The Federal Role in Highway Research and Technology: Special Report 261 (2001)

Information collection and transfer related to commercial vehicle operations (CVO) and regulatory compliance is estimated to cost carriers and government agencies more than $6 billion annually (Rubel 1998). In an effort to improve operational efficiencies and reduce costs, the Federal Highway Administration (FHWA) and others began exploring ways to automate many of these collection and transfer activities. An initial research product developed by FHWA could keep track of much of the safety, credentials, tax, insurance, and hazardous materials information needed to meet the requirements of a host of federal and state regulations and permit processes.

In 1996, researchers recognized that intelligent transportation systems (ITS) products, such as on-board transponders, offered the potential of transmitting information to roadside scanners. However, without a common architecture and standards, systems and databases could not communicate with each other. FHWA therefore began work on a system that would link ITS and automation elements into a single architecture that could eventually be shared by all CVO interests in North America. This system, Commercial Vehicle Information Systems and Networks (CVISN), was aimed at removing travel and information boundaries for interstate carriers. CVISN would collect and exchange motor carrier safety information, automate interstate carrier registration and fuel tax payments, and screen commercial vehicles at fixed or mobile roadside sites. Moreover, the information would be accessible almost instantly to all authorized parties. FHWA fostered partnerships among state governments, motor carriers, shippers, insurance companies, and others to ensure that major stakeholders would be involved in the development and implementation of the system and that key issues would be addressed. Research was undertaken to standardize the network of information and communication systems. The states of Maryland and Virginia agreed to participate in a prototype program in 1996, and by 2001, all 50 states were participating to some degree in CVISN.

Once a pilot program was under way in eight states, FHWA began focusing on implementation issues and working with the states to facilitate

widespread deployment. The estimated benefits are significant (see the CVISN Deployment Tracking Database at www.itsdeployment.edu.ornl. gov/cvisn/). They include a dramatic reduction (from 90 days to 60 min) in the time it takes for a truck safety inspection report to be made available to state motor carrier safety enforcement authorities. In a study of 40,000 commercial motor vehicle inspections, safety inspectors using the advanced safety information systems were able to remove an additional 4,000 (an increase from 8,000 to 12,000) unsafe drivers and vehicles from the nation’s highways (DOT 1998). Better information means government agencies can focus limited resources on operators whose records indicate a history of safety problems, and low-risk carriers, vehicles, and drivers face fewer and simpler roadside inspections.

Significant cost savings can be achieved with CVISN. In a case study involving eight states, it was estimated that deployment of the electronic credentials portion of CVISN would have a benefit-cost ratio as high as 6:1. The greater reliability of truck data from CVISN can also help deter tax evasion and save individual states $500,000 to $1.8 million per year (DOT 1996). Cost-benefits can also accrue to the motor carriers. The American Trucking Associations Foundation has estimated that electronic screening could reduce time spent at weigh stations, resulting in lower labor costs for companies that pay their drivers by the hour. The savings-to-cost ratio ranges from 2:1 to 7:1, depending on the company size (ATA 1996).

Earthquake engineering and seismic design of bridges are comparatively young disciplines. However, extensive bridge damage and traffic disruptions due to earthquakes in California in 1971 and 1989 stimulated considerable research aimed at both improved seismic design of highway structures and better retrofit techniques for existing bridges. Between 1971 and 1986, research sponsored by FHWA and the California Department of Transportation (Caltrans) and performed at the University of California at San Diego (UCSD) led to significant changes in seismic design practice for constructing new bridges and for constructing existing bridge columns with steel jackets. Many bridges have been strengthened using these new materials.

After the 1989 Loma Prieta earthquake, researchers at UCSD, with support from FHWA, Caltrans, and the Advanced Research Projects Agency, investigated potential applications of composite materials for both new construction and repair of older bridges. Advanced composites have been found to improve the strength of bridge columns and supporting elements. Tests on epoxy-impregnated fiberglass and carbon fiber materials have shown that they strengthen existing structures. Although advanced composite materials are expensive, their long life expectancy and resistance to corrosion make them competitive if the life-cycle cost of a bridge in a highly corrosive environment is considered.

