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Section 6: Bridge Design

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Overview

This section includes tasks typically performed by a structural engineer. The Engineer of Record (EOR) typically reviews the shop drawings for these items. The Engineer (E) typically reviews other items classified as working drawings.

The EOR is typically the Design Engineer who signs and seals the contract plan set (Bridge Division, District, or Consultant). The E is usually the Area Engineer for the project. Format electronic submittals and provide sign/sealed engineering calculations, as required.

Bridges include bridge-class culverts.

This section includes the following groups of tasks, listed in chronological order.

50600. Perform final geotechnical surveys

50610. Prepare preliminary bridge layouts

50620. Prepare bridge details

50630. District reviews bridge plans

50640. Submit Exhibit B to railroad company

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Final Geotechnical Surveys

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50600: Perform final geotechnical surveys

Description. Geotechnical investigations are necessary to design for satisfactory long-term performance of structure foundations. For major projects, some geotechnical data may have been collected during preliminary design. All required data to finish designs should be obtained at this time. See Task 20505: Perform preliminary geotechnical surveys.

To make a single data collection effort, coordinate obtaining geotechnical data for designing and planning the following:

Pertinent Project Types. Projects involving foundation design

Responsible Party. Project manager

Subtasks.

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  • Gather and review existing geotechnical data.
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  • Evaluate project for changes made after original geotechnical investigations are performed during advance planning (e.g., added structures, changed structure limits).
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  • Contact the Bridge Division, as necessary, for guidance in obtaining additional geotechnical data.
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  • Identify additional data required to finalize design.
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  • Prepare or obtain a work authorization for this additional work.
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  • Perform field and laboratory investigations. Site conditions may require additional evaluations for additional types of failure.
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  • Report results of investigations.

Resource Material.

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Bridge Layouts

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50610: Prepare preliminary bridge layouts

Description. A preliminary bridge layout depicts proposed features of a structure and is used to obtain early approvals before beginning detailed design. Submit preliminary bridge layout review to Bridge Division – Project Development for review and approval before any detail work is performed. Preliminary layouts are reviewed for bridge cost information (BCI) and compliance to specific design standards. Preliminary bridge layout reviews include bridge class culverts.

For a bridge project involving a railroad, Exhibit A includes the bridge layout with additional information of interest to the railroad owner. See Task 50480: Develop Exhibit A for railroad agreements.

Pertinent Project Types. Projects including bridges to be newly constructed, replaced, or modified.

Responsible Party. Project manager

Subtasks.

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  • Review commitments made during the public involvement phase for information related to restrictions on bridge types.
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  • Obtain preliminary engineering recommendations, as-built construction plans, and bridge inspection reports for existing structures.
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  • Obtain layouts depicting existing structures, utilities, rights of way, crossroads, and railroad crossings.
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  • For rehabilitation and/or widening projects, contact the Bridge Division - Project Development staff to obtain a load rating and condition survey.
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  • Coordinate preliminary bridge hydraulics with the drainage engineer.
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  • Obtain additional geotechnical or survey data needed to finalize designs. See 50600: Perform final geotechnical surveys.
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  • Identify necessary design exceptions.

Helpful Suggestions.

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  • The Bridge Division - Project Development staff are available for assistance with preparing preliminary layouts, particularly if a bridge will be widened or modified in any way, or if unusual features exist.
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  • A site visit is highly recommended. Items such as stream gages and utilities seldom appear on as-built construction plans.
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  • Assuming a structural engineer is working on the project team at this time, alert the structural engineer to commitments made to resource agencies. These may affect wetland and natural resources impact minimization, bent locations, substructure type, and construction methods.
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  • The designer should determine and document the need for design exceptions before submitting layouts to the Bridge Division.

Critical Sequencing.

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  • Start bridge layouts after developing final alignments and preliminary bridge hydraulics.
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  • Finalize bridge layouts after completing bridge hydraulics, including scour analysis, and any geotechnical investigations.
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  • Obtain district approval of bridge layouts, hydraulic calculation sheets, and hydraulic reports before submitting them to the Bridge Division.

Resource Material.

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Bridge Design and Details

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50620: Prepare bridge details

Description. Update bridge layouts, as necessary, after Division preliminary review and approval of the layouts. Bridge design includes determining superstructure and substructure of span bridges and culvert details to handle design loads. Structure type is usually determined while preparing bridge layouts. Bridge details provide information for the contractor to build all structural elements.

Pertinent Project Types. Projects including bridge class culverts requiring non-standard design and new, rehabilitated, or modified span bridges

Responsible Party. Structural engineer

Subtasks.

Helpful Suggestions.

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  • A site visit is highly recommended.
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  • Notify the structural engineer about commitments made to natural resource agencies. These may affect wetland impact minimization, floodplain constraints, bent locations, substructure type, superstructure type, and construction methods.
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  • Bridge design and detailing also includes many areas, such as retaining walls, bridge rails, structural pedestrian features, lateral restraint, fender systems, utility attachments, bridge illumination, landscape/aesthetic components and drainage systems.

Resource Material.

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50630: District reviews bridge plans

Description. Once bridge plans and details are prepared, the district is responsible for a final review to determine what changes are made to the initial bridge layout and to verify the quantities. Review any significant changes made to the initial layout with the Bridge Division - Project Development Section. The district is also responsible for incorporating these structural details into the final plan set (e.g., updating the index of sheets, numbering the plan sheets).

Pertinent Project Types. All projects

Responsible Party. Project manager

Helpful Suggestions.

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  • If structural plans are prepared by a consultant, they should be reviewed by a member of TxDOT with structural expertise. The Bridge Division is available for assistance, if needed.

Resource Material.

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50640: Submit Exhibit B to railroad company

Description. Railroad company approval of Exhibit B (as-let PS&E plan set) is required for underpass and overpass projects.

After receiving the final PS&E, an Exhibit B to the railroad Construction and Maintenance (C&M) Agreement is prepared and forwarded to the appropriate railroad company for final approval of all aspects of a proposed bridge.

Pertinent Project Types. Bridge projects involving grade separated railroad crossings

Responsible Parties. District Project Manager and RR Coordinator

Critical Sequencing.

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  • Overpass projects typically require all signatories on the Exhibit B title sheet before the contractor can access the right of way. Exhibit B signed title sheet is attached to all original copies of the C&M Agreement.
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  • Underpass projects require a signed Exhibit B prior to execution of C&M Agreement.

Resource Material.
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