Table 4. Events coded per hour of video record at intervention and comparison sites.*
* This table does not represent a count of the number of vehicles that actually appeared in the video record for each wave and site, and should not be taken as a count of traffic volume. The majority of vehicles in the video record did not commit a violation near a semi truck or cross paths with a semi truck. Under the coding rules of the study, these video segments were not coded. The numbers presented here only represent those vehicles that committed a violation (i.e. speeding, cutting-off truck, tailgating) near a semi truck, or crossed paths with a semi truck. The values in this table could be affected by a reduction in speeding and tailgating. A reduction in these types of violations would lead to fewer events being coded because these types of violations do not involve crossing paths with a truck, rather a reduction would lead to more vehicles simply passing semi trucks without committing a violation. For example: a vehicle that was speeding in the immediate vicinity of a semi truck in Wave 1 would have been coded as an event even if it did not cross paths with the truck. This same vehicle, now obeying the law and not speeding and not crossing paths with a truck, would not be coded as an event in subsequent waves. In this case there would be a reduction in the events coded but not in the actual traffic volume.