Transportation Intelligence

Volume 6 Number 1

February 2008

Administration

Safety

Pavements

Environment

Construction

Feedback

Maintenance
Deformation and tracking of bituminous sealants in summer temperatures: pseudo-field behaviour
Bituminous sealants used for road maintenance sometimes fail due to the excessive deformation or flow under the shearing action of tires in summer temperatures. To better understand this failure mode, a small-scale tracking test was developed and applied to twenty-one sealants held at temperatures between 46°C and 82°C - typical pavement temperatures in North America. The sealant flow characteristics acquired from the testing provide the basis for developing a performance-based method for identifying sealants with good resistance to shearing action. (National Research Council of Canada Institute for Research in Construction Report NRCC-49480, February 2008, 30 p.)

Pavements
Study of crumb rubber materials as paving asphalt modifiers
Waste tire crumb rubber materials (CRM) were used to modify paving asphalts. The mixing time, hot-storage stability, Superpave grades, pumping and handling properties, phase separation tests, and repeated creep properties of the modified asphalts were studied using base asphalts of different hardness. Applying the Long-Term Pavement Performance (LTPP) program and the Transportation Association of Canada (TAC) model, optimal levels of CRM and suitable base asphalts were selected for the climatic conditions of Lethbridge, Alberta, Canada. High-temperature grade bumping protocol, regarding traffic volume and speed, was also considered. With joint efforts from the Tire Recycling Management Association of Alberta (TRMA), Husky Energy, and the City of Lethbridge, three test sections in different Lethbridge locations with various traffic volumes were paved from the years 2003 to 2005. So far, the City of Lethbridge is pleased with the initial performance of the test sections. (Canadian Journal of Civil Engineering, October 2007, pp. 1276-88.)

Administration

Managing Selected Transportation Assets: Signals, Lighting, Signs, Pavement Markings, Culverts, and Sidewalks
This synthesis was designed to gain a better understanding of the state of the practice for managing transportation infrastructure assets other than pavements and bridges, identify best practices, and document gaps in knowledge and areas for further study. It examines key aspects of asset management related to selected infrastructure assets (traffic signals, lighting, signs, pavement lane striping and other markings, drainage culverts and pipes, and sidewalks), including primary sources of technical guidance for management; basic approaches to budgeting for and conducting preservation, operation, and maintenance; organizational responsibilities for ongoing maintenance; and other elements. (TRB National Cooperative Highway Research Program (NCHRP) Synthesis 371, 2007, 199 p.)

Proceeding from the Best Practices: Coordination of Transit, Regional Transportation Planning and Land Use Conference
The proceedings are now available from the Best Practices: Coordination of Transit, Regional Transportation Planning and Land Use Conference held on August 26-28, 2007, in Denver, Colorado. The conference was designed to explore best practices for integrating transit and land use planning. Sessions examined the Denver story; transit-oriented development from the national, international, regional, corridor, and neighborhood perspectives; and regional planning, transit involvement, and analysis. (Transportation Research Board conference, 26-28 August 2007.)

Effective Use of Weigh-in-Motion Data: The Netherlands Case Study
Transportation and law enforcement agencies in the Netherlands have developed a robust weigh-in-motion (WIM) data management system that supports a broad array of vehicle weight regulation and enforcement activities, as well as long-term planning and decision-making. The system, which Dutch officials describe as "a better way of doing business," has potential for application in U.S. states that want to expand their use of WIM data. (US Federal Highway Administration Office of International Programs Report FHWA-PL-07-028, October 2007, 6 p.)

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Safety

Assisting the older driver: Intersection design and in-car devices to improve the safety of the older driver
Drivers aged 75 years or older have a higher fatality rate. The main cause is their physical vulnerability; if they are involved in a crash they have a relatively high risk of being killed. In addition, they have a slightly higher risk than younger motorists of being involved in a crash. They are particularly often involved in crashes which happen when they want to turn left at an intersection. For her PhD thesis SWOV researcher Ragnhild Davidse studied two types of measures that can assist the older driver: adjustments to the intersection design and in-car electronic assistance. (SWOV Institute for Road Safety Research - PhD Dissertation, 2007, 261 p.)

