10.1-i 

Table of Contents

Section 10 ..................................................................................................................................................

Inspection and 

Evaluation of 

Substructures 

 10.1 Abutments and Wingwalls................................................................... 10.1.1 

 10.1.1 Introduction............................................................................. 10.1.1 

 

 10.1.2 Design Characteristics of Abutments...................................... 10.1.2 

 Abutment Types ............................................................... 10.1.2 

 Full Height Abutments and Stub Abutments ............. 10.1.5 

 Open Abutments ........................................................ 10.1.6 

 Integral Abutments..................................................... 10.1.6 

 Less Common Abutment Types and Abutment 

 Elements .............................................................. 10.1.8 

 Mechanically Stabilized Earth Abutments................. 10.1.8 

 Geosynthetic Reinforced Soil Abutments.................. 10.1.9 

 Primary Materials ........................................................... 10.1.11 

 Primary and Secondary Reinforcement.......................... 10.1.13 

 Abutment Elements ........................................................ 10.1.14 

 Foundation Types........................................................... 10.1.16 

 10.1.3 Inspection Procedures and Locations for Abutments............ 10.1.17 

 Vertical Movement......................................................... 10.1.17 

 Lateral Movement .......................................................... 10.1.19 

 Rotational Movement ..................................................... 10.1.22 

 Material Defects ............................................................. 10.1.24 

 Concrete and Stone Masonry ................................... 10.1.24 

 Steel ......................................................................... 10.1.26 

 Timber...................................................................... 10.1.26 

 Scour and Undermining.................................................. 10.1.28 

 Drainage Systems ........................................................... 10.1.30 

 Areas Subjected to High Stresses................................... 10.1.30 

 Areas Exposed to Traffic................................................ 10.1.30 

 Fatigue Prone Details and Fracture Critical Members ... 10.1.30 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1-ii

 10.1.4 Design Characteristics of Wingwalls.................................... 10.1.31 

 General ........................................................................... 10.1.31 

 Geometrical Classifications............................................ 10.1.31 

 Construction Classifications........................................... 10.1.33 

 Primary Materials ........................................................... 10.1.34 

 Primary and Secondary Reinforcement.......................... 10.1.35 

 10.1.5 Inspection Procedures and Locations for Wingwalls............ 10.1.35 

 10.1.6 Evaluation ........................................................................... 10.1.39 

 NBI Rating Guidelines ................................................... 10.1.39 

Element Level Condition State Assessment................... 10.1.40 

 
10.1.1

Section 10 

Inspection and Evaluation of 

Substructures 

Topic 10.1 Abutments and Wingwalls 

10.1.1 

Introduction The substructure is the component of a bridge that includes all elements 

supporting the superstructure. Its purpose is to transfer the loads from the 

superstructure to the foundation soil or rock. 

An abutment is a substructure unit located at the end of a bridge. Its function 

is to provide end support for the bridge superstructure and to retain the 

approach roadway embankment. Wingwalls are also located at the ends of a 

bridge. Their function is only to retain the approach roadway embankment 

and not to provide end support for the bridge. 

Wingwalls are considered part of the substructure component only if they are 

integral with the abutment. When there is an expansion joint or construction 

joint between the abutment and the wingwall, that wingwall is defined as an 

independent wingwall, i.e. a retaining wall, and not considered in the 

condition evaluation of the abutment/substructure component. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.2

10.1.2 

Design 

Characteristics of 

Abutments 

Abutment Types Abutments are classified according to their locations with respect to the 

approach roadway embankment. The most common abutment types are 

presented in Figure 10.1.1 and include: 

3⁄4 Full height or closed type 

y Gravity 

y Counterfort 

y Cantilever 

y Curtain wall/Pedestal 

y Timber bent 

y Crib 

3⁄4 Stub, semi-stub, or shelf type 

3⁄4 Open or spill-through type 

3⁄4 Integral type 

Foundations consist of either spread footings or deep foundations. See page 

10.1.16 for a detailed description of abutment foundation types. 

Less common abutments used to support highway bridges are shown in 

Figure 10.1.2 and include: 

3⁄4 Mechanically Stabilized Earth (MSE) 

3⁄4 Geosynthetic Reinforced Soil (GRS) 

Detailed descriptions of abutment elements are provided on page 10.1.14. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.3

footing

(breast wall)

backwall

FULL HEIGHT ABUTMENT

wingwall

bridge seat

footing

abutment

stem

backwall

footing

abutment stem

backwall

STUB ABUTMENT

wingwall

bridge seat

footing

backwall

footing

cap beam

backwall

OPEN ABUTMENT

wingwall

bridge seat

footing

cap 

beam backwall

column column

INTEGRAL ABUTMENT

(breast wall)

abutment stem

abutment

stem

beam

footing/

pile cap

piling piling

*

cheekwall

(if present)

cheekwall

(if present)

cheekwall

(if present)

ELEVATION

ELEVATION

ELEVATION

ELEVATION

SECTION VIEW

SECTION VIEW

SECTION VIEW

SECTION VIEW

beam

* Some states weld beam and piles prior to concrete placement 

Figure 10.1.1 Schematic of Common Abutment Types 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.4

Figure 10.1.2 Section View of Less Common Abutment Types 

GEOSYNTHETIC REINFORCED SOIL (GRS) 

MECHANICALLY STABILIZED EARTH (MSE) 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.5

Figure 10.1.3 Full Height Abutment

Figure 10.1.4 Stub Abutment

 Full Height Abutments and Stub Abutments 

Full height abutments are used when shorter spans are desired or if there are Rightof-Way or terrain issues. This reduces the initial superstructure costs. Stub 

abutments may be used when it is desirable to keep the abutments away from the 

underlying roadway or waterway. Longer spans are required when stub abutments 

are used. Using stub abutments reduces the cost of the substructure but increases 

the cost of the superstructure. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.6

Figure 10.1.5 Open Abutment

 Open Abutments 

Open, or spill-through, abutments are similar in construction to multi-column 

piers. Instead of being retained by a solid wall, the approach roadway embankment 

extends on a slope below the bridge seat and between (“through”) the supporting 

columns. Only the topmost few feet of the embankment are actually retained by 

the abutment cap. 

The advantages of the open abutment are lower cost since most of the horizontal 

load is eliminated, so the massive construction and heavy reinforcement usually 

associated with the abutment stem is not needed. This substructure type has the 

ability to convert the abutment to a pier if additional spans are added in the future. 

Open abutment disadvantages include a tendency for the fill to settle around the 

columns since good compaction is difficult to achieve in the confined spaces. 

Excessive erosion or scour may also occur in the fore slope. Rock fill is sometimes 

used to counter these problems. 

This abutment type is not suitable adjacent to streams due to susceptibility to 

scour. 

 Integral Abutments 

Most bridges have superstructures that are independent of the substructure to 

accommodate bridge length changes due to thermal effects. Expansion devices 

such as deck joints and expansion bearings allow for thermal movements but

deteriorate quickly and create a wide range of maintenance needs for the bridge. 

In extreme cases, lack of movement due to failed expansion devices can lead to 

undesirable stresses in the bridge. Integral abutments supported by a single row of 

piles are becoming more popular and provide a solution to these problems. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.7

In this design, the superstructure and substructure are integral and act as one unit 

without an expansion joint (see Figure 10.1.6). Relative movement of the 

abutment with respect to the backfill allows the structure to adjust to thermal 

expansions and contractions. Pavement joints at the ends of approach slabs are 

provided to accommodate the relative movement between the bridge and the 

approach roadway pavement. 

The advantage of the integral abutment is that it lacks bearing devices and joints to 

repair, or replace, or maintain. There are two disadvantages of integral abutments: 

settlement of the roadway approach due to undercompaction of backfill and 

cracking of the abutment concrete due to movement restriction caused by 

overcompaction of backfill. 

