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Section 4: Roadway Design

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Overview

This section discusses tasks necessary to finalize plan/profile and cross sections of the proposed facility and additional details related to roadway design.

Note that final determination of right of way requirements and preparation of a remedial action plan for hazardous waste clean up are important, relative to the project schedule. These two items have the potential to affect project schedules and costs greatly if not given proper attention.

This section includes the following tasks, which may be performed concurrently.

50400. Prepare cross sections and compute earthwork

50410. Review right of way requirements

50420. Design landscape/aesthetic plans

50430. Develop plan and profile sheets

50440. Design pedestrian walkways and bicycle transportation facilities

50450. Design miscellaneous details

50460. Review project for design exception/waivers

50470. Prepare hazardous material remediation plan

50480. Develop Exhibit A for railroad agreements

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Earthwork

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50400: Prepare cross sections and compute earthwork

Description. Plotting proposed cross sections and estimating earthwork volumes are important steps to be conducted early in the design process. Cross sections should be plotted at critical locations while finalizing project alignments. Once final alignments are set, including ditch and cross structure preliminary sizing, develop final cross sections, and earthwork volumes. See Task 50300: Design final controlling conditions.

Pertinent Project Types. All projects involving earthwork

Responsible Party. Roadway design engineer

Subtasks.

Helpful Suggestions.

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  • Volumes and haul distances are an important economic consideration for roadways on new alignment. Earthwork volumes are of minor importance, typically, in setting grades for roadway widening projects.
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  • Roadside safety, in terms of side slopes, ditch size and configuration, and use of roadside barriers must be properly considered in preparing proposed cross sections. These items are detailed in the TxDOT Roadway Design Manual.

Critical Sequencing.

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  • Develop proposed roadway cross sections and earthwork volumes after setting alignments and reviewing stream crossing hydraulics.

Resource Material.

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50410: Review right of way requirements

Description. Once alignments are finalized, determine proposed right of way (ROW).

ROW acquisition types include fee title, drainage easements, and control of access, etc. Access to private property during construction may require temporary construction easements. Rights for continuous maintenance of permanent construction facilities should be acquired in fee title or an easement interest in areas requiring minimum maintenance. A drainage easement may also be required in areas without permanent highway structures to protect against development that would restrict the natural drainage flow, and to allow access for maintenance of the drainage channel.

See Task 40200: Prepare right of way map and property descriptions.

Pertinent Project Types. Projects requiring additional ROW

Responsible Party. Roadway design engineer

Subtasks.

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  • Plot existing ROW and lateral limits of earthwork construction on plan sheets using cross-sections generated while computing earthwork. See Task 50400: Prepare cross sections and compute earthwork.
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  • Show proposed ROW limits on plans.
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  • In coordination with the drainage engineer, determine the need for drainage easements at water crossings and possibly for long parallel channels.
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  • Determine control of access lines and show on plan layout; ensure that control of access lines match those shown on the ROW map.
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  • Schematic revisions and resubmittal are required as a result of changing control of access.
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  • Determine the need for temporary construction easements and incorporate into the ROW map.
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  • Coordinate acquisition with the district ROW section.

Helpful Suggestions.

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  • Many aspects of ROW acquisition are controlled by our legal system. It is important for the engineer to coordinate unclear issues with the district ROW section.
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  • Consider safety, constructability, and future maintenance in all ROW recommendations.
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  • ROW acquisition must be supported by a legitimate transportation necessity.

Critical Sequencing.

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  • Final ROW limits should be established before beginning the ROW acquisition process.

Resource Material.

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Landscape and Aesthetics

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50420: Design landscape/aesthetic plans

Description. Landscaping and aesthetics can enhance public acceptance and appreciation of a project. A project does not necessarily need an area of land for “landscaping” to make the facility more attractive. For example, simple aesthetic treatments such as color and texture of materials used (e.g., retaining walls) can have a positive impact. Consult with a landscape architect, in the district or division, to obtain ideas and assistance with developing landscape and aesthetic plans.

