Friday, September 27, 2019

Accelerated roundabout construction to close Medical Lake/SR 902 interchange for 10 days

By Ryan Overton

Fall has arrived and in most cases our road projects are starting to wind down. But for one project just west of Spokane, it is quite the opposite.

The Medical Lake/SR 902 interchange improvements project is about to pick up quite a bit. At 4 a.m. Monday, Sept. 30, contractor crews will close the westbound I-90 on- and off-ramps, including the intersection at SR 902 at the westbound ramp terminals. The intersection of SR 902 and Geiger Boulevard will also close. They are scheduled to reopen early on October 10.
This closure will allow crews to completely build the second of three roundabouts for the project in just 10 days. On October 10, not only will the second roundabout open but the roundabout currently being constructed at the Geiger Blvd and SR 902 intersection will open as well.
The Medical Lake/SR 902 interchange will fully close for 10 days for roundabout construction.

This project was accelerated due to delays associated with utility conflicts on the project worksite. Accelerating the roundabout construction will allow for the second roundabout to be completed this year and keep the contractor on schedule.

So how do you build a roundabout in 10 days? 
Normally, roundabout construction might take 6 or 7 weeks. In this case, we’re packing the work into 10 days, which takes a lot of careful planning, communication and coordination. Originally the contractor was slated to build the roundabout in about 28 working days, typically five days a week, 8 hours a day. The total number of hours equates to about 240-252 working hours. On this accelerated schedule, crews will work 10 days straight, 24 hours per day, equaling about 240 working hours.

Fully closing the interchange allows the crews to work in a much safer environment than if traffic was still moving through. This will allow work to flow in a way that isn’t possible when live traffic is also present.
The concrete being used for this project is also unique. During typical construction, concrete takes about seven days to gain enough strength after pouring to allow other work to happen around it. During the accelerated construction a special concrete mix will be used for curbing and the islands, which will gain the required strength in about 18 hours.
This concept drawing shows the locations of the two new roundabouts being constructed in Medical Lake.

What sort of coordination is needed to pull this off?
Since there is little room for schedule delays, constant communication and planning with subcontractors is vital. Getting time and date commitments for the various construction work is crucial in pulling this off. It also means crews will work different shifts, so communication and transition of work needs to be seamless.  For example, the asphalt paving subcontractor can’t start their work until the curbing subcontractor is finished.

The other challenge was finalizing detour routes and coordinating with local businesses. The Medical Lake/SR 902 interchange is a key access point for trucking, businesses and a link to the city of Medical Lake. Detours can take weeks or even months to develop and that had to be expedited. That included coordinating with the City of Airway Heights and Spokane County to get approvals to use their roadways, as well as soliciting feedback from local businesses.

How to navigate the closure:
  • Drivers traveling on westbound I-90 who normally get off at the westbound Medical Lake/SR 902 off-ramp will have two options:
    • Taking the Geiger/Grove exit will allow for better access to the south side of the Medical Lake/SR 902 interchange. The route will take you south on Grove Road, west on Thorpe Road, south on Thomas Mallen Road and west on Hallett Road.
    • The Four Lake interchange will be ideal for drivers wanting access to SR 902 and travel to Medical Lake.
  • Business owners along Geiger Blvd, Hayford Road and SR 902 will have local access by taking the Geiger/Grove interchange, traveling west on Geiger Blvd to Electric Ave, then can access local businesses from Hayford Road or travel north to Hayford Road, west on McFarlane Road and then south on Craig Road to access local business along SR 902 or White Road.
  • While I-90 in both directions and the eastbound on- and off-ramps will remain open, travelers needing access to I-90 are encouraged to drive east on I-90 from the Medical Lake/SR 902 interchange, exit at the Geiger/Grove interchange to then head back west on I-90.
Once completed, drivers will begin using both new roundabouts and traffic will flow seamlessly through the intersection.