Transportation Research Record: Journal of the Transportation Research Board

Bridges are a cultural resource that must be considered for historic significance under the Historic Preservation Act of 1966. The Virginia Transportation Research Council conducted pioneering studies of Virginia’s early metal truss bridges and concrete and masonry arch bridges during the 1970s and 1980s. However, no comprehensive evaluation of nonarched concrete bridges in Virginia had been undertaken, and it had become standard practice to evaluate these bridges on a case-by-case basis as projects arose that might affect them. Most of these studies were done by outside consultants, a time-consuming and expensive method. The Virginia Transportation Research Council’s Survey of Non-Arched Historic Concrete Bridges in Virginia Constructed Prior to 1950 has rectified the lack of information and analysis of these bridges (1950 was chosen as a cutoff date because structures generally must be at least 50 years old to be considered historically significant under National Register criteria). A field survey and data tabulation were completed, and criteria for the evaluation of historic significance were developed and applied to the results of the survey and analysis. Of 1,420 nonarched concrete bridges built before 1950, fewer than a dozen were found to be individually eligible for the National Register of Historic Places. The project identified Virginia’s few significant bridges of this type for appropriate management, and cleared more than 1,400 bridges, the great majority of Virginia’s nonarched concrete bridges, for maintenance and upgrade as needed. It is estimated that this project has already saved the Virginia Department of Transportation $500,000 and eliminated a typical 3- to 4-month delay for each project. Projected savings arising from this project are estimated at approximately $2.5 million over the next 10 years.

Oregon’s Coastal Bridge Program was designed to preserve the economic and cultural resources invested in Oregon’s coastal bridges. The Oregon Coast Highway contains a significant concentration of bridges listed on or eligible for the National Historic Register. Many of these reinforced concrete structures are suffering extensive corrosion damage resulting from years of exposure to the marine environment. Oregon has developed this program to evaluate, prioritize, and preserve these magnificent bridges. Preservation of these bridges has relied on the innovative application of cathodic protection technology. This new technology has been applied successfully through a project design and construction process that includes ongoing interaction among design engineers, researchers, construction project management personnel, and contractors.

Transportation facility and system options for the greater Vancouver region are evaluated using the provincial guidelines for full-cost accounting. The impact of the monetized environmental accounts on the overall evaluation is presented, using facility, system option, and pricing examples from the regional plan. Within project options that are homogeneous with respect to travel demand management or modal split, environmental account values do not differ much, just as in the user cost accounts. Monetized environmental account values are two to three times smaller than the user cost in project-level cases. At the system level, in which travel demand management and modal choice are among the principal objectives, environmental benefits are decisive, whereas user benefits may be inconclusive. The estimated monetized subsidy to full costs of the automobile underpricing of personal transport has increased from 20 percent to more than 50 percent with analytical advances since 1993. Serious intangible externalities remain unmonetized, but should nevertheless be considered. Limitations of transportation demand model and data (peak spreading, 24-hr operation, and determination of vehicle speeds) require remediation for accurate environmental accounting. Fuel consumption and vehicle operating costs at low levels of service, and impacts of travel demand management on travel behavior, are decisive for system appraisals. At the project level, queueing data, level of service, and capacity must be available. Speed-and vehicle-specific emission rates are also necessary for accurate accounting at the project and system levels.

In recent years, transportation agencies have become increasingly interested in using corridor preservation to protect future highway locations from development. However, the preparation of National Environmental Policy Act (NEPA) documents in the late stages of the transportation planning process makes uses of these measures difficult. In an attempt to make the corridor preservation and NEPA processes more compatible, the North Carolina Department of Transportation and FHWA have developed the phased environmental approach, an environmental review process that allows early selection of highway location and makes the use of protection techniques feasible and effective. Although the phased approach has been used in several pilot projects and is intended to become a part of the state’s standard planning process, the procedure’s compliance with the requirements of NEPA has not been evaluated. The compliance of the phased environmental approach with NEPA is examined. Several disparities are identified that place the new procedure in violation of the statute. Considering these problems, three options for modifying the phased approach to provide for compliance with NEPA are identified. These options are compared on the basis of their capacity to provide those benefits offered by the phased approach. A tiered environmental impact statement (EIS) is determined to be the best alternative to the phased environmental approach. This option provides the same benefits as the phased approach while remaining consistent with NEPA. Although several potential problems have been cited regarding the practicality of using a tiered EIS in transportation projects, these concerns may not apply in many cases.

Expert systems can be useful tools to assist and guide practitioners through particularly difficult and complex decision-making environments. The process of assessing the requirements and conceptualizing an expert system architecture for the New York State Department of Transportation to enhance its environmental analysis functions is described. Using expert system techniques presents a proactive and innovative approach to systematize and improve the environmental process within transportation design. Among the system’s objectives are to treat effectively the logic and inference process associated with the breadth and depth of environmental analysis resource areas, promote compliance with federal and state environmental requirements, enhance project management through estimating staff resources, and be responsive to the needs of multiple user classes to include environmental staff, designers, planners, and managers.

