Transportation Intelligence

Volume 8 Number 6

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December 2010
Administration
Environment
Feedback

Traffic Control
Quantifying the Benefits of Coordinated Actuated Traffic Signal Systems: A Case Study
The purpose of this study was to quantify the benefits of coordinated actuated traffic signal systems by conducting an analysis of before-and-after data. The travel time on the coordinated arterials and the stopped delay on a few key approaches were selected as measures of effectiveness. Synchro, a macroscopic traffic signal timing evaluation and optimization software, was used to generate the coordinated actuated traffic signal timing plans for comparison purposes. In addition, the performance of an adaptive split feature, implemented within the coordinated actuated traffic signal system, was evaluated through a before-and- after study. (Virginia Department of Transportation report VTRC 11-CR2, September 2010, 32p.)

Safety
Public lighting for safe and attractive pedestrian areas
The Australian/New Zealand standard Lighting for roads and public spaces, part 3.1: pedestrian area (category P) lighting – performance and design requirements (AS/NZS 1158.3.1:2005) sets out specifications for pedestrian lighting. This research project complements and extends the standard by investigating pedestrian lighting practices to make walking not only safe, but also more attractive. The project highlights issues and perspectives from which to view the effectiveness of the pedestrian lighting. This research is partly based on the observation that most lighting in the public arena has traditionally been driven by the needs of motorists, but pedestrians’ needs are different. It studies those differences and guides on lighting techniques that can appropriately and specifically cater for pedestrians. The findings are based on a review of literature incorporated with information from the lighting industry. (New Zealand Transport Agency research report 405, 2010, 46p.)
Structures
Concrete Cracking in New Bridge Decks and Overlays
There appears to be a trend for new bridge decks in the state of Wisconsin to develop early-age transverse cracks and map cracks on concrete overlays. A comprehensive literature review of the potential causes of concrete bridge deck cracking is provided. Fifteen bridge structures found in the recently completed Marquette Interchange were analyzed using 21 variables thought to cause early-age bridge deck cracking. Visual inspection of sixteen bridges in Milwaukee is described. The inspections show that the continuous superstructures have more cracks than the simply-supported bridges. A finite element model was created for a typical two-span continuous superstructure with HL-93 truck loads and concrete shrinkage-induced strains. The FE simulations indicate that the normal traffic load by itself will not cause concrete deck cracking. However, tensile stress introduced by concrete shrinkage may cause transverse cracks as early as 4 to 8 days after pouring concrete. (Wisconsin Department of Transportation report WHRP 10-05, February 2010, 154p.)

Administration (voir aussi Administration)

Pavement Marking Warranty Specifications
This study updates information on the use of pavement marking warranties by U.S. and Canadian transportation agencies, including agency specifications. European experience is also presented, for comparison. Interest in applying warranties to pavement markings is driven by the importance of markings for traffic mobility and safety, and a desire to have better marking performance and greater cost-effectiveness. Information was gathered through a literature review, surveys of state and Canadian provincial/territorial transportation agencies, and interviews with pavement marking contractors and materials suppliers. Appendices D and E for NCHRP Synthesis 408 are available online at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_408Appendixes.pdf (TRB National Cooperative Highway Research Program Synthesis 408, 2010, 223p.)

Policy Issues in U.S. Transportation Public-Private Partnerships: Lessons from Australia
In this report, the authors examine Australia’s experience with transportation public-private partnerships (PPPs) and the lessons that experience holds for the use of PPPs in the United States. Australia now has decades of experience in PPP use in transportation, and has used the approach to deliver billions of dollars in project value. Although this report explores a range of issues, the authors focus on four policy issues that have been salient in the United States: (1) how the risks inherent in PPP contracts should be distributed across public and private sector partners; (2) when and how to use non-compete (or compensation) clauses in PPP contracts; (3) how concerns about monopoly power are best addressed; and (4) the role and importance of concession length. (San José State University. Mineta Transportation Institute report CA-MTI-10-2807, July 2010, 110p.)

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Pavements (voir aussi Chaussées)

Effectiveness of Chip Sealing and Micro Surfacing on Pavement Serviceability and Life
This report presents the details of an investigation to evaluate the effectiveness of chip seal and micro surfacing as preventive maintenance treatments. The study utilizes data from previously completed projects in Ohio and reflects current practices. The study focused primarily on the following two issues: 1. Optimal timing of treatment placement, 2. Cost-effectiveness of treatments. (Ohio Department of Transportation report FHWA/OH-2010/8, May 2010, 101p.)

