TAC Transportation Intelligence

Pavements

Long life pavements and success stories
This report includes the following elements:
• a definition of success stories;
• a comparison of the case studies with the more specific concept of Long Life Pavements;
• a brief overview of the papers received within the frame of inquiry;
• the different types and techniques suitable for success stories and possibly for long life pavements are highlighted;
• some conclusions and an indication of future work for a wider comparison between the true performance of pavements and existing design methods. (PIARC/AIPRC report 2009R06, 2009, 60p.)

The waterproofness of first-coat chipseals
This research project, undertaken in 2006 to 2008, confirms that traffic can force water through firstcoat chipseal surfacings that do not visually show signs of cracking. The research measured the change in moisture content after rain on a number of newly sealed sites. Although this testing showed a statistically significant increase in moisture over all sites, the increase was not dramatic. The research concludes that water ingress can occur where a water film collects on the pavement. The film of water can occur either through rutting of the pavements, or if the crossfall and longitudinal shape is such that a sheet of water forms above the surface texture of the pavement. (New Zealand Transport Agency research report 390, 2009, 24p.)

Hydraulic and Mechanical Properties of Recycled Materials
This study assessed the suitability of four recycled materials relative to virgin aggregates for use as base and subbase materials. The four recycled materials were the reclaimed asphalt pavement (RAP), fly ash (FA), reclaimed concrete material (RCM), and foundry sand (FS). Assessment of these materials was done in terms of their hydraulic, mechanical, and leaching properties when mixed in with various proportions of virgin aggregates. We concluded that FA, RAP, and RCM mixtures will be good substitutes of virgin aggregates as base and subbase materials. (Minnesota Department of Transportation Report 2009-32, October 2009, 219p.)

Concrete

A Mechanistic-Empirical Tie Bar Design Approach for Concrete Pavements
The current method of tie bar design is based on the concepts of subgrade drag theory (SDT). The theory determines the quantity of steel required to drag a concrete slab over an underlying layer without yielding or pulling out the steel bars. The dragging force is calculated based on the slab thickness, its unit weight, the friction between the slab and the underlying layer, and the distance to the closest free edge of the pavement. Based on this concept, the American Association of State Highway and Transportation Officials (AASHTO) 1993 Guide for Design of Pavement Structures provides charts for estimating tie bar sizes and spacings. However, this method fails to take into account the effects of temperature drop, drying shrinkage, and loading conditions on tie bar design when determining the required steel content. This report addresses the need for a more rational procedure for tie bar design based on mechanistic-empirical (M-E) concepts. (American Concrete Pavement Association Report, August 2009, 135p.)

Technology Evaluation on Characterization of the Air Void System in Concrete
The objective of this project was to evaluate current technologies that have the capability of characterizing the air void system in concrete within the first several hours of placement. This objective was met by developing a comprehensive technology assessment and literature review, and conducting a laboratory evaluation of two selected technologies: ultrasound and thermography. (Pennsylvania Department of Transportation Report FHWA-PA-2009-013-PSU 020, September 30, 2009, 122p.)

Structural Performance of Prestressed SCC Bridge Girders Made with Limestone Aggregates
Crushed limestone is commonly used for concrete production in western South Dakota. To assure the applicability of prestressed SCC concrete statewide, a study was designed to investigate the performance of prestressed SCC bridge girders made with limestone aggregates and to develop draft specifications, acceptance criteria, mix qualifications, and guidelines for use by SDDOT for prestressed SCC applications. The study in this report involves material testing of SCC mixtures and structural testing of full-scale prestressed bridge girders. (South Dakota State University Mountain-Plains Consortium report MPC-08-196, October 2009, 235p.)

Administration

L'impact des politiques de stationnement sur les émissions de gaz à effet de serre. Tome 1, Rapport synthèse (The Impact of Parking Policies on Greenhouse Gas Emissions. Volume 1, Summary Report)
The object of this research project is to identify and assess the impact of parking policy issues on greenhouse gas (GHG) emissions in order to establish the components of a GHG reducing parking strategy. Automobile-based transportation accounts for 14% of France's total GHG emissions, or 21.3 million tons of equivalent carbon dioxide. Insofar as technological improvements will undoubtedly prove insufficient to achieve the "Factor 4" objective for transportation-related emissions, parking may prove to be an important positive contributing factor. (Rapport de SARECO, France, Avril 2008, 123p.)