Federal cooperation with state and local agencies can provide opportunities for display of original works of art in the right of way. Designers should encourage the development of pollinator habitat, forage, and migratory way stations for monarch butterflies, honey bees, and other native pollinators by planting native forbs and grasses. Plant establishment durations should be sufficient for an expected survival in a highway environment.

Pertinent Project Types. All projects, except restoration (2R) projects

Responsible Party. Roadway design engineer

Subtasks.

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  • Determine funding available for landscape and aesthetic improvements. Costs and staff availability for future maintenance should be considered.
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  • Write an Assessment of Landscape and Aesthetic Issues, if needed.
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  • Develop landscape and aesthetic plans in coordination with project design engineers, maintenance personnel, and affected parties.

Helpful Suggestions.

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  • A well written “program” can help justify spending funds on aesthetics and can be used when discussing the project with the public regarding decisions on facility appearance.
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  • Aesthetic improvements must not compromise safety, such as a reduction in sight distance caused by vegetation or a distraction to motorists. For this reason, the roadway design engineer and the landscape architect must work closely with each other.
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  • Ensure that environmental justice issues are addressed.

Critical Sequencing.

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  • Develop landscape and aesthetic plans before, or concurrently with, roadway details since landscape improvements may require facilities added to roadway improvements such as irrigation systems or access for maintenance.

Authority.

Resource Material.

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Plan/Profile and Roadway Details

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50430: Develop plan and profile sheets

Description. Plan and profile sheets are used to depict horizontal curve radii, superelevation rate, stopping sight distance (SSD), grade, lane and shoulder widths, and related information for a project. Develop plan and profile sheets based on schematic layout sheets.

Pertinent Project Types. All projects, except preventive maintenance, restoration (2R), illumination, traffic signals, etc.

Responsible Party. Roadway design engineer

Resource Material.

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50440: Design pedestrian walkways and bicycle transportation facilities

Description. Legislation and regulations require consideration of pedestrian walkways and bicycle transportation facilities into transportation plans and project development. Transportation programs and facilities should accommodate users of all ages and abilities. It is federal policy for the department to integrate walking and bicycling into the transportation system, regardless of regional, climate, and population density differences. Non-motorists must be allowed to participate in the planning process to ensure inclusion of multimodal accommodations and operability of an intermodal transportation system.

Under The Moving Ahead for Progress in the 21st Century (MAP-21), several city-owned arterial streets were added to the NHS. A flexible, context-sensitive design approach is critical to achieving balanced design on these roadways.

The primary goal of a transportation system is to safely and efficiently move people and goods. Walking and bicycling are legitimate efficient modes of transportation for most short trips and can be linked to other transportation modes to significantly increase a trip distance.

Networks may include trails with an alignment separate from roadway, bridge structures used exclusively by pedestrians and bicyclists, or on-roadway bicycle lanes and walkways adjacent to roadways. Integrating pedestrian walkways and bicycle transportation facilities on new, rehabilitated, and limited access bridges with connections to streets and paths is encouraged.

Walking and bicycle transportation contribute to livability by tying the quality and location of transportation facilities to broader opportunities such as access to good jobs, affordable housing, quality schools, and safe streets. There are numerous individual and community benefits from non-motorized transportation including health, safety, environmental, and quality of life.

Pedestrian Elements. When any of the following factors are present, pedestrian accommodation and walkways should be included on a project:

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  • Facility is part of a locally adopted walkway planning document
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  • Parking lots
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  • Evidence of pedestrian traffic: pedestrians are observed, there is a beaten path, or significant potential exists for pedestrians to walk in the roadway.
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  • Pedestrian generators/attractors: residential areas, entertainment, businesses, schools, shops, or a transit route.

Pedestrian facilities are considered an accessible route with conditions and constraints unique to public rights of way. Curb cuts and other accessible provisions, as may be appropriate, are required on all Federal and Federal-aid projects involving the provision of curbs or walkways at all pedestrian crosswalks. Design according to the appropriate Standard(s) listed in the Resource Material section below.

Minimize use of smooth metal or diamond plates on walkways. Metal surfaces are low-friction surfaces and cause slipping for pedestrians and walking-aid users.

