On October 10 Seattle Department of Transportation nipped a potential problem in the bud, literally.

Using what SDOT calls a “nipper,” Staton construction crews deconstructed the damaged northern most girder of the West Emerson overpass above 15th Avenue West.

Staton Companies was contracted by SDOT for the demolition.

The overpass was built in 1959 and has provided essential access for residents to Magnolia and freight trucks to the train yard in Interbay and Fishermen’s Terminal.

SDOT speculates that the overpass was damaged last November or before by a large truck bearing a load too high to clear the overpass. SDOT does an inspection of the overpass every two years. The load hit the northern most girder causing a large chunk of concrete to break off. The overpass is supported by a series of girders that stretch 100 feet across its underbelly . The girder struck maintained support for the roadway deck on top and guardrail.

“We know at least sometime preceding last November something big ran into it, but we don’t know what it was since we don’t have cameras in that area. It was probably a big truck carrying an over height load that should have pulled permits, ”said Art Brochet, Communications Lead for SDOT.

Traffic was diverted and the demolition started at 9 p.m. and crews worked through the night sawing and chunking out the concrete pieces of the girder using the “nipper” – a large loader machine that uses a hydraulic “pincher” that resembles the head of a menacing dinosaur instead of a loader bucket.

The pincher plucked away at strategic points of the overpass causing a controlled deconstruction. Large pieces of concrete and rebar fell from the overpass and thudded on the streets. To prevent damage to the street, crews spread 18 inches of dirt to insulate the road surface from the impact. The vibration from the super sized jackhammer reverberated in this reporter’s chest. White dust plumed in the bright florescent-lit air as crews loaded the shattered pieces of concrete and steel in large trucks. The scrap was taken to a construction waste-processing site to be recycled.

On top of the damage to the girder, the joints were exhausted and needed replacing. Other than that Brochet said that the overpass was functioning fine for regular traffic but there were possible risks if no action was taken by SDOT.

“With this girder damaged, the load rating comes into question. If another vehicle carrying a load too high struck it again we might have had to close the overpass quickly because it would not have been able to bear the weight of passing traffic.”

Before deconstruction started, Brothel said, “The structural integrity is not impaired at present, but we are concerned about it being struck again. Even debris falling from a girder that’s breaking up would not be good for falling traffic.”

The project is expected to cost tax payers $5 million. However, SDOT did secure a Federal grant around $1.2 million for the road deck around the same time they decided to replace the girder.

“That’s ($5 million) one part of the project, but there is a Federal grant for the top of the road deck. Concrete is pretty tough stuff but it erodes after a while, and the deck was eroded almost down to the rebar. … We were persistent in securing the grant. We look for all the funding we can for the backlog of maintenance projects we have.”

The scheduled date for the projects completion is December 23rd;
and but Brochet said that’s if everything goes well and SDOT is able to proceed with no delay due to weather. Brochet said the project is likely going to be delayed due to rain.

“What we need at the end of the project are four days -- not necessarily consecutive days -- where the weather forecast is reasonable good enough so we can poor the concrete for the road deck. Driving rain or a forecast of that type we wouldn’t go foreword with it, so we think we are going to finish at the end of the year but more closer to the first week in January or a couple weeks later depending on weather.

Brochet also mentioned a future project much further down the pipeline. SDOT is looking into rebuilding the entire overpass in order to make it larger and handle more weight.

“There is a plan like so many others on the books that would need supplemental funding and would replace the existing overpass with a new one with more capacity and would be higher, but that is 25 years out and there are lots and lots of other structures that serve more traffic and need more attention.”

SDOT states on their website that the repair work will require the complete closure of the West Emerson Street overpass to all traffic (including pedestrians) beginning on October 9, 2014 and will last through the duration of the work (approximately 12 weeks). The detour for west-bound vehicular traffic on West Nickerson Street will be a double crossing of the Ballard Bridge (using Leary Way Northwest for the turnaround) to reach West Emerson Street.

Long term detours beginning Oct. 9th include (Information provided by SDOT):
• Westbound to Magnolia: Travelers will have a signed detour route to Northwest Leary Way and back via the Ballard Bridge.
An alternate route (not suitable for freight movements) exists via the one-way Nickerson-15th Avenue West Ramp and southbound 15th Avenue West to cross Interbay using West Dravus Street and reconnect with West Emerson Street via 20th Avenue West and Gilman Avenue West.
• Eastbound to Fremont: Travelers will have a signed detour route to West Emerson Street. Traffic will be detoured to West Dravus Street and back using 15th Avenue West. 
An alternate eastbound route (not suitable for freight movements) exists via Gilman Avenue West and 20th Avenue West to cross Interbay at West Dravus Street and then reconnect with West Nickerson Street via northbound 15th Avenue West.
• Pedestrian and bicycle routes: Pedestrians and bicyclists will need to use the Ship Canal Trail to cross under 15th Avenue West. The stairways just south of the West Emerson Overpass will be closed; all other stairways will remain open.
• Some residential parking restrictions along the detour routes will be in place to provide King County Metro buses adequate turning room.

For more information on the long term closured scheduled, SDOT advises citizens to visit the project website for maps of detours and alternate detour routes at www.seattle.gov/transportation/15thAveWestOverpass.htm. In addition, email updates on the project can be requested at 15thAveWestOverpass@seattle.gov.