States estimate that collectively they spend more than $10 billion annually on asphalt—more specifically, hot-mix asphalt (HMA)— pavements. Even modest improvements in HMA performance mean significant savings. Longer-lasting pavements also require fewer rehabilitation projects, reducing the incidence of work zone congestion and delays and the attendant hazards.

Superior performing asphalt pavements (Superpave), an HMA design system developed to provide a smooth ride over an extended life at a reasonable cost, offers such performance improvements. The Superpave system addresses predominantly two forms of pavement distress: rutting (permanent deformation), which is caused by inadequate shear strength in the asphalt mix, and low-temperature cracking, which results when the tensile stress of the pavement exceeds that of the asphalt cement. Developed under the Strategic Highway Research Program (SHRP), a 5-year research program that focused on a few key areas of highway technology, the Superpave system unifies HMA pavement design, mix design, and construction and, when fully mature, will include a sophisticated model for predicting pavement performance among competing mix designs.

When the SHRP research ended in 1993, some aspects of Superpave, such as software that would facilitate the design of pavement mixes and predict their performance, were incomplete. The SHRP sponsors—FHWA, the American Association of State Highway and Transportation Officials, and the Transportation Research Board—decided to continue the innovation effort and carry out an implementation program. A task force of energetic champions from state highway agencies developed a program of technical assistance and support to encourage rapid and widespread implementation of Superpave. By 2000, more than half of the HMA projects awarded by state departments of transportation were using the Superpave design, and this percentage is expected to continue to increase.

Assessing the potential value of Superpave and the research that led to its development is difficult until the pavements prove themselves through

their design lives. According to one study, switching to Superpave binders could yield annual savings to the nation of $1.8–$2.9 billion. New York state engineers have estimated that if Superpave extends pavement life by 1 year, it will save that state $1 billion over 30 years. Although work is under way to document more fully the benefits of the Superpave system, that effort could take years. Meanwhile, pavement engineers point to the growing acceptance of the Superpave design, especially for high-level roadways (e.g., Interstates, major arterials) as a key indicator of a successful research product.

The history of research on roadside safety hardware closely follows the evolution and increasing use of the nation’s highway system. Improvements in roadside safety hardware are based on many individual research successes. In the 1960s, a significant number of fatalities were occurring at exit ramp gore areas. Research sponsored by FHWA and the Texas Department of Transportation (TxDOT) and performed at the Texas Transportation Institute produced design concepts and prototype designs for crash impact attenuators. Private industry saw an opportunity and eventually developed the family of impact attenuators seen on today’s highways. As a result, fatalities on crash cushions and impact attenuators are relatively rare events.

In the early 1970s, the (then) New York State Department of Highways developed a family of weak post guardrails and median barriers, sometimes called light post guiderails (because they flex). Although these traffic barriers were not intended to handle heavier vehicles, they significantly reduced the severity of impacts by automobiles in such states as New York, Pennsylvania, Connecticut, Virginia, South Dakota, and North Dakota. Today, there is renewed interest among many states in using three-cable roadside barriers and median barriers because they cost less than other alternatives.

During the 1960s and 1970s, General Motors (GM) conducted many median barrier and roadside safety studies. One such study led to the development of a concrete crash barrier designed to guide a striking vehicle back onto the roadway. In 1973, FHWA sponsored a pooled-fund study on such concrete crash barriers to determine their potential for wider application. Crash tests showed that the original GM shape caused small cars to roll over. Another barrier design, the Jersey barrier designed by the New Jersey Department of Highways, was shown to be superior to the GM barrier and is still widely used. A later study resulted in the development of another alternative, the F-shape, which performs even better than the Jersey barrier in tests. During the last 15 years, more and more states have been switching from the Jersey barrier to the safer F-shape barrier. A recent in-service study of the Jersey

barrier indicated that of 62 collisions occurring during a 7-month period, only 14 were serious enough to be reported to police. Remarkably, none of the 62 collisions involved an occupant injury (Fitzpatrick et al. 1999).