Effective Utility Accommodation Study
Delays in design and construction projects resulting from the existing utility relocation and coordination process often causes construction cost increases. Pennsylvania Department of Transportation (PennDOT) seeks to identify changes to policy, procedure, and legislation that will improve this process. PennDOT also seeks to determine if the lack of a career path, improper entry-level skill sets, and/or the pay level of the District Utility Technicians contribute to loss of institutional knowledge, which thus reduces the effectiveness of the utility relocation and coordination process. The project goal is to improve design project delivery times and minimize construction delays due to utility coordination by conducting a study of the current best practices used by six (6) similar state transportation departments, selected PennDOT District staff, consulting engineers, and utility agencies/owners. (Pennsylvania Department of Transportation report FHWA-PA-2009-016-071302, September 8, 2009, 200p.)

Encouraging Innovation in Locating and Characterizing Underground Utilities
This report presents the findings of the first two phases of SHRP 2 Project R01: Encouraging Innovation in Locating and Characterizing Underground Utilities. The project identified existing and emerging technologies and developed recommendations for subsequent research in this area. The report provides a thorough and insightful review of locating practices, current and emerging technologies, and recommended improvements. A third phase was added to this project to develop software to serve as decision support for identifying effective utility-locating methods for particular site or project environments. The software will expand on capabilities already developed under the R01 project. (US Second Strategic Highway Research Program (SHRP-2) report S2-R01-RW, 2009, 143p.)

Traffic Control

Study of a Glass Bead Gun Angle When Applying Glass Beads to Waterborne Paint
Retroreflectivity of pavement markings is an important measure of their nighttime effectiveness. In Pennsylvania, retroreflectivity is achieved by placement of spherical glass beads in the pavement marking paint using a bead gun attached to a paint truck. The purpose of this project was to investigate the application of glass beads on waterborne paint to determine which angle(s) result in optimum nighttime visibility from a paint truck moving at various speeds. The results indicate that the 12 mph truck application speed and -20 degree bead gun angle provides the optimum nighttime visibility based on the laboratory and field evaluations performed in the present study. (Pennsylvania Department of Transportation Report FHWA-PA-2009-017-510401-016, October 2009, 114p.)

Evaluation of Truck Lane Restrictions in Virginia: Phase II
Virginia, like many other states, has used truck lane restrictions on parts of its interstate system in an attempt to improve mobility and safety. The Code of Virginia currently specifies two types of lane restrictions. First, trucks may not travel in the left-most lane of interstates with three or more lanes by direction (1) when the speed limit is 65 mph or higher, (2) along all of I-81, and (3) along interstates in the Virginia Department of Transportation’s (VDOT) Northern Virginia District. Second, trucks may not travel in the left lane of two-lane directional interstate segments when their speed is below the posted speed limit. This report describes Phase II of a 2007 study that found that the safety impact of the first type of restriction appeared to be affected by traffic volume. (Virginia Transportation Research Council Report VTRC 10-R12, October 2009, 44p.)

Guidelines for Traffic Signal Energy Back-Up Systems
Power outages affect traffic signalized intersections, leading to potentially serious problems. Current practices of responding to power failures are very basic, ranging from ‘do nothing’ to installing portable generators. The purpose of this research project was to provide the NYSDOT with a better understand the practices of other agencies in dealing with dark traffic signals and to develop guidelines for instrumenting uninterrupted backup power at intersections across the state. The main goals of the project are to: (1) recommend cost effective methods for alternative power at traffic signals in NYS; (2) identify the pros and cons of each of alternative power source; and (3) develop a methodology for identifying those NYS traffic signals for installation of alternative energy power sources. (New York State Department of Transportation Report C-06-08, August 2009, 105p.)

