An almost-completed construction project has transformed the once-familiar interchange at Mill Plain Boulevard and Interstate 205 in East Vancouver into a towering runway that seems for many like a more expensive version of its former self.
With a price-tag of $26 million, taxpayers and commuters alike might be wondering: "Where's the improvement?"
The answer lies in the complex area of highway design. And like all design, it begins with analysis: in this case focusing on specific areas covering pavement, bridges, safety, mobility, environmental concerns, economic vitality and other highway assets.
According to Bart Gernhart, regional engineer for the Washington State Department of Transportation, faults in a number of these sectors catapulted the Mill Plain Connector to the top of the list of scheduled regional road construction projects, especially in the one essential area – susceptibility to collisions.
Congestion and safety analyses indicated that pileups stemming from heavy traffic from I-205, Highway 14 and Mill Plain Boulevard were on the rise. The same study also identified 1,000 peak-hour vehicles exiting Mill Plain to access N.E. 112th Avenue.
To alleviate this stress, the project created a direct connector ramp to 112th Avenue by bisecting an off-ramp to Mill Plain Boulevard heading westbound. As a result, the existing Mill Plain on-ramp to I-205 North required a modification to a flyover/bridge-style ramp to shoot freeway-bound traffic up and over the new direct connector.
A second stage of this project – scheduled to break ground in 2014 – will incorporate a new half-diamond interchange at N.E. 18th Street, where the majority of peak hour traffic needs accumulate, according to WSDOT.
Another well-known Clark County traffic blight is also set for relief using some of the same highway design principles used at the Mill Plain Connector.
Currently, four main traffic arterials intersect and utilize N.E. 134th Street in Salmon Creek, resulting in a tangled mess of traffic headed to homes, businesses and community resources such as Washington State University Vancouver and Legacy Salmon Creek Medical Center.
One signal in particular on this strip of closely-situated lights symbolizes the mess. It's a feature Gernhart refers to jokingly as "Sigzilla" – a traffic light with no less than 22 signal heads.
"No matter how many lanes you add, you can't get that many people in and out," Gernhart said. "That's why we need to build another road a little further away to provide additional routes for folks that will eliminate some of the signal phases."
The other road Gernhart's referring to is a $140 million nickel-tax funded project to create an overpass spanning across both the 1-5 and I-205 at N.E. 139th Street. The project will create a corridor connecting N.E. 10th Ave. to N.E 20th Ave., as well as new I-5 ramps.
The project, scheduled to begin next summer, will take place with minimal disruption for motorists, according to Gernhart. "It's kind of like working on plumbing in your house without turning off the water," he said.
Though the goal of the Mill Plain Connector and the new Salmon Creek Interchange project is to alleviate traffic congestion, another ongoing highway construction effort has another target in mind – increased local development.
Regarding the effort to upgrade the interchange between S.R. 501 and I-5 in Ridgefield, public works director Justin Clary said his city is being proactive by adding specific highway design elements to serve future community and business needs.
"The new interchange is sized to serve Ridgefield into the foreseeable future, which will not only incentivize economic development, but also provide sufficient capacity for our citizens," Clary said.
The new interchange, when completed, will provide significantly lengthened ramps for improved acceleration and deceleration for motorists merging on and off I-5. It will also raise the overpass to allow the majority of northbound and southbound I-5 truck traffic to pass underneath.
The upgrade also includes sidewalks for pedestrian and bicycle travel to promote more foot traffic along retail frontage. In addition, a second as-yet unfunded stage of the project looks to cater to future retail and manufacturing locations by means of alternative transportation.
"There are actually more overall goals of the interchange than just economic development," Clary said. "There are also goals of improvement to safety and transportation capacity, and enhancement of pedestrian facilities."
Whether the goal is a reduction in traffic congestion, or economic development, highway design determines the fate of both the travelers and businesses that rely on a functioning transportation stream.
