Link light rail construction across Southbound I-5 at Boeing Access Road almost complete – Northbound work scheduled to begin

Sound Transit’s construction of a new light rail overpass across I-5 just south of the Boeing Access Road is nearing the halfway point. Full closures of I-5 southbound plus partial lane closures on northbound I-5 are scheduled through this Wednesday night-Thursday morning. Crews are employing a construction method and schedule that keeps the freeway open during the day, limiting lane closures and traffic impacts to nighttime hours.

During the full Southbound I-5 closures, all traffic on I-5 southbound will exit at Boeing Access Road (BAR), turn left onto BAR, and then turn right at MLK onto the I-5 southbound on-ramp. Motorists should expect delays and plan for extra time.

Lanes will begin closing progressively at 8:00 p.m. with the full southbound freeway closure occurring at midnight. All lanes will reopen by 6:00 a.m.

After all the pre-cast concrete sections of the western half of the overpass are placed, work over I-5 will halt for several days while crews move equipment to the east side of the freeway for the second half of the project. Beginning next week, crews will also be working on the NB I-5 ramps. This schedule is subject to change, especially due to weather conditions.
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About the construction

The construction utilizes pre-cast concrete segments in a balanced cantilever design, a method first used in the Puget Sound region last summer when Sound Transit built a light rail bridge crossing the Duwamish River. For the I-5 overpass two large bridge piers have been built, one on each side of the freeway just south of the existing Boeing Access Road overpass. Starting with the pier adjacent to southbound I-5, giant cranes are hanging the pre-cast segments one at a time on alternating sides to keep the structure in balance. Steel tensioning cables running through the segments keep them in place as the structure extends in each direction. After the structure is built over the southbound lanes of I-5, the structure over the northbound lanes will follow, and the two structures will connect above the freeway.

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Fact Sheet >>>  (pdf, 380 kb)
Graphic >>> (pdf, 167 kb)
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