Spring kicks off next phase of construction on SR 532

As spring brings warmer nights and longer days, improvements along the SR 532 corridor are picking up speed.

The white plastic draping the embankments on either side of the highway between I-5 and Stanwood will come off in April, to reveal green grass waiting underneath. This will be a huge, immediately visible improvement, said Dave Chesson, a Washington State Department of Transportation (WSDOT) communications official.

Paving is also scheduled for April. Greg Pindras, project manager for Parsons Kuney, the construction company completing the work, said April 15 should kick off the paving.

The section of roadway between I-5 and 12th Avenue has been widened to accommodate a new lane from the off ramp. The existing right-turn only lane will be pushed through to join the westbound truck-climbing lane, Pindras said.

On the south side of the roadway near 12th Avenue, the land slopes steeply to a creek below. Pindras said geo-technicians bored into the ground for samples of the soil profile and discovered clay layered over silt, a relatively unstable profile.

Crews are building concrete forms for diaphragms that will cement the girders together and provide support for the bridge deck. A voided slab will connect these easternmost girders with an MSE wall fashioned from PHOTOS BY JEREMIAH O “Based on that,” Pindras said, “we’re going to decrease the angle of the grade to prevent slope failure.”

Farther west, by Lenz Trucking, crews have widened the road and are ready to pave. The road will then be re-striped, adding a westbound center acceleration lane for trucks making left turns out of Lenz. The westbound deceleration lane for trucks turning into Lenz will also be lengthened and lighting will be installed.

Near the high school, the intersection of SR 532 and 72nd Avenue NW is getting a drastic overhaul.

Pindras said when it’s finished, it will be a wheelbase (WB) 50 intersection, meaning it has widened corners to accommodate large truck and trailer rigs.

All four sides of the intersection will have three lanes: a left-hand turn lane, center through-lane and right-hand turn lane. Crews will also install new lighting and traffic signals.

The new configuration should ease congestion from school-related traffic, Pindras said.

Between 72nd Avenue NW and Pioneer Highway, crews are working to clear the south embankment so the roadway can be widened to include an eastbound truck-climbing lane.

This SR 532 and Pioneer Highway intersection is also having its corners widened for a WB 50 rating, and a retention pond has been added near the fire station.

This pond is one of eight total in the project.

Pindras said the ponds are mandatory for controlling runoff, because so much impervious surface is being added. Regulations have also changed since the existing roads were built, and any improvements to those roads must include bringing them up to current code.

Also coming up are improvements to SR 532 from the viaduct west to the new Mark Clark Bridge.

The entire roadway will be resurfaced and re-striped, and some driveways and curbs will be reconfigured to improve traffic flow and safety.

Near Rite Aid and QFC, crews will repave over the existing roadway, but downtown, where the pavement is in especially bad shape, and where the elevation of grade is especially critical, the roadway will be ground out and then repaved.

At the new Mark Clark Bridge, crews are moving quickly to build the embankment and mechanically stabilized earth (MSE) wall that will bring the westbound approach road up to the level of the bridge deck. Crews are using heavy-gauge wire baskets filled with rock and interlocking layers of synthetic mesh to create structural integrity, Pindras said.

All 17 of the bridge girders are in place atop the columns, and crews are building the concrete forms for the pours that will cement everything together.

Pindras explained that the process has three essential steps.

First, he said, crews will build the forms for the diaphragms (the concrete that fills the gaps where the ends of the girders meet). Then, they will pour in a layer of concrete about one foot deep. This will cement the girders in place atop the pier caps, but still allow them to flex, which is important for the next step.

Secondly, Pindras said, crews will pour the bridge deck, leaving a void where the girders meet. The bridge deck will “load” the girders, causing them, basically, to sag under the weight. The ends will “deflect,” or pivot slightly, to release the tension.

Finally, the gaps between the girders will be filled and the bridge deck finished.

This is important, Pindras said, “so you don’t lock tension into the bridge.”

If the ends weren’t allowed to deflect, the girders would be like springs, and the tension would decrease the bridge’s longevity and capacity for weight.

A section of voided slab will connect the approach road to the first set of girders on the east side of the bridge. Voided slab is a low profile, pre-cast material that allows the minimum clearance over the railroad spur running beneath the bridge, while lowering the overall height of the bridge deck to increase visibility as motorists travel across.

Pindras said this will drastically increase the safety of motorists turning on Eide Road, which is nearly a blind intersection due to the arch of the existing bridge.

Chesson said Aug. 7 is the target date for opening the new bridge.

Motorists will be treated to 12-foot-wide lanes with a 4-foot median between them. 14-foot shoulders will provide plenty of room for pulling over, as well as for pedestrians and cyclists.

Once the new bridge is open, crews will proceed with disassembling the existing bridge.

Another set of work platforms will be built on the south side of the bridge, one on each side of the slough, to support the demolition equipment.

The pavement and steel will be cut up and hauled away, and the concrete structures will be crushed and recycled after the rebar is separated out.

The large, existing columns will be broken off two feet below grade and backfilled over.

One of the final steps will be reshaping the existing embankments and tying them into the new approach roads.

If all goes according to schedule, the entire project should be completed by end of the year or beginning of next.