Concrete or

Steel Beam 

Finished

Ground

Construction

Joint

Approach Slab Deck

H-Pile

Figure 10.1.6 Integral Abutment 

Figure 10.1.7 Integral Abutment
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.8

Less Common Abutment 

Types and Abutment 

Elements 

Mechanically Stabilized Earth Abutments 

Mechanically Stabilized Earth (MSE) Support Abutment typically consists of 

precast concrete panels, metallic soil reinforcing strips (flat strips or welded bar 

grids), and backfill to support the superstructure and support the roadway approach

roadway embankment (see Figure 10.1.8). “Reinforced Earth” and “Retained 

Earth” are trademarked names given to these systems by suppliers of the 

components. Two MSE Abutment design concepts have been used. The first 

utilizes an MSE wall supporting a slab, or coping, on which the bridge bearings 

rest. Vertical loads are transmitted through the reinforced fill. The second concept 

utilizes piles or columns to support a stub abutment at the top of the reinforced fill. 

The piles provide vertical support for the bridge. The MSE provides lateral support 

for the approach roadway embankment. 

Precast concrete panels are erected first, followed by the placement and 

compaction of a layer of backfill. The layers of backfill are sometimes referred to 

as “lifts.” Soil reinforcement is then placed and bolted into the panels and covered 

with more backfill (see Figure 10.1.9). This process, which allows the wall to

remain stable during construction, is repeated until the designed height is attained. 

Advantages of this substructure are its internal stability and its ability to counteract 

shear forces, especially during earthquakes. It is generally lower in cost and has 

favorable esthetics when compared to a reinforced concrete full height abutment. 

Disadvantages include difficulty in repairing failed soil reinforcement and limited 

site applications. Another disadvantage is the possible settlement of an MSE wall 

that directly supports the superstructure (i.e. no stub abutment with piles). 

Figure 10.1.8 Mechanically Stabilized Earth Abutment (Note Precast Concrete 

Panels) 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.9

Figure 10.1.9 Mechanically Stabilized Earth Wall Under Construction

 Geosynthetic Reinforced Soil Abutments 

Another less common, fairly new type of abutment is the geosynthetic reinforced 

soil (GRS) abutment, developed by the Federal Highway Administration. GRS 

abutments are basically constructed on a level surface starting with a base structure 

of common, but high quality, cinder blocks. Fill is then placed and compacted 

with a sheet of geosynthetic reinforcement, which can be a series of polymer 

sheets or grids. These materials are layered until the designed height is attained. 

GRS abutments, which are internally supported, use friction to hold the blocks 

together and obtain their strength through proper spacing of the layers of 

reinforcement. Advantages of GRS abutments are their simplicity to construct, 

their durability, and their aesthetic appearance. GRS technology works well with 

simple overpasses; however, they are not ideal where severe flooding could occur 

(see Figures 10.1.10 and 10.1.11). 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.10

Figure 10.1.10 GRS Bridge Abutment Developed at the Turner-Fairbank 

Highway Research Center 

The stabilized earth concepts, using metallic or geosynthetic reinforcement, are 

more commonly used as retaining walls or wing walls than as abutments. See 

Report No. FHWA-SA-96-071 (Demo 82 Manual) for a detailed description of 

these systems. 

 

Figure 10.1.11 View of the Founders/Meadows Bridge Supported by GRS 

Abutments
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.11

Primary Materials The primary materials used in abutment construction are plain cement concrete, 

reinforced concrete, stone masonry, steel (although not very common), timber, or a 

combination of these materials. 

Figure 10.1.12 Plain Unreinforced Concrete Gravity Abutment 

Figure 10.1.13 Reinforced Concrete Cantilever Abutment 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.12

Figure 10.1.14 Stone Masonry Gravity Abutment

Figure 10.1.15 Combination: Timber Pile Bent Abutment with Reinforced 

Concrete Cap
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.13

Figure 10.1.16 Steel Abutment 

Primary and Secondary 

Reinforcement 

The pattern of primary steel reinforcement used in concrete abutments depends on 

the abutment type (see Figure 10.1.17). In a cantilever abutment, primary tension 

reinforcement include: vertical bars in the rear face of the stem and backwall, 

horizontal bars in the bottom of the footing (toe steel), and horizontal bars in the 

top of the footing (heel steel). In a concrete open or spill-through abutment, the 

primary reinforcement consists of both tension and shear steel reinforcement. 

Tension steel reinforcement generally consists of vertical bars in the rear face of 

the backwall and cap beam, horizontal bars in the bottom face of the cap beam, 

vertical bars in the columns and horizontal bars in the bottom of the footing.

Stirrups are used to resist shear in the cap beam. The column spirals or ties are 

generally considered to be secondary reinforcement to reduce the un-braced length 

of the vertical bars in the column. The spirals or ties may be considered primary 

reinforcement in seismic zones. All other bars would be temperature and 

shrinkage reinforcement, which is secondary reinforcement. 

Cantilever Open

Primary Reinforcing

Figure 10.1.17 Primary Reinforcement in Concrete Abutments 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.14

Cantilever Open

Figure 10.1.18 Secondary Reinforcement in Concrete Abutments 

Abutment Elements Common abutment elements include: 

3⁄4 Bridge seat 

3⁄4 Backwall 

3⁄4 Footing/Pile cap 

3⁄4 Cheek wall 

3⁄4 Abutment stem (breast wall) 

3⁄4 Tie backs 

3⁄4 Soil reinforcing strips 

3⁄4 Precast panels 

3⁄4 Deep foundations 

3⁄4 Geotextiles 

The basic abutment elements are shown in Figure 10.1.1, Figure 10.1.2 and 

described below. 

The bridge seat provides a bearing area that supports the bridge superstructure.

The backwall retains the approach roadway subbase and keeps it from sliding onto 

the bridge seat. It also provides support for the approach slab and for the 

expansion joint, if one is present. The cheek wall is mostly cosmetic but also 

protects the end bearings from the elements, (see Figure 10.1.19). A cheek wall is 

not always present. 

The abutment stem or breast wall supports the bridge seat and retains the soil 

behind the abutment. The foundation either spread footing or deep foundation 

(piles, drilled shafts, etc.), transmits the weight of the abutment, the soil backfill 

loads, and the bridge reactions to the supporting soil or rock. It also provides 

stability against overturning and sliding forces. The portion of the footing in front 

of the wall is called the toe, and the portion behind the wall, under the approach 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.15

embankment, is called the heel. 

Mechanically stabilized earth (MSE) walls consist of a reinforced soil mass and a 

concrete facing which is vertical or near vertical. The facing is often precast 

panels which are used to hold the soil in position at the face of the wall. The 

reinforced soil mass consists of select granular backfill. The tensile 

reinforcements and their connections may be proprietary, and may employ either 

metallic (i.e., strip- or grid-type) or polymeric (i.e., sheet-, strip-, or grid-type) 

reinforcement. The soil reinforcing strips hold the wall facing panels in position 

and provide reinforcement for the soil. Geotextiles are used to cover the joint 

between the panels. Geotextiles are placed behind the precast panels to keep the 

soil from being eroded through the joints and allow excess water to flow out. Tie 

backs are steel bars or strands grouted into the soil or rock behind the abutment 

stem. Tie backs, if present, are used when lateral earth forces cannot be resisted 

by the footing alone.

Figure 10.1.19 Cheek Wall 

Wingwall Back Wall

Stem

Footing Deep 

Foundation

(Optional)

Figure 10.1.20 Spread Footing/Deep Foundations 

Cheek Wall 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.16

Foundation Types Foundations are critical to the stability of the bridge since the foundation 

ultimately supports the entire structure. The two basic types of bridge foundations

shown in Figure 10.1.20 are: 

3⁄4 Spread footings 

3⁄4 Deep foundations 

A spread footing is used when the bedrock layers are close to the ground surface or 

when the soil is capable of supporting the bridge. A spread footing is typically a 

rectangular reinforced concrete slab. This type of foundation “spreads out” or 

distributes the loads from the bridge to the underlying rock or soil. While a spread 

footing is usually buried, it is generally covered with a minimal amount of soil. In 

cold regions, the bottom of a spread footing will be placed below the recognized 

maximum frost line depth for that area. 

