Roadway Projects Research Articles

Solid Waste Generation in Asphalt and Reinforced Concrete Roadway Life Cycles

Conserving natural resources for future generations is a common objective of sustainable design and construction. Making use of materials in an efficient manner to improve sustainability is especially applicable on roadway construction projects which can consume significant quantities of materials. An understanding of how best to eliminate material waste on roadway projects requires knowledge of the amount of material waste generated during the various phases of the roadway life cycle. This paper presents a research study undertaken to quantify the amount of materials wasted during the roadway life cycle. The study included life-cycle inventory assessments (LCI) of a continuously reinforced concrete (CRC) roadway and an asphalt concrete (AC) roadway with respect to the waste generated from extraction of raw materials through the end-of-life (EOL) of the roadways. For the CRC roadway, waste was primarily generated at the roadway EOL, accounting for approximately 53% of the total amount of waste generated over the roadway’s entire life cycle. A similar trend was observed for the AC roadway in which 59% of the total waste occurred at EOL. For both CRC and AC roadways, waste created during placement of materials is almost negligible compared to that generated during the manufacturing phase and at EOL. The results suggest that application of sustainable concepts (reduce, recover, reuse, and recycle waste) and use of recycled instead of natural materials would help create sustainable roadways.

Estimating User Costs and Economic Impacts of Roadway Construction in Six Federal Lands Projects

The Federal Lands Highway (FLH) Division staff faces myriad challenges when designing roadway construction projects for roads located on federal lands. An increasingly prevalent challenge is considering not only the “hard” costs of a construction project (e.g., labor and materials) but also the “soft” costs of user delay and the economic impacts on roadway users (e.g., residents, visitors, staff, and local businesses). These soft costs affect every roadway construction project but rarely are considered in design and operation because they often are difficult to estimate and justify. FHWA's 1998 report Meeting the Customer's Needs for Mobility and Safety During Construction and Maintenance Operations identifies this issue and recommends that engineers begin to address it, for small- as well as large-scale projects. As part of its responsibility to promote the development and deployment of applied research, FLH staff initiated the development of FLH-QuickZone to help estimate these soft costs of roadway construction. As part of its development, FLH-QuickZone was tested and prototyped in six FLH construction projects: three in national parks, two on forest highways, and one in a national recreation area. Where FLH-QuickZone fits in a spectrum of other estimation tools for work zone delay and how it was used in the six FLH roadway construction projects are summarized. Observations about the challenge of addressing the soft cost of roadway construction projects–with FLH-QuickZone or other analytical tools–also are presented.

Alternative Strategies for Rehabilitation of Low-Volume Roads in Nevada

An overview of the attempt by the Nevada Department of Transportation (NDOT) to find alternative rehabilitation strategies to rehabilitate its low-volume road network effectively is provided. Because of Nevada's continuing growth, NDOT is faced with the challenge of how to balance its available funding between pavement preservation and capacity improvement projects. NDOT is responsible for 13,000 lane miles of roadway, of which 3,385 lane miles (26%) qualify as low-volume roads. The low-volume roads have a two-directional average daily traffic of 400 or less. Five roadway projects with a combined total of 111 centerline miles were rehabilitated with 29 combinations of structural and surface strategies. The rehabilitation strategies investigated included full-depth reclamation with lime, cement, asphalts, and foamed asphalt. Various cold-mix, cold-in-place recycling with millings and different rejuvenating agents, and surface treatment test sections were constructed. The constructability issues that were reported during construction are discussed. In addition, pavement condition is examined and laboratory testing is reviewed. Results suggest that NDOT can use alternative rehabilitation strategies in place of its conventional method of 2-in. plant-mix bituminous surface overlay and chip seal to rejuvenate its low-volume roadway network. A cost saving of approximately $100,000 per centerline mile is anticipated.

