Transportation Intelligence

Volume 5 Number 3

June 2007

Structures

Environment

Safety

Urban

Concrete

Pavements

Feedback

Environment
Habitat Connectivity and Rural Context Sensitive Design within the Northern Rockies and Upper Great Plains: A Synthesis of Practice
This report looks at context sensitive design/context sensitive solutions (CSD/CSS) in a rural setting relating to habitat connectivity, roadside aesthetics, and land use planning. It investigates programmatic procedures used by selected states in implementing and guiding CSD/CSS. Specifically, how can states prioritize design options in a CSD/CSS context so as to maximize the return (e.g., CSD/CSS benefits) on the limited funding for construction and maintenance? It also provides some examples of CSD/CSS design elements and specific case studies. (Montana Department of Transportation Report FHWA/MT-06-012/8117-31, February 2007, 56 p.)

Traffic Operations
Guidelines for Operating Traffic Signals During Low-Volume Conditions
The main objective of this research is to investigate the performance of flashing traffic signals as a device to control traffic periods with low traffic volumes, particularly during late night/early morning hours. First, the study identifies the main factors that affect the performance of flashing traffic signals. Next, it defines the main guidelines and precautions that should be considered when implementing flashing traffic signals in yellow/red or red/red modes, during late night/early morning hours. (Transportation NorthWest Report TNW2006-12, August 2006, 50 p.)

Structures

Evaluation of Products That Protect Concrete and Reinforcing Steel of Bridge Decks from Winter Maintenance Products
The objectives of this study were to identify commercially available products and/or systems that could readily be utilized to improve the durability of CDOT's bridge decks in resisting the effects of deicing products. Construction Technical Services (CTS) was to determine physical effectiveness and relative costs, whereas CDOT would later determine cost effectiveness of the options. The principal tests utilized in this study were resistance to surface abrasion, rapid chloride permeability (RCP), and long-term ponding with full strength magnesium chloride solution. (Colorado Department of Transportation Report CDOT-2006-4, December 2006, 91 p.)

Improving Predictions for Camber in Precast, Prestressed Concrete Bridge Girders
This research was conducted to develop improved methods of predicting camber in prestressed concrete girders. A computer program was written to calculate camber as a function of time. It takes into account instantaneous and time-dependent behavior of the concrete and steel and performs the calculations in a series of time steps. It was calibrated by comparing its predictions with the camber from 146 girders, measured in the fabricators yard both after release and at a later time. Its long-term predictions were then compared with the responses of 91 girders that were monitored during construction at the Keys Road Bridge site. (Washington State Department of Transportation Report WA-RD 669.1, March 2007, 342 p.)

Improvements in Design Scour Depth Prediction
A series of local sediment scour experiments with model complex bridge pier shapes were performed in the Hydraulics Laboratory at the University of Auckland in Auckland, New Zealand as part of this study. The experiments were designed to fill in voids in existing data for partially and fully buried pile caps and pile groups with different centerline spacings and orientations to the flow. The results from these tests were compared with scour depth predictions using the complex pier scour equations developed at the University of Florida and currently used by the Florida Department of Transportation. (Florida Department of Transportation Report BD 545-34, December 2006, 64 p.)

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Environment

Wildlife-Highway Crossing Mitigation Measures and Associated Costs/Benefits: a Toolbox for Montana Department of Transportation
This report reviews 39 mitigation measures that reduce animal-vehicle collisions and that provide habitat connectivity for wildlife across highways. The overview is restricted to mitigation measures aimed at large terrestrial mammals (deer size and larger). In addition to the detailed information for each mitigation measure, a summary table is provided that provides at-a-glance information on the costs and benefits of the individual mitigation measures for which such data were available. Furthermore, the report graphically illustrates which measures have the best monetary balance (the difference between benefits and costs) and which measures reduce animal-vehicle collisions and associated costs best.. (Montana Department of Transportation Report FHWA/MT-07-002/8117-34, May 2007, 126 p.)