A deep foundation is used when the soil is not suited for supporting the bridge. A 

pile is a long, slender support which is typically driven into the ground but can be 

placed in predrilled holes. Piles can be partially exposed and are made of steel, 

concrete (cast-in-place or precast), or timber. Various numbers and configurations 

of piles can be used to support a bridge foundation. This type of foundation 

transfers load to sound material well below the surface or, in the case of friction 

piles, to the surrounding soil. 

“Caisson”, “drilled shafts”, or “bored pile” is another type of deep foundation 

typically used when the soil stratum is typically less than 3 meters (10 feet) from 

the footing bottom to bedrock. Holes are drilled through the soil and filled with 

reinforced concrete. Temporary or permanent steel casing is utilized during the 

construction process to support and retain the sides of a borehole. Temporary steel 

casing is removed after the concrete is placed and is capable of withstanding the 

surrounding pressures. The minimum diameter used for bridge substructure 

construction is normally 0.75 meters (30"). Caissons, drilled shafts or bored piles

may be extended beyond 3 meters (10 feet) if economically feasible or if there are 

voids such as caverns or mines within the bedrock under the bridge. 

Figure 10.1.21 Stub Abutment on Piles with Piles Exposed
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.17

10.1.3 

Inspection 

Procedures and 

Locations for 

Abutments 

Inspection procedures for abutments are similar to superstructures, particularly 

when it involves material deterioration. See Topics 2.1 and 13.1 (Timber), Topics 

2.2 and 13.2 (Concrete), 2.3 and 13.3 (Steel), or Topic 2.4 (Stone Masonry) for 

specific material defects and inspection procedures. However, because stability is 

a paramount concern, checking for various forms of movement is required during 

the inspection of abutments. 

The locations for inspection are not particularly specific, but can be related to 

common abutment problems. 

The most common problems observed during the inspection of abutments are: 

3⁄4 Vertical movement 

3⁄4 Lateral movement 

3⁄4 Rotational movement 

3⁄4 Material defects 

3⁄4 Scour and undermining of the foundation 

3⁄4 Drainage system malfunction 

3⁄4 Areas subjected to high stresses 

3⁄4 Areas exposed to traffic 

3⁄4 Fatigue prone details and fracture critical members 

Vertical Movement Vertical movement can occur in the form of uniform settlement or differential 

settlement. A uniform settlement of all bridge substructure units, including 

abutments and piers/bents, will have little effect on the structure. Uniform 

settlements of 0.3 m (1 foot) have been detected on small bridges with no signs of 

distress. 

Differential settlement can produce serious distress in a bridge. Differential 

settlement may occur between different substructure units, causing damage of 

varying magnitude depending on span length and bridge type (see Figure 10.1.22). 

It may also occur under a single substructure unit (see Figure 10.1.23). This may 

cause an opening of the expansion joint between the abutment and wingwall, or it 

may cause cracking or tipping of the abutment, pier, or wall. 

The most common causes of vertical movement are soil bearing failure, 

consolidation of soil, scour, undermining and subsidence from mining or solution 

cavities. 

Figure 10.1.22 Differential Settlement Between Different Substructure Units 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.18

Vertical/Diagonal 

Crack

Sand and Gravel

Soft Clay

Dense Gravel Settlement in Clay

Figure 10.1.23 Differential Settlement Under an Abutment

Inspection for vertical movement, or settlement, should include: 

3⁄4 Inspect the joint opening between the end of the approach slab and the 

deck. In some cases, pavement expansion or approach fill expansion could 

conceivably cause vertical movement in the approach slab. 

3⁄4 Investigate existing and new cracks for signs of settlement (see Figure 

10.1.24). 

3⁄4 Examine the superstructure alignment for evidence of settlement 

(particularly the bridge railing and deck joints). 

3⁄4 Check for scour and undermining around the abutment footing or 

foundation. 

3⁄4 Inspect the joint that separates the wingwall and abutment for proper 

alignment.
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.19

Figure 10.1.24 Crack in Abutment due to Settlement 

Lateral Movement Earth retaining structures, such as abutments and retaining walls, are susceptible to 

lateral movements, or sliding (see Figure 10.1.25). Lateral movement occurs when 

the horizontal earth pressure acting on the wall exceeds the friction forces that hold 

the structure in place. 

Original wall position

Original grade Pavement settlement

Granular 

backfill

Soft clay

Slide failure 

plane

Heaved 

embankment

Figure 10.1.25 Lateral Movement of an Abutment due to Slope Failure 

The most common causes of lateral movement are slope failure, seepage, changes 

in soil characteristics (e.g., frost action and ice), and time consolidation of the 

original soil. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.20

Inspection for lateral movement, or sliding, should include: 

3⁄4 Inspect the general alignment of the abutment. 

3⁄4 Check the bearings for evidence of lateral displacement (see Figure 

10.1.26). 

3⁄4 Examine the opening in the construction joint between the wingwall and 

the abutment. 

3⁄4 Investigate the joint opening between the deck and the approach slab (see 

Figure 10.1.27). 

3⁄4 Check the approach roadway for settlement. 

3⁄4 Check the distance between the end of the superstructure and the 

backwall. 

3⁄4 Examine for clogged drains (approach roadway, weep holes, and 

substructure drainage). 

3⁄4 Inspect for erosion, scour or undermining of the embankment material in 

front of the abutment (see Figure 10.1.28).

Figure 10.1.26 Excessive Rocker Bearing Displacement Indicating Possible 

Lateral Displacement of Abutment 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.21

Figure 10.1.27 Depressed Approach Slab due to Rotating Abutment

Figure 10.1.28 Erosion at Abutment Exposing Footing
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.22

Rotational Movement Rotational movement, or tipping, of substructure units is generally the result of 

unsymmetrical settlements and / or lateral movements due to horizontal earth

pressure (see Figure 10.1.29). Abutments and walls are subject to this type of 

movement. 

Sand and Gravel

Soft Clay

Dense Gravel

Settlement in 

Clay

Figure 10.1.29 Rotational Movement of an Abutment 

The most common causes of rotational movement are undermining, scour, 

saturation of backfill, soil bearing failure, erosion of backfill along the sides of the 

abutment, and improper design. 

Inspection for rotational movement, or tipping, should include: 

3⁄4 Check the vertical alignment of the abutment using a plumb bob or level; 

keep in mind that some abutments are constructed with a battered or 

sloped front face (see Figures 10.1.30 and 10.1.31). 

3⁄4 Examine the clearance between the beams and the backwall. 

3⁄4 Inspect for clogged drains or weep holes. 

3⁄4 Investigate for unusual cracks or spalls.

3⁄4 Check for scour or undermining around the abutment footing. See Topic 

11.2 for a detailed description of scour and undermining. See Topic 11.3 

for a detailed description of underwater inspection. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.23

Figure 10.1.30 Rotational Movement at Abutment 

Soft Soft

Firm Firm

Fill Fill

Soft Soft

Firm Firm

Fill Fill

Abutment Movement

Thrust

Settlement

Soft Soft

Firm Firm

Fill Fill

Soft Soft

Firm Firm

Fill Fill

Soft Soft

Firm Firm

Fill Fill

Soft Soft

Firm Firm

Fill Fill

Abutment Movement

Thrust

Settlement

Figure 10.1.31 Rotational Movement due to “Lateral Squeeze” of Embankment 

Material
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.24

Material Defects A common problem observed during the inspection of abutments is the presence of 

construction material defects. Refer to Topics 2.1 – 2.4 for a more detailed 

description of the types and causes of deterioration observed in timber, concrete, 

steel and stone masonry. 

