September 20, 2001

Urban mobility: it’s make or brake

It is no surprise to anyone living in the Puget Sound region that traffic congestion is at an all-time high, especially freeway congestion.

The state Department of Transportation has embarked on a major reconstruction of the transportation corridor between Tukwila and Federal Way.

Many factors have contributed to the congestion including suburban population growth, increase in vehicle travel, no major freeway expansion in the last 10 years, and continued reliance on the automobile as the preferred transportation mode.

There are two types of congestion, recurring and nonrecurring. Recurring congestion is mainly due to too many vehicles and not enough lanes. This means we are reaching the capacity of the system. Nonrecurring congestion is due to incidents on the freeway system. This type of congestion is becoming very common due to accidents, disabled vehicles and debris on our freeway system.

Freeways are clogging up faster than we can build them. Even if we embark on an ambitious freeway expansion program, things will not change overnight. It will take a long time before we see and feel any relief.

Wondering why? Consider this: the planning, design and construction cycle for a major freeway project is approximately 10 years. This is due to many factors such as permitting, environmental regulations and agency coordination, to name a few.

To make things worse, freeway congestion is spilling over to city arterials and collectors. The potential for gridlock on city streets is very real. When freeways are congested, daily commuters try to bypass the congestion by using alternative surface streets. Though drivers should use these roadways to get to their final destination, most streets are not capable of handling the extra traffic.

Unlike freeways, which typically are congested due to overcapacity, accidents, and egress-ingress points, city streets suffer from the following shortcomings:

• They have traffic signals that meter traffic flow. At best the traffic lights are green for no more than 70 percent of the time along major city streets. During the remaining 30 percent, traffic has to come to a complete stop whether or not streets are at capacity.

• Many city streets have multiple access points (such as driveways and intersections) and other design features, including center-turn lanes or right-turn lanes, that cause friction and delay for drivers along these streets.

• City streets typically have pedestrians using them, which creates friction with automobiles and thus reduces the overall throughput of these streets.

So are we in for more congestion on city streets?

Our regional transportation planners and engineers are working on many fronts in an effort to manage existing and future congestion on the freeway and arterial systems. I will highlight a few of the projects they are deploying along the region’s arterial system.

The regional planners and engineers are using among other things the following techniques to reduce arterial congestion and improve traffic flow:

• HOV (carpool) lanes and access management.

• Traffic signal-timing synchronization.

• Transit speed and reliability enhancements.

The Washington State Department of Transportation, in cooperation with several municipalities located along International Boulevard and Pacific Highway South, has embarked on a major reconstruction of this corridor from Tukwila to Federal Way. The project is being completed in several phases. The work in SeaTac is mostly complete, while construction in Des Moines, Kent and Federal Way is under design.

The project will add HOV lanes and manage access on this corridor. HOV lanes are being used to provide incentives for carpooling while enabling buses to meet their schedules.

Access-management is intended to provide a safer and more efficient corridor by reducing friction and conflicts between business-access and pass-through traffic. Various national studies have shown that access management techniques alone can decrease crash rates and stops by approximately 25 percent to 50 percent.

King County’s transit speed and reliability program recently embarked on an effort to work with local jurisdictions in order to coordinate traffic-signal timings. The intent of this effort is to synchronize the traffic signals to provide fewer stops and delays along some of the busiest corridors in the region.

The county has allocated approximately $400,000 in grants for project, which includes planning, implementation and evaluation phases. The final project evaluation should be completed by the end of 2001.

In addition to signal-timing optimization, King County Metro is deploying a transit signal priority system that provides extra green time for buses who meet a minimum set of criteria such as being behind schedule, number of riders and route number. Two pilot projects have been deployed with another on the way. The two pilot projects — one on Rainier Avenue South and the other on Aurora Avenue North — have shown a reduction in bus travel times in the range of 8 percent to 10 percent.

Also WSDOT, King County, and other local agencies have started to plan and deploy what is called Intelligent Transportation Systems along some regional corridors such as 124th Street in Kirkland, 148th Avenue in Bellevue and Redmond, and the TransValley Corridor in the Tukwila, Kent and Renton areas. These projects will deploy advanced communications technologies and improved signal systems to improve traffic flow for buses and general vehicles in these corridors.

Despite the efforts of the local planners and engineers there are major challenges in the region. The plans under way and discussed above are not sufficient to avert a major gridlock on the regions streets.

The biggest challenge for the Puget Sound region is finding stable and long term funding sources for transportation projects. Some of the region’s challenges include:

• The planning, design, and construction of the region’s megaprojects. These include but not limited to state Route 520 bridge, Tacoma Narrows bridge and the Interstates 5 and 405 corridors. These projects will require stable funding sources for years to come.

• Agencies that are unable to keep up with the most basic level of maintenance and operation of their existing transportation infrastructure. This is mainly due to funding and staffing constraints. With this in mind, agencies will continue to struggle in providing anything but the most urgent and basic of traffic operation and maintenance.

• Institutional issues facing the Puget Sound region. The different agendas out there represent a major challenge that will always make or break any potential transportation solutions for this region.

The bottom line is that it will take political courage, will and stamina to meet the region’s transportation challenges.

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