The impact of drivers with cell phones on the traffic efficiency of urban freeways

As the number of people subscribing to wireless services continues to increase, so does the proportion of vehicles with people who are holding a phone conversation while driving. Driving while on the phone diminishes driver attention and compromises driver safety because driving ability is reduced by the distraction of phone conversing while driving. The impact of cell phones on safety is well researched. We know little about the impact of cell phones on the efficiency of traffic streams. The research presented here addresses this new facet of cell phone induced driver distraction: the effect on the traffic stream efficiency on urban freeways. With case-specific integrations between driver simulation and microscopic traffic modeling, the research investigates the efficiency of the traffic stream as diminished by drivers' behavior in both free-flowing and congested traffic regimes.;The experiments on the driving simulator were created to capture the behavior of drivers in free-flowing traffic regimes. The tests show that the influence of cell phone distraction on driving behavior is complex. The research presented here focuses on the influence of cell phone use on speed. Detailed tests of various free-flowing traffic demands show that the presence of slower moving cell phone distracted drivers reduces optimum speed, and, consequentially, increases overall delays---even for the drivers who are not using cell phones.;Drivers' behavior in congested traffic regimes was documented in previous research. The difference in car-following behavior distinguishes between drivers with and without cell phone. Here, the car-following parameter sets for drivers with and without cell phones in traffic microsimulation are calibrated using genetic algorithm optimization techniques to match the findings from the driving simulator experiments. These parameter sets were used in traffic micro simulation to find the relationship between the proportions of cell phone drivers and diminished traffic efficiency (i.e., drop in mean speed and capacity). There is a near linear relationship between these variables: as the traffic demand increases, the percentage of cell phone drivers causing traffic inefficiency is decreasing.;The research is presented through six papers.