Abutments, Piers, and Walls - 11.1 - Design and Detailing

Oct 23, 2026

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Guidance covers the design and detailing of abutments, piers, retaining walls, and noise walls for bridge support and earth retention. It explains how superstructure-to-substructure connections depend on bridge geometry, contrasting integral designs with expansion bearings to manage loads. It specifies selection rules for integral, semi-integral, and parapet abutments, including constraints on bridge length, skew, wingwall geometry, exposure, and reinforcement detailing. Additional notes address live-load requirements for a specific railroad, utility placement, and presentation conventions for plan and construction joints.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages200

Reading Time8 h 24 min

AccessFree to download

11. ABUTMENTS, PIERS, AND WALLS

11.1 Abutments

Abutment Type Selection

Detailing/Reinforcement

11. ABUTMENTS, PIERS, AND WALLS 11.1 Abutments This section contains guidance for the design and detailing of abutments, piers, retaining walls, and noise walls. Abutments and piers are used to support bridge superstructures, whereas walls primarily function as earth retaining structures. In most cases, abutments, piers, and walls are reinforced concrete elements. The preferred details for connecting the superstructure to the substructure are dependent on the geometry and type of bridge. For example, flexible substructure units supported by a single line of piles may be constructed integral with the superstructure. Conversely, stiff substructure units are detailed with expansion bearings between the superstructure and substructure to reduce the design loads in the substructure units. General Abutments function as both earth retaining structures and as vertical load carrying components. Integral and semi-integral abutments are designed to accommodate movements at the roadway end of the approach panel. Parapet abutments are detailed to accommodate movements with strip seal or modular expansion joint devices between the concrete deck and the abutment end block. Railroad bridge abutments shall be designed according to the AREMA Manual for Railway Engineering, Volume 2, for the live load specified by the railroad. Design all other abutments according to the AASHTO LRFD Bridge Design Specifications. The Duluth Mesabe & Iron Range Railway requires a special live load. The live load surcharge is found by taking the axle load and distributing it over an area equal to axle spacing multiplied by the track spacing, generally 70 square feet. Do not reduce the surcharge loading for skew. Refer to Article 2.4.1.6.2 when locating utilities near an abutment. When footings are perched on an embankment, consult with the Regional Construction Engineer regarding the use of spread footings. Abutment Type Selection Integral abutments are the preferred type of abutment when all of the following criteria are met: 􀁸 The bridge length and skew meet one of the following:(See Figure 11.1.1) o Bridge length ≤ 300 feet and skew ≤ 20 degrees o Bridge length ≤ 100 feet and skew ≤ 45 degrees o Bridge length is between 100 feet and 300 feet, and skew ≤ [45 - 0.125 (L - 100)] degrees, where L is the length of the bridge in feet. 􀁸 Bridge horizontal alignment is straight. Slight curvature can be allowed, but must be considered on a case-by-case basis. 􀁸 The length of wingwall cantilevers are ≤ 14 feet (measured from the back face of abutment to the end of the wingwall) . • Abutment wingwalls do not tie into roadway retaining walls. 􀁸 Bridge configuration allows setting the abutment front face exposure on the low side of the bridge at 2 feet. 􀁸 Maximum abutment stem height ≤ 7’-0” 􀁸 Depth of beams is ≤ 72 inches. Figure 11.1.1 Semi-integral abutments are the preferred type of abutment when the following circumstances apply: 􀁸 The wingwall length, abutment exposure or superstructure depth requirements for integral abutments cannot be met. 􀁸 The bridge length and skew meet the requirements given above for integral abutments, except that when wingwalls are parallel to the roadway, the maximum skew limit for semi-integral abutments is 30 degrees. (See Figure 11.1.1.) Also, note that a guide lug is required for skews greater than 30 degrees to limit unwanted lateral movement. Parapet abutments should only be considered where integral and semiintegral abutment criteria cannot be met. A parapet abutment supported by a pile foundation can be used behind a mechanically stabilized earth (MSE) retaining wall where high abutments would be required and where it is economical to use an MSE wall. Locate the front face of the MSE wall a minimum of 6’-0” from the centerline of bearing. Do not batter the piles. Place the bottom of the abutment footing and the bottom of the MSE wall cap at the same elevation. Slope protection betwe

FAQs

What are the primary structural functions of abutments, piers, and walls in bridge applications?

Abutments and piers support the bridge superstructure, while walls primarily act as earth retaining structures. In most cases, these elements are reinforced concrete.

How do integral, semi-integral, and parapet abutments differ in selection criteria?

Integral abutments are preferred when length/skew, alignment, wingwall cantilevers, exposure, stem height, and beam depth limits are met. Semi-integral abutments are preferred when integral criteria cannot be met, with a lower maximum skew when wingwalls are parallel to the roadway. Parapet abutments are considered when the other criteria cannot be satisfied.

What connection approach is used between the superstructure and substructure to reduce design loads?

Flexible substructure units supported by a single line of piles may be constructed integral with the superstructure. For stiff substructure units, expansion bearings are detailed between the superstructure and substructure to reduce loads.

Oct 23, 2026

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