Publication Number: FHWA-RD-00-060
Date: July/August 2000

Conference to Feature Strategies for Improving Traffic Data Collection

Weigh-in-motion sites collect data on such things as vehicle volume and axle weights.

Nearly 500 researchers, consultants, and representatives from State and Federal highway agencies will journey to Madison, Wisconsin, this summer to attend the biannual North American Travel Monitoring Exhibition and Conference (NATMEC) 2000 on August 27-31. Hosted by the Wisconsin Department of Transportation, in conjunction with the Transportation Research Board and the Federal Highway Administration (FHWA), the conference will focus on improving traffic data collection and management.

Traffic data are one of the data elements that are needed to determine highway performance. The data are used to assess the longevity and performance of a pavement and determine which pavement construction methods are most effective.

The conference will include sessions on such topics as using global positioning system and cellular technology for traffic and travel monitoring, building intelligent transportation system data archives, and analyzing and using traffic data. The featured sessions will also include "Setting the Standards for Research Quality Data at Long-Term Pavement Performance (LTPP) Specific Pavement Studies (SPS) Sites." The SPS experiments were designed to learn how such factors as cumulative traffic loading affect pavements of different compositions, environmental conditions, and layer thicknesses. However, at some of the sites, traffic data collection has been inadequate. A Traffic Data Collection and Analysis Expert Task Group (ETG) has recommended solutions to this problem, including such ideas as implementing a State pooled-fund study and transferring the responsibility for SPS traffic data collection to an outside contractor. Larry Wiser of FHWA's LTPP program will discuss the plans being considered by the ETG and the LTPP program.

As part of this session, John Weaver of Indiana DOT will give a presentation on "Smoothness Criteria for Construction and In-Service Conditions at LTPP SPS Weigh-in-Motion Sites." The quality of data obtained from weigh-in-motion (WIM) sensors, which collect information on such things as vehicle volume and axle weights, is highly dependent upon the pavement in which they are installed. Smoother pavements provide more accurate and less variable measurements. To ensure that WIM equipment is installed in smooth pavements, and to achieve more uniform conditions among different SPS test sites, criteria have been developed to help a State evaluate the pavement both at the time of construction and while it is in service.

In a related presentation, Barbara Ostrom, a contractor to FHWA, will discuss WIM equipment selection and installation for SPS sites. Until now, traffic data collection at SPS sites has not been conducted using identical WIM equipment at all locations. In consultation with the Traffic ETG, FHWA's LTPP team has developed specifications for WIM systems that include accuracy requirements and construction guidelines.

For more information on NATMEC, check out the conference Web site at www.cae.wisc.edu/~natmec/. For more information on the LTPP sessions, contact Larry Wiser at 202-493-3079 (fax: 202-493-3161; email: larry.wiser@fhwa.dot.gov).

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