Thursday, November 10, 2016

The new SR 520: An award-winning corridor with integrated, multimodal design

By Roger Millar

As Henry Ford's groundbreaking Model T began rolling off a Detroit assembly line more than a century ago, the fledgling Washington State Highways Department set about transforming dirt wagon trails into our state's first network of modern roadways. Fast-forward to the 21st century, and the construction and maintenance of highways remains a core responsibility for the renamed Washington State Department of Transportation. But just as our communities have grown and diversified over the years, so too has our mission.
The world’s longest floating bridge opened to traffic in April 2016.

We are no longer just a "highways department." Today, we work to create and maintain a sustainable, integrated transportation system that supports multiple modes of travel, whether for driving solo, sharing a carpool, hauling freight, commuting by bus, taking a ferry, riding heavy or light rail, bicycling, or simply walking to your destination.

A prime example of our multimodal pursuit is the new State Route 520 floating bridge on Lake Washington and its connecting SR 520 corridors on both sides of the lake, between I-405 and I-5. The rebuilt highway – still a work in progress – demonstrates how interwoven strategies for moving people and goods can create more livable communities while supporting regional growth and economic vitality.
A bicyclist pedals on the new floating bridge’s 14-foot-wide shared-use path, which in 2017 will extend from Seattle to the Eastside.

We are pleased to see the highway's improvements drawing positive reviews both regionally and nationally.

Last month, the Puget Sound Regional Council gave us a Vision 2040 Award for completion of the new floating bridge, citing the structure's role in helping to "ensure a sustainable future as the region grows." And in early November, the bridge project earned the national 2016 Excellence in Design (Engineering) Award from the Design-Build Institute of America. Meanwhile, the highway's completed Eastside segment, from Medina to I-405, won a 2016 Quality of Life / Community Development Award from the American Association of State Highway Transportation Officials. We'll find out in mid-November if our Eastside project is the association's national Grand Prize winner for state highway projects.
Design consultant KPFF and WSDOT won the Excellence in
Design (Engineering) Award from the Design-Build Institute
of America this year for work on the SR 520 bridge.

Unlike the old highway corridor we're replacing, the new SR 520 is a multidimensional transportation system, with forward-looking features drawn from more than a decade of public outreach and engagement. Some of the noteworthy enhancements include:
  • Bigger, stronger pontoons, anchors and anchor cables for the new floating bridge – it opened last spring – that enable the bridge to withstand much stronger winds and waves.
  • Replacement of the highway's structurally vulnerable, hollow-column approach bridges with new, solid-column bridges built to modern seismic standards.
  • The addition of bus/carpool lanes in both directions to improve transit safety and trip reliability.
  • Five landscaped, community-connecting lids over the highway, three with direct-access transit stops and better, safer transit connections for bicyclists and pedestrians.
  • A regional, cross-lake bicycle and pedestrian path from Seattle to Redmond, with numerous connections to local shared-use trails.
  • Full shoulders so disabled vehicles will no longer block the SR 520 mainline and snarl traffic.
  • An engineered floating-bridge design that will accommodate a retrofit for light rail should the region's voters someday choose that option.
Improving traffic mobility was, of course, one priority for a reconstructed SR 520. Traffic studies predict that when the highway is fully built out to I-5, HOV travel time from Seattle to Bellevue will be 25 minutes shorter during peak periods, and 31 minutes shorter in the general-purpose lanes.
A bus enters the HOV lane on the new SR 520 floating bridge.

The improved highway also reflects the public's desire for a more environmentally friendly transportation system. For the first time, SR 520 runoff and the pollutants it carries will be captured and filtered, either in on-land stormwater-detention sites in Seattle and the Eastside, or in innovative catch basins and stormwater lagoons constructed on the new floating bridge.

Project accolades from industry peers are nice, I'll admit. But much more rewarding for me and my colleagues is the personal conviction that, day by day, year by year, we're designing and building smartly integrated, sustainable public infrastructure – infrastructure that will benefit our neighbors and the communities we share for generations to come.

That is the road we're taking. And the journey continues.


Jeff Lykken said...

The bridge may look nice in design and all, but it is missing one important aspect; it does not have enough capacity. No where else in the country would praise a facility that after spending billions of dollars and did not add any general purpose lanes. Only adding 1 HOV lane has been a huge mistake and a joke. When the bridge opened it didn't have enough capacity and will need to be expanded.

WSDOT said...

Jeff- The decision to replace the old, four-lane floating bridge (and adjoining highway) with six lanes followed years of public discussion and debate. Some people advocated a deep-bore tunnel under Lake Washington. Others wanted an eight-lane highway. Still others wanted no highway expansion at all -- just a retrofit of SR 520’s aging, vulnerable bridges. In the end, the state Legislature approved a six-lane corridor, including bus/HOV lanes in each direction. It’s important to note that the new HOV lanes will improve traffic flow both for buses and carpools and for drivers in the general-purpose lanes. Traffic studies indicate that when the highway is rebuilt all the way to I-5, peak-hour commutes between Bellevue and Seattle could be about a half hour shorter for all motorists and transit riders when compared to the old, four-lane highway.

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