No description available.

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.

We introduce a perturbative method for studying photoinduced electronic transitions through conical intersections. Our approach uses a quadratic vibronic coupling Hamiltonian and second order cumulant approximation for the diabatic coupling to derive an analytical expression for time evolution of electronic populations at given temperatures. The formalism is an extension of a previous method called the non-equilibrium Fermi golden rule approach which used the linear vibronic coupling Hamiltonian with the same cumulant treatment for diabatic coupling. The advantage of the quadratic Hamiltonian is that it can include electronic states with different frequencies and normal modes. We explore these advantages with 2D models showing the improved accuracy of the new quadratic method over the linear method. We then apply our formalism to some real molecules, 2,6-bis(methylene) adamantyl cation, and its dimethyl derivative, with parameters obtained from electronic structure calculations followed by diabatization. The results show good agreement with quantum dynamics techniques.

We introduce a perturbative method for studying photoinduced electronic transitions through conical intersections. Our approach uses a quadratic vibronic coupling Hamiltonian and second order cumulant approximation for the diabatic coupling to derive an analytical expression for time evolution of electronic populations at given temperatures. The formalism is an extension of a previous method called the non-equilibrium Fermi golden rule approach which used the linear vibronic coupling Hamiltonian with the same cumulant treatment for diabatic coupling. The advantage of the quadratic Hamiltonian is that it can include electronic states with different frequencies and normal modes. We explore these advantages with 2D models showing the improved accuracy of the new quadratic method over the linear method. We then apply our formalism to some real molecules, 2,6-bis(methylene) adamantyl cation, and its dimethyl derivative, with parameters obtained from electronic structure calculations followed by diabatization. The results show good agreement with quantum dynamics techniques.

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Meyer, Michael; Committee Member: Amekudzi, Adjo; Committee Member: Garrow, Laurie

This thesis is an intersection. This thesis is at an intersection. This thesis is about an intersection. / Master of Architecture

The aim of this research is to determine the effect of unsignalised intersection geometry on the rates of the various types of accidents occurring at unsignalised intersections. A literature review has identified that there is little consistency between the results of previous studies. Some studies found that particular parameters had an opposite effect to what was expected. With this in mind, the research identified reasons for these results and developed two basic approaches to mitigate some of the problems with multi-factor type studies. These approaches are 'maximise the efficiency of data collection' and 'develop techniques for analysing less than perfect data'. A database consisting of 206 unsignalised intersection sites from throughout Queensland was used for analysis. The outcome of this research confirms the validity of several of the current design standards for unsignalised intersections, in addition to identifying new engineering procedures.

published_or_final_version / Urban Planning and Design / Master / Master of Science in Urban Planning

No description available.