 Concrete and Stone Masonry 

Inspection for concrete and stone masonry material defects in abutments should 

include: 

3⁄4 Examine the bearing seats for cracking and spalling, particularly near the 

edges; this is particularly critical where concrete beams bear directly on 

the abutment seat (see Figure 10.1.32). 

3⁄4 Inspect for the presence of debris and standing water on the bearing seats. 

3⁄4 Investigate for deteriorated concrete in areas that are exposed to roadway 

drainage, particularly below the joint between the backwall and the deck 

(see Figure 10.1.33). 

3⁄4 Check the backwall for cracking and possible movement. 

3⁄4 Examine the construction joint between the backwall and the abutment 

stem. 

3⁄4 Inspect stone masonry for mortar cracks or loss of mortar in the joints (see 

Figure 10.1.34). 

3⁄4 Examine stone masonry for vegetation, water seepage through cracks, 

loose or missing stones, weathering, split, spalled, loose or missing blocks.

Several advanced techniques are available for concrete inspection. Nondestructive 

and other methods are described in Topics 13.2.2 and 13.2.3. 

Figure 10.1.32 Cracking in Bearing Seat of Concrete and Stone Abutment 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.25

Figure 10.1.33 Deteriorated Concrete in Abutment Backwall

Figure 10.1.34 Deteriorated Stone Masonry Abutment
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.26

 Steel 

Although a steel abutment is uncommon (see Figure 10.1.35), the following items 

should be inspected if one is encountered: 

3⁄4 Examine bearing seat area for buildup of dirt and debris. 

3⁄4 After cleaning, check bearing seat area for corrosion and section loss. 

3⁄4 Inspect cap beam, piles, and any other steel elements for corrosion, 

cracking, and section loss. 

3⁄4 Investigate piles closely at the ground line. 

3⁄4 Check for scour and erosion around the piles. 

3⁄4 Examine all fasteners and connections for condition and tightness.

Several advanced techniques are available for steel inspection. Nondestructive and 

other methods are described in Topics 13.3.2 and 13.3.3. 

Figure 10.1.35 Steel Abutment 

 Timber 

Inspection for timber defects in abutments should include: 

3⁄4 Examine bearing seat for accumulated dirt and debris and prolonged 

exposure to moisture. 

3⁄4 Inspect for decay, insect damage, and crushing of the cap beam. 

3⁄4 Investigate for local failures in lagging or piles due to lateral movement 

(see Figure 10.1.36). 

3⁄4 Check crib timbers, timber lagging, and piles for splits, cracks, decay, 

insect damage, fire damage, and chemical attack (see Figure 10.1.37). 

3⁄4 Inspect for scour around the piles (see Figure 10.1.38). 

3⁄4 Examine piles very closely for decay at or near the ground line or 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.27

waterline. 

3⁄4 Investigate splices and connections for tightness and for loose bolts. 

3⁄4 In marine environments, examine piles for the presence of marine borers 

and caddis flies.

Several advanced techniques are available for timber inspection. Nondestructive 

and other methods are described in Topics 13.1.2 and 13.1.3. 

Figure 10.1.36 Local Failure in Timber Pile due to Lateral Movement of 

Abutment 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.28

Figure 10.1.37 Decay in Lagging of Timber Crib Abutment

Figure 10.1.38 Decayed Lagging and Scour at a Timber Pile Bent Abutment

Scour and Undermining Scour is the removal of material from a streambed as a result of the erosive action 

of running water (see Figure 10.1.39). Scour can cause undermining or the 

removal of supporting foundation material from beneath the abutments when 

streams or rivers flow adjacent to them. Refer to Topic 11.2 for a more detailed 

description of scour and undermining. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.29

Figure 10.1.39 Abutment with Undermining due to Scour 

Inspection for scour should include probing around the abutment footing for signs 

of undermining (see Figure 10.1.40). Sometimes silt loosely fills in a scour hole 

and offers no protection or bearing capacity for the abutment footing. 

Figure 10.1.40 Inspector Checking for Scour 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.30

Drainage Systems Water can build up horizontal pressure behind an abutment. Allowing the water to 

exit from behind the abutment relieves this pressure. Weep holes, normally 100 

mm (4 inches) in diameter, allow water to pass through the abutment. Sometimes 

abutments have subsurface drainage pipes that are parallel to the rear face of the 

abutment stem. These pipes are sloped to drain the water out at the end of the 

abutment. 

Check weep holes and subsurface drainage pipes to see that they are clear and 

functioning. Be careful of any animal or insect nests that may be in the weep 

holes. Look for signs of discoloration under the weep holes, which may indicate 

that the weep holes or substructure drainage pipes are functioning properly. Check 

the condition of any drainage system that is placed adjacent to the abutment that 

may result in deterioration of the abutment. 

Areas Subjected to High 

Stresses 

Closely examine the high bearing zones, high shear zones, and high flexural areas. 

High bearing zones include the bridge seats, the abutment stem/footing 

connection, and the area where the footing is supported by earth or deep 

foundations. In timber abutments, look for crushing. Look for cracking or 

spalling in concrete and masonry members. Examine steel members for buckling 

or distortion. 

Horizontal forces cause high shear zones at the bottom of the backwall, and 

bottom of abutment stem. In timber abutments, look for splitting. Look for 

diagonal cracks in concrete and masonry. Examine steel members for buckling or 

distortion. 

High flexural moments caused by horizontal forces occur at the bottom of the 

backwall and abutment stem connection. High flexural moments may be 

occurring at the footing toe/abutment stem. Moments cause compression and 

tension depending on the load type and location of the member neutral axis. Look 

for defects caused by overstress due to compression or tension caused by flexural 

moments. Check compression areas for splitting, crushing or buckling. Examine 

tension members for cracking or distortion. 

Areas Exposed to Traffic Check for collision damage from vehicles passing adjacent to structural members. 

Damage to concrete abutments may include spalls and exposed reinforcement and 

possibly steel reinforcement section loss. 

Steel abutments may experience cracks, section loss, or distortion which must be 

documented. 

Fatigue Prone Details and 

Fracture Critical 

Members 

Steel abutments may contain fatigue prone details. Closely examine these details 

for section loss due to corrosion and cracking. The members of a steel abutment 

may be fracture critical. See Topic 8.1 for a detailed description of fatigue prone 

details and fracture critical members. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.31

10.1.4 

Design 

Characteristics of 

Wingwalls 

General Wingwalls are located on the sides of an abutment and enclose the approach fill. 

Wingwalls are generally considered to be retaining walls since they are designed 

to maintain a difference in ground surface elevations on the two sides of the wall 

(see Figure 10.1.41). 

A wingwall is similar to an abutment except that it is not required to carry any 

loads from the superstructure. The absence of the vertical superstructure load 

usually necessitates a wider footing to resist the overturning moment or horizontal 

sliding. 

Figure 10.1.41 Typical Wingwall 

Geometrical 

Classifications 

There are several geometrical classifications of wingwalls, and their use is 

dependent on the design requirements of the structure: 

3⁄4 Straight - extensions of the abutment wall (see Figure 10.1.42) 

3⁄4 Flared - form an acute angle with the bridge roadway (see Figure 10.1.43)

3⁄4 U-wings - parallel to the bridge roadway (see Figure 10.1.44)
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.32

Figure 10.1.42 Straight Wingwall 

Figure 10.1.43 Flared Wingwall
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.33

Figure 10.1.44 U-wingwall 

Construction 

Classifications 

There are several construction classifications of wingwalls: 

3⁄4 Integral - constructed monolithically with the abutment (see Figure 

10.1.45) normally cast-in-place concrete 

3⁄4 Independent - constructed separately from the abutment; usually an 

expansion or mortar joint separates them from the abutment stem (see 

Figure 10.1.46)

Figure 10.1.45 Integral Wingwall
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.34

Figure 10.1.46 Independent MSE Wingwall

Primary Materials Wingwalls may be constructed of concrete, stone masonry, steel, or timber or a 

combination of these materials. 

