Maple Valley Highway: Way past time for an upgrade

When it was first built in the 1930s, what is now the Maple Valley Highway was a relatively idyllic road passing through rural Southeast King County. Its two lanes were usually enough for the traffic it carried to service the farming, forestry and coal-mining communities of the area.

That era is long gone, but the road — and its limited capacity — remains as a daily reminder of the need for infrastructure investment in Southeast King County.

Today, the route, also known as Highway 169, is a state highway that begins at Interstate 405 in Renton and winds through Maple Valley and Black Diamond before ending in downtown Enumclaw. It runs through some of the most dynamic portions of the county.

Traffic volumes increased 53 percent in the past nine years in Maple Valley's section of road. Most of Highway 169 is now a T-1 freight corridor and it increasingly has become a route for Pierce County commuters.

The burgeoning resident, commuter and freight use of Highway 169 has led to a gridlock that makes many morning commuters look forward to the relative free flow of traffic on I-405.

As Black Diamond and Enumclaw come out of their respective growth moratoriums, there will soon be many more cars on Highway 169. Black Diamond's population could more than quadruple in the future, as 1,800 acres are set to be developed. Most of those new residents will drive the Maple Valley Highway. Action must be taken now to prevent what is today a frustrating situation from becoming much worse.

To try and spur activity to improve this highway, the SR-169 Improvement Consortium was formed three years ago. This group is made up of all the cities and chambers of commerce, as well as most of the school districts and fire districts along the route.

By working closely with area legislators — primarily from the 5th, 11th, 31st, 41st and 47th legislative districts — this consortium has done several things in the past three years, which include:

• Getting a "route-development plan" funded for the Washington State Department of Transportation to outline needed improvements and plan for the future.

• Earmarking state funding for five bottleneck projects to get traffic flowing more smoothly.

• Passing legislation redesignating Highway 169 as a "Highway of Statewide Significance," which puts it in the highest category for future state funding.

While these developments are substantial and Highway 169 is no longer a "forgotten highway," as it had been despite decades of growth, much more remains to be done.

The WSDOT route-development plan draft for the highway outlines $300 million in needed improvements, including $110 million that it categorizes as "high-priority projects."

Unfortunately, the Legislature did not allocate any state funds this year for these high-priority projects, nor any other "new" projects that were not on WSDOT's project list in past years.

Using seniority to prioritize project lists is a frustrating policy. Instead, basing project decisions on utilitarianism (the most good for the most people), safety and cost-effectiveness would be welcomed.

The average daily traffic, or ADT, for Renton's section of Highway 169 is about 55,000 vehicles. In Maple Valley, it is about 45,000. WSDOT estimates the corridor needs $300 million in improvements. Compare that to the project that is most written about in King County — the Alaskan Way Viaduct replacement in Seattle. The viaduct has an ADT of a little more than 100,000 and a cost — depending on the option chosen — of at least $3 billion.

Using the above to calculate on a per-trip basis makes investing in Highway 169 improvements one-fifth the cost of the same (much shorter) trip on the viaduct.

While of course some sort of viaduct replacement is needed for safety and location reasons, the point here is that future funding also needs to go toward clearly cost-effective projects like improving the Maple Valley Highway.

It is time for 1930s infrastructure to catch up with 21st-century development in Southeast King County.