ODOT will activate 17 new advisory speed signs on southbound Interstate 5 and southbound Interstate 405 Thursday July 31, the next in a series of projects using new technologies to provide real time information to drivers.

The advisory speed signs, part of ODOT’s new RealTime technologies, will display an advisory speed when weather, congestion, a crash, a stall or other obstruction slows traffic.

The signs will give drivers a heads-up to slow down before they reach a problem area, helping reduce rear-end crashes and the congestion they cause. As traffic slows, the signs will display a lower advised speed. The advised speed will continue to decrease as drivers approach the backup. 

Here are a few details:

•The signs are along southbound Interstate 5, from the Marquam Bridge to the Ross Island Bridge, and along southbound Interstate 405 approaching the intersection with I-5.

•ODOT chose the I-5/I-405 area south of downtown Portland because it’s particularly prone to rear-end crashes. 

•Rear-end crashes most commonly take place when motorists unexpectedly encounter a line of vehicles slowed by congestion. 

•The advisory speed will be generated automatically by sensors in the road. The signs will go dark when not needed. 

Drivers will not be ticketed simply for exceeding the advisory speed. However, the Oregon Basic Rule still applies, which provides that drivers can be cited for driving recklessly or too fast for conditions, regardless of the speed limit.

Advisory speed signs are also part of the ODOT RealTime signs activated last week on OR 217.

National studies show that advisory speed signs have reduced overall crashes by 20 percent, reduced rear-end collisions by 30 percent and reduced secondary crashes by 40 percent.

Reducing secondary crashes will mean fewer days with delays on this critical corridor. Secondary crashes cause serious injuries, costly car repairs, costly medical insurance co-pays, and lost time at work and with family.