Figure 10.1.47 Masonry Wingwall 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.35

Primary and Secondary 

Reinforcement 

In a concrete cantilever wingwall, the primary reinforcing steel consists of vertical 

bars in the rear face of the stem, horizontal bars in the bottom of the footing (toe 

steel), and horizontal bars in the top of the footing (heel steel) (see Figure 10.1.48). 

Secondary reinforcement is used to resist temperature and shrinkage. 

Primary 

Reinforcement

Figure 10.1.48 Primary Reinforcement in Concrete Cantilever Wingwall

10.1.5 

Inspection 

Procedures and 

Locations for 

Wingwalls 

The inspection procedures and locations for most wingwalls are similar to those 

for abutments (see Topic 10.1.3). Many of the problems that occur in abutments 

are common in wingwalls also, including: 

3⁄4 Vertical movement 

3⁄4 Lateral movement 

3⁄4 Rotational movement (see Figure 10.1.49) 

3⁄4 Material defects (see Figure 10.1.50) 

3⁄4 Scour/undermining (see Figure 10.1.51) 

3⁄4 Drainage systems

3⁄4 Areas subjected to high stresses

3⁄4 Areas exposed to traffic 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.36

Figure 10.1.49 Rotational Movement at Concrete Wingwall 

Figure 10.1.50 Deteriorated Concrete Wingwall
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.37

Figure 10.1.51 Scour and Possible Undermining of Concrete Wingwall

Material defects to look for include shoulder erosion, cracks, concrete 

deterioration, stone masonry deterioration, timber decay, and steel buckling (see 

Figures 10.1.52 to 10.1.55). 

Figure 10.1.52 Roadway Shoulder Erosion Behind Wingwall 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.38

Figure 10.1.53 Settlement Cracks at Integral Concrete Wingwalls

Figure 10.1.54 Deteriorating Stone Masonry Wingwall
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.39

Figure 10.1.55 Timber Wingwall

Wingwall problems are similar to problems in abutments. Refer to Topic 10.1.3 

for a detailed description of common abutment problems. 

Integral wingwalls should be inspected with the abutments, and they are included 

in the substructure evaluation and condition rating. However, only that portion up 

to the first construction or expansion joint is considered. Independent wingwalls 

should also be inspected, but their condition does not affect the evaluation and 

condition rating of the substructure. The condition of integral and independent 

wingwalls should be noted on the inspection form. 

10.1.6 

Evaluation State and federal rating guideline systems have been developed to aid in the 

inspection of substructures. The two major rating guideline systems currently in 

use are the FHWA's Recording and Coding Guide for the Structural Inventory and 

Appraisal of the Nation's Bridges used for the National Bridge Inventory (NBI) 

component rating method and the AASHTO element level condition state 

assessment method. 

NBI Rating Guidelines Using NBI rating guidelines, a 1-digit code on the Federal Structure Inventory and 

Appraisal (SI&A) sheet indicates the condition of the entire substructure including 

abutments and piers. Rating codes range from 9 to 0, where 9 is the best rating 

possible. See Topic 4.2 (Item 60) for additional details about NBI Rating 

Guidelines. 

The previous inspection data should be considered along with current inspection 

findings to determine the correct condition rating. 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.1: Abutments and Wingwalls 

10.1.40

Element Level Condition 

State Assessment 

In an element level condition state assessment of an abutment or wingwall 

structure, the AASHTO CoRe element typically is one of the following: 

Element No. Description

215 Abutment – Reinforced Concrete 

216 Abutment – Timber 

217 Abutment – Other (masonry, steel, etc.) 

Some bridge owners use the following CoRe elements for abutments similar to 

those shown in Figures 10.1.5, 10.1.15, 10.1.16, 10.1.36, and 10.1.38, 

Element No. Description

201 Unpainted Steel Column or Pile Extension (EA) 

225 Unpainted Steel Submerged Pile (EA) 

230 Unpainted Steel Cap (m or ft) 

202 Painted Steel Column or Pile Extension (EA) 

231 Painted Steel Cap (m or ft) 

204 Prestressed Concrete Column or Pile Extension (EA) 

226 Prestressed Concrete Submerged Pile (EA) 

233 Prestressed Concrete Cap (m or ft) 

205 Reinforced Concrete Column or Pile Extension (EA) 

220 Reinforced Concrete Submerged Pile Cap/Footing (EA) 

227 Reinforced Concrete Submerged Pile (EA) 

234 Reinforced Concrete Cap (m or ft) 

206 Timber Column or Pile Extension (EA) 

228 Timber Submerged Pile (EA) 

235 Timber Cap (m or ft) 

The unit quantity for the substructure elements is meters or feet, measured 

horizontally across the abutment and the total length must be distributed among the 

four available condition states depending on the extent and severity of 

deterioration. The unit quantity for columns and piles is each and the total quantity 

must be placed in one of the available condition states. In all cases, Condition state 

1 is the best possible rating. See the AASHTO Guide for Commonly Recognized 

(CoRe) Structural Elements for condition state descriptions. 

A Smart Flag is used when a specific condition exists, which is not described in the 

CoRe element condition state. The severity of the damage is captured by coding 

the appropriate Smart Flag condition state. The Smart Flag quantities are measured 

as each, with only one each of any given Smart Flag per bridge. 

For settlement of the abutment or wingwall, the “Settlement” Smart Flag, Element 

No. 360, can be used and one of three condition states assigned. For scour at the 

abutments or wingwalls, the “Scour” Smart Flag, Element No. 361, can be used 

and one of three condition states assigned. 
10.2-i 

Table of Contents

Section 10 ..................................................................................................................................................

Inspection and 

Evaluation of 

Substructures 

 10.2 Piers and Bents ................................................................................... 10.2.1 

 10.2.1 Introduction............................................................................. 10.2.1 

 

 10.2.2 Design Characteristics............................................................. 10.2.1 

 Pier and Bent Types.......................................................... 10.2.1 

 Primary Materials ............................................................. 10.2.7 

 Primary and Secondary Reinforcement.......................... 10.2.10 

 Pier and Bent Elements .................................................. 10.2.13 

 Foundation Types........................................................... 10.2.13 

 Pier Protection ................................................................ 10.2.14 

 

 10.2.3 Inspection Locations and Procedures.................................... 10.2.18 

 Vertical Movement......................................................... 10.2.18 

 Rotational Movement ..................................................... 10.2.20 

 Lateral Movement .......................................................... 10.2.20 

 Material Defects ............................................................. 10.2.22 

 Concrete................................................................... 10.2.22 

 Steel ......................................................................... 10.2.25 

 Timber...................................................................... 10.2.28 

 Stone Masonry ......................................................... 10.2.32 

 Scour and Undermining.................................................. 10.2.32 

 Areas Subjected to High Stresses................................... 10.2.33 

 Areas Exposed to Traffic................................................ 10.2.33 

 Fatigue Prone Details and Fracture Critical Members ... 10.2.34 

 Dolphins and Fenders..................................................... 10.2.34 

 10.2.4 Evaluation ............................................................................. 10.2.36 

 NBI Rating Guidelines ................................................... 10.2.36 

Element Level Condition State Assessment................... 10.2.37 
SECTION 10: Inspection and Evaluation of Substructures 

TOPIC 10.2: Piers and Bents 

10.2-ii

This page intentionally left blank 
10.2.1

Topic 10.2 Piers and Bents 

10.2.1 

Introduction A pier or bent is an intermediate substructure unit located between the ends of a 

bridge. Its function is to support the bridge at intermediate intervals with minimal 

obstruction to the flow of traffic or water below the bridge (see Figure 10.2.1). 

