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Sacramento, CA, United States

Fang F.,University of Hartford | Elefteriadou L.,University of Florida | Elias A.,Dowling Associates Inc.
Transportation Research Record | Year: 2012

Interchange ramp terminals provide connections between various highway facilities (freeway-arterial, arterial-arterial, freeway-freeway, etc.), so their efficient operation is essential. NCHRP Project 3-60 developed analysis methods for evaluating the operational performance of signalized interchange ramp terminals. Those methods were based primarily on simulated data. Further research used collected field data to evaluate the interchange analysis methodology developed under NCHRP Project 3-60 to identify application limitations and to suggest improvements. Data were collected at eight sites representing various types of interchanges with different geometric and traffic characteristics. Video cameras, mounted on existing poles on the side of the road and on nearby buildings, were used to gather traffic operation data, including demand, lane utilization, and queue length at each site. The research evaluated both individual analytic model components (such as lane utilization factors and internal queue length) and the performance of the interchange (reflected in average queue lengths and control delay). Overall, the models performed well. However, large discrepancies were observed when operating conditions of the interchange were close to capacity. The queue length prediction at the beginning of the upstream arterial or ramp phase was calibrated to modify the effective green time estimation. A new lane utilization model was based on field data for a four-or five-lane external arterial approach where the two leftmost lanes were extensions of the downstream dual left turn lanes. The findings of the work were incorporated into the 2010 Highway Capacity Manual. Source


Khasnabis S.,Wayne State University | Mishra S.,University of Maryland University College | Safi C.,Dowling Associates Inc.
Journal of Transportation Engineering | Year: 2012

The purpose of evaluating mutually exclusive alternatives is to select the one with the most benefits for implementation. A number of analytic techniques are available for such evaluation purposes. This paper discusses four such techniques: cost effectiveness C/E, benefitto- cost ratio B/C, internal rate of return (IRR), and payoff period (PP), including their theoretical foundation and data requirements. Also discussed are the measures of effectiveness (MOEs) associated with each of these techniques and how they are to be interpreted. Alternatives to be selected for implementation following such evaluation can typically be funded under different policy objectives. This paper identifies three such objectives: Objective A, constrained resource perspective; Objective B, investment perspective; and Objective C, face-value perspective. The possible relationship between the alternative selection and the program is discussed in the paper. A case study for a set of six mutually exclusive highway safety alternatives is presented using the four analytic techniques and three objectives, resulting in various possible solutions. Results show that under compatible assumptions, and for a given policy objective, the outcome of the evaluation is not affected by the choice of the analytic technique. However, for a given analytic technique, the outcome may be affected by the choice of the policy objective chosen. The principles presented are relevant for most public projects (e.g., transit, airports) involving the investment of taxpayer resources, even though the case study involves a highway safety project. © 2012 American Society of Civil Engineers. Source


Dissanayake S.,Kansas State University | Parikh A.,Dowling Associates Inc.
Advances in Transportation Studies | Year: 2011

Increasing seat belt usage among motor vehicle occupants is considered one of the most effective ways of reducing negative effects of motorization in terms of fatalities. Even though the effectiveness of seat belts is widely known and accepted, seat belt usage remains relatively low in the United States. In addition to types of seat belt laws and associated enforcement practices, there seem to be many human factors related to nonuse of seat belts. Therefore, this study conducted road-user surveys with the intention of identifying human factor-related issues that are playing a role in relation to seat belt use. Perceptions, attitudes, understandings, stated compliance levels, potential motivators, etc. of road users were obtained through the survey in order to suggest more effective countermeasures to improve seat belt use. Based on identified critical areas, more focused education and training programs need to be developed. In addition, enforcement levels need to be increased, specifically in areas where the most benefit in terms of seat belt usage could be achieved. It was however, interesting to observe that even drivers themselves agree that stricter laws, higher fines, and other penalties are helpful in increasing the self-discipline needed to wear seat belts more frequently. Source


Khasnabis S.,Wayne State University | Dhingra S.L.,Indian Institute of Technology Bombay | Mishra S.,Wayne State University | Safi C.,Dowling Associates Inc.
Journal of Urban Planning and Development | Year: 2010

In this paper, the writers examine different investment mechanisms for transportation infrastructure projects involving the private enterprise in developing countries. Roles identified vary from those of a financier to an operator for successful public-private ventures. A case study involving such a joint venture in India, the Mumbai-Pune Expressway/National Highway 4 is presented, and fiscal implications of the program, both from the perspective of the public and the private enterprise, are examined. The study concludes that if properly planned, joint ventures can be mutually beneficial. A joint public-private program may enable the public agency to use the resources saved for other public projects. It also provides the private agency an opportunity to invest funds in a profitable enterprise that yields social benefits, (e.g., improving mobility, promoting economic development, etc.). Careful analysis must be conducted before the project is undertaken to assess the financial and economic implications of the project from each participant's viewpoint, with due regard to risks and uncertainties associated with such long-term investments. © 2010 ASCE. Source


Elias A.,Dowling Associates Inc.
Transportation Research Record | Year: 2011

In recent years, the transportation profession has started shifting away from considering only the automobile mode of travel when designing urban streets. The new emphasis is on designs that accommodate all users and make what was once an automobile-oriented street into a complete street. Recognizing this growing trend, NCHRP funded a project to develop a multimodal level of service (LOS) methodology for inclusion in the Highway Capacity Manual (HCM). This new chapter in the HCM will make it possible to easily compare various designs to determine the one that provides the greatest LOS to all users. But what exactly are the most important criteria for designing a complete street? This research seeks to answer part of this question by exploring various cross-section layouts and how they affect the LOS scores of two of the four modes (bicycle and pedestrian) in the new methodology. Four right-of-way (ROW) widths were selected to provide a broad spectrum of possible ROWs from a small collector to a large arterial. Within each of these four widths, an automobile-oriented design is compared with a complete street design. The relationship between each of the bicycle and pedestrian LOS scores is then explored, along with the impact the complete street design has on the automobile throughput. Source

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