Abstract:
This report assesses various elements of the Washington State Department of Transportation (WSDOT) hot-mix quality assurance (QA) specification. Current WSDOT QA specifications contain measures of in-place density, asphalt content, and aggregate gradation for contractor pay and special provisions allow for additional pay factor items based on volumetric properties. Data from production paving projects suggests that use of the original pay items are adequate in determining the quality of hot-mix asphalt (as opposed to pay items based on volumetric mix properties). Additionally, the option of increasing the minimum compaction level (currently 91 percent of theoretical maximum density) is recommended to increase quality. In addition, a contractor quality control (QC) program is recommended for consideration by WSDOT.

Authors:
Willoughby,K. A., Mahoney,J. P.

Keywords:
specification, statistics, hot mix asphalt, HMA, asphalt concrete, pay factor, precision, Superpave, compaction, quality control, quality assurance

Download Report:

Abstract:
This report documents the development of data collection methodologies that can be used to cost effectively measure truck movements along specific roadway corridors selected by transportation agencies in Washington State. The intent of this study was to design and test methodologies that could be used to measure the performance of freight mobility roadway improvement projects against benchmarks, or selected standards, that would be used both as part of the project selection process and to report on speed and volume improvements that resulted from completed freight mobility projects. One technology tested was Commercial Vehicle Information System and Networks (CVISN) electronic truck transponders, which are mounted on the windshields of approximately 20,000 trucks in Washington. By using software to link the transponder reads from sites anywhere in the state, the transponder-equipped trucks could become a travel-time probe fleet. The second technology tested involved global positioning systems (GPS) placed in volunteer trucks to collect specific truck movement data at 5-second intervals. With GPS data it was possible to understand when and where the monitored trucks experienced congestion and to generate useful performance statistics. The study found that both data collection technologies could be useful; however, the key to both technologies is whether enough instrumented vehicles pass over the roadways for which data are required. This basic condition affects whether the technologies will be effective at collecting the data required for any given benchmark project. The report also recommends the traffic data that should be collected for a benchmark program and the potential costs of using either data collection technology.

Authors:
McCormack,E. D., Hallenbeck,M. E.

Keywords:
agencies, commercial vehicle, condition, congestion, construction, corridors, cost, costs, data, data collection, design, development, freight, freight mobility, freight movement reliability, global positioning, global positioning systems, GPS, improvement, methodology, mobility, networks, performance, positioning, probe program, project, research, roadway, software, speed, statistics, Study, System, systems, technology, traffic, traffic data, transportation, travel time, truck, truck monitoring, trucks, volume, Washington, Washington state

Download Report:

External Links: http://www.wsdot.wa.gov/research/reports/fullreports/607.1.pdf http://wsdot.wa.gov/Research/Reports/600/607.1.htm

Abstract:
In 2003, the Washington State Department of Transportation (WSDOT) initiated a research effort to develop and test a methodology for estimating congestion delay on Seattle area freeways. The initial phase of the research developed a preliminary methodology for both measuring congestion and assigning that congestion to specific lane blocking incidents. In Phase 2 of this study, that methodology was automated and extended to include an examination of the effects of incidents occurring on the shoulders of the freeway, spillback from incident-caused congestion on one freeway that affects a second freeway that feeds traffic onto the initially congested facility, special events, and weather. Because funding for this effort was extremely limited, only three corridors (with both directions analyzed independently) and two months of data were analyzed. The project found that the Phase 1 methodology works well in assigning traffic congestion that occurs in the immediate time frame and geographic location of incidents to those incidents. It also showed that this process can be automated, making the data preparation effort now the primary determinant of the cost of additional work of this kind. Unfortunately, even with the addition of shoulder incidents, special events, and weather to lane blocking events, the automated process is unable to assign a significant proportion of the non-recurring delay occurring on Seattle freeways. The detailed analysis of freeway performance showed that much of the delay caused by specific incidents occurs in places or at times removed from the incident itself. The result is that much of the observed non-recurring delay can not be assigned to specific causes by the current analytical process. New analytical procedures will need to be developed in Phase 3 of this work. The Phase 2 analysis also confirmed that the congestion effects of specific incidents and other traffic disruptions are highly dependent on the background traffic conditions at the time of the disruption. While the Phase 2 analysis did not produce all of the results desired, the additional analyses showed that the summary statistics output from the Phase 2 software are useful as input to other analytical procedures.

Authors:
Kopf,J., Nee,J., Ishimaru,J. M., Hallenbeck,M. E.