The difference between a pier and a bent is simply in physical appearance. There 

is no functional difference between the two. A pier generally has only one column 

or shaft supported by one footing. Bents have two or more columns and each 

column is supported by an individual footing. 

Figure 10.2.1 Example of Piers as Intermediate Supports for a Bridge 

10.2.2 

Design 

Characteristics 

Pier and Bent Types The most common pier and bent types are: 

3⁄4 Solid shaft pier (see Figure 10.2.2) 

3⁄4 Column pier (see Figure 10.2.3) 

3⁄4 Column pier with web wall (see Figures 10.2.4 and 10.2.5) 

3⁄4 Cantilever pier or hammerhead pier (see Figures 10.2.6 and 10.2.7) 

3⁄4 Column bent or open bent (see Figure 10.2.8) 

3⁄4 Pile bent (see Figure 10.2.9) 

Detailed descriptions of pier and bent elements are provided on page 10.2.13. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.2 

Figure 10.2.2 Solid Shaft Pier 

Solid shaft piers are used when a large mass is advantageous or when a limited 

number of load points are required for the superstructure. 

Figure 10.2.3 Column Pier 

Column piers are used when limited clearance is available under the structure or 

when narrow superstructure widths are required. 

 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.3 

Footing

Columns

Deep Foundation 

(optional)

Pier Cap

(optional)

Web 

Wall

Figure 10.2.4 Column Pier with Web Wall 

A web wall can be connected to columns to add stability to the pier. The web wall 

is non-structural relative to superstructure loads. Web walls also serve to 

strengthen the columns in the event of a vehicular collision. 

Figure 10.2.5 Column Pier with Web Wall
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.4 

Figure 10.2.6 Single Stem Pier (Cantilever or Hammerhead) 

The cantilever or hammerhead pier is a modified column pier for use with multibeam superstructures. 

Figure 10.2.7 Cantilever Pier

Cap

Shaft or

Stem

Footing
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.5 

Figure 10.2.8 Column Bent or Open Bent

The column bent is a common pier type for highway grade crossings. 

Figure 10.2.9 Concrete Pile Bent

Pile bents may be constructed of concrete, steel or timber. Typically, piles are 

driven in place and support a continuous cast-in-place concrete cap. 

Two other specialized types of pier include the hollow pier and the integral pier. 

Hollow piers are usually tall shaft type piers built for bridges crossing deep valleys 

Being hollow greatly reduces the dead load of the pier and increases it’s ductility. 

Whether precast or cast-in-place, hollow piers are constructed in segments. If 

precast, the segments are post-tensioned together and the joints are epoxy-sealed. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.6 

The decrease in the dead load, or self-weight, of the piers provides ease in 

transporting them to the site, and the high ductility provides for better performance 

against seismic forces. 

 

Integral piers incorporate the pier cap into the depth of the superstructure. Integral 

piers provide for a more rigid structure, and they are typically used in situations 

where vertical clearance beneath the structure is limited. Integral piers may consist 

of steel or cast-in-place caps within a steel girder superstructure. The concrete cap 

would likely be post-tensioned rather than conventionally reinforced (see Figures 

10.2.10 to 10.2.12). 

Figure 10.2.10 Integral Pier Cap 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.7 

Figure 10.2.11 Integral Pier and Pier Cap

Figure 10.2.12 Integral Pier and Pier Cap

Primary Materials The primary materials used in pier and bent construction are plain cement 

concrete, reinforced concrete, stone masonry, steel, timber, or a combination of 

these materials (see Figures 10.2.13 to 10.2.17). 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.8 

Figure 10.2.13 Reinforced Concrete Piers under Construction 

Figure 10.2.14 Stone Masonry Pier
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.9 

Figure 10.2.15 Steel Bent

Figure 10.2.16 Timber Pile Bent
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.10

Figure 10.2.17 Combination: Reinforced Concrete Column with Steel Pier Cap

Primary and Secondary 

Reinforcement 

The pattern of primary reinforcement for concrete piers depends upon the pier 

configuration. Piers with relatively small columns, whether of the single shaft, 

multi-column, or column and web wall design, have heavy vertical reinforcement 

confined within closely spaced ties or spirals in the columns. Pier caps are 

reinforced according to their beam function. Cantilevered caps have primary 

tension steel near the top surface. Caps spanning between columns have primary 

tension steel near the bottom surface. Primary shear steel consists of vertical 

stirrups, usually more closely spaced near support columns or piles. 

Wall type piers are more lightly reinforced, but still have significant vertical 

reinforcement to resist horizontal loads. 

If primary steel is not required at a given location, then temperature and shrinkage 

steel will be provided. All the concrete faces should be reinforced in both the 

vertical and horizontal directions. 

Pier foundations are likewise reinforced to match their function in resisting applied 

loads. Shear stirrups are generally not required for footings as they are designed 

thick enough to permit only the concrete to resist the shear. Modern designs, 

however, do incorporate seismic ties (vertical bars with hooks at each end) to tie 

the top and bottom mats of rebar together. 

Figures 10.2.18 – 10.2.21 illustrate typical reinforcement patterns. 

New design specifications may call for epoxy coated reinforcement if the 

substructure will be subjected to de-icing chemicals or salt water. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.11

Tension 

Reinforcement

Shear Reinforcement Tension 

Reinforcement

Figure 10.2.18 Primary Reinforcement in Column Bent with Web Wall 

Temperature and Shrinkage Reinforcement 

Shown

Figure 10.2.19 Secondary Reinforcement in Column Bent with Web Wall 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.12

Tension 

Reinforcement

Shear 

Reinforcement

Figure 10.2.20 Primary Reinforcement in Column Bents

Tension Reinforcement Shear Reinforcement

Tension Reinforcement

Figure 10.2.21 Primary Reinforcement for a Cantilevered Pier 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.13

Pier and Bent Elements The primary pier and bent elements are: 

3⁄4 Pier cap or bent cap 

3⁄4 Pier wall / stem / or shaft 

3⁄4 Column 

3⁄4 Footing 

3⁄4 Piles or Drilled Shafts 

The pier cap or bent cap provides support for the bearings and the superstructure 

(see Figures 10.2.22 and 10.2.23). 

The pier wall or stem transmits loads from the pier cap to the footing. 

Columns transmit loads from the pier or bent cap to the footing (see Figure 

10.2.22). 

The footing transmits the weight of piers or bents, and the bridge reactions to the 

supporting soil or rock. The footing also provides stability to the pier or bent 

against overturning and sliding forces. 

Foundation Types Foundations are critical to the stability of the bridge since the foundation 

ultimately supports the entire structure. There are two basic types of bridge 

foundations: 

3⁄4 Spread footings 

3⁄4 Deep foundations 

Spread footing and deep foundations are described on page 10.1.16 of Topic 10.1, 

Abutments and Wingwalls. 

Figure 10.2.22 Two Column Bent Joined by a Web Wall
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.14

Figure 10.2.23 Pile Bent

Pier Protection Piers can be vulnerable to collision damage from trucks, trains, ships and ice 

flows. Wall type piers are resistant to this type of collision damage and are often 

used in navigable waterways and waterways subject to freezing for this reason. 

Web walls can also serve to protect columns (see Figures 10.2.24 and 10.2.25). 

