping– Uplift– Loose connections

• Usually not possible to inspect since they are submerged or covered with ice or debris– If not visible rate “N”

• If piping, rate 4 or less– Also affects Bevel End and Barrel Rating




24

Downstream End

Bevel End

Invert Above/Below Stream Bed

H eaving (m m )

Above/Below (m m )

Ends - Bevel End

• Sloped section at the end of the culvert• Permanently attached to the barrel• Generally parallel to the culvert axis• Bevel types

– Full bevel– Step bevel




25

Ends - Bevel End

• Compared to projecting ends, bevel ends are more:– Aesthetic– Economical– Hydraulically efficient

• Compared to projecting ends, bevel ends on corrugated steel culverts are more flexible and susceptible to:– Deform due to lateral earth pressure– Uplift due to buoyancy– Heave due to frost action




26

Ends - Bevel End

• Measure or estimate heaving of bevel and record amount




27

Ends - Bevel End

• Record whether invert at end of bevel is above or below streambed

• Measure or estimate height above or depth below streambed and record amount

• Find a representative natural streambed location– May have hole or deposits at end of culvert




M easureH ere

M easureH ere

M easureH ere

InvertBelow

Stream bed

InvertAbove

S tream bed

H eaved InvertAbove

S tream bed

Invert

Invert

Invert

28

Ends - Bevel End




29

Ends - Bevel End

• Look for:– Deformation– Impact damage– Corrosion– Abrasion

• If piping, rate 4 or less– Also rated under End Treatment and Barrel

• Defects or deformations not affecting function rate 5 or more

• Corrosion affecting strength or function rate 4 or less

• If no bevel, rate “X” and provide explanation– Underpasses typically have square or projecting ends




30

Downstream End

Scour P rotection

(Type : )

(Avg. R ock S ize (m m ) : )

Ends - Scour Protection

• Usually heavy rock riprap• The current version of standard plan S-1418

shows the minimum requirements for riprap– Coverage– Size– Minimum thickness– Gradation




31


• Purpose is to prevent scour and erosion at culvert ends which may:– Undermine the culvert– Undermine the sideslopes– Cause the formation of sand bars




32


• Record the type of scour protection– If none exists and none is required, record type as

“NATURAL”– If none exists and some is require, record type as

“NONE”

• Estimate and record the average size (for riprap only)

• Look for:– Durability of riprap - e.g. sandstone not acceptable– Displacement or movement– Scour– Current standards on S- 1418




33


• No scour/erosion or displacement rate 5 or more

• If none exists and none is required (type “NATURAL”), rate 7 or more

• If none exists and some is required (type “NONE”), rate 4 or less

• Do not rate higher than scour if scour rated 4 or less




34

Downstream End

Scour/E rosion

Ends - Scour / Erosion

• Removal of material from the streambed, banks or sideslopes by the action of flowing water

• Effects:– Undermine the culvert– Undermine the sideslopes– Impede fish passage– Alter culvert hydraulics




35


• Look for:– Scour holes, especially at downstream ends– Undermining of culvert end or sideslopes– Slumping of sideslope or banks– Areas where flow impinges on banks, sideslopes or

protection systems– Areas susceptible to high velocities and undermining

• culvert footings• ends or bottoms of wingwalls and cutoff walls• sides of collars• ends or bottoms of ends of protection systems




36


• Rate the presence and extent of scour and adverse effects on culvert, embankment, streambed and banks

• Scour/erosion affecting culvert, rate 4 or less• If culvert and embankment are not affected,

rate 5 or more




37

Downstream End

Beavers (Y /N )

Ends - Beaver Activity

• Beavers frequently construct dams at inlet or inside culverts

• Effects:– reduced flow capacity– Flooding upstream– Scour– Ponding of water inside culverts preventing

inspection




38

Ends - Beaver Activity

• Indicate the presence of beaver dams in or near the culvert by Yes or No

• If “yes”, explain• No rating required but may affect

– End General Rating– Scour– Waterway Adequacy in Barrel section




39

Ends - General Rating

• Governed by ratings :– Headwall– Collar– Wingwall– Cutoff Wall– Bevel end– Inadequate scour protection– Scour/erosion




