A Highway Travel Information System: Forecasting and Publicizing Delays in the Indiana State Highway Network

The Highway Travel Information System (HTIS) is a long-term pre-trip information system providing information about expected events, such as road construction. The HTIS can be beneficial to both highway travelers and roadway project schedulers. Project schedulers can use the HTIS to check the forecasted traffic impacts of a proposed construction project schedule. If the schedule would cause unacceptable delays, a scheduler can try new schedules to reduce the delay. Travelers who have flexible schedules and would like to do pre-trip planning can obtain knowledge of traffic conditions in the near future from HTIS to avoid unnecessary delays. An approach called Workzone Delay Equilibrium Estimation (WDEE) is used by the HTIS to predict traffic conditions as construction zones age. Two extreme values of link volumes are calculated based on two scenarios: “no information”, in which no drivers know about a new road capacity reduction, and “complete information”, in which all drivers have adequate information about road construction zones. A relationship between link volumes and the age of a construction project has been hypothesized and applied to the two extreme cases to estimate link volumes during construction periods. Finally, the expected delays on links under construction are estimated based on the estimated link volumes. The HTIS is divided into three subsystems for the purpose of meeting the needs of different groups of users. They are the modeling, project scheduling, and web access subsystems. The modeling and project scheduling subsystems are for management purposes and the web access subsystem is for use by the traveling public. The modeling subsystem is built using Excel VBA and TransCAD GISDK interfaces. The main function of the modeling subsystem is to model traffic conditions and generate a delay database. The project scheduling subsystem is built on the TransCAD GISDK interface. The major tasks for the project scheduling subsystem include schedule database management and assisting project scheduling. The web access subsystem is built on several scripting languages, including Hyper Text Markup Language (HTML), JavaScript, VB-script, and Active Server Pagers (ASP). With the web access subsystem, travelers may input their proposed departure times and receive information about expected delays at workzones that are expected to be active during their trips. Motorists can use the information to plan their trips up to two months in advance