Engineering Commons^™

Development Of A Mash Test Level 4 Open Concrete Bridge Rail, Jacob Delone

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

An open concrete bridge rail was designed and developed according to safety performance guidelines in the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). Systems designed and developed under previous guidance were studied, and their geometric information and full-scale crash testing performance was studied to establish the geometry of the new bridge rail. Yield-Line Theory and the AASHTO Post and Beam design methods were studied, and a modified version of the AASHTO Post and Beam method was utilized to determine the capacity of the new open concrete bridge rail. …

Road Diet Feasibility Analysis For Nebraska, Brandon L. Purintun

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

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 …

Broadening Understanding Of Roundabout Operation Analysis: Planning-Level Tools And Signal Application, Ahmed Buasali

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

In United States, roundabouts have recently emerged as an effective and efficient alternative to conventional signalized intersections for the control of traffic at junctions. This thesis includes two investigations related to the operations of roundabouts.

The first investigation examines the ability of a planning-level tool (the critical sum method) to serve as an indicator variable for the results of the Highway Capacity Manual’s average delay per vehicle measure for a roundabout facility; to what extent do the results of one predict the results of the other? The critical sum method was found to accurately predict the HCM average delay per …