40

Barrel - Rigid Types

• Made from concrete and timber• Designed to carry loads without deflection• Culvert carries entire load with no reliance on

surrounding fill for support Can directly inspect entire load carrying system (I.e. culvert)




41

Barrel - Flexible Types

• Made from corrugated steel• Low strength• Dependent on surrounding backfill for support• Culvert deflects under load until the backfill

picks up the stress• Entire load carrying system cannot be

inspected directly (I.e. can inspect culvert but not backfill)

• Flexible culverts more susceptible to failure caused by:– Change in shape due to excessive deflection– defective joints - cracks, open joints, cusped seams,

etc.– Corrosion of plates– Uplift of ends due to buoyancy forces




42

Bridge C ulvert Barre l

(P ipe # : )

Sag (m m )

M easured at R ing num ber

Longitudinal Seam s

Bulge (m m )

M in. R em ain ing Stee lBetw een C racks (m m )

(Type : )

(Type : )

S idew all

M easured R ise (m m )

Percent D eflection

Tota l num ber of R ings w ith Tw oC racked Seam s

Abrasion (Y /N )

Proper Lap (Y /N )

Specia l Feature

Specia l Feature

Percent Sag

R oof

D eflection (m m )

Tota l num ber of C racked R ings


M easured Span (m m )

Separation (m m )


F loor

C ircum ferentia l Seam s

Longitudinal Stagger (Y /N )

Barre l Last Accessib le D ate




43


(P ipe # : )

C oating

(C orrosion by W ater (Y /N )

(Type : )

Ic ing (Y /N )

D rift (Y /N )

S ilting (Y /N )

C orrosion By Soil (Y /N )

Baffle

W aterw ay Adequacy

C am ber PO S/ZER O /N EG

Ponding (Y /N )

F ish Passage Adequacy




44

Bridge Culvert Barrel

Barre l Last Accessib le Date

Barrel - General

• If barrel accessible provide current date• Not accessible explain why & retain previous

date• Rate elements N if not visible• Previous comments are retained and dated• If more than one barrel indicate location (west)

or span number




45

Bridge Culvert Barre l

(Type : )

(Type : )

Specia l Feature

Specia l Feature

Barrel - Special Features

• Cannot be rated under another component• May be temporary or permanent• Must be inspectable

– Special design features not usually inspectable (ribs, thrust blocks, etc.)




46

Barrel - Special Features

• Examples– Struts– Shotcrete beams– Abrasion plates– De-icing devices

• Record type• Provide additional information in Explanation

of Condition– Description– Location– Dimensions– Inspection procedures

• Provide a suitable condition rating




47


Sag (m m )


Bulge (m m )

S idew all

M easured R ise (m m )

Percent D eflection

Abrasion (Y /N )

Percent Sag

Roof

Deflection (m m )


M easured Span (m m )

Separation (m m )


F loor


Barrel - Deformation




48

Barrel - Ring

• Three items Roof, Sidewall & Floor make up complete ring

• Purpose:– Carry water flow or traffic– carry loads and transmit to surrounding soil– Prevent infiltration of fill




49

120

120

6060

Floor

Roof

Sid

ew

all

Sid

ew

all

Barrel - Ring

• For round culverts, use approximate arcs shown– Use longitudinal seam if close




50

Barrel - Ring

• Look for:– Deformation– Localized crimping– Longitudinal seam problems– Corrosion– Abrasion on floor

• On concrete culverts– Structural problems

• Cracking

– Material defects• Corrosion• Scaling and freeze-thaw damage




51

Barrel - Ring

• Record rise and span measurements a location measured, calculate %

• Indicate abrasion on floor by Yes or No• Rate flexible culverts as per Table 13.3• Deformations- 7% or less, rate 5 or more,

10% or more, rate 3 or less, reverse curvature rate 2 or less.