Public Outreach in Pedestrian Plan for Durham, North Carolina

Roadway and bridge projects serve a broad population, most of which can readily accommodate changes in travel routes. Pedestrian projects, however, frequently have direct impact on specific populations that are highly sensitive to changes in the transportation network and the level of service to pedestrians. Therefore pedestrian plans must have both targeted and broad-sweeping public involvement programs. For many projects, the public involvement program is restricted by the total level of resources applied to the project. Durham, North Carolina, an extremely diverse city, undertook the preparation of a pedestrian plan. A combined 6.6% of Durham's workers take public transit or walk to work. The Durham pedestrian plan process was accompanied by an intensive public involvement and outreach program, which took a two-pronged approach. First, a stakeholder committee was established. Second, the public outreach effort created a series of opportunities for the general public to learn more about the plan and to provide comment. The Durham pedestrian plan does not support the oft-cited claim that insufficient project funding is an insurmountable obstacle to conducting a successful public involvement effort. Recommendations for improving public outreach programs include implementing a variety of techniques to incorporate diverse citizens, clearly stating public outreach objectives early and often, and devoting time and resources to assessing the effectiveness of public outreach efforts, both during and after the study.

A simulation-based multi-objective genetic algorithm (SMOGA) procedure for BOT network design problem

Solving optimization problems with multiple objectives under uncertainty is generally a very difficult task. Evolutionary algorithms, particularly genetic algorithms, have shown to be effective in solving this type of complex problems. In this paper, we develop a simulation-based multi-objective genetic algorithm (SMOGA) procedure to solve the build-operate-transfer (BOT) network design problem with multiple objectives under demand uncertainty. The SMOGA procedure integrates stochastic simulation, a traffic assignment algorithm, a distance-based method, and a genetic algorithm (GA) to solve a multi-objective BOT network design problem formulated as a stochastic bi-level mathematical program. To demonstrate the feasibility of SMOGA procedure, we solve two mean-variance models for determining the optimal toll and capacity in a BOT roadway project subject to demand uncertainty. Using the inter-city expressway in the Pearl River Delta Region of South China as a case study, numerical results show that the SMOGA procedure is robust in generating ‘good’ non-dominated solutions with respect to a number of parameters used in the GA, and performs better than the weighted-sum method in terms of the quality of non-dominated solutions.

ITS Devices Used to Collect Truck Data for Performance Benchmarks

This paper documents the development of data collection methodologies that can be used to measure truck movements along specific roadway corridors in Washington State cost-effectively. The intent of this study was to design and test methodologies that could provide information to ascertain the performance of freight mobility roadway improvement projects. The benchmarks created would be used to report on speed and volume improvements that resulted from completed roadway projects. One technology tested consisted of Commercial Vehicle Information System and Networks electronic truck transponders, which were mounted on the windshields of approximately 30,000 trucks traveling in Washington. These transponders were used at weigh stations across the state to improve the efficiency of truck regulatory compliance checks. With transponder reads from sites anywhere in the state being linked through software, the transponder-equipped trucks can become a travel time probe fleet. The second technology tested involved G...

ITS Devices Used to Collect Truck Data for Performance Benchmarks

This paper documents the development of data collection methodologies that can be used to measure truck movements along specific roadway corridors in Washington State cost-effectively. The intent of this study was to design and test methodologies that could provide information to ascertain the performance of freight mobility roadway improvement projects. The benchmarks created would be used to report on speed and volume improvements that resulted from completed roadway projects. One technology tested consisted of Commercial Vehicle Information System and Networks electronic truck transponders, which were mounted on the windshields of approximately 30,000 trucks traveling in Washington. These transponders were used at weigh stations across the state to improve the efficiency of truck regulatory compliance checks. With transponder reads from sites anywhere in the state being linked through software, the transponder-equipped trucks can become a travel time probe fleet. The second technology tested involved Global Positioning Systems (GPS) placed in volunteer trucks to collect specific truck movement data at 5-s intervals. GPS data made it possible to locate when and where monitored trucks experienced congestion. With this information aggregated over time, it was possible to generate performance statistics related to the reliability of truck trips and even to examine changes in route choice for trips between high-volume origin–destination pairs. The study found that both data collection technologies could be useful; however, the key to either technology is whether enough instrumented vehicles pass over the roadways for which data are required.

