Washington

City: 
Seattle
Facilities: 
I-90
Facility Type: 
Interstate
Length of Controlled Section: 
40 mi
Objectives: 
weather related safety improvement
Date Implemented: 
1997-1998
Operational Information
Concerned Vehicles: 
all
Type of Control: 
manual (safe speed automatically calculted)
Operating Partners: 
WSDOT
Speed Information
Speed Limit: 
regulatory
Speed Variability: 
10mph incr., 55mph if traction tires advised, 45mph if traction tires required, 35mph if tire chains required
Maximum Speed: 
65mph
Traffic Control Devices
Speed Signs: 
Variable message sign downstream of on-ramps (9 total in test area), speed limit displayed on the left hand side and three line message on the right
ITS: 
(6 weather stations), radar detection, speed and volume detection (loops?)
Performance Measures
Lane Speeds: 
One speed limit for all lanes
Costs and Financing: 
$5 million
Enforcement
Enforcement: 
Enforceable