Nationwide, United States
Vehicle infrastructure integration (VII) based road-condition warning system for highway collision prevention
Summary Information
The Vehicle Infrastructure Integration (VII) program was a major ITS initiative designed to create an enabling communication infrastructure that would open up a wide range of safety applications. The road-condition warning system was an application of VII technology, meant to provide drivers with real-time information about unexpected roadway conditions ahead, such as accidents, speed reduction zones, hazardous weather conditions. This study investigated three different types of warning systems: Rural Highway Driver Warning Systems (RHDWS), Highway Lane Change Warning Systems (HLCWS) and Work Zone Driver Warning Systems (WZDWS), These systems were designed and tested in the designed highway scenarios by driving simulator experiments. The experimental results show that all three systems can reduce the crashes in the designed environment.
Methodology
The designed system was tested by conducting driving simulator experiments. For the WZDWS, three different types of driving scenarios were designed and tested: (1) the baseline scenario with the basic traditional work zone safety control measures, (2) the comparison scenario which uses the prevailing work zone control measures, and (3) the study scenario which employs the proposed VII technology based work zone collision prevention systems.
After conducting the driving simulation experiments, the participants’ driving performance under different driving scenarios were evaluated based on the outputs of the driving test. In this study, the following measures of effectiveness (MOE) were derived for analyzing driving performance:
- Number of Collisions
- Minimum Time-To-Collision
- Number of Critical Events
- Maximum Deceleration
- Speed Limit Conformity
Results
For the designed WZDWS, when the sight distance is limited at the work zone and/or the speed difference between lanes at the merge point are high, the designed VII based WZDWS can significantly reduce the work zone collision risk compared to the prevailing work zone safety control measures, including static warning signs, flashing arrow signs and police enforcement. When the sight distance is not limited at the work zone and the speed difference between lanes are not high, no significant improvement is observed for all of the five MOEs between the comparison and study scenarios.
After the experiments, the participants were surveyed to obtain their opinions of the following work zone control measures:
- Static Signs Work Zone Ahead Traditional
- Dynamic Signs Flashing Arrow Traditional
- Police Enforcement Police Car with Flashing Light Traditional
- In-Vehicle Driver Warning Work Zone Ahead
- In-Vehicle Driver Warning Speed Limit
- In-Vehicle Driver Warning Keep Safe Headway
- In-Vehicle Driver Warning Prevailing Speed
Tukey's Test* was used to analyze the results, which show that Flashing Arrow and Work Zone Ahead Voice Warning are the most preferred work zone control measures while Police Enforcement is the least preferred work zone control measure.
These findings indicate that VII technology has the potential to reduce the safety risks at work zones under situations where the drivers cannot be well informed about the coming work zone due to the limited sight distance of the work zone and/or the speed difference between lanes at the merge point is high. When a work zone can be easily identified in advance, the deployment of VII technology is less likely to bring additional safety benefits.