Retroreflectivity Database Study
The Pennsylvania Department of Transportation (PennDOT) developed a program in 2005 designed to periodically collect pavement marking retroreflectivity data on longitudinal lines throughout the Commonwealth of Pennsylvania. The purpose of this program was to develop a comprehensive analysis database that could be used to create a pavement marking management system for both waterborne and durable (epoxy) pavement markings on a variety of roadway types. In order to develop a cost-effective pavement marking management system, the service life of pavement markings must be well understood. Consequently, the main objective of the present study was to estimate the service life of longitudinal pavement markings using pavement marking retroreflectivity data provided by PennDOT's Bureau of Highway Safety and Traffic Engineering. Various statistical models were specified to produce pavement marking degradation estimates that PennDOT can use to estimate re-stripe times for longitudinal pavement markings. (Pennsylvania Department of Transportation report PA-2009-007 004, July 16, 2009, 68p.)

Efforts to Address Highway Congestion through Real-Time Traffic Information Systems Are Expanding but Face Implementation Challenges
This GAO report addresses, among other things, (1) how the public and private sectors disseminate real-time traffic information to the public, (2) actions DOT has taken to establish the Real-Time System Management Information Program, and (3) experts’ views on the need for a nationwide real-time traffic information system and its potential characteristics. (US Government Accountability Office Report GAO-10-121R, November 2009, 43p.)

Safety

Designing Roads that Guide Drivers to Choose Safer Speeds
This report describes an investigation into whether or not physical characteristics of the roadway and the roadside environment are associated with actual vehicle running speeds, and how actual vehicle running speeds are associated with the occurrence and severity of motor vehicle crashes in conjunction with other roadway and roadside characteristics. Actual vehicle running speeds were observed at about 300 locations in urban, suburban and rural areas across Connecticut, at locations without horizontal curves or traffic control devices. Only vehicles traveling through the section unimpeded either by leading or turning vehicles were observed in order to get true free flow traffic speeds. Roadway and roadside characteristics were observed, and statistical prediction models were estimated to learn more about how free flow vehicle speed, roadway and roadside characteristics and crash incidence and severity are related. (Connecticut Department of Transportation Report JHR 09-321, November 2009, 115p.)

Construction Project Administration and Management for Mitigating Work Zone Crashes and Fatalities: An Integrated Risk Management Model
The goal of this research is to mitigate the risk of highway accidents (crashes) and fatalities in work zones. The approach of this research has been to address the mitigation of work zone crashes through the creation of a formal risk management model to be utilized during the construction management and administration of highway projects for all stages of the project life-cycle. The result of these efforts is realized through the design of an integrated risk management model. The intent of this research is to develop a formalized risk management plan to identify potential hazards on plans, designs, or jobsites and to cue a risk response to the hazards. Mitigation strategies may take the form of a mitigation “method” (alert motorist, assist worker/motorist, control motorist, inform motorist, and protect worker/motorist). (Midwest Transportation Consortium Report 2008-02, October 2009, 116p.)

Factors Related to Fatal Single-Vehicle Run-Off-Road Crashes
Run-Off-Road crashes cause a large proportion of fatalities and serious injuries to the vehicle occupants. In this study, fatal crashes from the Fatality Analysis Reporting System for passenger vehicles (passenger cars and LTVs) during the period 1991 to 2007 were used to identify the roadway-(e.g., rural/urban nature and curve existence), driver- (e.g., age, gender, drowsy, and alcohol use), environmental- (e.g., weather, lighting condition), and vehicle-related factors (e.g., speeding) associated with the fatal single-vehicle run-off-road crashes.

The results show that the factors driver sleep, drivers with alcohol use, roadway alignment with curve, speeding vehicle, passenger car, rural roadway, high speed limit road, and adverse weather were significant factors related to the high risk of fatal single-vehicle run-off-road crashes. Also, in the adverse weather condition and for the younger drivers, the vehicle speeding would increase the risk of fatal single-vehicle run-off-road crashes by an additional factor. (US National Highway Traffic Safety Administration report DOT HS 811 232, November 2009, 30p.)

Transportation Intelligence

Volume 7 Number 6

December 2009

Pavements

Concrete

Administration

Traffic Control

Safety

Feedback

Pavements

Concrete

Administration

Traffic Control

Safety