Erosion Risk Assessment Tool For Construction Sites
The impact of erosion and sediment from construction sites can be reduced by using a variety of onsite and offsite practices. The WATER model was developed to be a tool to assess the effectiveness of different sediment control practices. The WATER model evaluates risk by performing many simulations of a construction site response for different weather conditions. A particularly important component of the WATER model is the prediction of daily climate variables and storm characteristics called WINDS. This model uses the statistics for the analyzed data to predict many years of possible weather conditions. Predicted weather and storm characteristics are in very good agreement with those observed. The WATER model simulates surface runoff, plant processes, and erosion and sediment transport as major hillslope processes. Four runoff events (spring dry run, spring wet run, fall dry run, and fall wet run) from artificial rainfall conditions were measured. (Minnesota Department of Transportation Report, July 2006, 72 p.)

Cost effectiveness of CO2 mitigation in transport: An outlook and comparison to cost effectiveness of measures in other sectors
In climate policies, CO2 emissions of the transport sector are getting increasing attention. Emissions are rising continuously due to increases in passenger and freight transport demand, and the question how this trend can be reversed has not yet been answered. The report analyzes the cost-effectiveness of CO2 mitigation options in the transport sector and compares these with similar options in other sectors. The cost-effectiveness of an environmental measure is a comparison of the effects of a measure with the costs of implementing it. A more cost-effective measure will have achieved the desired results for less money or more results for the same amount of money. (CE Netherlands Report 06.4184.20 for European Conference of Ministers of Transport, January 2006, 53 p.)

Factors Impacting the Health of Roadside Vegetation
This study provides an ecological impact assessment of factors affecting the health of roadside vegetation in the state of Colorado including potential biotic and abiotic plant stressors and deicer applications. Across eight field sites, an evaluation was completed for foliar injury, physiology by leaf-level gas exchange, salt exposure, long-term drought stress, nutrient availability, pollutant exposure, disease, and insect damage in roadside lodgepole (Pinus contorta) and ponderosa (Pinus ponderosa) pines. These measures were compared with conifers away from the roadside environment in the same location in the winter/spring and summer/ fall of 2004. Additionally, a controlled assessment of the impacts of sand/salt and magnesium chloride deicers on foliar injury and leaf-level gas exchange in saplings of P. ponderosa and P. contorta was performed. (Colorado Department of Transportation Report CDOT-DTD-2005-12, April 2007, 264 p.)

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Safety

Synthesis of the Median U-Turn Intersection Treatment, Safety, and Operational Benefits
In the United States, congestion at intersections throughout urban and suburban areas continues to worsen. Crashes reported at intersections have continued to increase. One potential treatment to combat congestion and safety problems at intersections is the Median U-Turn Intersection Treatment (MUTIT), which has been used extensively in Michigan for many years and has been implemented successfully in Florida, Maryland, New Jersey, and Louisiana in recent years. This synthesis summarizes the advantages and disadvantages of the MUTIT compared to conventional, at-grade signal-controlled intersections with left turns permitted from all approaches. The synthesis presents design guidelines including the location and design of the median crossovers on the major roads. (US Federal Highway Administration Techbrief FHWA-HRT-07-033, 2007, 16 p.)

Evaluation of Rumble Stripe Markings
This study evaluated flat thermoplastic edge markings (FTM) and Rumble Stripes (also called edgeline rumble strips) installed on highways maintained by the Alabama Department of Transportation. The primary objectives of this evaluation were to compare service life, life-cycle costs, and wet-night visibility (measured by wet retroreflectivity) of the two edge marking types. Nighttime dry and wet retroreflectivity of sixteen one-mile segments of FTM and five, two-mile segments of Rumble Stripe were measured using a mobile retroreflectometer. The limited number of segments of Rumble Stripe represented all Rumble Stripe available at the time of testing. (University Transportation Center for Alabama Report 04405, November 2006, 65 p.)