During the mid-1970s, FHWA and TxDOT conducted a series of tests on luminaire supports with slipbase, coupling, or frangible bases. The objective of these support designs is to reduce damage to vehicles and injuries to vehicle occupants should they be struck during a run-off-the-road crash. Research and tests led to several breakaway luminaire support designs that are widely used today as an alternative to fixed-post designs.

In 1978 FHWA conducted crash tests on bridge rails designed in accordance with loading and geometric design criteria in the 1965 American Association of State Highway and Transportation Officials (AASHTO) Bridge Specifications. All of the aluminum bridge rails tested failed as a result of wheel snagging and barrier penetration problems. These findings led state highway agencies to discontinue installing aluminum beam-and-post bridge rails. In addition, FHWA and AASHTO began requiring that bridge rail designs be crash tested prior to installation. A series of pooled-fund studies has been undertaken to crash test a large variety of bridge rail designs. Today, vehicle penetration of a bridge rail is a rare event.

In the early 1980s, blunt-end and turned-down guardrail terminals and guardrail-to-bridge rail transitions were contributing significantly to the number of people killed in guardrail collisions. FHWA devised a promising alternative design, and several private firms subsequently developed a series of energy-absorbing terminals based on that design. In-field evaluations of these devices led to the conclusion that design improvements would lead to a higher likelihood of proper installation and improved safety. In a limited sample, approximately 5 percent of all impacts resulted in serious and fatal injuries with the new design, as compared with 20 to 35 percent with the earlier design (Buth et al. 2000).

In 1993 FHWA adopted the proposed standards developed in a National Cooperative Highway Research Program project, which provided design standards to accommodate the light truck class of vehicles as mandated by Congress. Tests of the existing guardrail designs showed that when mounted on strong steel posts, they did not meet the new standards. Research led to alternative designs with significantly improved performance for vehicles such as vans, sport utility vehicles, and pickup trucks.

As the nation strives for greater compatibility between highways and the communities they serve, efforts are under way to accommodate pedestrian and bicycle travel in planning and operations. In 1998, 5,220 pedestrians and 761 bicyclists were killed, accounting for 14 percent of all traffic fatalities. An additional 69,000 pedestrians and 53,000 bicyclists were reported to be injured as a result of collisions with motor vehicles. As part of its pedestrian–bicycle safety effort in response to these collisions and their consequences, FHWA has developed a tool to assist highway planners and engineers in analyzing the causes of pedestrian and bicycle crashes and identifying potential countermeasures. The agency, in cooperation with the National Highway Traffic Safety Administration (NHTSA) and the North Carolina Highway Safety Research Center, has developed a pedestrian and bicycle safety crash analysis tool (PBCAT).

PBCAT enables the user to develop a database that focuses on crash types and describes the precrash actions of the parties involved. The software can then generate analyses of crash types by location and provide a basis for developing alternative countermeasures to help prevent bicycle and pedestrian accidents. PBCAT draws on an extensive crash database prepared by NHTSA in the 1990s to form the basis for identification of countermeasures.

Research on PBCAT and related tools continues. Future plans for wider application of PBCAT involve the development of an expert system to assist planners and engineers in selecting appropriate countermeasures on the basis of local traffic conditions and roadway geometry. FHWA is developing an expert system for identifying alternative countermeasures, based on the PBCAT database. The agency is also planning to conduct several improvement projects to assess countermeasures using intelligent transportation system technologies.

