Examining Driver Compliance with a Move-Over/Slow Down Law in Consideration of Vehicle Type and Messages Displayed on Upstream Dynamic Message Signs

Abstract

Move-over laws are intended to enhance the safety of road agency and law enforcement personnel who are working on or near the roadway. This study examined driver behavior through a series of field studies where these types of vehicles were located on the outside shoulder of a freeway with their lights activated. The study also evaluated the use of upstream dynamic message signs (DMS) to discern whether targeted safety messages had any impact on behavior under this scenario. Upstream and downstream speed and lane position data were collected from vehicles originally traveling in the rightmost lane upstream of the DMS and emergency/service vehicle at two locations in Michigan. Logistic regression models were estimated to assess driver compliance with the law while considering important contextual factors, such as the type of vehicle on the shoulder and the message displayed on the DMS. The results indicated that drivers were more likely to move over or reduce their speeds when a police car was located on the shoulder as compared to a transportation agency pickup truck. In general, the type of message displayed had minimal impact on driver behavior. The one exception showed that drivers were likely to drive at or below the speed limit when targeted move-over messages were shown as compared to standard travel time messages. For all message types, both speed and lane compliance improved if the roadside vehicle was a police car.

Evaluation of Enforcement and Messaging Campaign Focused on Reducing Cell Phone-Related Distracted Driving

“…However, the results again did not indicate any observable pattern with respect to the specific messages that were displayed on the roadside DMS. This was similar to a previous study that showed drivers were more likely to move over when law enforcement vehicles were present on the shoulder, but no clear patterns were observed among four different message types that were evaluated ( 15 ).…”

“…In another study, message type was shown to have minimal impact on the rate of driver compliance with a move-over law requiring motorists to reduce their speeds and provide space when passing emergency and service vehicles on the roadside. This same study showed that compliance rates were higher when the roadside vehicle was a police car as opposed to a transportation maintenance vehicle, which suggests a potential synergistic effect between enforcement and messaging campaigns ( 15 ).…”

Driver Understanding and Secondary Task Performance While Viewing Traffic Safety Messages on Dynamic Message Signs

“…For example, some studies have found little or no change in seat belt use or speeding in response to BTS messages targeting those behaviors ( 4 – 12 ). Likewise, the effects of displaying BTS messages pertaining to state move-over laws or warnings about possible animal crossings have had a very limited effect on speeds ( 13 , 14 ). However, other studies suggest that messages discouraging cell phone use or tailgating may yield some changes in those types of behaviors ( 3 , 15 , 16 ).…”