Shared-use paths, which are multi-use paths, provide off road transportation and recreational use by pedestrians, bicyclists, and persons with disabilities using various modes of travel. A shared-use path is unlike a sidewalk since most are physically separated from streets by open space or barrier. A shared-use path is also different from a trail; a trail’s primary design purpose is for recreation.

If total bid items for all pedestrian elements (new or removed, signals, striping, walkways, ramps) are greater than $50,000, a plan review is required eight weeks in advance of advertising the project for bids. Submit electronic plan set by email (Dropbox Service for larger plan files) or mail hardcopy to the department-contracted Registered Accessibility Specialist (RAS) and Construction Division (CST) ADA Inspector along with completed electronic Project Registration and Plan Review Registration forms. CST pays all fees for state let projects.

Pertinent Project Types. All projects, except preventive maintenance and restoration (2R) projects

Responsible Party. Roadway design engineer

Subtasks.

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  • Obtain reports on planning and public involvement conducted for the project. See Task 20480: Develop bicycle and pedestrian accommodation.
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  • Determine the scope of pedestrian walkways and bicycle transportation facilities to be provided.
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  • Establish design criteria appropriate to the condition and funding. See the Resource Material section below.
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  • Prepare preliminary facility layouts and typical sections, and develop preliminary cost estimates for the project.
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  • Coordinate the project with local governments or jurisdictions benefiting from and supporting improvements, including related disciplines such as landscape architecture.
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  • Coordinate the project with other stakeholders such as railroad or utility owners whose right of way is being used for the improvements.
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  • Obtain additional design survey data needed to finalize designs.
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  • Prepare final plans and cost estimates.

Helpful Suggestions.

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  • Bicycle and pedestrian facilities usually have strong support from local citizens. Public support is important for a successful project.
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  • Avoid placing obstructions, tripping hazards, or reducing route through-width on walkways due to: guardrail, on-walkway surface curbs, trash bins, benches, transit shelters, utility structures, etc.
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  • Coordinate alignments with proposed utility locations. Avoid power poles or utility cabinets obstructing walkways.
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  • When crossing driveways, maintain walkway cross slope and grade according to PROWAG and TAS requirements. Refer to TxDOT PED Standard Detail sheet.

Critical Sequencing.

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  • Bicycle and pedestrian transportation facility design should begin during the project preliminary design phase.
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  • Public input should be encouraged.
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  • Design work can begin once design surveys and coordination with local governments and stakeholders are near completion.
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  • Required RAS plan review eight weeks in advance of advertising the project for bids allows time for revisions before bids are solicited.

Authority.

Resource Material.

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50450: Design miscellaneous details

Description. Miscellaneous details sheets are typically developed to show design details, which are not shown on standard detail sheets and areas where more detailed information will benefit the contractor’s understanding of the project.

Examples include, but are not limited to, the following:

Pertinent Project Types. Projects requiring construction details that are not provided on standard sheets

Responsible Party. Roadway design engineer

Resource Material.

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50460. Review project for design exceptions/waivers

Description. As the project progresses through final design, the need for a design exception or design waiver may be identified. Form 1002 PS&E Transmittal Data, Page 3, is the official place where PS&E basic design criteria are documented, as well as waivers or design exceptions for design features that did not meet nominal safety design of the controlling criteria minimum values or ranges. A second concern in a design exception or waiver is the continuum of substantive safety over actual long term or expected performance of the roadway.

For NHS and those routes added to the NHS by MAP-21, FHWA adopted design requirements apply, regardless of funding source. The department may consider designs which deviate from the NHS standards when warranted based on conditions, context, and consequences of the proposed project.

Design exceptions may be approved any time prior to finalizing the design of the project. See Task 20720: Design exceptions or waivers.

Pertinent Project Types. All projects

Responsible Party. Roadway design engineer

Critical Sequencing.

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  • Submit design exception/waiver requests to district design exception committee soon after identifying the need.
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  • The design will have to be modified if the request is not approved.

Authority.

Resource Material.