Pavement Management System Based On Financial Consequence

One of the biggest challenges for any public organization is how to prioritize projects to maximize existing funding. With so many programs competing for the same funding, it is especially important to optimize pavement rehabilitation programs to allow for funding for other programs, such as safety, capacity improvements, and environmental improvement projects. This report describes how the Nevada Department of Transportation (NDOT) optimized its available funding while improving pavement condition by using an eight-step pavement management system based on financial consequence. This eight-step procedure includes administration support, contract database implementation, roadway system division, performance models, project prioritization, and strategy selection. This procedure can easily be adopted by other states. A nominal amount of information is required to initiate this system, and the reward can be exceptional. NDOT saves $42 million a year with this methodology. An advantage of a pavement management system based on financial consequence over a conventional network optimization system is that process allows engineers to communicate with top administrators in a nontechnical way. Administrators can understand the concept and make good roadway funding choices without needing a great deal of technical input from engineers. For example, administrators see that the cost of delaying a 10-mi roadway section on an Interstate system by 2 years can cost the agency an additional $6 million for rehabilitation; but that delaying a 10-mi roadway section on a relatively low-volume road can cost only a few thousand dollars.

Pavement Management System Based on Financial Consequence

One of the biggest challenges for any public organization is how to prioritize projects to maximize existing funding. With so many programs competing for the same funding, it is especially important to optimize pavement rehabilitation programs to allow for funding for other programs, such as safety, capacity improvements, and environmental improvement projects. This report describes how the Nevada Department of Transportation (NDOT) optimized its available funding while improving pavement condition by using an eight-step pavement management system based on financial consequence. This eight-step procedure includes administration support, contract database implementation, roadway system division, performance models, project prioritization, and strategy selection. This procedure can easily be adopted by other states. A nominal amount of information is required to initiate this system, and the reward can be exceptional. NDOT saves $42 million a year with this methodology. An advantage of a pavement management system based on financial consequence over a conventional network optimization system is that process allows engineers to communicate with top administrators in a nontechnical way. Administrators can understand the concept and make good roadway funding choices without needing a great deal of technical input from engineers. For example, administrators see that the cost of delaying a 10-mi roadway section on an Interstate system by 2 years can cost the agency an additional $6 million for rehabilitation; but that delaying a 10-mi roadway section on a relatively low-volume road can cost only a few thousand dollars.

New Capital Cost Table for Highway Investment Economic Analysis

The FHWA maintains the Highway Economic Requirements System (HERS) model to enable the estimation of highway investment requirements for the biennial Status of the Nation's Highways, Bridges, and Transit: Conditions and Performance report to Congress. The HERS logic relies on the application of benefit–cost analysis to evaluate and select the best set of roadway improvements for systemwide implementation. Benefits of roadway improvements are calculated from user and agency cost savings (including externalities), and cost is considered simply the capital cost of the improvement. The current research seeks to improve the knowledge of the unit capital costs of improvements modeled in HERS with the use of as-built road construction cost data previously developed for FHWA and bid–schedule data published by various highway agencies. The construction cost dataset used contained detailed data on more than 2,500 construction projects in six states; however, it lacked enough samples to apply either econometrics or generalized statistical analysis to make reliable estimates for all roadway improvement and cost categories in HERS. Both deterministic and probabilistic methods were applied to engineering specifications along with bid–schedule data on various roadway improvement projects to generate capital cost data for each of the classification variables. The final cost table data developed resulted in national highway improvement capital cost data that most realistically corresponded with a typical cost variation across land terrain and urban population density for a given improvement type. For some classification variables the new cost data are 60% to 150% higher than the previous HERS cost estimates.

Multidimensional Framework for Context-Based Design of Major Urban Thoroughfares

During the post-World War II period, conventional roadway design has been based on a functional classification system that addresses levels of vehicle movement and access to abutting properties. Traffic-carrying capacity has been the dominant consideration. In recent years, more attention has been given to other characteristics of local streets and a small number of major streets. New design standards have been developed for local (neighborhood) streets by some organizations and local agencies. At the same time, the National Environmental Policy Act has increased the importance of environmental considerations in the design of major streets and roads and highlighted the importance of minimizing impacts of roadway projects on natural resources, particularly in rural environments. However, no widely accepted design guidelines have yet been developed for urban major streets. Street design and urban design professionals share a need for a two-dimensional framework that ties together ( a) roadway design criteria for an expanded palette of street types (number of lanes; target speed; pedestrian, transit, bicycle, and motor vehicle functions; other functional criteria) and ( b) a set of place types that reference features of both the public right-of-way and private development fronting on the roadway and in the broader area. The conventional functional class-based design criteria do not satisfy this need. The basic structure of such a framework is discussed.

