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U.S. Department of Transportation
Comprehensive Truck Size and Weight Study
Report No. 4
Activity V
Document North American and European Experiences
January 1996
Prepared by
and
Fred P. Nix
Transportation Consultant
We want to thank Robert Clarke, Kit Mitchell, and Peter Sweatman
for presenting at the workshop and for reviewing this report.
The primary objectives of the U.S. Department of Transportation's
Comprehensive Truck Size and Weight (TS&W) Study are to:
o assess the potential economic, safety, and
environmental impacts of changing existing TS&W limits;
and
o identify opportunities to increase the efficiency
of freight transportation while preserving safety and
highway infrastructure.
Reports which have been completed for the TS&W Study, to date,
include the following:
(1) Synthesis of Truck Size and Weight Studies and Issues
(2) Analysis of the Truck Inventory and Use Survey from the
Truck Size and Weight Perspective for Trucks with
Five-Axles or More
(3) Truck Size and Weight Modelling Workshop
(4) Truck Size and Weight Performance-Based Workshop
(5) Western U.S.-Canada Crossborder Case Study.
For more information, call Jim March, FHWA, 202-366-9233,
202-366-7696 (FAX), or e:mail: jim.march@fhwa.dot.gov
This document was prepared for use in the U.S. Department of
Transportation's Comprehensive Truck Size and Weight Study. The
views expressed are those of the author(s) and are not
necessarily those of the U.S. Department of Transportation.
Table of Contents
1.0 Introduction. .. . . . . . . . . . . . . . . . . . . .1
1.1 Outline. . . . . . . . . . . . . . . . . . . . . . . .1
1.2 Purpose and Goals. . . . . . . . . . . . . . . . . . .2
2.0 Implementation of Performance-Based Size and Weight
Limits. . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Proposed Approach. . . . . . . . . . . . . . . . . . .3
2.2 Basis for Proposal . . . . . . . . . . . . . . . . . .3
2.3 Factors Affected When Size and Weight Regulations
Change. . . . . . . . . . . . . . . . . . . . . . . . 4
2.4 Issues to be Addressed and Resolved . . . . . . . . .5
2.5 Breakout Session Potential Implementation Mechanisms
and Procedures. . . . . . . . . . . . . . . . . . . . 5
3.0 Vehicle Stability and Control . . . . . . . . . . . . . . .7
3.1 Roll Stability . . . . . . . . . . . . . . . . . . . .7
3.2 Rearward Amplification . . . . . . . . . . . . . . . .8
3.3 Off tracking . . . . . . . . . . . . . . . . . . . . .8
3.4 Implementation . . . . . . . . . . . . . . . . . . . .8
3.5 Breakout Session Vehicle Stability and Control . . . .9
4.0 Vehicle-Pavement Interaction . . . . . . . . . . . . . . 11
4.1 Performance Standards and Pavement . . . . . . . . . 11
4.2 The European Union's Approach to Pavement-Friendly
Suspensions. . . . . . . . . . . . . . . . . . . . . 11
4.3 The Approaches of the European Union and the United
Kingdom . . . . . . . . . . . . . . . . . . . . . . .12
4.4 Breakout Session Vehicle-Pavement Interaction. . . . 13
5.0 Summary . . . . . . . . . . . . . . . . . . . . . . . . . 15
List of Tables
Table 1. Potential Performance Measures . . . . . . . . . . . 10
1.0 Introduction
This is a summary of a workshop on performance-based regulations
for truck size and weight (TS&W) organized by the U.S. Department
of Transportation's (US DOT) Federal Highway Administration
(FHWA). The workshop was held on June 30, 1995, at the Chrysler
Center in Ann Arbor, Michigan, on the day after the Fourth
International Symposium on Heavy Vehicle Weights & Dimensions.
This is not a verbatim record of the proceedings. Rather, this
account follows the discussion as it happened with explanations,
definitions, and examples added for clarity.
1.1 Outline
There were three keynote speakers in the morning session as
follows:
o Robert Clarke, National Highway Traffic Safety
Administration of the US DOT, set the stage by outlining one
approach to performance-based regulations. This approach is
described in the section entitled "Implementation of
Performance-Based Size and Weight Limits."
o Peter Sweatman, Roaduser Research, Australia, discussed
vehicle stability and control issues related to
performance-based standards. His remarks are summarized in
the section entitled, "Vehicle Stability and Control.".
o Kit Mitchell, formerly of Transport Research Laboratory,
U.K., looked at the interaction of heavy vehicles and
pavements and his discussion is summarized in the section
entitled "Vehicle-Pavement Interaction."
The afternoon of the workshop consisted of three breakout
sessions, each led by a keynote speaker. These are described
immediately after the summary of the keynote speeches in the
above-mentioned sections. There was insufficient time for the
workshop to develop conclusions as such; nevertheless, a summary
interpretation of the day's discussion is provided in the last
section of this report.
1.2 Purpose and Goals
Chris Winkler, University of Michigan Transportation Research
Institute (UMTRI), opened the workshop with two questions:
o What aspects of performance should be regulated?
o What performance can be regulated?
The first question raises the issue of the scope of
performance-based regulations. Do they only cover the technical
and in-use operational aspects of vehicle performance and vehicle
operation; or, do they also attempt to address political,
economic, and social considerations? Winkler's second question
raises the issue of implementation. "How can performance-based
regulations be enforced? How would they fit within the existing
structure of state and Federal regulations? And, how do we
change from the existing system?" These are all questions which
Winkler indicated must be addressed if performance-based
standards are to become a reality.
