Using Geographic Information System in Analyzing Hospital Accessibility : A Case Study in New Orleans

This paper examines the use of Geographic Information System (GIS) methods to analyze the special accessibility to primary healthcare /hospitals in New Orleans. Census data at the census track level were used to define the population distribution (demand) and the related socioeconomic attributes, as well as the hospital distribution (supply) at the zip code level. The first part of the paper examined potential population in the catchment area using simple GIS overlay analysis based on circular buffers around each hospital by creating concentric rings of 1000, 1500 and 2000 meters around the hospitals. Different scores ranging from 1 to 4 were assigned to each concentric ring with 4 being the highest/closest score and 1 being the lowest/furthest one. The second part of the paper examined the possible inequality among different ethnic minorities and income subgroups using Spatial Cluster Analysis (SCA) tools in GIS. Basic statistics were summarized for the entire population (White and three major ethnic minorities (Black, Asian and Hispanic)) with various accessibility scores. Generally, it was found that that hospital accessibility is very poor in New Orleans for the entire population with a weighted average access score of 1.81

Methodological Notes on the Regional Level Validation of a Microscopic Traffic Simulation Model

Traffic simulation models have been increasingly used to evaluate and compare alternative complex real-world traffic problems. Simulation is safer, less expensive and faster than field testing. The past few years have witnessed substantial development of transportation network modeling tools and stronger emphasis on addressing the need to model large-scale networks more accurately and efficiently. While these simulation models can be helpful to transportation engineers, the models must be well calibrated and validated before they can provide credible results. However, simulation models have been often conducted under default parameters. This is mainly due to either the difficulties in field data collection or the lack of knowledge of the appropriate procedure to calibrate and validate traffic simulation models. This paper presents the results of a recent effort to microscopically simulate the regional evacuation plan for New Orleans Metropolitan Area during the hurricane Katrina. The model involved over 300,000 vehicles moving within a road network that covered several thousand square miles over a 48 hour period. Output statistics were generated on a second-by-second basis for each traveler in the system. Model validation was based upon a comparison of the TRANSIMS generated traffic volumes to the corresponding traffic volumes actually observed during the 2005 hurricane Katrina evacuation. The validation process included the percent error estimation and the regression analysis between the simulated and observed traffic volume data. This study was unique in that it is among the first to develop validation criteria for a regional model based on actual traffic data collected during a live regional mass evacuation. Analysis was performed utilizing percent errors estimation based on direct comparisons of the hourly volumes at each counting station. Also, an alternative validation approach was carried out using regression analysis between the cumulative observed and simulated volumes for the same stations by analyzing the fit for the regression line y =a + bx + ε. The error percentage and the fit were found to be reasonable with an error percentage less than 25 percent and an R-squared value of over 0.80. This indicated that the TRANSIMS simulation model was a realistic representation of the evacuation operations observed during the hurricane Katrina

Transit-based emergency evacuation modeling with microscopic simulation

Several recent mass evacuations, including those in advance of Hurricane Katrina in New Orleans and Hurricane Rita in Houston, have demonstrated the effects of limited planning for carless populations. The lack of planning left a significant portion of the mobility-limited population of both these cities unable to flee in advance of the storms. Since 2005 however, both of these cities (as well as others across the United States) have developed transit assisted mass evacuation plans at various levels of detail. Since these plans are relatively recent and do not have a history of experience on which to base their performance, it is difficult to know how well, or even if, they will work. This research describes one of the first attempts to systematically model and simulate transit-based evacuation strategies. In it, the development of and the results gained from an application of the TRANSIMS agent-based transportation simulation system to model assisted evacuation plans of New Orleans are described. In the research, a range of varying conditions were evaluated over a two-day evacuation period, including two alternative evacuation transit routing scenarios and four alternative network loading and demand generation scenarios resulting in eight evacuation scenarios. In the research, average travel time and total evacuation time were used to compare the results of a range of conditions over a two-day evacuation period, including two alternative transit evacuation routing plans and four alternative network loading scenarios. Among the general findings of the research was that the most effective scenarios of transit-based evacuation were those that were carried out during time periods during which the auto-based evacuation was in its “lull” (non-peak/overnight) periods. These conditions resulted in up to a 24 percent reduction in overall travel time and up to 56 percent reduction in the total evacuation time when compared to peak evacuation conditions. It was also found that routing buses to alternate arterial routes reduced the overall travel time by up to 56 percent and the total evacuation time by up to 22 percent. The impact of including transit evacuation on the network traffic operation was also tested using average evacuation speed and queue length, it was found that the transit evacuation had no impact on arterial traffic operation but it increased the average queue length on the interstate evacuation route. An evaluation of the transit-based evacuation plan was also completed. It was found that at least 68 percent of the transit dependent evacuees spent half an hour or less not on transit (walking towards the bus stop and/or waiting at the bus stop) and only 0.19 percent of them spent more than an hour not on transit in their evacuation trip. Finally, the number of buses needed for the carless evacuation under each evacuation scenario was estimated. A total of 56, 42, 61, and 43 local buses, for transporting people from the pickup locations to the processing centers, were required for network loading scenarios A, B, C, and D respectively. Also, 601 RTA buses, for transporting people from the processing centers to shelters, were needed

