Browsing by Author "Nagui Rouphail, Committee Member"

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Determining Path Flows in Networks: Quantifying the Tradeoff between Observability and Inference
(2008-04-24) Demers, Alixandra; Billy Williams, Committee Member; William A. Wallace, Committee Member; Nagui Rouphail, Committee Member; Yahya Fathi, Committee Member; George F. List, Committee Chair
Evaluating the Use of Red Light Running Photographic Enforcement Using Collisions and Red Light Running Violations
(2005-02-15) Cunningham, Christopher Michael; Joseph E. Hummer, Committee Chair; Billy Williams, Committee Member; Nagui Rouphail, Committee Member
The issue of red light running (RLR) has long been a problem throughout the United States. There is considerable debate within the general public and public agencies regarding the use of photographic enforcement to deter red light violations. Many studies have been conducted on the effectiveness of red light cameras (RLCs) at reducing collisions. However, the question still remains as to whether RLCs actually change driver behavior. Many municipalities across the State of North Carolina have relied on studies conducted in other states or countries to validate the use of cameras within their jurisdiction. Many of these studies are weak and could be more rigorous. The need for more thorough study motivated this research effort to help define the effectiveness of RLCs within the City of Raleigh, North Carolina. Four specific tasks were identified to help in this research effort. First, a literature review was conducted to determine the reported effects of other research efforts throughout the United States and other countries. Various types of studies have been conducted around the world. Of particular interest were studies that were rigorous in nature, such as those using comparison sites. Many studies completed in previous research indicate that RLC enforcement reduces the frequency of collisions at treated intersections. However, there are a limited number of rigorous studies (especially those in the United States, particularly in North Carolina). Analyses that used comparison sites usually did not perform tests to see if comparison sites acted in a similar manner to treatment sites. Six focus groups were convened in an effort to gather information on attitudes, opinions, and beliefs associated with photographic enforcement to better enhance traffic law enforcement. Two community and four professional focus groups were assembled. Overall, the perception of photographic enforcement was positive. Suggested improvements included enhancing the appeal process, using profit for local government support such as schools or more enforcement, and placing traffic signals in flashing red and yellow at low volume intersections during early morning hours of operation. The majority of participants agreed that the presence of RLCs would make them more aware of individual driver behavior; however, most of the groups agreed that the range of driver education varied widely and that educating the public should be a priority. In an effort to analyze the effect of RLCs on driver behavior, two types of analyses were completed. The first type of analysis was a before-after collision study. The following three types of improved before-after collision studies were used: accounting for causal factors, a comparison group analysis, and an improved comparison group analysis accounting for the halo-effect. Each of these studies analyzed four categories of collisions including the following: total, red light running related, angle, and rear end. Based on the comparison group study, collisions were effectively reduced by 17%, 22%, 42% and 25%, respectively. In addition to the analysis of collisions, red light running violations were analyzed to see if there was a change in driver behavior related to dangerous violation times (violations considered to possibly cause collisions) greater than two seconds. Using the Chi-Square Test of Independence, the frequency of unsafe red light running violations reduced significantly with a p-value less than 0.001. Based on these findings, RLCs appear to have a positive effect on driver behavior. Focus groups indicate that overall there is a positive perception of RLCs as a countermeasure to deter red light running. Based on the comparison group collision study, all collision group types decreased considerably. Lastly, red light running violations related to dangerous red light violation times dramatically decreased, providing further justification for the use of RLCs as a red light running countermeasure.
Operational Effects of Signalized Superstreets in North Carolina.
(2010-05-12) Haley, Rebecca; Joseph Hummer, Committee Chair; Billy Williams, Committee Member; Nagui Rouphail, Committee Member
Safety Effects of Superstreets in North Carolina.
(2010-10-01) Ott, Sarah; Joseph Hummer, Committee Chair; Nagui Rouphail, Committee Member; Billy Williams, Committee Member
Torque Converter Interactions in a Parallel Post Transmission Hybrid Driveline.
(2010-10-27) Pritchard, Ewan Gareth David; Richard Gould, Committee Chair; Nagui Rouphail, Committee Member; Tiegang Fang, Committee Member; Richard Johnson, Committee Member
Using GIS Based Property Tax Data For Trip Generation.
(2002-12-02) Tanaka, Krista Mari; Joseph E. Hummer, Committee Member; Nagui Rouphail, Committee Member; John R. Stone, Committee Chair
This project assesses the feasibility of using statistically clustered property tax data instead of windshield survey data for input into the Internal Data Summary (IDS) trip generation model used by the North Carolina Department of Transportation. The report summarizes the clustering analysis and its data requirements. To gauge clustering resource requirements for a case study application, NCSU researchers examine the Town of Pittsboro. Comparing the traffic flow outputs of the traditional modeling techniques and those resulting from the use of the clustering method to 56 ground count stations, the research finds that clustering and tradition methods yield similar results. An 85% reduction in person-hours required to gather the input data is the main benefit resulting from the use of the clustering technique. The major drawback is that advanced statistical training is required to implement the technique.