Intersections are the most complex locations in a traffic system and are likely to have a higher crash count than any other location in the system. Intersection safety is related to traffic operations, such as traffic signal and approaching volume. The objective of this study is to determine the contributing factor for left-turn crashes at signalized intersections by a statistical modeling process and to develop crash prediction models. Potential contributing factors representing the characteristic of a left-turn operation were identified and considered for inclusion in crash prediction models. HCS (Highway Capacity Software) 2000 was utilized for computing some traffic indicators such as volume to capacity ratio for potential inclusion in the models. Three years of crash data were collected in the College Station area. The Signal timing and Volume data were obtained from public works in College Station. The volume data was sorted into three time periods and signal timing data were obtained for three different time periods: AM, noon, and PM. The division of time periods results from timing plans being changed for different periods. Relationship between crash count and each factor was explored to identify whether the factor has the potential to influence the crash count. Afterwards, the prediction models were developed using the negative binomial structure because of many zero samples. Akaike Information Criteria was used for selecting the model having the best fit. Wald tables provided that variables have significance in affecting the left-turn crash count. Left-turn type, sequence, volume, control delay, and post speed limit were identified as significant factors impacting left-turn crash count at a signalized intersection.

Intersections are the most complex locations in a traffic system and are likely to have a higher crash count than any other location in the system. Intersection safety is related to traffic operations, such as traffic signal and approaching volume. The objective of this study is to determine the contributing factor for left-turn crashes at signalized intersections by a statistical modeling process and to develop crash prediction models. Potential contributing factors representing the characteristic of a left-turn operation were identified and considered for inclusion in crash prediction models. HCS (Highway Capacity Software) 2000 was utilized for computing some traffic indicators such as volume to capacity ratio for potential inclusion in the models. Three years of crash data were collected in the College Station area. The Signal timing and Volume data were obtained from public works in College Station. The volume data was sorted into three time periods and signal timing data were obtained for three different time periods: AM, noon, and PM. The division of time periods results from timing plans being changed for different periods. Relationship between crash count and each factor was explored to identify whether the factor has the potential to influence the crash count. Afterwards, the prediction models were developed using the negative binomial structure because of many zero samples. Akaike Information Criteria was used for selecting the model having the best fit. Wald tables provided that variables have significance in affecting the left-turn crash count. Left-turn type, sequence, volume, control delay, and post speed limit were identified as significant factors impacting left-turn crash count at a signalized intersection.

Thesis (MTransportSysEngineering)--University of South Australia, 2006.

Thesis (MTransportSysEngineering)--University of South Australia, 2006.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 211-220).

Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 117-127).

Thesis (M.S.)--University of Central Florida, 2009. / Adviser: Mohamed Abdel-Aty. Includes bibliographical references (p. 325-331).

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 53-55). Also available on the World Wide Web.

Thesis (MScEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Capacity waste happens when right-turn vehicles have right-of-way during a separate right-turn phase and lanes (e.g., through lanes) of the same approach of the intersection cannot discharge vehicles during that green phase. Right-turn traffic consumes the capacity which otherwise could be provided to through traffic movements at an at-grade signalized intersection. Therefore, it is widely considered that it would lower intersection capacity and increase total delay (Lin, Machemehl, Lee & Herman, 1984). The pre-signal strategy proposed in this research is specifically designed to improve this problem. The following aspects of this strategy were studied in this research, - Capacity benefits of this strategy, - Relationships between the capacity and the length of sorting area (the area between the two signals), - Signal timing of both main signal and pre-signal, - Clearance time of the sorting area, - Main signal phasing options - Signal coordination between the main signal and the pre-signal, - Utilization of the sorting area, and - Pre-signal strategy performance in a simulated environment. The results of this study showed that right-turn movement benefits significantly from this pre-signal strategy. For example, right-turn capacity can be doubled if a presignal is installed on one through lane of an approach with one right-turn lane. It was also found, the maximum approach capacity benefit is not affected significantly by the length of the sorting area for a given green period. The optimal green time and the available pre-signal green time for right-turn movement were also derived in this research. Different main signal phasing options were studied and compared. Phasing options which fit the proposed pre-signal strategy were found. Recommended values for right-turn green time of both signals were given based on different lengths of sorting area. The case study, which compared the performance of some critical movements at the intersection with and without the proposed pre-signal system, confirms the results concluded in this study. A potential problem with this strategy when applied at a real intersection is that it may confuse drivers. Drivers need to be educated and will need time to get familiar with this signal control method. / AFRIKAANSE OPSOMMING: Beskermde regsdraaifases vir verkeer by gelykvlak seinbeheerde kruisings gebruik die kapasiteit wat benut kon word deur deurbewegings. Dit verlaag interseksie kapasiteit en totale oponthoud verhoog. Die voorseinstrategie wat in die navorsing studie voorgestel word is spesifiek ontwikkel om die probleem op te los of te verminder. Die volgende aspekte van die strategie is ondersoek in die navorsingsstudie: - Kapasiteitsvoordele van die strategie. - Die verhouding tussen die kapasiteit en die lengte van die sorteringsarea (die area tussen die twee seine). - Seintydstoedeling van beide die hoofseinfase en die voorseinfase. - Ontruimingstyd van die stoorarea. - Hoofseinfaseopsies. - Seinkoordenasie tussen die hoofsein en die voorsein. - Benutting van die sorterings area, en - Voorseinstrategieprestasie in ‘n gesimuleerde omgewing. Die resultate bewys dat die regsdraaibeweging grootliks bevoordeel word nadat die voorseinstrategie ingestel is. Byvoorbeeld, regsdraaikapasiteit kan verdubbel word as ‘n voorseinfase ingestel word op een van die deurlane tesame met ‘n enkele regsdraailaan. Daar is ook gevind dat die kapasiteit nie grootliks beinvloed word deur die lengte van die stoorgebied nie. Die optimale groentyd en die beskikbare voorsein groen tyd vir die regsdraaibeweging is ook afgelei in die navorsing. Verskillende hoofseinfaseopsies is bestudeer en vergelyk. Faseringsopsies vir die voorgestelde voorseinstrategie is gevind. Voorgestelde waardes vir regsdraaigroentyd van voorseine en hoofseine is bereken om kapasiteit te verbeter, gebasseer op verskillende lengtes van die stoorarea. Die gevallestudie wat die prestasie op ‘n aanloop met en sonder die voogestelde voorseinstrategie vergelyk, bewys resultate wat ooreenstem met die bevindinge in die studie. Die verwagte probleem met die voorseinstrategie, wanneer dit ingestel word by ‘n werklike interseksie, is verwarring van die bestuurders. Bestuurders sal opgevoed moet word en sal tyd nodig hê om gewoond te raak aan die voorseinmetode.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 211-220). / Also available by subscription via World Wide Web / xviii, 220 leaves, bound ill. 29 cm