External barriers are often provided for single- or multi-column piers. Dolphins

are single, large diameter, sand-filled, sheet pile cylinders; clusters of timber piles 

or steel tubes; or large concrete blocks placed in front of a pier to protect it from 

collision (see Figures 10.2.26 and 10.2.27). Fenders are protective fences 

surrounding a pier to protect it from marine traffic. They may consist of timber 

bent arrangements, steel or concrete frames, or cofferdam sheets (see Figures 

10.2.28 and 10.2.29). 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.15

Cap

Columns

Collision

Wall

Footing

Figure 10.2.24 Collision Wall 

Figure 10.2.25 Collision Wall 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.16

Figure 10.2.26 Concrete Block Dolphin

Figure 10.2.27 Timber Dolphin
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.17

Figure 10.2.28 Pier Fender

Figure 10.2.29 Fender System
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.18

10.2.3 

Inspection 

Locations and 

Procedures 

Inspection procedures for piers and bents are similar to superstructures, 

particularly when it involves material deterioration. See Topics 2.1 and 13.1 

(Timber), Topics 2.2 and 13.2 (Concrete), Topics 2.3 and 13.3 (Steel) and Topic 

2.4 (Masonry). However, because stability is a paramount concern, checking for 

various forms of movement is required during the inspection of piers or bents. 

The locations for inspection are not particularly specific, but can be related to 

common pier and bent problems. 

The most common problems observed during the inspection of piers and bents are:

3⁄4 Vertical movement 

3⁄4 Rotational movement and lateral movement 

3⁄4 Material defects

3⁄4 Scour and undermining

3⁄4 Areas subjected to high stresses

3⁄4 Areas exposed to traffic

3⁄4 Fatigue prone details and fracture critical members 

3⁄4 Dolphins and fenders

Vertical Movement Differential settlement at piers can cause serious problems in a bridge (see Figure 

10.2.30). Deck joints can open excessively or close up completely. Local 

deterioration, such as spalling, cracking, and buckling, can also occur. 

The most common causes of vertical movement are soil bearing failure, soil 

consolidation, scour, undermining, and subsidence from mining or solution 

cavities. 

 

Figure 10.2.30 Differential Settlement Between Different Substructure Units 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.19

Sand and Gravel

Soft Clay

Dense Gravel Settlement in Clay

Figure 10.2.31 Differential Settlement Under a Pier

Inspection for vertical movement, or settlement, should include: 

3⁄4 For bridges with multiple simple spans, examine the joint in the deck 

above the pier as well as at adjacent piers and at the abutments. 

3⁄4 Check for any new or unusual cracking in the pier or bent. 

3⁄4 Investigate for buckling in steel columns of the pier or bent. 

3⁄4 Check the superstructure for evidence of settlement. Sight along parapets, 

bridge rails, etc. (see Figure 10.2.32). 

3⁄4 Investigate for scour and undermining around the pier footing. 

3⁄4 In some cases, a check of bearing seat or top of pier elevations using 

surveying equipment may be necessary.
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.20

Figure 10.2.32 Superstructure Evidence of Pier Settlement 

Rotational Movement Differential settlement or excessive longitudinal or transverse forces, such as those 

experienced during an earthquake, may cause rotational movement (tipping) and 

lateral (horizontal) movement of piers or bents. 

Inspection for rotational movement, or tipping, should include: 

3⁄4 Checking vertical alignment of the pier using a plumb bob or level. 

3⁄4 Investigating the clearance between the ends of the simply supported 

beams at piers. 

3⁄4 Inspect for unusual cracking or spalling. 

Lateral Movement Inspection for lateral movement, or sliding, should include: 

3⁄4 Checking the general alignment. 

3⁄4 Check the bearings for evidence of lateral displacement. 

3⁄4 Investigate the deck joints. The deck joint openings should be consistent 

with the recorded temperature. 

3⁄4 Inspect for cracking or spalling that may otherwise be unexplained; in the 

case of inspections after earthquakes, such damage will be readily 

apparent (see Figure 10.2.33). 

3⁄4 Check for scour or undermining around the pier or bent footing (see 

Figures 10.2.34 – 10.2.35). Refer to Topic 11.2 for a more detailed 

description of scour and undermining. Refer to Topic 11.3 for a more 

detailed description of underwater inspection. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.21

Figure 10.2.33 Cracks in Bent Cap due to Lateral Movement of Bent during 

Earthquake

Figure 10.2.34 Pier Movement and Superstructure Damage due to 

Scour/Undermining 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.22

Figure 10.2.35 Tipping of Bent due to Scour/Undermining 

Material Defects A common problem encountered during the inspection of piers and bents is 

material defects. Refer to Topics 2.1 – 2.4 of this manual for detailed descriptions 

of the types and causes of deterioration observed in timber, concrete, steel, and 

masonry. 

Concrete 

Inspection of concrete in piers and bents should include the following: 

3⁄4 Inspect for deterioration of the concrete, especially in the splash zone (i.e., 

up to 600 mm (2 feet) above high tide or mean water level), at the 

waterline, at the ground line, and wherever concrete is exposed to roadway 

drainage (see Figure 10.2.36). 

3⁄4 Examine the pier columns and the pier bent caps for cracks (see Figure 

10.2.37). 

3⁄4 If steel reinforcement is exposed, check for section loss. 

3⁄4 Check the pier caps and bearing seats for cracking and spalling (see Figure 

10.2.38). 

3⁄4 Examine grout pads and pedestals for cracks, spalls, and deterioration. 

3⁄4 Investigate any significant changes in clearance for pier movement. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.23

3⁄4 Check all pier and bent members for structural damage caused by collision 

or overstress (see Figure 10.2.39). 

3⁄4 Determine whether any earth or rock fills have been piled against piers, 

causing loads which were not provided for in the original design and 

producing unstable conditions.

Several advanced techniques are available for concrete inspection. Nondestructive 

and other methods are described in Topics 13.2.2 and 13.2.3. 

Figure 10.2.36 Concrete Deterioration due to Contaminated Drainage 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.24

Figure 10.2.38 Severe Concrete Spalling on Bent Cap

Figure 10.2.37 Crack in Concrete Bent Cap
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.25

Figure 10.2.39 Collision Damage to Pier Column

 Steel 

Inspection of steel in piers and bents should include the following: 

3⁄4 Check pile bents for the presence of corrosion, especially at the ground 

line. 

3⁄4 Over water crossings, investigate the splash zone (i.e., up to 600 mm (2 

feet) above high tide or mean water level) and the submerged part of the 

piles for indications of corrosion and loss of section (see Figure 10.2.41). 

3⁄4 Check for debris around the pile or pier bases; debris will retain moisture 

and promote corrosion. 

3⁄4 Examine the steel caps for rotation due to eccentric connections. 

3⁄4 Inspect the bracing for broken connections and loose rivets or bolts (see 

Figure 10.2.42). 

3⁄4 Check the condition of the web stiffeners, if present. 

3⁄4 Check the pier columns and pier caps for cracks (see Figure 10.2.43). 

3⁄4 When there are any significant changes in clearance, visually inspect and 

measure for pier movement. 

3⁄4 Examine all pier and bent members for structural damage caused by 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.26

collision, buckling, or overstress. 

3⁄4 Where a steel cap girder and continuous longitudinal beams are framed 

together, inspect the top flanges, welds, and webs for cracking. 

Several advanced techniques are available for steel inspection. Nondestructive and 

other methods are described in Topics 13.3.2 and 13.3.3. 

Figure 10.2.40 Deterioration of Concrete Pedestal Supporting Steel Column 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.27

Figure 10.2.41 Corrosion and Debris at Steel Pile Bent

Figure 10.2.42 Steel Column Bent
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.28

Figure 10.2.43 Steel Column Bent with Cantilever

 Timber 

Inspection of timber in piers and bents should include the following: 

3⁄4 Check for decay in the piles, caps, and bracing. The presence of decay can 

be determined by tapping with a hammer or by test boring the timber. 

Drilling with a decay detection device can also be used (see Figure 

10.2.44). Inspect particularly at the ground line or waterline, joints and 

splices, checks in the wood, bolt holes, caps, or other connections, since 

decay usually begins in these areas (see Figures 10.2.45 to 10.2.47). 

3⁄4 Examine splices and connections for tightness and for loose bolts. 

3⁄4 Investigate the condition of the cap at those locations where the beams 

bear directly upon it and where the cap bears directly upon the piles. Note 

particularly any splitting or crushing of the timber in these areas. 

