Impact Analysis of Dynamic Message Signs on Driver Behavior
M A Mohammadi, B K Venkat, G H Bham, M Leu, Missouri University of Science and Technology, US
To valuate the effects of Dynamic Message Signs (DMS) on driver behavior in a work zone. This study aims to identify the effectiveness of DMS using field analysis and driving simulator, and evaluate the effect of DMS on traffic flow characteristics.
Conducting field observations are challenging and resource intensive especially when measuring change in driving patterns. This study uses a driving simulator to evaluate the effects of Dynamic Message Signs (DMS) on driver behavior deployed in a highway work zone. Various studies have been conducted in the past that used a driving simulator to evaluate the performance of DMS. Ullman et. al. (2005) conducted a similar study on portable changeable message signs (PCMS) to investigate adequacy of driver interpretation and comprehension of split messages. Hardy et. al. (2006) employed a driving simulator to evaluate the effects of static and enhanced DMS displaying wildlife advisory messages on driving response. Pareja (2007) used a driving simulator to model various 3D text and graphics on DMS. To the authors? best knowledge, most of the reviewed studies that employed driving simulators have dealt with message formatting and subjective evaluation of comprehension of displayed messages in a simulated environment. There are very few researches in this area that have used a driving simulator to quantitatively assess the effects of DMS on traffic flow characteristics. To fill this gap and overcome the challenge of field data collection, this project aims to use a driving simulator to quantify the impact of DMS on drivers' speed and traffic flow characteristics in a virtual environment.
The DMS in this study provides real time information upstream of a work zone to harmonize the speeds of vehicles and improve highway safety. When the vehicle speeds are high, and traffic volume is low, driver behavior is affected by messages on DMS. The Missouri S&T driving simulator was employed to evaluate the effects of different displayed messages on driver behavior. A four factor experiment (Age group, gender, displayed message, and education level) was designed and the potential measures of effectiveness were determined. The messages shown on DMS were "CAUTIONWORKZONEAHEAD/ REDUCESPEEDAHEAD", "SPEEDAHEADXX MPH/ XX MINTO ENDOF WZ", "PREPARETOSTOP/ XX MINTO ENDOF WZ", and "PREPARETOSTOP/ STOPPED TRAFFICAHEAD" for the average speed values of more than 50 mph, 20-50 mph, 5-20 mph, and less than 5 mph, respectively. Driving simulator runs for each factor combination will result drivers? responses to each message in real time including traffic flow characteristics and the variation in mean, standard deviation, 85th percentile speeds, etc.
Field data (vehicle speeds) were also collected at four sensor locations on I-44 in Missouri. DMS with different messages were displayed based on the level of traffic congestion in a work zone. Time-space diagrams generated by the field data will be used to validate the results of speed variation attained from the simulator study of the same environment. The paper will present the results of the study in addition to the statistical analyses conducted on simulator data to quantify the impact of DMS on driver behavior. The results of the paper can provide useful insights for transportation agencies in employing DMS for traffic control, operation and management of work zones.
The Missouri S&T driving simulator was used for this project. The subject vehicle was modeled and various scenarios of virtual environment were developed with four DMS replicating the real world environment upstream of the work zone on I-44, near Waynesville, Missouri. Blender 3D (an open source modeling software) was used to model the roads according to specifications of the Missouri Department of Transportation. Modeling of the vehicles and roadway was first carried out for each of the environment and then they were appended together to create a single environment. Dynamics were defined and the game engine in Blender-3D and the python physics were used to develop the script for the gaming scenarios. Open source gaming module, Vdrift, was used to import and test the scenarios that were modeled and rendered in Blender-3D.
Ullman G. L., B. R. Ullman, C. L. Dudek, A. Williams, and G. Pesti (2005). Advanced notification messages and use of sequential portable changeable message signs in work zones. Technical Report: FHWA/TX-05/0-4748-1.
Hardy A. R., J. Fuller, S. Lee, L. Stanley, A. Al-Kaisy (2006). Bozeman Pass wildlife channelization ITS project. A report prepared for the Montana Department of Transportation.
Pareja I. (2007). Modeling of variable message signs for driving simulation. International conference of road safety and simulation. Rome, Italy.
Association for European Transport