Evaluation of the Operational Performance of Continuous Green T-Intersection under Different Levels of Congestion

The main objective of this paper is to evaluate and compare the operational efficiency of a conventional signalized T-intersection with an unconventional Continues Green T-intersection under different congestion levels. The analysis was performed using Synchro.8 micro-simulation software. A total of 48 hypothetical scenarios, 24 scenarios for each design, were created by changing the approach volumes and turning percentages on the major / minor intersecting roadways to reflect different levels of congestion that may occur on any urban intersection. Total intersection delay, Level of Service, maximum queue length and volume-to-capacity ratio (v/c) were the measures of effectiveness used for comparison purposes. These performance measures were selected because they demonstrated the overall efficiency of the intersection design. The simulation results showed that the Continuous Green T-intersection operates the best under stable traffic conditions and that it is not an effective solution for signalized T-intersections under heavy traffic volume

Unconventional Intersection Designs for Improving Traffic Operation Along Arterial Roads

The main objective of this paper is to evaluate the effect of implementing four Unconventional Arterial Intersection Designs (UAIDs) including median U-Turn, Superstreet, Jughandle and Single Quadrant Intersection on a major arterial road using SYNCHRO microscopic simulation software. For this purpose, Wadi Saqra Signalized Intersection on Shaker Bin Zaid major arterial road in Amman, Jordan was selected. The simulation results showed that only the Jughandle improved the intersection Level of Service (LOS) slightly, F–E. Nevertheless, the intersection delay was significantly reduced by 64.81%, 76.6%, 91.28% and 75.60% on the proposed Median U-Turn, Superstreet, Jughandle and Single Quadrant unconventional intersection design, respectively. This indicated that these UAIDs don't perform well under heavy traffic volumes. Also, since the Jughandle was the only UAID which improved the LOS on the main intersection, the operational performance of Prince Shaker Bin Zaid arterial after implementing the Jughandle at the main intersection was evaluated including the main intersection: Wadi Saqra intersection, one prior to the main intersection and one after the main intersection. It was found that the use of the Jughandle increased the average travel speed by 35% and decreased the average stopped delay by 28.68% on the arterial road. Also, this paper evaluated the current transportation system and road user's attitude towards UAIDs' implementation through a questionnaire survey. The results indicated high acceptance of UAIDs. Finally, the construction cost for each UAID type was estimated. It was found that the Jughandle had the highest construction cost due to its high acquisition cost

An In-depth Statistical Analysis of Driver Speeding Attitudes and Behavior

Speeding, which encompasses driving above the speed limits, is an aggravating factor in the severity of crashes. It has also serious consequences on the environment and energy consumption.This paper aims to thoroughly investigate the speeding behavior of Jordanian drivers through a comprehensive statistical analysis of driver speeding attitudes and behavior reaching to the most effective interventions and strategies that would mitigate this phenomenon.Data were collected through distributing a pre-designed questionnaire and receiving a total of 1,049 responses. The Public Security Directorate (PSD) provided the speed-related data.The collected data were subjected to rigorous statistical analysis including factor analysis, bivariate Pearson's correlation test, bivariate analysis, and multivariate logistic regression analysis.Based on the outcome of the study, potential measures for reducing speeding that would be both effective and personally acceptable in Jordan are recommended. The dominant measures were mainly law enforcement actions since it is believed that financial disincentives are most effective