3⁄4 Observe caps and piles that are under heavy loads for excessive 

deflection(see Figure 10.2.48). 

3⁄4 Check all piers and bent members for structural damage caused by 

collision or overstress. 

3⁄4 In marine environments, check for the presence of marine borers, 

shipworms, and caddisflies (see Figures 10.2.49 to 10.2.50).

3⁄4 Check for evidence of insect damage.

Several advanced techniques are available for timber inspection. Nondestructive 

and other methods are described in Topics 13.1.2 and 13.1.3. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.29

Figure 10.2.44 Drilling a Timber Bent Column for a Core Sample 

Figure 10.2.45 Decay in Timber Bent Cap (Note “Protective” Cover / Flashing) 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.30

Figure 10.2.46 Timber Bent Columns in Water

Figure 10.2.47 Decay of Timber Bent Column at Ground Line
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.31

Figure 10.2.48 Timber Pile Bent with Partial “Brooming” Failure at First Pile

Figure 10.2.49 Timber Pile Damage due to Limnoria Marine Borers
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.32

Figure 10.2.50 Timber Bent Damage due to Shipworm Marine Borers

 Stone Masonry 

Inspection of stone masonry in piers and bents should include the following: 

3⁄4 Inspect stone masonry for mortar cracks or loss of mortar in the joints. 

3⁄4 Examine stone masonry for vegetation, water seepage through cracks, 

loose or missing stones, weathering, split, spalled, loose or missing blocks 

(see Figure 10.2.51).

Scour and Undermining Scour is the removal of material from a streambed as a result of the erosive action 

of running water. Scour can cause undermining or the removal of supporting 

foundation material from beneath the piers or bents when streams or rivers flow 

adjacent to them. Refer to Topic 11.2 for a more detailed description of scour and 

undermining. 

Inspection for scour should include probing around the pier or bent footing for 

signs of undermining. Sometimes silt loosely fills in a scour hole and offers no 

protection or bearing capacity for the pier or bent footing. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.33

Figure 10.2.51 Deteriorated and Missing Stone at Masonry Pier

Areas Subjected to High 

Stresses 

Closely examine the high bearing zones, high shear zones, and high flexural areas. 

High bearing zones include the bridge seats, the pier cap, the pier shaft or bent 

column/footing connection, and the area where the footing is supported by earth or 

deep foundations. In timber piers or bents, look for crushing. Look for cracking 

or spalling in concrete and masonry members. Examine steel members for 

buckling or distortion. 

Horizontal forces cause high shear zones on the bottom of the pier shaft or bent 

column. In timber piers or bents, look for splitting. Look for diagonal cracks in 

concrete and masonry. Examine steel members for buckling or distortion. 

High flexural moments caused by horizontal forces occur at the bottom of the pier 

shaft or bent column. High flexural moments may be occurring at the footing 

toe/pier shaft. Moments cause compression and tension depending on the load 

type and location of the member neutral axis. Look for defects caused by 

overstress due to compression or tension caused by flexural moments. Check 

compression areas for splitting, crushing or buckling. Examine tension members 

for cracking or distortion. 

Areas Exposed to Traffic Check for collision damage from vehicles passing adjacent to structural members. 

Damage to concrete piers or bents may include spalls and exposed rebars. Steel 

piers or bents may experience cracks, section loss, or distortion which must be 

documented. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.34

Fatigue Prone Details and 

Fracture Critical 

Members 

Steel piers or bents may contain fatigue prone details. Closely examine these 

details for section loss due to corrosion and cracking. 

Steel piers or bents may be considered to be fracture critical (see Figure 10.2.52). 

See Topic 8.1 for a detailed description of fatigue prone details and fracture 

critical members. 

Figure 10.2.52 Fracture Critical Steel Bent 

Dolphins and Fenders The condition of dolphins and fenders should be checked in a manner similar to 

that used for inspecting the main substructure elements. 

In concrete pier protection members, check for spalling and cracking of concrete 

or corrosion of the reinforcing steel (see Figure 10.2.53). Investigate for hourglass shaping of piles due to abrasion at the waterline, and check for structural 

damage caused by marine traffic. 

In steel pier protection members, observe the splash zone (i.e., up to 0.6 m (2 feet) 

above high tide or mean water level) carefully for severe corrosion. Where there 

are no tides, check the area from the mean water level to 0.6 m (2 feet) above it. 

Also examine all other steel parts for corrosion, and check for structural damage 

(see Figure 10.2.54). 

In timber pier protection members, observe the portions between the high 

waterline and the mud line for marine borers, caddisflies, and decay, and check for 

structural damage (see Figure 10.2.55). Also, check for hourglass shaping of piles 

at the waterline. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.35

Figure 10.2.53 Concrete Dolphins 

Figure 10.2.54 Steel Fender 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.36

Figure 10.2.55 Timber Fender System 

10.2.4 

Evaluation State and federal rating guideline systems have been developed to aid in the 

inspection of substructures. The two major rating guideline systems currently in 

use are the FHWA's Recording and Coding Guide for the Structural Inventory and 

Appraisal of the Nation's Bridges used for the National Bridge Inventory (NBI) 

component rating method and the AASHTO element level condition state 

assessment method. 

NBI Rating Guidelines Using NBI rating guidelines, a 1-digit code on the Federal Structure Inventory and 

Appraisal (SI&A) sheet indicates the condition of the entire substructure including 

abutments and piers. Rating codes range from 9 to 0, where 9 is the best rating 

possible. See Topic 4.2 (Item 60) for additional details about NBI Rating 

Guidelines. 

The previous inspection data should be considered along with current inspection 

findings to determine the correct condition rating. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.37

Element Level Condition 

State Assessment 

In an element level condition state assessment of a pier or bent structure, the 

AASHTO CoRe element typically is one or more of the following: 

Element No. Description

201 Unpainted Steel Column or Pile Extension (EA) 

225 Unpainted Steel Submerged Pile (EA) 

230 Unpainted Steel Cap (m or ft) 

202 Painted Steel Column or Pile Extension (EA) 

231 Painted Steel Cap (m or ft) 

204 Prestressed Concrete Column or Pile Extension (EA) 

226 Prestressed Concrete Submerged Pile (EA) 

233 Prestressed Concrete Cap (m or ft) 

205 Reinforced Concrete Column or Pile Extension (EA) 

210 Reinforced Concrete Pier Wall (m or ft) 

220 Reinforced Concrete Submerged Pile Cap/Footing (EA) 

227 Reinforced Concrete Submerged Pile (EA) 

234 Reinforced Concrete Cap (m or ft) 

206 Timber Column or Pile Extension (EA) 

228 Timber Submerged Pile (EA) 

235 Timber Cap (m or ft) 

211 Other Pier Wall (m or ft) 

The unit quantity for the pier cap elements is meters or feet, measured horizontally 

across the pier cap and the total length must be distributed among the four 

available condition states depending on the extent and severity of deterioration. 

The unit quantity for columns and piles is each and the total quantity must be 

placed in one of the available condition states. In all cases, Condition state 1 is the 

best possible rating. See the AASHTO Guide for Commonly Recognized (CoRe) 

Structural Elements for condition state descriptions. 

A Smart Flag is used when a specific condition exists, which is not described in 

the CoRe element condition state. The severity of the damage is captured by 

coding the appropriate Smart Flag condition state. The Smart Flag quantities are 

measured as each, with only one each of any given Smart Flag per bridge. 

For settlement of the pier or bent, the “Settlement” Smart Flag, Element No. 360, 

can be used and one of three condition states assigned. For scour at the piers or 

bents, the “Scour” Smart Flag, Element No. 361, can be used and one of three 

condition states assigned. 
 SECTION 10: Inspection and Evaluation of Substructures 

 TOPIC 10.2: Piers and Bents 

10.2.38

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