Human activities often adversely affect natural landscapes or ecosystems. Natural landscapes typically consist of habitats differing in size, shape, structure, and composition. These components create biodiversity, which is broadly defined as the variety of the world’s organisms. Impacts on biodiversity—including direct impacts from development, secondary impacts, and impacts from active consumption—are increasing as the human population continues to grow. Impact on biodiversity is emerging as a concern of environmental groups. Highway construction may contribute to biodiversity loss because transportation corridors tend to disrupt normal patterns in the landscape. Transportation agencies, such as the Pennsylvania Department of Transportation, are interested in evaluating the need to analyze the effects on habitat fragmentation and biodiversity caused by roadway construction projects. Evaluation of such effects is a relatively new issue. There are currently no regulatory requirements to perform these types of evaluations. Therefore, the opportunity exists to develop rational and practical guidance to use on transportation projects. Even though no formal guidance exists, a number of similar methods in use could be modified for analyzing and quantifying impacts on biodiversity caused by highway projects. The decision whether to assess biodiversity for a project depends on the existing environment and the types of impacts the project will have on that environment. Whether mitigation of these biodiversity impacts should occur depends on the overall impacts on all resources by the proposed project. Much work still needs to be done in the development of an acceptable method for assessing the potential impacts of transportation projects on biodiversity. The general state analysis should be molded into an acceptable method for use by state departments of transportation. This method would need support in the form of a new mandate for implementation under the National Environmental Policy Act.

Although forested wetlands are relatively abundant on the coastal plain of North Carolina, restoration of forested wetlands is becoming more common since these communities are frequent targets for impact or destruction, especially as a result of road construction projects. Successful restoration of ecosystems is made difficult by a lack of basic knowledge about the soil and hydrologic characteristics of different types of forested wetlands. The plant community composition of two forested wetlands types is described: bottomland hardwood communities and a coastal plain small stream swamp. The edaphic and hydrologic characteristics of each community type were also compared. Many researchers have suggested the construction of detailed water budgets to describe the hydrologic regimes of natural forested wetlands and for use in restoration projects. Although several soil and hydrologic characteristics were associated with variation in plant community composition, the results of this investigation suggest that using a particular flood frequency as a surrogate measure of several flood frequencies may be sufficient to explain this variation. Use of this information would simplify the reconstruction of appropriate hydrologic regimes in forested wetlands and perhaps increase the success of restoration projects.

The completion of the largest Ohio Department of Transportation traffic noise abatement project in 1995 was met with public controversy over the effectiveness of the noise barriers. A public opinion survey was designed to obtain the perceptions of the residents in the project area. In a departure from most surveys of traffic noise barrier effectiveness, the coverage was not limited to the first or second row of houses, but was extended to 800 m on each side of the roadway. It was found that the larger survey area was needed to avoid misleading conclusions. Overall perceptions of noise barrier effectiveness were found to vary with distance from the roadway and with noise barrier configuration.

Noise barriers have become a prominent feature on today’s landscape. Unfortunately, they have also become a feature associated with insensitivity toward the built environment. Designers could avoid the negative visual impact that noise barriers frequently create by increasing their awareness of aesthetics in the design process. In an effort to improve the quality of noise barrier design, the New Jersey Department of Transportation’s, Bureau of Environmental Analysis (BEA) altered the design process for its I-76/I-295 Type II noise abatement study. The first objective of the study was to acoustically engineer a barrier that would abate the noise for residents along the affected roadway corridor. The second was to develop an architectural design that would be aesthetically pleasing to the corridor resident and the roadway users. Typically, architects were brought into the design process at the end to review the aesthetic impact of the wall and add architectural features. On the I-76/I-295 project, BEA initiated a parallel process with the architectural design running concurrent with the engineering. The architectural design process and the interfacing of this process with the engineering are described. Community involvement was essential to the architectural objective of designing an aesthetically pleasing barrier. Ideas reflecting community concerns and comments were refined into final recommendations for construction of a noise barrier with gateways and a unifying corridor theme. The noise barrier should then become a representation of the community and stand as an icon in the built environment. Noise barriers can have a positive impact on the built environment if a commitment is made to aesthetics throughout the design process.

Several models are available for predicting traffic noise levels. The FHWA-promulgated model, STAMINA 2.0, is the most widely used noise model in the United States and is used to model free-flow vehicular traffic. STAMINA 2.0 cannot directly model interrupted-flow traffic. Sound levels from interrupted-flow traffic can be approximated with STAMINA 2.0 using the method presented in NCHRP Report 311. This method is time-consuming and difficult to use. These limitations demonstrate the need for a traffic noise model that can model the acceleration and deceleration behavior of interrupted-flow traffic. The University of Central Florida has developed the American Automobile Manufacturers Association Community Noise Model (CNM). The CNM is a traffic simulation model that determines sound levels at receivers by modeling vehicles as discrete moving point sources. The vehicle energy is determined from acceleration, deceleration, idle, and cruise reference energy mean emission level curves. Sound energy attenuation is calculated from distance, ground absorption, and user input barriers. The model sums the energy at receivers from all vehicles and then calculates the L_eq noise level at the receivers. It is demonstrated that the CNM predicts receiver L_eq levels that are very close to STAMINA 2.0 results for constant-speed traffic. The CNM can also accurately predict sound levels at receivers located before and after intersections. In addition to the advantages of a real simulation model, the CNM is user friendly, allowing the user to place lanes and receivers using the mouse.

