Transportation Intelligence

Volume 9 Number 2-3

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April-June 2011

Administration

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Safety
Investigation on the performance of fire detection systems for tunnel applications - Part 2: full-scale experiments under longitudinal airflow conditions
This paper presents the results of the full-scale experiments conducted in a laboratory tunnel facility under longitudinal airflow conditions and in the Carré-Viger Tunnel. The performance of nine fire detection systems representing five types of the fire detection technologies for road tunnel applications was investigated using representative tunnel fire scenarios. The changes in fire characteristics caused by longitudinal airflow, such as fuel burning time, fire growth rate, temperatures and smoke spread in the tunnel, were measured and analyzed. The experimental results showed that the detection time of the fire detection systems under longitudinal airflow conditions could be increased or decreased, depending on the fuel type, fire size and location, airflow velocity and detection method. (National Research Council of Canada Institute for Research in Construction report NRCC-53966, January 2011, 29p.)

Traffic Control
Understanding Commuter Patterns & Behavior; An Analysis to Recommend Policies Aimed at Reducing Vehicle Use
The objective of the study was to make alternative transportation a more viable option by identifying commuting preferences and patterns in order to recommend policies aimed at reducing vehicle miles travelled. This study focused on the use of single occupancy vehicles by employee and student commuters at the University at Albany and the nearby Harriman Campus. The study revealed that the success of alternative transportation is hindered by limitations in scheduling, frequency of routes, length of trip, unavailable routes, the need for commuters to make additional trips outside their commute travel and a distrust of bus reliability during high stress periods (i.e. tests). The report includes a handbook for conducting a similar analysis at other institutions. (New York State Department of Transportation report C-08-30, August 2010, 213p.)

Administration (voir aussi Administration)

Key Performance Indicators in Public-Private Partnerships
This report provides a state-of-the-practice description of domestic and international practices for key performance indicators (KPIs) in public-private partnerships (PPPs). The report is based on a comprehensive literature review and eight case studies from Australia, British Columbia, the United Kingdom, and the United States. The report identifies how government-developed performance measures reflecting societal goals such as congestion management or environmental impact are translated through KPIs and included in project documents for designing, constructing, operating, and maintaining transportation facilities. The report shows that it is possible to align projects with these higher goals. The findings are applicable to agencies that wish to align overarching organizational and societal performance measures through KPIs not only to PPP projects, but also to conventionally bid projects. (US Federal Highway Administration’s Office of International Programs report FHWA-PL-10-029, March 2011, 124p.)

Advancing Public Interest in Public-Private Partnership of State Highway Development
Facing rapidly increasing demand for new or additional transportation capacity, many states are exploring public-private partnership (PPP) in state highway development. The confusion and controversy surrounding recent asset-monetization leasing concession cases in the US have led to widespread public concerns and legislative caution, in particular on the question of whether a PPP project is advancing the public interest. The purpose of this project is to study the public interest associated with PPPs, with the goal to maximize efficiency gains, mitigate potential risks, and address public concerns in launching and deploying PPPs in state highway development. In particular, we focus on three aspects of PPP consideration: (1) Understanding economic rationales of PPPs, (2) Legal and political aspects of PPP decision-making, and (3) Managerial issues in implementing PPP projects. (Minnesota Department of Transprtation report MN/RC 2011-09, February 2011, 66p.)

The Intersection of Urban Form and Mileage Fees: Findings from the Oregon Road User Fee Pilot Program
This report analyzes data from the 2006-2007 Oregon Road User Fee Pilot Program to assess if and how urban form variables correlate with travel behavior changes that participants made in response to the mileage fee program. The study tested the impact of two fee structures, a variable charge and a flat rate, on seven types of vehicle miles traveled (VMT), and finds that charging a noticeably higher fee for driving in congested conditions can successfully motivate households to reduce their VMT in those times and places where congestion is most a problem. Households in both traditional (mixed use, dense, transit-accessible) and suburban (single-use, low density) neighborhoods will likely reduce their peak-hour and overall travel under a charging scheme that charges a high-rate for peak-hour travel, though households in the traditional neighborhoods will do so more. (Mineta Transportation Institute report 10-04, March 2011, 68p.)

Long term evaluation of individualized marketing programs for travel demand management
This research examines the use of individualized marketing as a transportation demand management (TDM) strategy, using the City of Portland’s SmartTrips program. This research project has two specific aims: (1) to evaluate whether the benefits of these individualized marketing programs continue to at least one year after the project ends; and (2) to examine whether the theory of planned behavior (TPB) can help explain the behavior changes identified. (Oregon Transportation Research and Education Consortium report OTREC-RR-10-08, July 2010, 80p.)