Evaluation of Automated Enforcement Program in Amman

This study aims, in a first attempt, to evaluate the effectiveness of using the Automated Enforcement Program (AEP) to improve traffic safety in Amman, Jordan. The evaluation of the program on crashes and violations was examined based on a “before-and-after” study using the paired t-test at 95 percent confidence level. Twenty one locations including signalized intersections monitored by red light cameras and arterial roads monitored by excessive speed cameras were selected. Nine locations were used to study the effectiveness of the program on violations, and twelve locations were used to determine the effectiveness of the program on frequency and severity of crashes. Data on number and severity of crashes were taken from Jordan Traffic Institution. Among the general findings, it was found that the AEP was generally associated with positive impact on crashes. Crash frequency was significantly reduced by up to 63%. Crash severities were reduced by up to 62.5%. Also, traffic violations were significantly reduced by up to 66%.  Finally, drivers’ opinion and attitude on the program was also analyzed using a questionnaire survey. The questionnaire survey revealed that 35.5% of drivers are unaware of AEP in Amman, 63.9% of drivers don’t know the camera locations, most drivers knew about excessive speed and red light running penalties, most drivers reduce their speed at camera locations, 44.4% of drivers think that the program satisfies its objective in improving traffic safety and 52% of drivers encourage increasing the number of camera devices in Amman

The Possibility for Implementing the Superstreet Unconventional Intersection Design in Jordan

This paper provides policy makers with an objective assessment on the possibility for implementing an unconventional arterial intersection design, the Superstreet, for improving safety and operational characteristics for an existing signalized intersection. The signalized intersection selected for analysis was Tabarbour, located in Amman, Jordan. Tabarbour intersection is considered one of the most significant signalized intersections in Amman. The intersection currently suffers from the following problems: long queues, delays and excessive emissions. SYNCHRO microscopic simulation software was used for signal optimization of the current conventional intersection. VISSIM microscopic simulation software was used to analyze and compare the Superstreet design to the conventional design. It was found that the proposed Superstreet reduced the average delay per vehicle by up to 87% and reduced the maximum queue length by almost 97%. This resulted in improving the level of service from F to C. Finally, five year future traffic demand analysis was performed; it was found that the Superstreet design didn’t perform as expected under heavy traffic volume

Identifying Optimum Taper Lengths for Zipper Merging Applications using Real Data and Microscopic Simulation

Motorists lack of understanding on the proper way to maneuver through lane closures during congested periods cause driver confusion. This confusion directly and indirectly creates inconsistent flow patterns, forced merges, travel time delays, and crashes. Engineers and developers have tried to improve the merge systems used in construction zones to reduce driver frustration, improve travel time, and increase safety. Encouraging drivers to use the zipper merge approach has been assumed by some to target these issues. When implemented, drivers jointly merge together in an alternating fashion at two-to-one lane closures/reductions. There is a difference in opinion between traffic officials concerning the taper length required to efficiently accommodate these types of merging patterns – particularly those that occur near construction sites. Current practice uses the taper design guideline presented in the MUTCD. However, some believe this unique approach to merging at lane reductions should be accompanied by a shorter/longer taper. This study simulated 192 scenarios consisting of eight different percent truck compositions, six different transition lengths, and four different traffic volumes in VISSIM. The simulation models were calibrated with field data taken while a zipper merge configuration was in operation on a freeway. The main objective was to identify the optimum transition length when placing a zipper merge configuration because it visually and physically promoted alternating merging maneuvers. The results indicated none of the six tested taper lengths had a clear advantage over the other under multiple traffic volumes and truck percentages. Although statistically equal, operational differences in response to taper lengths were present and became more pronounced as volumes and truck percentages increased