A New Approach to Private Roads

Roadway privatization offers many benefits, from decreasing transportation's dependence on public coffers to using market forces to decrease the number of white elephant roadway projects. But, in the United States, only two private road projects have been undertaken during the last century, in part because potential investors and the government worry about the financial risks of such projects. We believe those risks can be overcome through government awarding of Present-Value-of-Revenue franchises to private roadway companies, which would protect those companies' investment but would also protect taxpayers.

Pedestrian Safety Through a Raised Median and Redesigned Intersections

Documentation was done on the effect of a raised median, signalized and redesigned intersections, curbs, and sidewalks on vehicle speed, pedestrian exposure risk, driver predictability, and vehicle volume along a four-lane suburban roadway in central New Jersey. The analysis used both quantitative tools (speed and volume counts, timing runs) and qualitative methods (pedestrian tracking, video, before-and-after photography). The results are that the 85th-percentile vehicle speed fell by 2 mi/h and pedestrian exposure risk decreased by 28%. Also, the median allows pedestrians to cross one direction of traffic at a time and signals, curbs, median, redesigned intersections, and striping patterns work together to manage driver behavior. In regard to vehicles, it was found that vehicle volumes were not affected and that vehicle speeds acted independently of vehicle volumes. A collision analysis projected a savings of $1.7 million over the next 3 years in direct and indirect costs. The goal of the report was to produce a simple and straightforward analysis tool for similar projects in the area. Some of the benefits of roadway projects such as these can be quantified numerically, whereas others rely on qualitative analyses. For example, before-and-after speeds are easily gathered and compared, whereas before-and-after pedestrian behavior at the raised median requires a more in-depth approach made easier by digital cameras. Together, before-and-after data and before-and-after imaging present a more holistic picture of the benefits and limitations of a project.

Mean-Variance Model for the Build-Operate-Transfer Scheme Under Demand Uncertainty

A mean-variance model was developed for determining the optimal toll and capacity in a build-operate-transfer (BOT) roadway project subject to traffic demand uncertainty. This mean-variance model involves two objectives: maximizing mean profit and minimizing the variance (or standard deviation) of profit. The variance associated with profit is considered as a risk. Because maximizing expected profit and minimizing risk are often conflicting, there may not be a single best solution that can simultaneously optimize both objectives. Hence, it is necessary to explicitly consider this as a multiobjective problem so that a set of nondominated solutions can be generated. In this study, the optimal toll and capacity selection for the BOT problem under demand uncertainty is formulated as a special case of the stochastic network design problem. A simulation-based multiobjective genetic algorithm was developed to solve this stochastic bilevel mathematical programming formulation. Numerical results are also presented as a case study.

Air Convection Embankment for Roadways: Field Experimental Study in Alaska

During 1996—1997, an experimental air convection embankment (ACE) was constructed in Fairbanks, Alaska, using very coarse [1- to 6-in (25- to 150-mm)], poorly graded, crushed rock fill material on top of icerich permafrost foundation. The highly permeable ACE installation was designed to test the cooling effectiveness of the ACE concept in an actual roadway project. Using thermistor sensor strings, temperature data were collected from the ACE test section and an adjacent control section. Results showed that the ACE technique can be used to generate a passive cooling effect. This effect manifested as a depression of mean annual temperature at the base of the ACE cross section compared with mean embankment surface temperatures. The data indicated that this thermal offset is on the order of 7°F (Δ = 4°C) for this installation. The measured data also showed that mean annual temperatures are generally near or above the freezing value in the upper portion of the ACE embankment but significantly below freezing at the base. The temperature offset caused a gradual cooling of the foundation soil beneath the embankment with maximum base temperatures that have decreased from more than 40°F (4.4°C) to near freezing during the 5-year measurement period. Within a few more years of operation, it is anticipated that the permafrost table will move up into the base of the ACE cross section, completely eliminating any seasonal thaw in the foundation soil below and thus preventing future subgrade thaw–consolidation.

Comparison of Two Approaches for Modeling Freight Movement at Seaports

Seaports host international cargo operations and are primary generators of freight traffic in the United States. Truck/rail trip generation and modal split models provide public agencies with valuable information necessary to prioritize funds for roadway upgrade projects and port infrastructure modifications. This paper presents two approaches for developing freight trip generation models: regression analysis and backpropagation neural networks (BPN). These models are used for predicting the levels of cargo truck traffic moving inbound and outbound at seaports. Based on the Port of Miami case, it was found that the BPN model is more accurate than the regression model. However, the BPN model requires a sizable database. Using the BPN approach, the paper presents a new combined truck trip generation and truck-rail modal split model for the Port of Jacksonville. It was found that the primary factors affecting truck-rail volume are the amount and direction of cargo vessel freight, commodity type, and the particular weekday of operation. In summary, the neural network model results were found significantly accurate for both Florida ports.