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Pavements

Testing Wisconsin Asphalt Mixtures for the AASHTO 2002 Mechanistic Design Procedure
The intent of this project was to examine typical hot mix asphalt (HMA) pavements that are constructed in the state of Wisconsin. The analysis compares the suggested pavement structures based on the 1972 pavement design guide currently used in Wisconsin and the same ones based on the new Mechanistic-Empirical Pavement Design Guide. In order to develop the pavement structure as outlined by the new Design Guide, the mechanical properties of the HMA layers were measured from 21 field sampled mixtures. Properties of the other layers in the system have been obtained from the Wisconsin Department of Transportation pavement design inputs. The objective was to account for typical construction variability that occurs and to determine its impact upon both mechanical tests. Further, the authors examined these mechanical test results on pavement design to determine if the performance tests and new Design Guide, as they currently exist, are ready for implementation by owners/agencies. (Wisconsin Highway Research Program Report WHRP 07-06, July 2007, 264 p.)

Investigation of Low Temperature Cracking in Asphalt Pavements - National Pooled Fund Study 776
Good fracture properties are an essential requirement for asphalt pavements built in the northern part of the US and in Canada for which the predominant failure mode is cracking due to high thermal stresses that develop at low temperatures. Currently, there is no agreement with respect to what experimental methods and analyses approaches to use to investigate the fracture resistance of asphalt materials and the fracture performance of asphalt pavements. This report presents a comprehensive research effort in which both traditional and new experimental protocols and analyses were applied to a statistically designed set of laboratory prepared specimens and to field samples from pavements with well documented performance to determine the best combination of experimental work and analyses to improve the low temperature fracture resistance of asphalt pavements. (Minnesota Department of Transportation Report MN/RC 2007-43, October 2007, 338 p.)

Optimized Thin Layers for Highways - Paper for Inter-Noise 2007
The concept for pavement noise reduction is to create a pavement texture, with big cavities at the pavement surface in order to reduce the noise generated from air pumping, and ensuring a smooth surface so noise generated by vibration of the tyres will not be increased. Four different pavement concepts are used: Open graded asphalt concrete (DAC-open), Stone Mastics Asphalt (SMA), a thin layer constructed as an UTLAC (Ultra Thin Layer Asphalt Concrete), and semi porous pavement (PAC). In 2006 10 optimized thin layers were laid on a Danish highway near Herning. The results from the first series of SPB noise measurements are presented in this paper. (Danish Road Institute Report 153, September 2007, 24 p.)

Truck/Pavement/Economic Modeling and In-Situ Field Test Data Analysis Applications Volume 4: Effects of Slab Shape and Load Transfer Mechanisms on Portland Cement Concrete Pavement
A jointed concrete pavement on I-490 near Rochester, NY, was reconstructed using three different dowel bar spacings in eastbound test sections. Two sections in the westbound direction were instrumented to monitor environmental strain, deflections, and pavement temperatures. Monitoring of the westbound sections was conducted at the time of construction, after 28 days of curing, and at various intervals over the next two years. The instrumentation included deep and shallow linear variable differential transducers (LVDTs) to measure displacements in the center and the corners of the slabs, thermocouples at four depths near the center and at one corner of the slab, and vibrating wire strain gages with built-in thermistors in the center and the left wheel path. Air temperature data were also gathered during monitoring periods. Data were taken from the instruments at the time of construction, and at 37 days (after curing), 12 months, 16 months, and 28 months after construction. In addition to instrumentation readings taken over an approximately 24-hour period, each visit included slab shape measurements made with a Dipstick®, and deflections measured with a falling weight deflectometer (FWD) on the westbound sections. The final data collection visit, in October 2004, also included FWD testing and profilometer measurements on the eastbound sections. (Ohio Department of Transportation report FHWA/OH-2006/3D, September 2007, 110 p.)

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Environment

Erosion Control Treatment Selection Guide (30 MB PDF)
This guide presents a strategy and information to assist professional judgment in developing cost effective erosion control treatments for conditions commonly encountered on USDA Forest Service lands. This guide focuses on erosion control treatment and does not specifically address sediment control. This guide is a starting point for treatment selection that considers site-specific conditions requiring professional judgment. (US Forest Service Report 0677 1203P, December 2006, 64 p.)

