Highway Alternatives Research Articles

Optimization of Urban Highway Bypass Horizontal Alignment: A Methodological Overview of Intelligent Spatial MCDA Approach Using Fuzzy AHP and GIS

Selection of urban bypass highway alternatives involves the consideration of competing and conflicting criteria and factors, which require multicriteria decision analysis. Analytic hierarchy process (AHP) is one of the most commonly used multicriteria decision making (MCDM) methods that can integrate personal preferences in performing spatial analyses on the physical and nonphysical parameters. In this paper, the traditional AHP is modified to fuzzy AHP for the determination of the optimal bypass route for Eldoret town in Kenya. The fuzzy AHP is proposed in order to take care of the vagueness type uncertainty encountered in alternative bypass location determination. In the implementation, both engineering and environmental factors comprising of physical and socioeconomic objectives were considered at different levels of decision hierarchy. The results showed that the physical objectives (elevation, slope, soils, geology, and drainage networks) and socioeconomic objectives (land-use and road networks) contributed the same weight of 0.5 towards the bypass location prioritization process. At the subcriteria evaluation level, land-use and existing road networks contributed the highest significance of 47.3% amongst the seven decision factors. Integrated with GIS-based least cost path (LCP) analysis, the fuzzy AHP results produced the most desirable and optimal route alignment, as compared to the AHP only prioritization approach.

Bilevel Highway Route Optimization

A new bilevel highway route optimization model finds highway alternatives that best improve the existing roadway system while optimizing the alternatives' alignments on the basis of geometric, cost, and operational considerations. The upper level of the bilevel structure represents a decision-making process of system designers in which possible highway alternatives are generated and evaluated. The lower level represents highway users' route choice behavior and evaluates how traffic in an existing road network is redistributed by the new highways. Various highway agency and user-related costs (such as earthwork, right-of-way, and travel time costs) are included in the model's objective function and used as key evaluation criteria. The model is tested with an example to check its capabilities and use in real-world applications. The results show that the model can optimize solutions within a reasonable computation time and that locations of the new highways are sensitive to redistributed traffic in the modified road network as well as to unit costs and other inputs. It is expected that highway planners and designers can greatly benefit from the proposed model, which offers optimized candidate alternatives identified by comprehensive bilevel optimization procedures rather than merely satisfactory alternatives obtained from the trial-and-error process of the traditional approach.

Evaluation of Toll Options with Quick-Response Analysis Tools: Case Study of the Capital Beltway

Analysis tools in current use in transportation decision-making processes are not well suited for evaluating toll highway alternatives against more traditional free highway alternatives. How existing analysis tools might be used in evaluating toll options was examined. A case study demonstrates that relatively simple analytical procedures may be used to estimate the impact of pricing alternatives and to generate information for use by local decision makers. The case study also demonstrates that pricing alternatives often can accomplish the purpose of a major highway project more efficiently and more effectively than conventional alternatives that exclude pricing, while generating revenue to support bonds for project construction or to fund improved transit and paratransit services. With toll revenue to back bonds, project delays due to constrained funding can be avoided, and the public can be provided with superior mobility earlier and at lower public cost.

Planning and design of passing lanes for the Trans-Canada Highway in Yoho National Park

This paper describes the techniques used in the planning and design of a system of passing lanes for the Trans-Canada Highway in Yoho National Park. The techniques, which include a traffic simulation model, were developed to allow the evaluation of the impact of low-cost operational improvements such as passing lanes on the level of service. The traffic simulation model allowed the investigation of a wide range of highway alternatives in addition to changes in traffic flow, traffic stream characteristics, and vehicle performance characteristics. The passing lane designs described in the paper are based on the concept of incorporating passing lanes within the existing highway cross section. The design concept has evolved from the experimental passing lane project in Banff. In addition to geometric design, signing, and road marking guidelines, warrants for bicycle lanes on the Trans-Canada Highway are also presented. Key words: highway planning and engineering, two-lane highways, traffic simulation model, level of service, passing lanes, Trans-Canada Highway.

Impact of Environmental Controls on Highways

New federal and state environmental legislation and regulations have directly affected operations of highway departments and the ability of highway agencies to plan, design, and construct new public works facilities. A brief summary of environmental regulations analyzing environmental controls is presented. An illustrative example describes an analysis for comparing highway alternatives on the basis of road user and nonuser, social, economic, and environmental factors. The impact on the decision-making process is considered from the viewpoint of the multiplicity of approvals by different governmental agencies that are required in highway location and design. Interactions between land development and transportation are examined and the need for community involvement in the early stages of the decision-making process are stressed, particularly at that point in time when land development decisions that generate new travel demands are made. A series of questions are raised that appear to require answers regarding the impact of environmental controls on the organization and management of highway agencies.