The National Academies

SHRP 2 L07 [Completed]

Evaluation of Cost-Effectiveness of Highway Design Features

  Project Data
Funds: $3,600,000
Research Agency: Midwest Research Institute
Principal Investigator: Ingrid Potts
Effective Date: 1/7/2008
Completion Date: 8/31/2014

Project snapshot. More details below.

(Project Number)
Impact on Practice
Product Status

A design guide, consisting of a compendium of design treatments likely to affect non-recurring congestion plus an Excel-based tool that designers can use to evaluate the effects of such treatments on delay, safety, travel time reliability, and lifecycle benefits and costs.
The physical design of highway facilities is an important factor in achieving travel time reliability. With these tools, design engineers can better determine which design options contribute to improved traffic operations through actions that can mitigate the effects of crashes, work zones and bad weather.
The report is available here: http://www.trb.org/Main/Blurbs/169767.aspx

The guide is available here: http://www.trb.org/Main/Blurbs/169768.aspx

The tool is available here: http://www.trb.org/StrategicHighwayResearchProgram2SHRP2/Pages/L07_Analysis_Tool_708.aspx

The Information Dissemination Plan is available here: http://onlinepubs.trb.org/onlinepubs/shrp2/SHRP2_L07_IDP.pdf

Four pilot projects, L38A-D, are being conducted to test the functionality of the L07 research products along with products from projects L02, L05, L08, and C11. The pilots are due to be completed in mid 2014.


Staff Responsibility: William Hyman
The overall objective of this project is to identify the full range of possible roadway design features used by transportation agencies on freeways and major arterials to improve travel time reliability, assess their costs, operational effectiveness, and safety, and provide recommendations for their use and eventual incorporation into appropriate design guides.
Accomplishing the project objective will require a thorough knowledge of geometric design requirements and application; an understanding of how specific conditions affect design and operation of highway systems; alternative economic analysis techniques; and how operational effectiveness and safety are measured and estimated. Where existing effectiveness analysis methods are inadequate, alternative approaches will be needed to generate useful results.
The following task descriptions are intended to provide a framework for conducting the research. SHRP 2 is seeking the insights of proposers on how best to achieve the research objective. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meet the research objective.
PHASE I: Data and Information Gathering on Existing and Candidate Design Features
Task I-1: Identify the state of reliability-related design practice by gathering and synthesizing information (using, as appropriate, a literature search, telephone interviews, and other methods) on existing (customary and innovative) and promising design features capable of reducing delays due to key causes of non-recurrent congestion. The features can be either permanent or temporary and include new construction and retrofit applications. Information on the full range of the costs of such features and their safety and operational effectiveness, if they have been constructed, should also be sought. [See Special Note A.] Reports on previous NCHRP international scans (e.g., on incident management and motorists in work zones) should be examined for information on international experience and contacts for further information. [See Special Note B.]
Task I-2: Gather details and insights about selected design features and transportation agency experience with them in improving travel time reliability. This task can include focus group meetings with experienced design practitioners from the public and private sectors.
Task I-3: Based on the information from Tasks I-1 and I-2, the contractor shall undertake a preliminary assessment of design options to determine their potential for reducing non-recurring congestion. Proposers should provide a detailed description of how the assessment will be carried out and the range of factors to be considered. Proposers should anticipate that fundamental elements of some design options are not based on research data or are based on outdated data and that new data or information will be needed to bring these elements and the designs up-to-date. Proposers are urged to review the classification system used in the NCHRP Report 500 series on highway safety for its applicability or modification to this project; in that series safety improvement measures are classified under three broad categories: proven; tried; and experimental.
Task I-4: Prepare a Phase I interim report that describes (1) the information gathered; (2) the analysis methodology; (3) the results of the preliminary assessment undertaken in Task I-3; and (4) detailed plans for a more complete assessment including additional needed data collection on designs, life cycle costs, and benefits to enable the development of detailed design recommendations. The report should include aprioritized set of candidate design features for further study in Phase II. [The contractor will not proceed with Phase II unless and until the plan for Phase II has been approved by SHRP 2 staff.]
PHASE II: Assessment of Design Measures
Task II-1: Carry out the data collection plan prepared in the Task 1 report and approved by SHRP 2 staff.
Task II-2: Carry out the analysis as described in Task I-4 (with approved revisions) using the data and information collected in Task II-1. The assessment of measures may include detailed case studies of exemplary implementations. If undertaken, the case studies should reflect differences across the four AASHTO regions; the case studies might include paired analysis of two projects in the same state or of similar projects in different states. An aim of the case studies is to demonstrate principles of good design practice that can be used by agencies at other locations. Unique circumstances are not desirable unless a lesson can be learned and applied to a range of sites.
Task II-3: Prepare an interim report of the data collection and analysis activities; the report will also include an annotated outline for the guidebook on geometric design. The guidebook will include design suggestions as well as guidance for agencies for selecting and evaluating design features. [The contractor will not proceed with Phase III unless and until the report has been reviewed and approval is given by SHRP 2 staff.]
PHASE III: Develop Recommended Design Guidelines
Task III-1: Prepare the design guidebook according to the plan (and approved revisions) prepared in the Task II report.
Task III-2: Prepare a draft final report.
Task III-3: Prepare an information dissemination plan for the project results. The plan should include appropriate strategies for integrating the research results into design guides and practice, taking into account the potential audiences (decision makers; practitioners; and other key stakeholders). Prepare draft dissemination materials using appropriate media, targeted at state DOTs, MPOs, regional and local agencies, bridge and tunnel owner-operators, and other appropriate groups. Following review, prepare materials for dissemination.
Task III-5: Prepare and conduct five presentations to address appropriate AASHTO committees, the MUTCD committee, and others involved in design guide preparation aimed at describing the study results and getting the results into use.
Deliverables: (due dates are subject to proposer’s project plan and approval by SHRP 2 staff)
1. Phase I Interim Report
2. Phase II Interim Report
3. Final Report
4. Information Dissemination Plan

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