Integrating Roadway, Traffic, and Crash Data: A Peer Exchange
This Circular is the proceedings of a November 1-2, 2006, meeting held in Washington, D.C. The peer exchange was designed to bring both data and highway safety professionals together to share experiences and identify key issues relating to integrating roadway, traffic, and crash data sources used to support safety management. The exchange was also designed to introduce asset management concepts into the highway safety management arena. (TRB’s Transportation Research Circular E-C111, 2007, 140 p.)

Older Driver Safety - Knowledge Sharing Should Help States Prepare for Increase in Older Driver Population
As people age, their physical, visual, and cognitive abilities may decline, making it more difficult for them to drive safely. Older drivers are also more likely to suffer injuries or die in crashes than drivers in other age groups. These safety issues will increase in significance because older adults represent the fastest-growing U.S. population segment. GAO examined (1) what the federal government has done to promote practices to make roads safer for older drivers and the extent to which states have implemented those practices, (2) the extent to which states assess the fitness of older drivers and what support the federal government has provided, and (3) what initiatives selected states have implemented to improve the safety of older drivers. (US Government Accountability Office Report GAO-07-413, April 2007, 60 p.)

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Urban

Adjustment of Driver Behavior to an Urban Multi-Lane Roundabout
In the summer of 2006, the city of Springfield, Oregon installed the first urban multi-lane roundabout in the state. It was hypothesized that after installation, speed variability on approaches to the intersection would decrease from the values with the previous signalized intersection. It was also hypothesized that the initially observed high incidence of driving errors associated with specific areas of the roundabout would decrease over time. Before and after speed recordings of approach roads to the intersection revealed a significant increase in mean speed, but no consistent change in speed variability. Some design features caused initial confusion amongst drivers negotiating the roundabout, but the number of observed incidences of confused behavior declined over the first six months of operation at a rate that fit a classic logarithmic learning curve. (Oregon Department of Transportation Report FHWA-OR-RD-07-09, May 2007, 28 p.)

Comprehensive Evaluation on Transit Signal Priority Impacts Using Field Observed Traffic Data - Phase One
To improve the level of Community Transit (CT) services, the South Snohomish Regional Transit Signal Priority (SS-RTSP) project has been launched. To understand the overall benefit of this project, the SS-RTSP system (phase one) was tested and evaluated after the completion of the hardware and software installations on the 164th Street SW street corridor in Snohomish County, Washington State. In this study, impacts of the SS-RTSP system on both transit and local traffic operations were quantitatively evaluated based on field observed data. A simulation model was also built and calibrated to compute measures of effectiveness that cannot be obtained from field-observed data. With the simulation model and field observed data, the impacts of the SS-RTSP system on both transit and local traffic operations were quantitatively evaluated. (Transportation NorthWest Report TNW2006-10, August 2006, 58 p.).

Manual for Streets
Manual for Streets provides guidance for practitioners involved in the planning, design, provision and approval of new residential streets, and modifications to existing ones. It aims to increase the quality of life through good design which creates more people-orientated streets. (UK Department for Transport report, 29 March 2007.)

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Concrete

Petrographic Methods of Examining Hardened Concrete: A Petrographic Manual (revised 2004)
This manual provides a comprehensive discussion of equipment and techniques that have been found useful in performing petrographic examinations of hardened concrete and its constituent materials. It includes an introduction and chapters on equipment, general initial procedures, cracks, preparation of specimens, and voids (including determination of the air-void system); determination of volumetric proportions of constituents; examination with the stereomicroscope; the water-cementitious materials ratio; alkali-aggregate reactions; cementitious materials; and examinations with the petrographic, polarizing/epifluorescence, and scanning electron microscopes. An extensive reading list, glossary, and other appendixes are included. (US Federal Highway Administration Report FHWA-HRT-04-150, July 2006, 351 p.)