Performance of Recycled Asphalt Pavement in Gravel Roads
As more Recycled Asphalt Pavement (RAP) becomes available to use in roadways, The Wyoming T2/LTAP Center and two Wyoming Counties investigated the use of RAP in gravel roads. The Wyoming DOT and the Mountain-Plains Consortium funded this study. The investigation explored the use RAP as a means of dust suppression on gravel roads while considering road serviceability. Several test sections were constructed in two Wyoming Counties and were monitored for dust loss using the Colorado State University Dustometer. Surface distress evaluations of the test sections were performed following a technique developed by the U.S. Army Corps of Engineers in Special Report 92-26: Unsurfaced Road Maintenance Management. The data collected were summarized and statistically analyzed. (University of North Dakota. Upper Great Plains Transportation Institute report, October 2010, 285p.)

Development of Non-Petroleum Based Binders for Use in Flexible Pavements
Most bituminous adhesives or binders that are used for pavement materials are derived primarily from fossil fuels. With petroleum oil reserves becoming depleted and the drive to establish a bio-based economy, there is a push to produce binders from alternative sources, particularly from biorenewable resources. However, until now, no research has studied the applicability of utilizing bio-oils as a bitumen replacement (100% replacement) in the pavement industry. The main objective of this research was to test various properties of bio-oils in order to determine the applicability of using bio-oils as binders in the pavement industry. (Iowa Highway Resaerch Board project report TR-594, October 2010, 265p.)

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Concrete (voir aussi Béton)

Dowel Bar Retrofit Performance in Wisconsin
In 1999, WisDOT constructed test sections on I-39 to evaluate the dowel bar retrofit (DBR) rehabilitation technique for faulted concrete pavement slabs. Two years later, mortar deterioration and debonding were noted in the dowel slots. In response to this early distress, additional test sections were constructed on STH 13 to evaluate various mortar materials. The I-39 project was repaired, and test sections from both the I-39 and STH 13 projects were monitored between 2001 and 2007 for distress (PDI), pavement smoothness (IRI), and load transfer efficiency (LTE) between adjacent slabs. Additional DBR projects on USH 45, STH 21, and USH 18/151 were also surveyed in 2010. (Wisconsin Department of Transportation Report WI-02-10, May 2010, 42p.)

Controlled Composite Action (C2A) to Eliminate Transverse Cracking in Concrete Bridge Decks
Tens of thousands of bridges in the US develop transverse deck cracking due to concrete shrinkage. Transverse cracks are observed on various types of superstructures and in most geographical locations. Most researchers have tried to tackle this problem to date by focusing on changes in design and construction techniques, many of which have been implemented, but the problem still remains. This study focused instead on the possibility of controlling the composite action through the development of a mechanism to prevent the action (restraint) during early stages (i.e. as concrete shrinks), while activating necessary action later on when service load was greater. To achieve this objective, the connectors were wrapped in a carefully selected hyper elastic material, which, under low level of stresses, would not provide any resistance. (City College of New York. University Transportation Research Center report, July 2010, 59p.)

Abrasion-Resistant Concrete Mix Designs for Precast Bridge Deck Panels
The report documents laboratory investigations undertaken to develop high performance concrete (HPC) for precast and pre-stressed bridge deck components that would reduce the life-cycle cost of bridges by improving the studded tire wear (abrasion) resistance and the durability of bridge decks. Phase I of the project involved an initial investigation of candidate mixtures incorporating type I portland cement, supplementary cementitious materials (silica fume, slag, and fly ash), natural aggregate (river gravel), and crushed rock. Phase II of the project utilized the findings from Phase I and the Pilot Study to develop HPC mixtures that had improved abrasion resistance and durability characteristics relative to a newly-specified ODOT bridge deck mixture. (Oregon Department of Transportation report FHWA-OR-RD-11-04, September 2010, 196p.)

A Precast Bridge Bent System for Seismic Regions - Phase I Report
This report describes a precast concrete bridge bent system that is suitable for high seismic zones. Lateral load tests on both the top (column-to-cap) and bottom (column-to-footing) connections of the system have demonstrated that the connections have strengths and ductilities similar to those of comparable cast-in-place connections. Additional tests on the bottom connection of the system are ongoing, and construction of a demonstration bridge project will begin later this year. The final development of this system is partially funded by the FHWA’s Highways for LIFE Technology Partnerships Program (DTFH61-09-00005). Information on both the Highways for LIFE program and this project may be found at http://www.fhwa.dot.gov/hfl/. (US Federal Highway Administration Highways for LIFE report, 15 October 2010, 24p.)

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Environment (voir aussi Environnement)

Culvert Design for Aquatic Organism Passage - Hydraulic Engineering Circular Number 26
This document presents a stream simulation design procedure, methods and best practices for designing culverts to facilitate aquatic organism passage (AOP). The primary goal of this document is to incorporate many of the current geomorphic-based design approaches for AOP while providing a procedure based on quantitative best practices. It also provides important background information a designer should be familiar with including how culverts create barriers, techniques for culvert assessments and inventories, fish biology, fish passage hydrology, stream geomorphology, construction, and post-construction. Detailed technical information supporting the practices used within the design procedure and several design examples are included in the appendices. (US Federal Highway Administration Report FHWA-HIF-11-008 HEC-26, October 2010, 234p.)