More than 400 local and state agencies have ordered the first generation of this software since its release in December 1999. Use of the software

by the city of Orlando, Florida, illustrates its potential. In response to national media attention about the city’s high rate of pedestrian injuries and fatalities, Orlando used PBCAT to help identify crash types and potential countermeasures. Analysis of the data resulted in a detailed list of recommended pedestrian crash countermeasures and led to a safety improvement plan that has been adopted by the city to reduce pedestrian-related crashes. The analysis also helped the city select the most appropriate locations for countermeasures based on the severity of the problem being addressed and the funding available for various types of improvements. More information about this example is available at www.metroplanorlando.com/.

Fewer crashes, reduced costs, better service, fewer environmental impacts, and lower insurance rates are all potential benefits of the improved roadway weather information systems (RWIS) produced by research. With highways playing such a critical role in people’s everyday lives and snow and ice being a problem in 40 states, reliable predictions of when water on highways will turn to ice and when snow will stick to the road rather than melt are important. Sensors that monitor the temperature of roadway surfaces and subsurfaces, combined with forecasting and communication systems, have resulted in considerable accumulated savings in labor, equipment, and materials for transportation agencies in North America and Europe. Information from RWIS enables informed decisions about staffing, timing, strategies, and the amount of equipment and materials needed. In research conducted as part of SHRP, it was estimated that such systems would have a 5:1 benefit-to-cost ratio. The benefits of RWIS were also shown by a weather index that related costs of snow and ice control to weather severity and frequency of snow and ice events.

After SHRP ended, research on the RWIS technology continued, particularly investigations into the proactive use of chemicals to prevent snow and ice from bonding to pavement. Data collected on anti-icing methods during the mid-1990s in a cooperative research effort involving 15 state departments of transportation supported the hypothesis that pavement temperature is a key element when implementing anti-icing measures, and that precipitation character and traffic volume are also important (Ketcham et al. 1996).

The report of a recent study conducted for the National Cooperative Highway Research Program documents the benefits of the RWIS technology and describes current practice (Boselly 2001). It was found that careful application of RWIS and anti-icing techniques could result in roadways being cleared sooner, at lower cost, and with less damage to pavement, equipment, and the environment. A more dramatic example of

the benefits of RWIS and anti-icing technologies was their successful application in a critical period during the U.S. military involvement in the conflict in Kosovo. U.S. researchers and highway engineers provided direct advice to an American lieutenant charged with keeping 68 miles of road in Kosovo clear of snow and ice. By implementing RWIS and anti-icing technologies, the U.S. military was able to keep a vital supply link open for its troops despite a 2.5-ft snowstorm in the mountains of Albania (FHWA 2000).

The following is a sampling of successful state highway research efforts. Although the benefits of some of these projects are small, most have application across states.

Automated Hydrologic Analyses

Bridge and highway engineers must consider the frequency, magnitude, and timing of floods and the floods’ effects on highway infrastructure. Standard hydrologic modeling tools are not designed for engineering analyses and consider conditions at a single design point. They also require much time and effort; a change in the location of the proposed highway structure or an error in the data could negate weeks of work. A new geographic information systems (GIS)–based computer model developed at the University of Maryland for the Maryland State Highway Administration (MSHA) reduces the time required for such analyses and improves the integrity of the output. MSHA estimated that after using the model, GISHYDRO2000, on 83 projects, it had saved approximately $994,600 in staff costs. Such savings will continue for future projects.

Recycling of Used Tires to Reduce Costs

A series of research projects undertaken by the Maine Department of Transportation (MDOT) and the New England Transportation Consortium— a pooled-fund effort involving five New England states—has shown that tire shreds have acceptable engineering and environmental characteristics for use as lightweight fill for highway embankments and retaining-wall backfill. Seeking to make use of some of the more than 800 million discarded tires currently available nationally, MDOT has used tire shreds in several projects, with considerable cost savings. Its Portland JetPort Interchange project used about 1.2 million tires and saved an estimated $600,000. These savings included material costs and savings obtained relative to alternative disposal of the tires by the Maine Department of Environmental Protection.