Road Investment Needs to Support Agricultural Logistics and Economic Development in North Dakota
The purpose of this study is to analyze changes in agricultural production and logistics and the importance of roadway investments to the distribution of crops produced in North Dakota. The essential objective was to quantify the funding level required to maintain and improve the existing local road network. (Upper Great Plains Transportation Institute report, January 10, 2011, 41p.)

Synthesis of Congestion Pricing-Related Environmental Impact Analyses – Final Report
This report summarizes the state-of-the-practice and presents a recommended framework for before-after evaluations of the environmental impacts of congestion pricing projects, such as high-occupancy toll (HOT) lanes and cordon or area pricing schemes. The report focuses on the three environmental impact areas that have been most commonly examined in such evaluations: air quality, noise, and environmental justice (sometimes referred to as equity). Since environmental impacts are a function of the travel impacts of congestion pricing projects, this report also examines state-of-the-practice regarding evaluation of travel impacts such as traffic, transit and travel behavior. The state-of-the-practice results are based primarily on a review of the published literature associated with eight congestion pricing study projects from around the world. A number of gaps in existing practice and understanding are identified and recommendations are provided to address those gaps. (US Federal Highway Administration report FHWA-HOP-11-008, October 18, 2010, 96p.)

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Pavements (voir aussi Chaussées)

Mechanical Properties of Warm Mix Asphalts Prepared Using Formed Asphalt Binders
Concerns have been raised regarding the susceptibility of warm mix asphalt (WMA) to moisture-induced damage and permanent deformation due to the reduced mixing and compaction temperatures used during WMA production. Therefore, this study was conducted to develop a laboratory procedure to produce WMA mixtures prepared using foamed asphalt binders (WMA-FA), and to evaluate their performance in comparison to conventional hot mix asphalt (HMA). (Ohio Department of Transportation report FHWA/OH-2011/6, March 2011, 148p.)

Cost Benefit Analysis of Including Microsurfacing in Pavement Treatment Strategies and Cycle Maintenance
This project was developed to address the need to re-evaluate thin surface treatments, review available new technologies with the objective of recommending potentially beneficial systems, and assess the cost effectiveness of these treatments for conditions in Pennsylvania. (Pennsylvania Department of Transportation report FHWA-PA-2011-001-080503, January 18, 2011, 96p.)

Guidelines for the Preservation of High-Traffic-Volume Roadways
This research report documents the state of the practice for preservation treatment on asphalt and concrete pavements. Although the focus of the research project was on treatments suitable for application on high-volume roadways, this report also discusses current practices for low-volume roadways. The information presented is derived from a detailed survey of transportation agencies and a review of national and international literature. In addition, the report provides a general framework for how best practices are identified. Finally, general guidelines were developed on the application of preservation treatments on high-volume roadways. Presented as a separate document, the guidelines consider traffic volume, pavement condition, work-zone requirements, environmental conditions, and expected performance. (US Strategic Highway Research Program (SHRP 2) Report S2-R26-RR-2, 2011, 62p.)

Allowable Axle Loads on Pavements
This report documents the development of a procedure to determine the structural adequacy and need of seasonal axle load restrictions for Minnesota low-volume roads. This procedure has been implemented into a new program, TONN2010. Since it is anticipated that the results of this study will be widely used by Mn/DOT, city, and county engineers, as well as consulting engineers involved in analysis of the falling weight deflectometer (FWD) data collected by the transportation agencies, an emphasis was made on development of a simple, easy to implement procedure. (Minnestota Department of Transportation Report MN/RC 2011-02, December 2010, 52p.)

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Traffic Control (voir aussi Gestion de la circulation)

Evaluation of Bike Boxes at Signalized Intersections
This report presents a before-after study of bike boxes at 10 signalized intersections in Portland, Oregon. The bike boxes, also known as advanced stop lines or advanced stop boxes, were installed to increase visibility of cyclists and reduce conflicts between motor vehicle and cyclists, particularly in potential 'right-hook' situations. Before and after video were analyzed for seven intersections with green bike boxes, three intersections with uncolored bike boxes, and two control intersections. User perceptions were measured through surveys of cyclists passing through five of the bike box intersections and of motorists working downtown, where the boxes were concentrated. Both the observations and survey of motorists found a high rate of compliance and understanding of the markings. (Oregon Transportation Reearch and Education Consortium report OTREC-RR-11-06, January 2011, 126p.)

