Civil Engineering

 

First Advisor

John Sangster

Date of this Version

5-2018

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of the Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor John Sangster. Lincoln, Nebraska: May, 2018.

Copyright (c) 2018 Brandon L. Purintun

Abstract

Many rural towns and cities throughout Nebraska have experienced consistent population decline over the past 50 years, and the highway system once built to accommodate hoped-for growth is not serving the population as well as it could. These towns and cities would benefit from implementing a road diet conversion on their main highways. Within rural communities, road diets are an increasingly popular method of improving safety along major arterials through the reduction of excess capacity in favor of increasing refuge areas for turning vehicles. A typical application might be the restriping of a four-lane undivided highway into a three-lane highway comprised of two lanes of through movement and a two-way left-turn lane. Deciding when or if to implement a road diet conversion involves the consideration of many factors. The consideration of numerous factors can often lead to explanations on the feasibility of road improvement projects saturated with technical language. Since support for road improvement projects such as road diets lies in the public sector, the decision making process needs to be made easy to understand.

Public edification of the decision making process involves streamlining the process as well as reducing criteria which are technically sound yet abstract to the public. To streamline the decision making process, a case study and sensitivity analysis is conducted to determine best practices, evaluation methodology, and decision making processes. A before and after simulation analysis is performed using VISSIM, examining delay. Existing literature on road diets is used to establish broad guidelines and determine long-term effects, such as changes in crash rates. Existing literature is also used to help measure the effects of road diet improvements on roadway performance as economic benefits and costs, metrics which are more easily understood by the public. Existing volume conditions at the case study locations are found to be well-below capacity, and the facility performs equally well when modeling with and without the road diet improvements. Subsequently, sensitivity analysis is conducted to determine the impact of volume demands on the bottom line costs and benefits of a road diet conversion. This information is then used to create guidelines, with easily understood criteria, for making decisions on whether or not a road diet improvement should be implemented.

Advisor: John Sangster

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