S S Nambisan

Methodology for Evaluating the Safety of Midblock Pedestrian Crossings

Spatial and temporal characteristics of midblock pedestrian crashes (MBPCs) were evaluated toward a better understanding of where and when the MBPCs occur. Existing databases related to traffic crashes were used. Other data used include traffic and geometric characteristics of the roadways under consideration as well as analyses of pedestrian and driver behaviors. General statistical analysis methods were used to evaluate various hypotheses. The statistical Z-test was used to evaluate the age and gender distribution, light condition, fatalities, and alcohol- or drug-use–related characteristics involved in MBPCs. The results correlated these factors with the potential for the occurrence of MBPCs. The Wilcoxon Signed Rank test was used as a nonparametric test to compare the safety of midblock crossings with the safety of crossings at intersections. The methodology was tested and validated using midblock locations in the Las Vegas metropolitan area. The results indicate that there is a significantly lower potential for conflict if pedestrians cross at an intersection instead of crossing at a midblock location. Although this methodology was applied to data from the Las Vegas metropolitan area, it is applicable to evaluating the safety of MBPC anywhere else, provided that appropriate data are available.

Estimating Pedestrian Counts in Urban Areas for Transportation Planning and Safety Analyses

This paper investigates factors that can be used to quantify pedestrian counts in urban areas. The best subset regression is used to develop models to estimate pedestrian counts considering variables identified using general linear regression. The F-test is used to support the analysis. The models are developed using data collected at 15 selected locations with high pedestrian activity in the Las Vegas Metropolitan area. The findings show that the pedestrian counts are a function of the number of lanes, average annual household income and residential area proximity to the study location. Results show that the pedestrian counts are independent of the commercial area and the number of bus stops in the vicinity of the location. The developed models can be used to estimate pedestrian counts at any high pedestrian activity location provided the socioeconomic the demographic characteristics are known. The methodology is also applicable to other urban settings.

A DECISION-SUPPORT TOOL FOR AIRLINE YIELD MANAGEMENT USING GENETIC ALGORITHMS

Airline yield management has gained widespread acceptance in recent years. Yield management is used to estimate the number of passengers belonging to each fare class in order to maximize revenue-to increase profits. Forecasts of future booking for different classes and the fare for each class are assumed fixed and known. The complexity of the problem increases as additional attributes such as the effect of continued flights on pricing, ticket cancellations, and overbooking are considered. In addition, demand varies with time. Hence, to make the problem realistic, the dynamic nature of demand has to be accounted for in the model. The focus of this article is to develop a decision-support tool to estimate the number of seats allocated to each fare class in the yield management problem. This problem is formulated as a linear integer programming model. Genetic algorithms (GAs) are used as a solution technique. The model is coded using C programming language. The decision-support tool considers the effect of time-dependent demand, ticket cancellations, and overbooking policy. The results are consistent with expectations.

EVALUATING TRANSIT MARKET POTENTIAL AND SELECTING LOCATIONS OF TRANSIT SERVICE FACILITIES USING GIS

Accessibility to transit service facility (TSF) locations plays a significant role in the success of public transportation systems. The ease with which the end-user can reach a TSF (e.g., bus stops, rail stations, or multimodal centers) plays prominently in the decision making process of the individual. This paper presents a working definition for transit market potential based on accessibility in terms of walking distance and walking time. Further, a measure is constructed to evaluate transit market potential for TSF locations for a transit system. The measure of transit potential is represented by an index value based on demographic criteria such as employment, household size, vehicle ownership, etc. This index can be used to identify locations of TSFs that increase a routes potential for ridership. A methodology is proposed to estimate the Index of Transit Potential (ITP) for TSFs. This methodology involves identifying the accessible network of streets around each TSF that is within an acceptable access threshold for a transit rider, and estimating the transit market potential based on key demographic characteristics. The analytical and visualization capabilities of a Geographic Information Systems (GIS) program are utilizes to help attain the objective. A case study is used to demonstrate the application of the methodology.

Identification and Ranking of High Pedestrian Crash Zones Using GIS

The continued improvement and application of Intelligent Transportation System (ITS) data collection technologies has generated higher requirements on the hardware and software capabilities to store, transmit and process the data. A cost -effective approach to enhancing such required capabilities is to use an ITS data compression technique. T he purpose of an ITS data compression technique is to effectively compress and reconstruct the ITS data for being easily archived and transmitted. Nowadays, the signal-processing techniques have been widely used for the general data compression purposes. T hese techniques have a great application potential to the ITS data. This paper is intended to develop a new ITS data compression and reconstruction approach based on Wavelet Transform, Discrete Cosine Transform (DCT), Quantizing and Coding techniques in the signal-processing field, by designing the appropriate feature-distilling threshold and quantizer. The objective of the compression is to minimize the data redundancy, keep the maximum amount of useful information, limit the level of distortion and improv e the data quality and application efficiency. To illustrate the effectiveness of the proposed model, the traffic flow data from the Beijings 3 rd Ring Expressway are used for the case study. By comparing the reconstructed data with the original raw ITS da ta, it is demonstrated that the application of the proposed technique has increased the compression rate by 61.92 percent in comparison with the widely used WinZip software. On the other hand, only 5.35 percent of the data has shown a larger -than-five-percent error between the reconstructed and the original raw data. Therefore, the proposed approach has achieved a much higher compression rate with very limited level of distortion. The application of the proposed technique would contribute to the reduction o f the required storage space as well as the improvement of the transmission speed for the ITS data.

IDENTIFICATION OF HIGH PEDESTRIAN CRASH SITES AND SELECTION OF COUNTERMEASURES FOR THE LAS VEGAS METROPOLITAN AREA

This paper presents a model and evaluation of the effectiveness of safety improvement projects funded under the Hazard Elimination Program (HEP) and the Highway-Rail Grade Crossings Program (HRGCP) at the national level based on the crash, cost and traffic data of projects implemented from 1995 to 2000, which were obtained from the states. Major findings from the study include: (1) At the national level, projects implemented under the HEP showed a 28.6 percent reduction in the number of crashes, a 61.6 percent reduction in fatal crashes, and a 17.1 percent reduction in injury crashes; (2) Projects implemented under the HRGCP resulted in a 21.4 percent reduction in the number of crashes, a 100 percent reduction in fatal crashes, and a 31.3 percent reduction in injury crashes; (3) The benefit-cost ratio was 11.3 for projects implemented under the HEP, and 8.5 for projects implemented under the HRGCP; and (4) Of the various improvement types, the implementation of illumination projects showed the highest benefit-cost ratio.This paper presents a Geographic Information System (GIS) based methodology to identify high pedestrian crash sites ad then select safety countermeasures based on casual factors. The methodology to select high crash sites includes identifying the problem area, the high risk zones and then the high crash sites. Two types of crash indices were used to rank high risk zones. They are based on the number of pedestrian crashes in the vicinity of the zone by severity and length of the zone. Results obtained by applying the methodology in the Las Vegas metropolitan area are discussed in this paper.

Development of Spatial Data Tools to Manage Transportation Networks

This paper presents a summary of a process used to develop a spatial data system to help manage transportation networks. Issues related to the system architecture, and identification and integration of software and hardware elements are addressed. Commercial off-the-shelf software and hardware, along with customized interfaces are use to develop the system. Hardware considered includes portable digital assistants, Table PC, and laptop. Key aspects that were considered in selecting the hardware include the ease with which they can be used in the field, their durability, effectiveness, and portability. Compatibility and ability to integrate with other application software were also critical considerations. The software is selected based on the ease with which they can be used and integrated with web authoring software, thus enhancing collection, processing, and dissemination of data. In addition, the compatibility of the software with various data formats (i.e., prior versions of databases), and the potential for such compatibility to continue into the future is also important. Software considered and tested includes Autodesk MapGuide, ESRI, ArcIMS, ESRI, ArcPad, and Terrasync software. Using selected hardware and software, a pilot project is used to demonstrate the use of the system to assimilate, manage, process, and communicate transportation infrastructure related data.

FIELD DATA COLLECTION AND ANALYSES TO SUPPORT THE SELECTION OF PEDESTRIAN SAFETY COUNTERMEASURES IN LAS VEGAS

Crash reduction factors (CRFs) are used in highway safety studies to estimate how far a countermeasure may potentially reduce the number of crashes on a given roadway location. As with most states in the United States, Florida developed its CRFs based on the before-and-after approach, which requires the use of crash records and implemented safety improvement projects. The Florida Department of Transportation (FDOT) did not have a central database for safety improvement projects. Consequently, historical data for improvement projects were maintained separately at various district offices in various formats and were not easily accessible for the purpose of statewide CFR development. This paper describes an effort by FDOT to develop a user-friendly database system for the systematic maintenance of a new standard set of safety improvement projects and for continued update of CRFs as new data become available. Currently, no similar system is known to exist. It may serve as a prototype by states planning to develop a similar system that it tailored to their improvement projects and crash records.

Estimating Time-Dependent Origin-Destination Trip Tables with Trips Originating in Multiple Time Slices

Intelligent transportation system initiatives, such as travel information systems and travel demand management systems, have been used to ameliorate problems with congestion due to increasing travel demand. The success of these initiatives depends on the ability to accurately estimate the temporal variations in travel demand. A modeling framework based on arrival patterns of trips at workplaces and travel times in urban areas is presented. The peak period is divided into short, discrete intervals of time called time slices. Origin-destination trip tables for each time slice are estimated on the basis of when a trip with a certain travel time must have started to arrive at the destination in a specified time slice. There are two possibilities for the time slice in which a trip might have originated: (a) starting in time slice k - 1 and ending in time slice m and (b) starting in time slice k and ending in time slice m (m ≥ k). A model is presented to estimate the probability that the trip might have originated in time slice k - 1 and time slice k. On the basis of these probabilities, the performance of the model is tested using data for the Las Vegas metropolitan area.

Prototype Internet Applications for Transportation System Management

Technologies for integrating, communicating, analyzing, and displaying spatial information interactively have been evolving in recent years. Although dissemination and analysis of information over the Internet are efficient and time effective in reaching a multitude of users, it is still difficult to perform these operations with transportation data in a graphical format using the Internet. The development of a prototype system for this purpose is described in this paper. The system specifications include the need for versatility in utilizing several forms of data such as spreadsheets, AutoCAD drawings, as well as coverage produced from various geographic information system (GIS) programs (e.g., ARC/INFO). These specifications were designed to ensure maximum utilization of existing data and to facilitate data sharing within and among various organizations. The prototype system is demonstrated using a case study of projects from the Clark County Department of Public Works in Nevada. The system was developed using an off-the-shelf suite of software programs (MapGuide). Using this software greatly reduced startup costs, time, and configuration management tasks and did not compromise the desired functionality. Through its web site, the system facilitates communications between elected officials, public works agency staff, management, stakeholders, and constituents using the Internet or intranets. Various applications were designed and developed to support project management, resource allocation, and internal or external communications as well as information storage, retrieval, analysis, and display and office automation. Because of the promise shown by the prototype system, a variety of transportation and public-sector agencies have expressed an interest in its full-scale deployment to address their emergent needs.