Keywords:
congestion causes, freeway performance, traffic congestion, Washington, Washington state, transportation, WSDOT, research, methodology, congestion, seattle, freeway, developed, incident, Study, effects, traffic, facilities, corridors, data, project, cost, analysis, performance, in-place, condition, statistics, software

Download Report:

External Links: http://www.wsdot.wa.gov/research/reports/fullreports/619.1.pdf http://wsdot.wa.gov/Research/Reports/600/619.1.htm

Abstract:
This report documents the development of data collection methodologies that can be used to cost effectively measure truck movements along specific roadway corridors selected by the Freight Mobility Strategic Investment Board (FMSIB.) The intent of this study was to design and test methodologies that could be used to measure the performance of freight mobility roadway improvement projects against benchmarks, or selected standards, which would be used both as part of the project selection process and to report on speed and volume improvements that resulted from completed FMSIB projects. One technology tested was Commercial Vehicle Information System and Networks (CVISN) electronic truck transponders, which are mounted on the windshields of approximately 20,000 trucks traveling in Washington. These transponders are used at weigh stations across the state to improve the efficiency of truck regulatory compliance checks. By using software to link the transponder reads from sites anywhere in the state, the transponder-equipped trucks could become a travel time probe fleet. The second technology tested involved global positioning systems (GPS) placed in volunteer trucks recruited for this project to collect specific truck movement data at 5-second intervals. With GPS data it was possible to understand when and where the monitored trucks experienced congestion. By aggregating this information over time, it was possible to generate performance statistics related to the reliability of truck trips, and even examine changes in route choice for trips between high volume origin/destination pairs. The study found that both data collection technologies could be useful; however, the key to both technologies is whether enough instrumented vehicles pass over the roadways for which data are required. This basic condition significantly affects whether the transponder and GPS technologies will be effective at collecting the data required for any given FMSIB benchmark project . The report also recommends the traffic data that should be collected for a benchmark program and the potential costs of using either data collection technology.

Authors:
McCormack,E. D., Hallenbeck,M. E.

Keywords:
freight movement reliability, truck monitoring, development, data, data collection, methodology, cost, truck, roadway, corridors, freight, freight mobility, mobility, design, performance, speed, volume, commercial vehicle, networks, trucks, Washington, software, travel time, probe, global positioning, global positioning systems, positioning, systems, GPS, congestion, statistics, reliability, condition, traffic, traffic data, program, costs

Download Report:

Abstract:
The Service Patrol pilot demonstration in Seattle and Tacoma was managed by the Washington State Department of Transportation (WSDOT) and operated by Washington State Patrol (WSP) cadets and contracted registered tow truck operators (RTTOs). Two other roving services, not funded as part of this pilot effort but included to a limited extent in this evaluation, were the roving patrol service provided by WSDOT on the SR 520 and I-90 floating bridges and the privately sponsored motor assistance vehicle from AAA's RescueVan. The evaluation examines how the similarities and differences among the different service delivery modes (e.g., the intensity of deployment, equipment choices, service delivery, costs) affect the impact of the Service Patrol operation on traffic conditions (e.g., reductions in delay) and the level of motorist satisfaction. This report also discusses feedback by the agencies participating in the Service Patrol program on institutional and operational issues that contribute to or hinder the success of the program. Operational characteristics and operating statistics are reported to convey factors that describe program effectiveness. The results of the study indicate that the use of a combination of service providers has benefits that no single provider can duplicate, and the cost implications of changing the program are small enough that any potential savings would be fairly minor. The pilot project resulted in a variety of intangible benefits, such as improved interagency coordination and cooperation, more efficient utilization of personnel, and a better understanding of each partner's roles and contributions toward congestion relief. The positive viewpoint toward the Service Patrol was uniform, regardless the service mode. Therefore, no significant changes to the existing pilot program are recommended at this time.

Authors:
Nee,J., Hallenbeck,M. E.

Keywords:
service patrols, incident response time, traffic delay, traffic safety, research, seattle, Washington, Washington state, transportation, WSDOT, truck, evaluation, floating bridge, bridges, bridge, costs, cost, traffic, condition, program, statistics, benefits, benefit, congestion

Download Report:

Abstract:
This report clarifies the Washington State Department of Transportation (WSDOT) hotmix asphalt (HMA) statistical acceptance specification's statistical basis and how its key components influence overall specification performance and contractual pay.The WSDOT specification uses a variable sampling plan to measure in-place density, asphalt content, and aggregate gradation. Specification bands on these three quality characteristics are reasonable and consistent with typical material, sampling, testing, and construction variability. Pay is determined by calculating a percentage within limits (PWL), then applying a series of parabolic pay equations, depending on sample size.The methods used by WSDOT balance risk between the contractor and WSDOT well but result in two issues that differ from similar specifications: (1) expected pay for material produced at acceptable quality level (AQL) is greater than 1.0, and (2) WSDOT's AQL is 95 PWL but contractors seem to consistently produce material near 90 PWL The issues are not critical, and therefore, the specification should not be changed. However, if the third and final report in this series, which studies quality characteristics to be measured for Superpave design mixes, results in major recommended changes, then we recommend reviewing the AQL and pay factors to bring the specification into fine with actual practice.

Authors:
Muench,S. T., Mahoney,J. P.

Keywords:
asphalt concrete, HMA, hot mix asphalt, pay factor, research, specification, statistical acceptance specification, statistics, Washington state

Download Report:

Abstract:
This manual is intended for use by state departments of transportation to design and carry out highway research. The examples in the manual cover a wide range of typical research projects, from testing pavement overlays to evaluation of transportation system management experiments.The manual is divided into two parts. The first deals with issues in research design. Eight potential pitfalls in research are identified and ways to deal with them are discussed. The second section contains a discussion of simple statistical methods likely to be encountered in highway research.

