Evaluation of Work Zone Mobility by Utilizing Naturalistic Driving Study Data
Dr. Huaguo Hugo Zhou, Auburn University
Dr. Rod Turochy, Auburn University
As the National Highway System grows older, an increasing number of work zones have been implemented to address the growing needs of maintenance and construction. However, the reduced operating speed, narrowed lane width and shoulder clearance, and other construction activities, have not only resulted in crashes but also caused excessive delays.
Although the freeway work zone capacity methodology proposed in the latest edition of the Highway Capacity Manual (HCM) has been substantially improved over previous editions, it is still limited by the fact of the macroscopic model, which cannot account for various work zone configurations.
In order to understand how actual work zone layouts, traffic conditions, and driver behaviors affect work zone capacity, a one-year proof-of-concept study evaluated if existing Naturalistic Driving Study (NDS) work zone data collected by the second Strategic Highway Research Program (SHRP2) could be reused to develop new (or update existing) capacity and traffic flow models for work zones.
Results suggested that the capacities predicted by HCM are lower than that by NDS regression models, which implies the HCM might underestimate the work zone capacity or additional parameters (such as population factor), which should be included in HCM models. The results on headway selections by different types of drivers can also be applied to improve or calibrate work zone planning and simulation tools. More complete work zone NDS data that cover the entire work zone area should be collected to develop car-following models at work zones in the next phase.
The results offer a unique opportunity to observe actual driver behaviors negotiating different work zone configurations, which can be utilized by Department of Transportations (DOTs) and transportation agencies to improve the existing work zone planning and capacity analysis tools.
- Preliminary Headway Table for Traffic Simulation Software – A preliminary Headway Table for Traffic Simulation Software was developed from work zone data obtained from a Naturalistic Driving Study (NDS), which was reused to develop new (or update existing) capacity and traffic flow models for work zones.
Who can benefit from the finding(s) of this project?
- State DOTs and local transportation agency professionals who manage work zones
Although the freeway work zone capacity methodology proposed in the latest edition of the Highway Capacity Manual has been substantially improved over previous editions, it is still limited by the fact of the macroscopic model, which cannot account for various work zone configurations. The results from the NDS data offering a unique opportunity to observe actual driver behaviors negotiating different work zone configurations, which can be utilized to improve the work zone capacity method defined by HCM.
The comprehensive review of available literature conducted in the Phase I indicated that this is the first project that used NDS data to study car following and traffic flow modeling at work zones. Phase II of the project will be able to collect more NDS data for developing new methods for work zone capacity analysis and calibrating some work zone planning and simulation tools, for instance, new FFS table, new headway selection tables, distance traveled during speed change cycle, and average speed in queue for the work zone planning software (QUEWZ). The headway selection table by different driver types can be applied to develop driver population factors in estimating work zone capacity based on local population conditions. In addition, the NDS data contain the kinematics of participant vehicle and the front vehicle, which can be used to develop or calibrate simulation models to evaluate the performance of connected vehicles at work zone environment.
- Webinar – Impact of Driver Characteristics on Headway Selection & Free-Flow Speed at Work Zones by Utilizing Naturalistic Driving Study Data