Barriers to Implementing Low Impact Development Approaches in Washington State Roadways and Highways
Low impact development (LID) is an approach to stormwater management that seeks to mimic the natural hydrologic functions of stormwater runoff prior to development. In general, LID techniques emphasize infiltration and evapotranspiration to remove pollutants and attenuate flows from urban runoff. Washington State Department of Transportation (WSDOT) is interested in better understanding the challenges of applying LID techniques to a highway setting and learning ways to address those challenges. This report identifies barriers to implementing LID approaches in a state roadway setting and provides recommendations on how WSDOT can overcome those barriers. (Washington State Department of Transport report, June 2010, 38p.)

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Safety (voir aussi Sécurité)

Crash Factors in Intersection-Related Crashes: An On-Scene Perspective
In order to understand the crash scenarios at intersections, this study examines general characteristics of motor vehicle traffic crashes at intersections by analyzing the association of the critical reason with several crash factors such as driver’s sex and age, traffic control device, critical pre-crash event, and atmospheric condition. The National Motor Vehicle Crash Causation Survey data collected at crash scenes between 2005 and 2007 is used in statistical analyses such as descriptive analysis, generalized logit model, and configural frequency analysis. (US National Highway Traffic Safety Administration report DOT HS 811 366, September 2010, 37p.)

Best Practices in Traffic Incident Management
Traffic incident management (TIM) is a planned and coordinated program to detect and remove incidents and restore traffic capacity as safely and quickly as possible. Over time, various tools and strategies have been developed and implemented in an effort to improve overall TIM efforts. This report describes task-specific and cross-cutting issues or challenges commonly encountered by TIM responders in the performance of their duties, and novel and/or effective strategies for overcoming these issues and challenges (i.e., best practices). The reported tools and strategies for improving TIM range from sophisticated, high-technology strategies to simple, procedural strategies. Information to support this investigation was obtained through (1) a review of published and electronic information sources and (2) input from TIM personnel representing law enforcement, fire and rescue, emergency medical services, transportation, and towing and recovery agencies. (US Federal Highway Administration Report FHWA-HOP-10-050, September 2010, 123p.)

Achieving Traffic Safety Goals in the United States: Lessons from Other Nations
In recent decades nearly every high-income country has made more rapid progress than has the United States in reducing the frequency of road traffic deaths and the rate of deaths per kilometer of vehicle travel. The Transportation Research Board (TRB) formed the Committee for the Study of Traffic Safety Lessons from Benchmark Nations to document the experience of other high-income countries in reducing traffic deaths and injuries and to examine the safety programs that contributed to the reductions, in particular, interventions to alter driving behavior and strategies to build public and political support for safety interventions. The purpose of the committee’s study was to identify traffic safety strategies that could succeed in the United States. (US Transportation Research Board Special Report 300, 2010, 188p.)

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Urban (voir aussi Zone urbaine)

Bus Riding on Shoulders
Bus on shoulder (BOS) operations have been ongoing in several locations across the United States and abroad. Public transit buses in the designated highway and arterial shoulders are generally allowed to travel up to 15 mph faster than traffic in the general lanes, but no more than 35 mph. These operations are typically undertaken to give public transit riders a faster and more reliable traveling experience when highway and arterial general traffic lanes are congested. The research team reviewed the literature on safety and operational aspects of shoulder use and the ways in which shoulder use has been incorporated as a way to manage congestion in several regions. They also interviewed primary stakeholders, who might be involved in planning and operating a BOS system in Northeastern Illinois and analyzed their comments. (Illinois Department of Transportation report FHWA-ICT-10-073, August 2010, 58p.)

Advancing Metropolitan Planning for Operations: The Building Blocks of a Model Transportation Plan Incorporating Operations - A Desk Reference
This publication is a resource designed to enable transportation planners and their planning partners to build a transportation plan that includes operations objectives, performance measures, and strategies that are relevant to their region, that reflect the community’s values and constraints, and that move the region in a direction of improved mobility and safety. It offers practitioners a menu of options for incorporating operations into their plans through an organized collection of sample operations objectives and performance measures. It also features excerpts from a model metropolitan transportation plan, illustrating the results of an objectives-driven, performance-based approach to planning for operations. (US Federal Highway Administration report FHWA-HOP-10-027, April 2010, 162p.)

Increasing Carpooling in Vermont: Opportunities and Obstacles
Carpooling can increase personal mobility, access to services, reduce environmental and infrastructure impacts, reduce individual transportation costs and save energy. However, the percentage of commuters carpooling has significantly decreased since 1980 both nationally and in Vermont. The purpose of this research is to examine potential obstacles and opportunities to increasing carpooling for the journey-to-work commute in Vermont and provide research-based information for state policy-makers regarding programs and policies designed to increase carpooling in Vermont. (University of Vermont Transportation Research Center report 10-010, June 2010, 25p.)

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