Fiber-Reinforced Polymer Composites for Strengthening of Bridges in Oregon

Several historic reinforced concrete bridges in Oregon were found to be deficient for carrying current traffic loads. Engineers sought a solution that would strengthen the bridges without affecting their appearance. The Oregon Department of Transportation, in collaboration with Oregon State University and a private firm, examined the potential for using fiber-reinforced polymer (FRP) composites for structural reinforcement. Tests on the Horsetail Falls Bridge in the Columbia River Gorge, built in 1914, validated the use of FRP composite for bridge strengthening. The method used saved the state $37,000 over a conventional repair cost of $67,000 and did not significantly alter the appearance of the bridge. The state plans to use this method on at least four bridges per year for the next several years.

Biological Control of Purple Loosestrife

Purple loosestrife is a noxious weed species that has become a common problem throughout North America. For any highway construction project

that affects wetlands significantly, mitigation options that deal with landscape alterations must be identified. At many construction project sites, loosestrife quickly becomes established despite preventive measures. Because loosestrife grows vigorously and rapidly and adapts easily to many types of wetland habitats, it tends to overtake native vegetation, creating monotypic stands. The New Hampshire DOT, in conjunction with the state’s department of agriculture, undertook a study of biological control agents, focusing in particular on types of beetles that could be used to manage the purple loosestrife. The study, on a 9-acre wetland site at which loosestrife had become dominant, took place over a 2-year period. The beetles reduced the loosestrife population and enabled other indigenous plant species to return to the site. The beetles were subsequently introduced to 12 other sites. All 13 sites continue to be monitored. Use of the biological control at the initial site saved about $20,000 in labor costs alone.

Modified Aggregate Test to Expedite Superpave

The adoption of Superpave by the Kansas Department of Transportation (KDOT) was hindered because of the need for a microscopic examination of fine aggregates available at only one location in the state. KDOT engineers needed a field test method that could differentiate samples of crushed material with slight contamination from blends of crushed and uncrushed material. In addition, they needed practical limits for good performance. Research led to a field test method, accepted by ASTM, that required less than 30 min to complete. This method takes an estimated 3 h of employee time less per test as compared with the ASTM test method. The state expects to save about 1,900 employee hours per year with this method.

New Precast Bent Cap System

Faced with the replacement of 113 bridge spans on an elevated section of Interstate highway in downtown Houston, the Texas Department of Transportation (TxDOT) decided to use the existing concrete columns,

but needed a quicker method of replacing the bent caps (the horizontal connections between columns) than the traditional cast-in-place approach. User delay costs were estimated to be more than $100,000 a day, and TxDOT engineers needed an alternative approach to expedite construction. TxDOT therefore contracted with the Center for Transportation Research at the University of Texas to develop and test a precast design method that would enable contractors to connect new precast bent caps to the existing bridge columns with any of several alternative connection systems. The center developed and verified in laboratory tests the adequacy of a design that enabled the construction to be completed in only 99 days, as compared with the 548 days required for conventional construction. With research costs of $289,200, the research effort was deemed highly cost-effective.

New Ramp-Metering Algorithm to Improve Systemwide Travel Times

Ramp metering has the potential to improve freeway operations by restricting and evenly spacing the traffic entering a freeway. Ramp metering a freeway system requires an algorithm that can be used to calculate and implement the meter control system at tens of locations under a wide variety of traffic demand conditions and in the face of random traffic incidents and crashes. The Washington State Department of Transportation (WSDOT) contracted with the University of Washington Department of Electrical Engineering to develop an algorithm that would balance the conflicting objectives of ramp metering and take account of the variations in local traffic conditions. The algorithm was tested on two Interstate corridors, and the results were so promising that WSDOT decided to implement it on all ramps in the Seattle area. Although absolute benefits were difficult to determine, tests showed that on one Interstate segment, the algorithm decreased mainline congestion noticeably and increased flow. On another segment, the ramp queues decreased significantly, but mainline congestion increased only marginally.