Resumen de Preliminary Before and After Speed Studies as a Tool to Assess the Effectiveness of Centerline Rumble Strips in Rural Roads
Yanira Rivera, Benjamin Colucci, Fabiola Buitrago, Enrique González
A research study completed in 2016 by the National Highway Traffic Safety Administration (NHTSA), showed that 51% of the 32,675 motor vehicle traffic crash fatalities reported in 2014 occurred on the rural road network in the United States and 64% in Puerto Rico. Centerline rumble strips, (CLRS) have been proven in the United States to be an effective, low-cost countermeasure, however, it is yet to be tested in Puerto Rico. The focus of this research is to study the safety effectiveness of CLRS on highway PR-114, a rural two-lane two-way road connecting the municipalities of Hormigueros and San Germán in the Commonwealth of Puerto Rico. The CLRS and corresponding signage were installed from km 7.6 to 14.5 along this highway and is the first to be treated with this safety countermeasure in Puerto Rico. The primary focus of this paper is on the spot speed analysis of vehicles inside and outside of the segment treated with CLRS. The findings of this research are increased speeds within the CLRS by up to 3 mph. Vehicles traveling eastbound traveled on an average 2 mph greater than the opposing traffic. The posted speed limit of 35 mph was exceeded at both km 14.3 and 14.6 locations by up to 11 mph for mean speeds and 17 mph for 85th percentile speeds and the speeds recorded ranged from 27 to 69 mph. This suggests that the posted speed limit should be raised in order to decrease the large range of speeds which has been associated with serious and fatal crashes. When there is a large range of speeds, drivers will feel more inclined to pass slower vehicles, making them prone to head-on and sideswipe same direction crashes. The passing driver will then position their vehicle further into the opposing lane to prevent hitting the rumbles throughout the entire passing maneuver. Raising the speed limit to 40 or 45 mph is recommended combined with strict police enforcement during the first three months of implementation, and regular law enforcement afterwards.