• Corrosion– Roof/Sidewall - extensive corrosion & pitting rate 4,

severe perforations rate 1– Floor - isolated perforations rate 4, severe

perforations rate2




Span

Span

R ise

R ise

A

CB2B1

D esign Shape

D eform ed Shape

A = R oof SagB1 + B2 = S idewall D eflectionc = F loor Bulge

52

Barrel - Ring




53

Barrel - Deformation

• Sag is vertical deformation - i.e. change in rise– Positive sag is decrease in rise

• Deflection is horizontal deformation - i.e. change in span– Positive deflection is increase in span

• Bulging is vertical deformation of floor– Positive is bulging upwards

• Measurements always taken on inside of crests• Compare to original design dimensions on page

1• When measuring rise, must estimate floor

bulge and exclude from sag calculation• Measure at worst location and mark for future

comparison




54


Separation (m m )


Barrel - Circumferential Seams

• Refers to seams joining individual rings or sections of culvert– Does not include riveted seams or helical lockseams

• Found on most types of culverts– Bolted seams on SPCSP– Couplers on CSP– Joints in precast concrete– Construction joints in cast-in-place concrete




55


• Purpose– Join rings– Prevent infiltration of backfill

• Most common problems are separation caused by settlement or corrosion of couplers– Especially CSP and precast concrete

• Potential for safety problem if void develops in fill

• Look for:– Separation– Loose or missing couplers (corrosion)– Bent or broken edges on the rings– Misalignment of rings– Infiltration of backfill– Voids in surrounding fill




56


• Record width of worst separation• If infiltration of soil or void - rate 4 or less• If void large enough to cause safety concern -

rate 2 or less• Cracking larger than H or N due to roof sag,

rate 4 or less• May affect Roof, Sidewall or Floor rating




57


Longitudinal Seam s

M in. R em ain ing SteelBetw een C racks (m m )

Tota l num ber o f R ings w ith Tw oC racked Seam s

Proper Lap (Y /N )

Tota l num ber o f C racked R ings

Longitudinal Stagger (Y /N )

Barrel - Longitudinal Seams

• Applies to SPCSP and CSP riveted culverts• All others, Rate “X”




58


• Purpose– Join individual plates in ring– Transmit loads between plates

• Indicate if all seams properly lapped by Yes or No– If No, provide Explanation of Condition

• Indicate if seams staggered by Yes or No– Within same arc only– At change of arc should not be staggered– If No provide Explanation of Condition

• Most common problem is cracking– Especially on improperly lapped seams




INCORRECT LAP

CORRECT LAP

59


• Typical longitudinal seams




Cracked Seam

60

Typical longitudinal seams




61


• Record number of rings with cracked seams• Record number of rings with 2 or more cracked

seams• Record remaining steel between cracks &

record worst condition location• Mark and date ends of worst cracks




62


• Other problems– Poorly nested plates– Cusping– Plate deformation

• bolt tipping• Bolts pulling out

• Rate as per Table 13.3• If seams are in otherwise excellent condition

but not properly lapped - rate 8• Rating for longitudinal seams may also affect

Roof, Floor and Sidewall ratings• Seams with less than 50mm rate 2 or less




63


(P ipe # : )

C oating

(C orrosion by W ater (Y /N )

C orrosion By Soil (Y /N )

Barrel - Coating

• Applicable to steel culverts only• Applies mainly to zinc coating

– Can include other types, aluminized, bituminous

• Purpose is to protect the steel from corrosion– Zinc & aluminum protect by sacrificial action




64

Barrel - Coating

• Corrosion can occur on soil or water side of culvert

• Soil side corrosion not directly inspectable until perforation occurs– Difference in backfill resistivity– Corrosive chemicals in backfill or water in fill

• Water side corrosion usually occurs in invert area– Abrasion can remove protective coating– Water may have low pH or contain corrosive

chemicals– Anaerobic bacteria may live in stagnant water in

valleys




65

Barrel - Coating

• Look for:– Fabrication or installation defects or damage

• White rust

– Loss of coating– Corrosion– Rust stains from bolt holes or seams– Perforations

• Record if corrosion is on SOIL and/or WATER side

• Rate as per Table 13.1• If staining from bolt holes or seams, rate 6 or

less• Heavy rust and deep pitting, rate 4 or less• Rating of coating may affect Roof, Sidewall and

