SR 531 - Curbs Reducing Crashes

by guest blogger Bronlea Mishler

How do you curb collisions on a busy highway? With curbing – if you’ll pardon the pun. In the five years since we installed curbing along the center of SR 531 in Arlington, turning and driveway-related collisions have dropped by 70 percent. We’re not trying to pat ourselves on the back or anything, but we think that’s a pretty sweet deal  – and not just for us. Anyone who drives that road on a daily basis is benefiting from a safer, less congested commute.

We installed the curbs between I-5 and just past Smokey Point Boulevard in the fall of 2006 as part of two separate projects. Like a lot of construction projects, our ultimate goal was to improve traffic flow on SR 531 and reduce the risk of collisions.

The first project wrapped up in July 2006, and ultimately widened the SR 531 bridge over I-5 to six lanes. As part of that project, crews installed curbing down the center of the bridge to separate east and westbound traffic. The second project wrapped up a few months later, in September 2006. During that project, we added dedicated left-turn lanes, built bus pull-out locations and u-turn locations, and added curbing along the center of the highway, all the way from I-5 to just east of Smokey Point Boulevard.

It’s probably easy to see how a new, wider bridge could improve traffic flow. More lanes means more traffic getting through the area. But what about curbing? How does a little bit of concrete curb make such a big difference in reducing congestion and collisions? By limiting the number of places where drivers can turn across traffic, other drivers can better anticipate – and react to – turning traffic. More reaction time typically translates to fewer collisions. And dedicated turn pockets and u-turn locations give turning drivers a safe place to wait for a gap in traffic without backing up other drivers who aren’t turning. Fewer collisions? No waiting in line behind a driver turning left? Those are two big factors that help traffic flow better.

On SR 531, the curbing has paid off in a big way. In the three years before the curbing was installed, there were 95 driveway or turning-related collisions. In the three years after the curbing was installed, those collisions dropped by 70 percent, to only 27. Not only that, but the total number of collisions on SR 531 between I-5 and Smokey Point Boulevard dropped by 27 percent after curbing was installed. 
It’s nice to know that even a small piece of construction can make a big difference.