Design for Fish Passage at Roadway-Stream Crossings: Synthesis Report
This document places current culvert design techniques into four categories based on design premise and objectives. These categories include: No Impedance techniques; Geomorphic Simulation techniques; Hydraulic Simulation techniques; and Hydraulic Design techniques. Preliminary chapters covering the topics of fish biology and capabilities, culverts as barriers, fish passage hydrology, and design considerations aid in the selection of appropriate design techniques based on hydraulic, biologic, and geomorphic considerations. Examples of design techniques and case histories for a selection of design techniques are presented, followed by a discussion on construction, maintenance, monitoring, and future research needs. (US Federal Highway Administration Report HIF-07-033, June 2007, 280 p.)

Compaction Remediation for Construction Sites
The goal of this project is to develop a sub-soiling regimen that will enhance and be compatible with existing erosion control measures. This project is important in minimizing the effect of construction-induced compaction on the urban and rural landscape. This activity, if successful, will become a building block for use in Best Management Practices (BMPs) that will ensure full vegetative growth post construction, and save on the cost of reapplication of erosion control measures. For a good comparative study, several sites were selected for typical slope and soil type. (Minnisota Department of Transportation Report MN/RC 2008-01, January 2008, 33 p.)

Noise Control through Traffic Flow Measures - Effects and Benefits
Based on a thorough literature study, the effect of various traffic flow measures on noise and annoyance is assessed. The measures in the study range from typical traffic calming measures, the effects of which are limited to the specific location, to congestion charging which aims at changing traffic flows in large areas and entire cities. Of all the measures in the study, only vertical deflections (road humps and speed cushions) have been subject to sufficient testing to allow firm conclusions to be drawn regarding noise and noise annoyance effects. (Danish Road Institute Report 151, March 2007, 64 p.)

Traffic Management and Noise - Paper for Inter-Noise 2007 in Istanbul
As part of the EU research project SILENCE an extensive literature study of the noise and annoyance effects of various road traffic flow measures has been carried out. The effect on noise as well as on annoyance is highly dependent on traffic composition and speed, road layout and the use of individual measures such as road humps, chicanes, gateways, and mini-roundabouts. Other measures included in the study are rumble devices, junction layout, speed reductions using static and variable speed signs, automatic traffic control, congestion charging, parking information systems, city logistics and nighttime ban on trucks. (Danish Road Institute Report 155, September 2007, 28 p.)

Green Infrastructure Guide: Issues, Implementation Strategies and Success Stories
The Green Infrastructure Guide (the Guide) provides guidance on how local governments may, using legal and policy strategies, encourage or require more sustainable infrastructure designs. It refers readers to strategies, and highlights case studies of local governments that have already taken steps to incorporate a green infrastructure approach. The focus is on implementation mechanisms, issues and barriers, and on what lessons have been learned from experiences to date. (West Coast Environmental Law Research Foundation Report, 2007, 88 p.)

Developing Monitoring Plan for Structure Placement in the Aquatic Environment--Recommended Report Format, Listing of Methods and Procedures, and Monitoring Project Case Studies
Structures designed to restore or enhance the aquatic environment have been placed in almost every ecoregion in the United States. While the passage of the Endangered Species and Clean Water Act has created an increased emphasis on structure placement in the aquatic environment, limited information on the results of these projects has been published. In addition, little or no funding has been allocated for evaluating and reporting the results of this work. Therefore a need exists for determining whether structural additions and various bank stabilization methods are effective for improving stream stability, water and habitat quality, and restoring threatened and endangered species. (US Forest Service Report 0777 1811P, September 2007, 219 p.)

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Construction

Surface-Aggregate Stabilization with Chloride Materials
Road managers should consider chloride stabilization as a cost-effective method when selecting maintenance options and strategies for aggregate-surface roads. This stabilization technique also is a viable option for newly crushed aggregate. This publication provides Federal, State, county, and local road managers information on the performance and cost effectiveness of roadmixing high applications of calcium and magnesium chloride that are applied in a one-time construction process. Stabilization provides a much higher standard of road surface performance by improving ride quality and reducing dust, washboarding, and raveling (loose aggregate). Road managers can expect similar results when using this process with newly crushed aggregate. (US Forest Service Report 0677 1805P, December 2006, 36 p.)

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