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50470: Prepare hazardous material remediation plan

Description. Department personnel or environmental consultants under contract with the department will conduct an initial site assessment (ISA) and/or Phase I Environmental Assessment (ESA) of the project area to determine the likelihood that hazardous substances or petroleum contamination exist on the property and the extent to which further investigation and/or remediation may be necessary. On transportation projects, hazardous materials may vary from lead paint on bridges, asbestos in structures, or soil contaminated with gasoline from underground storage tanks.

The PS&E plans will provide a layout of anticipated areas of contamination within the project limits; the plan sheet(s) will have a list of contractor information notes to be followed while working in the layout area. An onsite qualified inspector will be required to monitor and supervise construction activities in the contaminated area.

Unanticipated hazardous materials encountered during construction, must be properly handled and disposed. Contact the district environmental project manager for procedures to follow.

Cleanup of contaminated materials will be done by properly trained and equipped personnel under a contract work authorization.

Pertinent Project Types. Projects involving known or anticipated hazardous materials

Responsible Party. Roadway design engineer and district environmental project manager

Subtasks.

Helpful Suggestions.

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  • Work closely with the district environmental project manager and the Environmental Affairs Division.

Resource Material.

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Railroad Agreements

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50480: Develop Exhibit A for railroad agreements

Description. The Exhibit A is a procedural document related to the development of an Agreement between the department and the railroad. The Agreement must be executed before a project can be awarded to a contractor.

Texas Railroad Information Management System (TRIMS) is a GPS and GIS-based data collection, inventory, and project management tool. The web-based Rich Internet Application (RIA) can be used to gather site data with a field computer, GPS unit, and digital camera. This system provides comprehensive railroad information to the designer.

An Exhibit A is a 30% plan set showing work to be performed within the railroad’s right of way. Information should include the project title sheet and map, index, railroad company, subdivision, milepost, and DOT numbers identified on the title sheets and title blocks of other sheets. For a bridge project involving a railroad, Exhibit A includes the bridge layout with some additional information of interest to the railroad owner. Final Exhibit A should be signed, sealed, and dated by a licensed Texas Professional Engineer. See the Rail-Highway Operations Manual listed below for more extensive information.

Maintenance-type project scopes with minimal impacts to railroad rights of way are handled by a Letter Agreement. A few of the project types are:

A Construction & Management Agreement is for more extensive heavy construction within the railroad right of way.

Pertinent Project Types. Projects containing work within railroad right of way

Responsible Party. District Project Manager, District Railroad Coordinator, TRF-RSS Contract Specialist

Subtasks.

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  • Obtain detailed geometry and as-built construction plans of existing railroad crossings, as applicable.
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  • Make a site visit to evaluate existing at-grade crossings for field panel conditions and/or “humped” crossing that can cause long wheelbase vehicles to get stuck on the crossing.
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  • Obtain train traffic frequency and speed from the railroad company or through department internal TRIMS database.
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  • Develop Exhibit A, including a description of work to be performed by TxDOT and the railroad company.
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  • Submit Exhibit A in accordance with the process outlined in the Rail-Highway Operations Manual .

Helpful Suggestions.

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  • Designers should familiarize themselves with the railroad company’s design standards prior to project design development.
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  • For bridge projects, additional information needed for Exhibit A can be added to the bridge layout.
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  • Be sure railroad Agreement provisions are included in the final PS&E.
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  • TRF-RSS is the office of primary negotiation with the railroads. For complex rail-highway grade separation projects, contact Traffic Operations Division-Rail Safety Section (TRF-RSS) if considering a meeting with railroad owner(s) when Exhibit A is nearly complete, especially where railroad passes over highway.

Critical Sequencing.

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  • Contact the TRF-RSS Contract Specialist at least 12 months before letting for railroad overpasses (new or modified), and 24 months before letting for railroad underpasses (new or modified) to coordinate rail planning and obtain a Construction & Maintenance Agreement.
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  • Projects will not be let until the railroad Construction & Maintenance (C&M) Agreement or Letter Agreement has been fully executed.

Resource Material.
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