Cost-Benefit Highway Pavement Maintenance

Many methods used in highway maintenance plans are complex, and agencies often exclude components related to user costs in the work zone (such as vehicle operating costs, delay costs, and crash costs) when making project improvement decisions. Highway users are taxpayers, and considering the user costs in project rehabilitation, resurfacing, and reconstruction provides the greatest return on project tax dollars spent. A simple five-step procedure that includes user work zone costs in the selection of highway maintenance projects has been developed and applied to the city of Gainesville, Florida, roadway improvement network projects: (1) collect distress data, (2) prepare inventory forms for the roadway networks, (3) prepare a maintenance cost plan, (4) prepare priority rankings for project improvements, and (5) select and implement project rehabilitation on the basis of priority ranking. These five steps assist highway agencies (public works officials and highway engineers) in simplifying maintenance programs in light of limited funding and help agencies choose priorities for highway maintenance funding for projects.

Truck Trip Generation Models for Seaports with Container and Trailer Operation

Freight movement throughout the United States continues to evolve as a significant challenge to the transportation industry. Seaport operations dominated by container and trailer movements will require operational and infrastructure changes to maintain the growth of international cargo operations. Transportation planning models can be used to determine the needs of port and street network modifications. Described is the research and initial development process of models for predicting the levels of cargo truck traffic moving inbound and outbound at the Port of Miami. The models were restricted to container and trailer truck configurations that transport virtually all of the Port of Miami’s freight. Consequently, this associated truck traffic moves through the nearby street network within downtown Miami. The purpose of the trip generation models is to predict volumes of large inbound and outbound trucks for specified time frames. The concern is to know how many large cargo vehicles are traveling on the only road leading to the port. Primary factors affecting truck volume were found to be the amount and direction of cargo vessel freight and the particular weekday of operation. Time series models for predicting seasonal variations in freight movements were developed as part of the study. These models are useful for long-term forecasts of the input variables used in the trip generation models. Truck trip generation models will provide transportation planners and public agencies with valuable information when making transportation management decisions and infrastructure modifications. This information also is necessary for prioritizing funds for roadway upgrade projects.

Dealing with Historic And Prehistoric Properties

A number of commuter rail, levee, and roadway construction projects from have come to a grinding halt in recent years because of federal law protecting archaeological resources. Part of the problem is the murky nature of historical preservation law, centered on federal requirements under section 106 of the National Historic Preservation Act of 1966 (NHPA) and its amendments. Although section 106 of the NHPA ostensibly covers only federal activities, most development, rehabilitation, and demolition projects of any size require a section 106 review. Any property listed in or eligible to be listed in the National Register of Historic Places is considered historic for purposes of section 106. The federal agency responsible for an undertaking must identify any historic properties, conduct a preliminary review, and from this review determine what types of surveys or field studies may be required and carry them out. In certain situations, contractors may prefer to have an archaeologist on-site during construction and forgo preliminary surveys. During the second phase of the review, the agency determines whether the undertaking will have any adverse effects. If the undertaking will result in any adverse effects, consultation with the state historic preservation officer and others is conducted to explore ways of avoiding or lessening these effects. This process should result in a memorandum of agreement, which outlines measures that the agency and contractor will take to reduce, avoid, or mitigate the adverse effects.

Development of Pavement Type Evaluation Procedure for Texas Department of Transportation

A rational procedure is presented for evaluating alternative pavement types for roadway projects. Agency costs, user delay costs, and performance levels are important factors for comparing alternative pavement strategies. These factors are included in the evaluation procedure. Economic evaluations are based on life-cycle cost analysis. Cost-effectiveness analysis is also included in the procedure and uses area under the performance curve as a measure of the effectiveness of a pavement design strategy. Limitations in economic evaluations and the role of other miscellaneous factors in pavement type selection are also discussed. A computer program, TxPTS, was developed to automate the evaluation procedure. Case studies are presented demonstrating the use of the program.