Floor rating




66


C am ber PO S/ZER O /N EG

Barrel - Camber

• Refers to longitudinal gradeline of invert• No rating is required• If water line is level can be used to determine

camber• Record whether camber is POSITIVE, Zero (0),

or NEGATIVE• If significantly POSITIVE or NEGATIVE provide

Explanation




Positive C am ber

N egative C am ber

R oof Sag

N o C am ber

67

Barrel - Coating




68


Ponding (Y /N )

Barrel - Ponding

• Refers to ponded water which adversely affects the culvert– Especially underpasses

• Does not refer to normal amounts of ponded water– Normal water level in stream– Invert normally set below streambed

• No rating required• Indicate presence of ponding by Yes or No• If “yes”, explain




69


(Type : )Baffle

F ish Passage Adequacy

Barrel - Fish Passage Adequacy

• Refers to ability of culvert to accommodate fish passage

• Designed for no more than 3 day delay during 1:10 flood

• May have fish baffles to:– provide rest areas– reduce velocities– provide minimum water levels




BeaverD am

O utfa ll

?

Steep G radient(h igh ve locity)

70






Fish Baffles

71




72


• Types of baffles– Spoilers

• Concrete or steel projections

– Large boulders– Weirs

• Extend fully across floor• May have notches

– Bolted to floor to prevent displacement– Baffles at outlet only may not be for fish passage




73


• Record type of baffle or NONE • Look for:

– Excessive velocities• Scour• Silt deposition downstream

– Steep gradient in culvert– Drops at ends of culvert– Anything which could block flow or affect water

levels• Dirt• Beaver dams

– Condition and functionality of baffles including anchorages




74


• Rate X if not a fish bearing stream or if not a water course culvert

• Rating includes condition of fish baffles and anchorages

• If fish passage is not possible, rate 3 or less




75


Ic ing (Y /N )

D rift (Y /N )

S ilting (Y /N )

W aterw ay Adequacy

Barrel - Waterway Adequacy

• Refers to the ability of the culvert to safely pass the design flow– Freeboard– Pass drift without damage– No damage from backwater created




76


• Adequately sized culvert may be affected by:– Ice build up– Silt deposition– Drift accumulation– Beaver dams– Ponding– Repair or rehabilitation work

• Shotcrete beams• Struts




77


• Indicate presence of ice build up (icing) by Yes or No if Yes explain– Not normal freezing of ponded water– Results from spring activity which freezes

and causes layers of ice to build up– If previously Yes - leave and retain

comments adding date of previous inspection

• indicate presence of silt build up (Silting) by Yes or No, if Yes explain– Invert normally below streambed– Minor accumulation of silt expected

• Indicate presence of drift by Yes or No• If “yes”, explain




78


• Look for:– High water marks– Potential damage from backwater– Potential for drift– Evidence of high velocities

• Scour• Silt deposition downstream

– Presence and effect of items which can affect adequacy




79


• Rate “X” if not a drainage culvert• Adequate opening rate 5• If potential for significant drift which culvert

cannot accommodate, rate 4 or less• If potential for damage due to backwater, rate

4 or less• HWM above crown, 4 or less• Culvert blockage 50% or more rate 3 or less




80

Barrel - General Rating

• Governed by ratings for:– Roof– Sidewalls– Longitudinal seams – Extensive corrosion and pitting– Severe circumferential seam problems

• Refer to Table 13.3• If barrel not accessible, may rate “N” (only case

this allowed)• If previous less than 5 carry over previous

rating and provide Explanation of Condition• If previous greater than 5 rate “N”




81

Effects of Struts onBarrel General Rating

• Inspector may increase rating by 1 or 2 points but not exceed rating of 4.

• Rating Conditions– struts in place more than 2 years– struts rated 5 or more– 1 permanent reference for monitoring– struts inspected after any significant event otherwise

1/2 cycle– consider depth of cover– does not apply when deflections >30% or cracked

seams less than 25% remaining– applied to general rating only, element ratings

remain unchanged

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