Development of a Framework for Evaluating Yellow Timing at Signalized Intersections
Studies show that the proper design of clearance intervals has significant implications for intersection safety. Driver behavior while the driver is approaching high-speed signalized intersections at the onset of a yellow indication varies as a function of many parameters. Some of these parameters are related to the driver’s attributes, e.g., age, gender, perception-reaction time, and acceptable deceleration levels. Other parameters that relate to the intersection geometry include the approach speed, distance, and time to the intersection at the onset of the yellow indication. This study developed a novice approach for computing the clearance interval duration that explicitly accounts for the reliability of the design (probability that drivers are not caught in a dilemma zone). Lookup tables based on the limited data available from this study are provided to illustrate how the framework could be used in the design of yellow timings. (Virginia Department of Transportation Report FHWA/VCTIR 11-R12, February 2011, 71p.)

Decision Support Tools to Support the Operations of Traffic Management Centers (TMC)
The goal of this project is to develop decision support tools to support traffic management operations based on collected intelligent transportation system (ITS) data. The project developments include new models to estimate travel time based on point detectors. These models were compared with existing travel time estimation methods including the one used in the SunGuide software. The results indicate that all of the tested methods perform at acceptable and comparable levels at low congestion levels. However, their performances vary with the increase in congestion levels. The comparison with other estimation methods shows that the developed models perform well in all cases. (Florida Department of Transportation report, 31 January 2011, 189p.)

Evaluation of Innovative Bicycle Facilities: SW Broadway Cycle Track and SW Stark/Oak Street Buffered Bike Lanes
Two innovative bicycle facilities installed in late summer and early fall 2009 in downtown Portland by the City of Portland Bureau of Transportation (PBOT) were evaluated to understand how they are functioning on multiple levels. All of these facilities involved removing a motor vehicle lane by restriping to provide additional roadway space to bicyclists. The facilities include:
- A cycle track (a seven-foot bike lane separated from motor vehicle traffic by a row of parked cars and a painted three-foot pedestrian buffer), and
- A couplet of buffered bike lanes (six-foot bike lanes with a two-foot painted buffer on either side separating them from motor vehicle traffic).

The facilities were evaluated after they had been in place for approximately one year. Data collected to support this evaluation consisted of surveys of multiple user groups for each facility type, and video data was collected by PBOT at intersections along each of the routes to understand the facilities’ impact on traffic flow, operations and user interactions. (Portland State University report, 14 January 2011, 89p.)

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Safety (voir aussi Sécurité)

Safety Analysis of Low-Volume Rural Roads in Iowa
Low-volume rural roads account for about half of all recorded traffic crashes in Iowa, including a high percentage of fatal and major injury crashes. This study was undertaken to examine these crashes, identify major contributing causes, and develop low-cost strategies for reducing the incidence of these crashes. (Iowa Department of Transportation project report InTrans 07-309, December 2010, 122p.)

Empirical Observation of the Impact of Traffic Oscillations on Freeway Safety
Traffic oscillations are typical features of congested traffic flow that are characterized by recurring decelerations followed by accelerations (stop-and-go driving). The negative environmental impacts of these oscillations are widely accepted, but their impact on traffic safety has been debated. This report describes the impact of freeway traffic oscillations on traffic safety. This study employs a matched case-control design using high resolution traffic and crash data from a freeway segment. (Oregon Transportation Research and Education Consortium report OTREC-RR-10-13, September 2010, 56p.)

Casualty crash reductions from reducing various levels of speeding
Casualty crash reductions from reducing various levels of speeding are estimated by applying the relative risk of involvement in a casualty crash to the proportion of vehicles travelling at a given speed. The greatest overall effect on casualty crashes involving vehicles travelling at speeds from 1 to 20 km/h above the speed limit will come from reducing speeds just above that limit in almost all cases. Analysis of where injury and fatal crashes occur indicates that while speed reductions of any type would be expected to reduce injuries and fatalities, the greatest potential gains for reducing injuries appear to be in targeting low level speeding on Adelaide low speed roads. For fatalities this would be extended to include low level speeding on high speed rural roads. (University of Adelaide Centre for Automotive Safety Research report CASR076, February 2011, 43p.)

Transportation Safety Data and Analysis Volume 1: Analyzing the Effectiveness of Safety Measures Using Bayesian Methods
Recent research suggests that traditional safety evaluation methods may be inadequate in accurately determining the effectiveness of roadway safety measures. In recent years, advanced statistical methods are being utilized in traffic safety studies to more accurately determine the effectiveness of roadway safety measures. These methods, particularly Bayesian statistical techniques, have the capabilities to account for the shortcomings of traditional methods. Hierarchical Bayesian modeling is a powerful tool that more fully identifies a given problem than a simpler model could. This report explains the process wherein a hierarchical Bayesian model is developed as a tool to analyze the effectiveness of two types of road safety measures: raised medians and cable barrier. (Utah Department of Transportation report UT-10.12a, December 2010, 160p.)