The origins of an annoying high-pitched sound emitted by highway traffic were investigated. Wayside noise levels of single vehicles passing over three types of pavement surfaces were measured using real traffic. Data based on a statistically significant number of samples are presented for automobiles and heavy trucks. All data were collected using a realtime analyzer with 1/3-and 1/12-octave band resolution. The measured data confirmed the transverse grooved pavement as the noisiest with a noticeable concentration of sound, often described as a “whine.” Data for the asphalt and longitudinally grooved surfaces indicated lower overall noise levels and a near absence of the whine.

It is now some 4 years since the New South Wales Roads and Traffic Authority (RTA) interim noise policy was released. The document sets out RTA policies on traffic noise along with guidelines relating to assessment and control. It is perhaps the most extensive document on the topic ever produced by an Australian road authority. The underlying philosophy of the policy is the importance of noise as an issue that must be addressed in all aspects of RTA road planning, design, construction, maintenance, and operation programs. Some recent advances in the traffic noise arena are considered. A spatial decision support system is then outlined for road planning that has been developed as part of an Australian Research Council industry collaborative research grant involving RTA and the University of New South Wales. This is built on object-oriented programming and geographic information system technologies and involves a library containing models in eight domains amounting to 33,000 lines of code. The noise estimation procedure included in this system is described together with how it has been adapted and implemented in an object-oriented way. Speculation is made on how the prototype may be integrated into the emerging corporate responsibilities of RTA in the area of communication and consultation.

Land use has always been a factor in developing site-specific cleanup objectives for contaminated property. However, land use is taking on major new significance in the “brownfield” legislation being enacted in a growing number of states. Under this method, a tiered approach is used to analyze the risk posed by contaminants and to derive cleanup objectives based on that risk. By many accounts on the leading edge of the brownfield movement, the Illinois Environmental Protection Agency (IEPA) is going so far as to propose a tiered approach to cleanup objectives (TACO) generally across its land pollution programs. TACO relies heavily on restricting land use to obtain less stringent cleanup objectives, and it is this aspect of TACO that represents both an opportunity and a challenge to Illinois transportation agencies and the shape of things to come nationally. The opportunity lies in much lower cleanup costs that these agencies will incur in dealing with contamination in their own yards and rights-of-way. The challenge lies in considering requests from property owners adjoining the rights-of-way for land use restrictions on the rights-of-way, in dealing with land use restrictions on property acquired through eminent domain, and in processing land use restrictions that will be imposed for IEPA’s own cleanups.

The destruction of two model petroleum hydrocarbons using a photocatalyst fixed on dry test surfaces was investigated as a basis for minimizing nonpoint hydrocarbon runoff to adjacent soils and receiving waters. The process is based on attaching photochemically active titanium dioxide (TiO₂) to pavement surfaces. Hexadecane and anthracene were used as model contaminants because they are common hydrocarbon constituents of gasoline, diesel, and motor oil. Six materials containing TiO₂ were evaluated for photocatalytic activity; concrete sealant and paint base were found to be the most effective materials tested. The TiO₂-sealant formulations were effective in promoting the degradation of hexadecane, providing more than 99 percent removal in 48 hr. Although the TiO₂-paint base formulation was less effective than the TiO₂ sealant, 98.2 percent degradation of hexadecane occurred on a 50 percent TiO₂-paint base surface in 72 hr. Anthracene degradation was not accelerated from the addition of the photocatalyst into the surface. On the basis of the capability of dry fixed TiO₂ to enhance rates of hexadecane photolysis, a full-scale demonstration project has been initiated to evaluate the in situ destruction of nonpoint highway runoff.

Surface area is a primary factor in determining many physical and chemical properties of solids, especially particles. In urban and highway runoff, solids can mediate the partitioning between the dissolved and particulate-bound phases of metal elements and organic compounds. Solids are also capable of adversely affecting roadway drainage appurtenances through sedimentation and clogging. Solids characteristics of primary importance for both solute adsorption and clogging and sedimentation are particle size distributions (PSDs), specific surface areas (SSAs), and mass loadings. PSD and SSA results are presented for rainfall and snowmelt solids from a heavily traveled urban roadway in Cincinnati. Integration of the PSD and SSA results indicates that particle surface area is greatest for the midrange (> 100 μm) to the coarser end (<2000 μm) of the gradation. SSA results determined using the assumption of smooth spherical particles are indicated to grossly underestimate actual SSA values.