Getting There: Spokane Valley preps for redesign of Sullivan and Trent

The city of Spokane Valley is preparing to completely redesign the intersection of Sullivan Road and Trent Avenue in the coming years. The city recently held an open house and did an online survey to get input on which of four designs people would prefer to see.

Project manager Rob Lochmiller said there is simply too much traffic for the current design, which has Sullivan passing over top of Trent with on- and off-ramps on each side, much like a freeway interchange. “There’s a lot of issues going on,” he said. “The existing signals can’t handle the traffic now. There are no left-turn pockets on Sullivan.”

Now that Bigelow Gulch has connected to Sullivan, traffic is only increasing. The intersection’s level of service is failing at certain times and locations each day, and it’s only projected to get worse. The east and westbound on-ramps from Sullivan to Trent are also short and don’t allow drivers enough space to get up to highway speeds, Lochmiller said.

“Those aren’t up to design standards,” he said.

Adding to the issues is that the bridge over Trent is more than a foot lower than is standard, providing 15 feet, 4 inches of clearance instead of 16 feet, 6 inches. “The bridge actually gets hit quite a bit,” Lochmiller said.

Lochmiller said the city also consulted with local school districts, large businesses such as Kaiser Aluminum and the Spokane Valley Industrial Park on Sullivan Road about their design preference. Getting public input is an important part of the process, Lochmiller said.

“This is the approach we’ve done on some of our larger projects,” he said. “We wanted feedback on what citizens think of these alternatives.”

In both the open house and the online survey, residents picked the diamond interchange with peanut roundabout design option. Lochmiller said it’s the option he plans to recommend to the City Council when they meet on Dec. 13. It will improve safety, as well as provide longer on-ramps and better movement for the many semi-trucks that use the busy roads.

“It ranks best for the level of service for traffic,” he said. “We think it’s more typical for these kinds of interchanges.”

The selected design would feature an elongated roundabout, which looks like a peanut, that provides all the needed turn movements to access the on- and off-ramps to Trent Avenue. The longer on-ramps would likely mean that access to Progress Road, located just to the west of the intersection, would be eliminated from Trent.

The interchange includes two bridges on Sullivan Road, one over Trent and one over a BNSF railroad line. Lochmiller said both of those bridges are about 65 years old and will have to be torn out. “They will be totally removed and replaced,” he said. “We won’t be able to save any of them.”

Since the city can’t completely sever such an important traffic route, engineers will have to figure out a way to leave Sullivan open while that happens, Lochmiller said. That could include building half of the new bridges at a time. “We have to find ways to shift traffic,” he said. “There’s a lot of traffic going through on Sullivan. You can’t close it.”

The estimated cost of the project is $42.2 million. So far, the city has received $3 million to pay for 60% of the design cost. Once the city is able to fully fund the project, which will likely be several years away, it may take two construction seasons to complete it, Lochmiller said.

Work to watch for

One lane of Riverside Avenue downtown will be closed Tuesday between Browne and Washington streets.

The westbound curb lane of Trent Avenue between Byrd and Langley streets will close Monday for a month.