Best Practices in Traffic Operations and Safety: Phase II: Zig-zag Pavement Markings
The Washington and Old Dominion (W&OD) Trail is a 45-mile multiuse trail that spans the Virginia counties of Fairfax and Loudoun. The more than 70 highway crossings of the trail create a significant potential for serious crashes between vehicles and bicyclists/pedestrians. In an attempt to increase safety at two of the crossings, VDOT installed zig-zag pavement markings in Loudoun County where the trail crosses Belmont Ridge Road and Sterling Boulevard. This study assessed the effectiveness of the zig-zag pavement markings. Effectiveness was defined as: (1) an increase in motorist awareness in advance of the crossing locations; (2) a positive change in motorist attitudes; and (3) motorist understanding of the markings. (Virginia Transport Research Council report VTRC 11-R9, December 2010, 94p.)

Methods for Identifying High Collision Concentration Locations (HCCL) for Potential Safety Improvements – Phase II: Evaluation of Alternative Methods for Identifying HCCL
The objective of network screening should ideally be to not only identify sites for safety investigation but also to prioritize those sites efficiently. Using roadway, intersection, and collision data from California, this study compared the performance of methods based on the EB procedure, the LOSS method, and the Table C method. Two intersection types (rural four leg stop controlled and rural four leg signalized) and two roadway types (rural two lane roads and urban freeways) were included in the evaluation. (California Department of Transportation report, January 21, 2011, 102 p.)

Low-Cost Portable Video-Based Queue Detection for Work-Zone Safety
Highway work-zone safety is a major concern for government agencies, the legislature, and the traveling public. In this study, a low-cost rapidly deployable and portable queue detection work zone intelligent transportation system (WZITS) warning system is proposed. To demonstrate WZITS feasibility, a queue detection algorithm was designed and tested using widely available, field proven, machine vision hardware that can be integrated into the current portable system prototype, using video data collected in the field from the portable device. The warning trigger generated by the algorithm can then be transmitted to a remote upstream location for triggering roadside emergency warning devices (such as VMS, flashers, etc.). (University of Minnesota Center for Transportation Studies report CTS 11-02, January 2011, 53p.)

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Structures (voir aussi Ouvrages d'art)

Design, Construction, and Field Testing of an Ultra High Performance Concrete Pi-Girder Bridge
The Jakway Park Bridge in Buchanan County, Iowa is the first bridge constructed with a new prestessed girder system composed of precast Ultra-High Performance Concrete (UHPC). These girders employ an integral deck to facilitate construction and are referred to as pi-girders for the resemblance of their cross-section to the Greek letter, “p”. The evolution of the girder geometry, simplifying assumptions, and finite element analysis techniques used in design of the bridge are examined, and the results of laboratory and live load field testing are presented to quantify behavior. The effectiveness of the finite element analysis and structural performance of the bridge, including live load distribution, are evaluated to provide guidance for future designs employing these girders. (Iowa Highway Research Board (IHRB) Project TR-574, January 2011, 93p.)

Performance Enhancement of Bridge Bracing Under Service and Extreme Loads
The purpose of this study was to develop and demonstrate the concept of retrofitting bridge brace elements with fiber reinforced composites in order to provide restraint against buckling. The advanced materials consisted of a combination of fiber reinforced polymer (FRP) composite pultruded sections and wet lay-up wraps, intended to be applied in the field. A selected number of prototype retrofit bracing specimens were constructed and tested using reverse cyclic loading, and the performance of these specimens was characterized by their compressive strength and their overall hysteretic behavior. (Oregon Transportation Research and Education Consortium report OTREC-RR-10-17, December 2010, 38p.)

Triage Evaluation of Gusset Plates in Steel Truss Bridges
The objective of this study is to develop a procedure to rapidly evaluate gusset plates in steel truss bridges. The procedure should be appropriately conservative and easy to apply and should be able to be implemented instead of the current FHWA recommendations. This study used analytical methods, originally developed for analysis of gusset plates in braced frames, to develop a rapid gusset plate assessment tool that meets that objective. (Washington State Department of Transportation report WA-RD-757.1, December 2010, 83p.)

Development of an Advanced Structural Monitoring System
With bridge infrastructure in Minnesota aging, advancing techniques for ensuring the safety of bridges and motorists is a fundamental goal of the Minnesota Department of Transportation (Mn/DOT). As such, developing health monitoring systems for fracture critical bridges is an essential objective in meeting the stated goal. This report applies the methodology and uses the information of a previous Mn/DOT report to investigate, select, and design a bridge health monitoring system for the Cedar Avenue Bridge. A procedure for installation of the suggested bridge health monitoring system follows the authors' recommendations and is applicable to any of the monitoring alternatives presented in this report. (Minnesota Department of Transportation report MN/RC 2010-39, November 2010, 66p.)

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