Date of Award

12-2012

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Civil Engineering

First Advisor

Dr. yasser Hawas

Second Advisor

Dr. Kamran Ahmed

Third Advisor

Dr. Essam Zaneldin

Abstract

In March 2008, a single accident resulted in three people being killed and nearly 350 injured in a horrific crash involving over 60 vehicles on the Abu Dhabi-Dubai highway near Ghantoot. The cause of this crash was attributed to failure by motorists to adhere to severe weather conditions (fog). In response to the increasing number of accidents on Abu Dhabi roads, the Abu Dhabi Department of Transport (DoT) has deployed approximately 40 portable Variable Message Signs (PVMSs) throughout the main DOT's highway network as one of the strategies to control driver behavior and to improve road safety. The objective of these PVMSs is to provide drivers with adequate warnings; especially during severe weather conditions (e.g., fog, dust, rain). They are also used within critical areas such as construction zones on the highway, at school crossings and during major events so as to minimize the chances of accidents.

The aim of the study was to evaluate the impact of PVMSs on road safety as well as their perceived satisfaction among road users. The effectiveness of PVMSs in Abu Dhabi has not yet been evaluated in this way the study adopted a longitudinal approach and involved the collection of vehicular speed, volume and classified data at three different highway sections. These covered one location close to a work-zone in Abu Dhabi with allowable speed limit of 100 km/hr., another location on freeway with allowable speed limit of 140km/hr. and one location on an arterial road with allowable speed limit of 120km/hr. Additionally, drivers and workers were interviewed in order to seek their perception on the use of PVMS.

Using descriptive and analytical statistical methods, the mean and 85th percentile speed differences before and after the deployment of PVMS were found not to be statistically significant at the study locations. At both urban and rural locations, PVMS was shown to have a minor impact in reducing highway speeds but it was found not to be statistically significant. The study showed that PVMSs were found to be effective, though statistically not significant (p-value > 0.005 at 95% confidence level), in reducing driver's speeds with about 1% on freeway and arterial roads. PVMSs are not significant statistically effective in reducing speeds at the work zones. Newly deployed PVMS at work zones confuse drivers especially when the posted speed limits are reduced gradually over a short span length. Further, the proportion of vehicles speeding excessively (i.e. vehicles traveling over the posted speed limit) was slightly decreased by the use of PVMS.

A significant number of road user's responses were positive and highly satisfied with the usefulness of PVMS as a tool to display the traffic information to drivers and to manage traffic safety at work zones. They also stated that PVMS is an effective tool in alerting drivers about the irregular traffic conditions and/or any incidents on the highway and within work zones. There were many comments on the current operation of the PVMS that are mainly on updating PVMS messages, messages shall be changed frequently, PVMS messages shall cover the benefit areas mentioned in the driver survey and more care shall be considered for PVMS as a communication tool with the roadways users in order to increase the convenience on PVMS.

In addition, surveys of road construction workers indicated that workers were aware of PVMS and considered PVMS to be the best tool available for traffic safety at work zones. Most of the road construction workers stated that they feel safer with the implementation of the PVMS during night shifts. The main comment was on implementation of the PVMS which are mainly about; not common in most of the work zone areas, it should be implemented immediately over all work zones within Abu Dhabi, should be well maintained through the whole construction period and moved away until work zone is cleared. Increasing public awareness of the use of PVMS suggested being a common tool used at work zones.

Some recommendations can be drawn from the study. The operation of PVMS shall take more care from Department of Transportation and Ministry of Interior – Police Department. The PVMS messages should be updated regularly and be varied to accommodate a wider range of incident warnings to assist in accident reduction. In general, PVMS messages should also be displayed as symbols to cover the illiterate drivers and workers and non-English/Arabic speakers.

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