Freeze-Thaw Resistance of Concrete with Marginal Air Content
This report describes a laboratory investigation of the behavior of concrete with “marginal” air void systems, in which the air content and other air void system parameters do not consistently meet commonly accepted thresholds for freeze-thaw durability. Some of the concretes did provide good durability—but others did not. The type of air-entraining admixture played a major role in performance. In addition to measuring air-void parameters by the linear traverse technique, special programmed equipment at Turner-Fairbank Highway Research Center (TFHRC) was used to measure and record each individual chord length across the air voids traversed. The air-void chord length distributions are presented and analyzed in this report. (US Federal Highway Administration Report FHWA-HRT-06-117, December 2006, 96 p.)

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Pavements

Rapid assessment of the tracking resistance of bituminous crack sealants
The bituminous sealants used in the preventive maintenance of pavements sometimes deform (track) under the action of passing vehicles. In summer, this is the prevalent mode of sealant failure. To assess the propensity of a sealant to deform in summer, a standard flow test is used, but the imprecision in the results has prevented any correlation with field performance. Two methods were evaluated in an attempt to find an alternative means of assessing deformation. The first method relied on the use of the French rut tester, and the second method relied on the use of a Taber abraser. The first method was found to be inappropriate to test sealants because of its severity, but the second method proved promising. The Taber abraser allowed for the measurement of sealant displacement at various temperatures and for distinguishing the deformation propensity of sealants. (Canadian Journal of Civil Engineering, January 2007, pp. 126-131.)

Resilient Modulus and Strength of Base Course With Recycled Bituminus Material
The objective of the research was to determine the strength and deformation characteristics of base material produced from recycled asphalt pavement (RAP) and aggregate. Various samples with different ratios of RAP and aggregate base were mixed (% RAP/aggregate): 0/100, 25/75, 50/50, 75/25. Laboratory compaction testing and field monitoring indicated that gyratory compacted specimens were closer to the densities measured in the field. Resilient modulus (MR) tests were generally conducted following the National Cooperative Highway Research Program 1-28A test protocol. MR increased with increase of confining pressure, but MR showed little change with deviator stress. The specimens with 65% optimum moisture contents were stiffer than the specimens with 100% optimum moisture contents at all confining pressures. Cyclic triaxial tests were conducted at two deviator stresses, 35% and 50% of the estimated peak stress, to evaluate recoverable and permanent deformation behavior from initial loading to 5000 cycles. The specimens with RAP exhibited at least two times greater permanent deformation than the 100% aggregate material. As %RAP increased, more permanent deformation occurred. In summary, the base material produced with various %RAP content performed at a similar level to 100% aggregate in terms of MR and strength when properly compacted. (Minnesota Department of Transportation Report MN/RC-2007-05, January 2007, 270 p.)

Accelerated load testing of pavements. HVS-Nordic tests at VTI Sweden 2003–2004
During 2003 and 2004, two accelerated load tests were performed at the VTI test facility in Sweden (SE05 and SE06). The objective of SE05 was to investigate the deformation behaviour of two different unbound base materials. Half of the test area was constructed with a base layer of natural granular material and the other half with a base layer of crushed rock aggregate. This means that the two structures were tested simultaneously. The objective of SE06 was to be the third test in a series of structural design tests with stepwise higher bearing capacity. (Swedish VTI Report 544A, 2006, 63 p.)

Installation of Warm-Mix Asphalt Projects in Virginia
Several processes have been developed to reduce the mixing and compaction temperatures of hot mix asphalt (HMA) without sacrificing the quality of the resulting pavement. The purpose of this study was to evaluate the installation of warm mix asphalt (WMA) to compile experiences and offer recommendations for future use. Three trial sections were installed using warm mix technologies between August and November of 2006. Two used the Sasobit technology, and the third employed the Evotherm technology. This report discusses the material makeup of these technologies and documents the production and placement of the three trial sections. The results of this study and further studies can serve as a basis for decision making by the Virginia Department of Transportation (VDOT) regarding the use of WMA technology.(Virginia Transportation Research Council Report FHWA/VTRC 07-R25, April 2007, 34 p.)

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