Authors:
Ulberg,C.

Keywords:
research design, statistics

Abstract:
This report documents potential enhancements in three areas for the Washington State Pavement Management System (WSPMS): (1) a checking scheme for the annual pavement condition survey, (2) models for use in estimating vehicle operating costs due to pavement deterioration and their use in the optimal timing of rehabilitation, and (3) an alternate method for estimating pavement performance equations. The earlier report prepared for this study (WA-RD 315.1, Statistical Methods for WSDOT Pavement and Material Applications) provides an overview of various statistical methods. A purpose of that report was to explain statistical methods (with special emphasis on regression analysis) in a straightforward manner to a broad group of users.

Authors:
Mahoney,J. P., Seferian,M.

Keywords:
pavement management systems, pavement, sampling, statistics, costs models, regression analysis, modules

Download Report:

Abstract:
The Washington State Department of Transportation (WSDOT) did a trial implementation of a quality assurance (QA) specification for asphalt concrete during the 1989 paving season. To assess the QA specification, data from both non-QA and QA projects built that year were compared. Based on these results, the QA projects were evaluated as having improved quality. Subsequently, the QA specification was fully implemented within WSDOT.

Authors:
Markey,S. J., Mahoney,J. P., Geitz,R. H.

Keywords:
quality assurance, statistics, asphalt concrete

Download Report:

Abstract:
This document is an upgraded version of Research Report WA-RD 143.2 (February 1988) and is principally the result of continuing work on the WSDOT Pavement Management System (WSPMS). Various statistical methods have been used in the WSPMS and the research team wanted to summarize some of these applications in a separate, straightforward report which may be of value to a broader group of users.

Authors:
Mahoney,J. P., Seferian,M.

Keywords:
statistics, regression, materials, pavement, models

Download Report:

Abstract:
This manual is intended for use by state departments of transportation to design and carry out highway research. The examples in the manual cover a wide range of typical research projects, from testing pavement overlays to evaluation of transportation system management experiments. The manual is divided into two parts. The first with issues in research design. Eight potential pitfalls in research are identified and ways to deal with them are discussed. The second section contains a discussion of simple statistical methods likely to be encountered in highway research.

Authors:
Ulberg,C.

Keywords:
research design, statistics

Download Report:

Abstract:
The WSDOT PMS database was used to develop regression equations for three pavement surface types: bituminous surface treatments, asphalt concrete and portland cement concrete. The primary regression equations developed were to predict Pavement Condition Rating(PCR) which is a measure of the pavement surface distress (ranges from 100 (no distress) to below 0 (extensive distress)). Overall, the equations fit the data rather well given the expected variation of pavement performance information. The relative effects of age (time since construction or reconstruction) were illustrated for the three surface types.

Authors:
Mahoney,J. P., Kay,R. K., Jackson,N. C.

Keywords:
pavement PCC, pavement, performance, statistics, regression, equations

Download Report:

Abstract:
This document represents the course notes used in training WSDOT personnel on regression modeling techniques. This work was done in conjunction with the development of pavement performance equations by WSDOT personnel which were based on data in the WSDOT Pavement Management System. This study was funded by the Federal Highway Administration.

Authors:
Mahoney,J. P.

Keywords:
regression, statistics, materials, pavement, models

Download Report:

Abstract:
Various methods of controlling traffic through construction zones are examined. The accident statistics concerning construction flagging are summarized, indicating the need for improvements in construction flagging techniques. A research methodology is presented for implementing and evaluating several flagging techniques.

Authors:
Hinze,J., Ifie,A. O.

Keywords:
construction, construction flagging, evaluation, flagging techniques, highway, highway construction, methodology, research, statistics, traffic, traffic control

Download Report:

Abstract:
The Telecom Link established between the University of Washington and the WSDOT Traffic Systems Management Center (TSMC) was updated during this project in order to handle the shift made by the TSMC from a 1700 loop surveillance system to a 2200 loop system. Special computer programs were also written to provide specialized summary statistics for key stations. The new software allowed statistics for key stations to be collected and summarized during data transfer. The entire transfer retrieval system was streamlined during the Telecom project to reduce costs. Finally, freeway incident analysis was performed with a data set to demonstrate the use of the new system for TSM research.

Authors:
Nihan,N. L.

Keywords:
analysis, computer, computer program, cost, costs, data, data management, data transfer, freeway, freeway surveillance and control, incident, management, program, ramp metering, research, software, statistics, surveillance, systems, telecommunications, telecommunications link, traffic, traffic systems management, transportation systems management, TSM, Washington, WSDOT

Download Report:

Abstract:
This report reflects a year of data gathering together with the completion of analysis programs. These include the initial tape conversion, data rejection and selection, fast Fourier transform coefficient computation. Complete statistics of measurements are given.

Authors:
Brown,C.

Keywords:
analysis, Annual, bridge, data, fatigue, maintenance, program, reliability, statistics, wind

Download Report: