Estimation of travel time on urban networks with midlink sources and sinks

This paper presents a methodology for estimation of average travel time on signalized urban networks by integrating cumulative plots and probe data. This integration aims to reduce the relative deviations in the cumulative plots due to midlink sources and sinks. During undersaturated traffic conditions, the concept of a virtual probe is introduced, and therefore, accurate travel time can be obtained when a real probe is unavailable. For oversaturated traffic conditions, only one probe per travel time estimation interval—360 s or 3% of vehicles traversing the link as a probe—has the potential to provide accurate travel time

Emergency response and traffic congestion: the dispatcher’s perspective

Traffic congestion may impede the ability of emergency vehicles to reach the site of a traffic incident or other disaster in a fast and reliable manner. It is imperative that emergency dispatchers use real time traffic information in order to improve dispatching of Emergency Medical Services (EMS) to the disaster site. Preliminary research indicates, however, that many dispatchers have not been trained to cope with severe congestion nor have they been given the tools that would allow them to consider traffic congestion in the dispatching process. In order to (a) document the extend of this problem in the state of Alabama and (b) understand how traffic congestion impacts emergency dispatching decisions and response, this study developed and conducted a statewide survey of emergency dispatchers on behalf of the University Transportation Center at the University of Alabama at Birmingham. The survey sought feedback from EMS dispatchers in Alabama on current practices, positive and negative experiences, preferences, as well as their perceptions on the use of real time traffic data to help optimize emergency response and transport times. The results of the survey analysis clearly show that there is a disconnect between dispatching decisions and conditions in the field. Traffic congestion was generally not viewed as a major concern among the dispatchers surveyed nor was any real time traffic information used to improve decision making at the dispatching control center. Availability of real-time traffic information for dispatching purposes, and education of dispatchers about the opportunities and benefits that can be realized by using such information are very important steps toward improving Emergency Medical Services (EMS) performance and reliability, which in return can improve survivability of victims requiring medical attention