Application of an Intelligent Transportation System in a Travel Time Information System: Safety Assessment and Management

Abstract

The research presented here evaluated road safety on the road sections included in the Intelligent Traffic Control System of the Podhale Region (ISSRRP) in Poland. This travel time information system consists of a remote traffic microwave sensor, cameras, as well as automatic plate number recognition on national roads with variable message signs and a mobile app to suggest alternative routes in the regional road network. The study analyzed changes in safety caused by transferring traffic volume from national to regional rural and suburban road networks. The assessment of the safety performance was performed with an empirical Bayes study, with periods of three years before and after the implementation of ISSRRP. No changes were identified in the safety performance of the national road network after to the introduction of ISSRRP. However, when the overall network is considered, a potential increase in the number of crashes may be expected, depending on the volume of traffic transferred from national to regional roads, and rural or suburban areas. Therefore, a new approach for system management was proposed, taking into account not only improvement in traffic flow, but also safety performance.

Impact on Road Safety and Operation of Rerouting Traffic in Rural Travel Time Information System

“…The TTIS, recommending alternative routes on the basis of travel time, is commonly used. It improves the level of service and may have controversial effects on road safety on the main regional and national road networks based on the magnitude of the rerouted traffic [2]. This preliminary study [2] considers the effects of the system by developing simulated scenarios of traffic redistribution on the network.…”

“…It improves the level of service and may have controversial effects on road safety on the main regional and national road networks based on the magnitude of the rerouted traffic [2]. This preliminary study [2] considers the effects of the system by developing simulated scenarios of traffic redistribution on the network. The main problem of those applications is that the TTIS may also influence the change in traffic at intersections.…”

“…The aim of the paper is an assessment of the road network covered by the TTIS in terms of road safety and traffic operation, considering a dynamic traffic distribution. The paper proposes the next stage of the study of road safety on roads included in the TTIS [2] with consideration for road safety and the impact of travel time at intersections as part of the network. Therefore, for road networks included in the TTIS: 1) a detailed systematic road safety and traffic operation analysis has been done, considering the predicted number of crashes on the basis of ad hoc calibrated SPFs, 2) traffic data and their monthly variability were considered by getting data from the measuring devices implemented in the system, and 3) the relation between traffic volume and speed was developed by the authors based on empirical data from the TTIS.…”

“…Furthermore, by assessing the safety level of each road section and intersection as a function of the Annual Average Daily Traffic (AADT) and geometric parameters, it was possible to simulate in real time the network performance in terms of road safety. This was possible since the effects of the TTIS system did not change the risk related to the different road categories and intersection types (the estimated crash modification factor for the TTIS was close to 1, as shown in [2]). In fact, by rerouting traffic, the TTIS affects crash frequency in non-homogenous road categories and intersection designs.…”

“…This paper is a further step to develop a preliminary analysis on the safety performance of the network when traffic is rerouted between paths with different road segment categories and characteristics [2]. The mentioned study has high reliability in the methodology and data but was conducted only in terms of road safety for road sections, while intersections were not included in the analysis.…”