Wednesday, June 17, 2015

Adding some friction to Bellevue, Everett ramps

By Michael Allende

As Morning Guy on our @wsdot_traffic Twitter account, I regularly advise drivers to watch their speed, especially on ramps and overpasses which can become slick in inclement weather. Still, every time it rains I watch our traffic cameras and I see vehicles spin out going down a ramp, which isn’t good for the driver or for traffic.

This summer, we’re revamping two ramps in Puget Sound with some of the highest percentages of wet weather related collisions. We will be using a process called high friction surface treatment, which is basically a robust sand-like substance that will be applied to the existing pavement with industrial strength glue to increase traction. The ramps getting the treatment are:
  • The 148th Avenue Southeast on-ramp to westbound I-90 in Eastgate interchange in Bellevue
  • The eastbound SR 526 on-ramp to southbound I-5 in Everett
Drivers on the 148th Ave SE Ramp to Westbound I-90
Drivers on the 148th Avenue SE ramp to westbound I-90 will
benefit from a high friction surface treatment on the ramp
that will help prevent spin-outs in inclement weather.
Both of these ramps have challenging S-curve designs and a downhill grade. And on a rainy day when some drivers overlook the posted advisory speed or just aren’t paying attention, we see crashes. By adding this treatment we expect to see a significant reduction in the number of collisions on these two ramps. The added traction improves both steering control and braking ability.

Drivers shouldn’t notice much difference in driving over the enhanced ramps. The asphalt will look basically the same, there won’t be any additional noise and it shouldn’t feel any different driving over for passenger vehicles or motorcycles.

High Friction Surface Treatment Appearance
WSDOT is adding a high friction surface treatment like
this to two ramps that have seen a high number
of spin-outs during wet weather.
Data shows that using this kind of roadway surface treatment reduces weather-related collisions by 60-85 percent and has been successful in Pennsylvania, Kentucky, South Carolina and California, among other states. We’ll monitor and test how it works on our two ramps and if results are as good as what we think they’ll be, we may implement it on other ramps in the area.

The ramp in Bellevue will also be closed from 10 p.m. Thursday, June 18, to 5 a.m. Friday, June 19. Drivers should expect a full weekend closure of the ramps starting Friday night, June 19, until 5 a.m. Monday, June 22. Crews plan to get both ramps finished in just one weekend. However, the work is weather dependent and could get pushed back.

The treatment won’t completely eliminate collisions on these ramps – it’s still up to drivers to recognize and adjust to roadway conditions – but it will go a long way in improving safety in those areas.

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