Why we are repairing the bridge?
The elevated bridge is now 40 years old and needs repair.
The bridge deck is wearing out. Worn concrete shows exposed steel rebar, potholes have formed and deep wheel ruts increase the risk of hydroplaning.
The expansion joints are failing. These joints connect the concrete spans which make up the freeway. Collisions and major traffic back-ups are a growing risk as the top steel plates of these joints detach more and more frequently. Also, the steel plates are more resistant to wear than the bridge deck material and currently act as a bump when car tires hit each joint. The bumps are not only a nuisance; they accentuate the wear and tear on both the bridge and on the vehicles driving over it.
How will WSDOT fix the problem?
Crews replaced joints and paved northbound I-5. In August, crews replaced 34 expansion joints and repaved on the northbound bridge. This created a consistent surface and smooth ride across the deck. The new joints and deck will extend the life of the bridge.
Crews will repair joints on southbound I-5. On southbound lanes, crews will repair the existing expansion joints and perform minor deck repairs. Some of this work was completed in July and more will occur in the weeks ahead. WSDOT will eventually replace those joints, but not until that bridge is overlaid, which is not scheduled until about 2015. Deck overlay work and replacement of the expansion joints are best performed concurrently.
Is this really necessary?
The expansion joints are failing and potentially pose a serious risk as the top steel plates of these joints detach more and more frequently. A steel plate easily becomes a dangerous obstacle on the roadway for drivers traveling at speeds of 60 mph and faster. The existing joints often require costly emergency repairs, sometimes in the middle of rush hour, putting drivers and WSDOT crews at risk. The failing joints also leak, risking corrosion to the bridge foundations. The deteriorating bridge deck creates a dangerous, uneven driving surface, especially in wet weather when pooling water in deep wheel ruts causes drivers to hydroplane.
Why didn’t you fix it before?
WSDOT crews have been able to maintain the bridge with short-term fixes for years. Funding is now available to implement a long-term solution to the northbound bridge. Since the northbound lanes are scheduled for a deck overlay this year, WSDOT will be able to replace the joints at the same time. The new joints and deck will wear at the same rate, extending the life of the bridge.
Why aren’t you replacing the joints on southbound I-5?
The bridge deck on this section of southbound I-5 is in better shape and isn’t due for new pavement until about 2015. Temporary repairs will extend the life of the joints until we can replace them and overlay deck at the same time.
Southbound work will require nighttime lane closures over the course of up to 45 nights, to be conducted before and after northbound lane construction.
Why will this take 19 days?
Crews must remove and replace expansion joints that connect concrete freeway slabs on I-5 by removing and replacing significant amounts of concrete. Given the time it takes for concrete to cure, or fully dry, it is not possible to complete this work overnight. We concluded that concentrating this work in a possible 19-day time period from Aug. 10 through Aug. 29 would allow us to get the job done as efficiently and safely as possible with the least effect on drivers and businesses.
Why not do the work on weekends and nights?
WSDOT examined dozens of ways to complete this construction work while keeping traffic moving. The 19-day intensive August closure will allow us to get in, get the work done and get out of drivers’ way as quickly and safely as possible.
We crunched the numbers. Our calculations showed the closures would require up to 68 nights and 11 weekends. This could extend the project into two construction seasons, creating a long-term construction nightmare in the middle of downtown Seattle. Delays could force nighttime closures to extend into the morning rush hour. Numerous weekend closures would interfere with events for months.
Why do the work in August?
August offered the fewest conflicts with other major events. WSDOT coordinated with the City of Seattle and many other agencies and organizations to schedule this project when it would not interfere with major city events like Seafair, the Bite of Seattle and Bumbershoot.
Traffic volumes and transit usage is lowest in August. Lower transit usage means more space in Park & Rides for drivers taking transit for a change.
August is the best time of year to ensure good weather and reduce the chance of delays. Cool or wet weather would force us to delay paving, or worse, force us to extend closures and/or keep lanes closed when no work is going on. Unexpectedly wet or cold weather would force us to extend the construction work into 2008, putting the job in direct conflict with other major construction projects in the region.