Spatial and temporal analyses of the variations in aggressive driving and road rage behaviors observed and reported on San Diego Freeways. Paper presented at the Aggressive Driving Issues Conference, October 16th to November 30th, 2000.

California Highway Patrol (CHP) in San Diego County receives cell phone calls reporting unsafe driving. The content of the calls varies, with drivers complaining about speeding cars driving over 100 miles per hour (estimated speed), other drivers weaving and cutting off or tailgating. In some cases, the driving conditions were even more volatile with drivers describing harassment, assaults with a weapon, running other vehicles off the road and so on. There were about 1987 reported incidents from the freeways of San Diego for the months of April, June and September 1998. The information received by the dispatchers was tabulated as shown in Table 1 and then put into five different categories: Aggressive Driving 1, 2, and 3, Speeding Alone and Road Rage based on definitions developed by the authors. Analyses indicated that 24.6% of the calls were for Aggressive Driving 1 (speeding and some other behavior); Aggressive Driving 2 (weaving and cutting) was reported most frequently (27.1% of all the calls), about 12.5% of the calls were for Aggressive Driving 3 (tailgating); Speeding Alone calls comprised 19.8% of the total, and the rest were for Road Rage (16.1%). Of the 1987 calls, 33% were generated on Interstate 5, the busiest and longest in the county, followed by Interstate 15 which accounted for 22% of the calls. The reason for the high number of calls can be attributed to high Average Daily Traffic volumes at each interchange (over 130,000 vehicles) and lengths (Interstate 5 with 79 miles and Interstate 15 with 94 miles within San Diego county). Likewise, Interstate 8 seemed to have a lower number of calls than expected because the urban portion of the freeway is less than 17 miles with volumes of 180,000 per day for each interchange while the remaining distance had less than 30,000 vehicles at each interchange. This was further corroborated and both volume, r (10) = .69, p < .029, and length, r (10) = .77, p < .001, were robustly correlated with the number of phone reports per freeway. Additionally, chi-square tests indicated that the time of the day and day of the week influenced the type and number of calls received. (Author/publisher)