The National Academies

NCHRP 15-21 [Completed]

Review of Truck Characteristics as Factors in Roadway Design

  Project Data
Funds: $250,000
Research Agency: Midwest Research Institute
Principal Investigator: Douglas Harwood
Effective Date: 12/13/2000
Completion Date: 7/31/2003

Background: The heavy truck vehicle fleet composes a significant percentage of the traffic on major routes in the United States, such as the interstate system. The volume of heavy truck traffic is increasing because of factors that include economic growth, advances in freight-transportation logistics such as just-in-time delivery systems, and changing trade patterns resulting from the North American Free Trade Agreement (NAFTA).

To provide a seamless and efficient national highway transportation system, it is important to understand the effects of the truck fleet on roadway geometric design criteria. Research is needed to identify the dimensions, performance, and operational characteristics of the current and future fleet, so that these characteristics can be evaluated and, if necessary, accommodated on a consistent basis in geometric design standards.

Transportation engineers rely on AASHTO's Policy on Geometric Design of Highways and Streets for information on design vehicles and roadway design criteria. Heavy truck operating characteristics are treated in a limited fashion in the present AASHTO policy but are based on generalized design vehicles that may not reflect the characteristics of the current fleet. The information currently in the AASHTO policy needs to be reviewed and updated as appropriate to account for the current and future truck fleet using our national highway transportation system.

The information developed in this project may also be useful as input to future editions of other documents such as the TRB Highway Capacity Manual, the FHWA Manual of Uniform Traffic Control Devices, and the AASHTO Roadside Design Guide.

The objective of this research is to ensure that geometric design standards for highways and streets can reasonably accommodate the dimensions and performance characteristics of the current and future heavy truck fleet using the U.S. highway system. The main product will be recommendations on modifications and/or additions that should be made to the current edition of the AASHTO Policy on Geometric Design of Highways and Streets.

The research should include the following tasks: (1.) Review, analyze, and critique all domestic and international research that is relevant to the relationship between heavy truck characteristics and roadway design criteria. This material should include published research as well as research in progress. (2.) Develop a descriptive profile of the current fleet (in terms of configuration, size, weight, and operational and performance characteristics) and provide a limited discussion of current trends in vehicle development and how these trends may influence the future fleet. (3.) Describe the relationships between heavy truck operating characteristics and geometric design requirements. These relationships should be illustrated in a matrix format to indicate whether and how specific operating characteristics affect specific geometric design elements. Identify those vehicle types and characteristics that may be critical in developing improved roadway design criteria. (4.) Determine what performance data are currently available, for the heavy truck fleet, relating to the critical vehicle characteristics identified in Task 3. Identify gaps where additional data are required, and provide a work plan to address these gaps. (5.) Develop or identify methodologies to determine the relationship of critical truck characteristics to roadway geometric design criteria. (6.) Submit the results of Tasks 1 through 5 in an interim report. (7.) Following NCHRP approval of the interim report, implement the data-collection plan developed in Task 4 and conduct the analysis developed in Task 5. (8.) Critically examine the AASHTO Policy on Geometric Design of Highways and Streets from the standpoint of truck operations. Determine the adequacy of existing design criteria to accommodate the heavy truck fleet. Identify vehicles and operating characteristics that are not currently included or considered in the policy. (9.) Develop and assess new or revised design criteria for those situations where the current criteria do not adequately address the current or anticipated truck populations. (10.) Submit a final report containing sections recommended for inclusion in future updates of the AASHTO Policy on Geometric Design of Highways and Streets and in other manuals or guides as appropriate. The final report should also document and summarize the results of the entire research effort.


Product Availability
: The final report has been published as NCHRP Report 505. The contents of the bound floppy disk are available in this ZIP file

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