While it waits for $150 million in funding from 2015 Connecting Washington Transportation Bill, the Washington State Department of Transportation continues to look at ways to improve safety around the often congested I-90/SR 18 interchange.
That funding won’t become available until 2023 – and even then the initial funding is for interchange design. Construction on the multi-year improvement project isn’t estimated to begin until 2025. WSDOT says final configuration of the interchange is not yet known and will be determined once transportation bill funding becomes available to work on the design.
With a longterm solution for the congestion and dangers at the signal-controlled interchange still a decade away, WSDOT is looking at low cost measures to enhance safety in and around the interchange, which it says “experiences significant congestion on every approach.”
One of the biggest dangers of the interchange is that traffic waiting to access SR 18 is often backed up onto the mainline of I-90, where traffic zips by at 70mph. Recent accidents on I-90 and SR 18 near the interchange have been attributed to drivers not slowing soon enough when these backups are present, which in turn caused chain reaction crashes.
In response, WSDOT is working to install signage that would help alert drivers earlier to these back ups. On eastbound I-90 new signs were installed last week alerting drivers who are traveling east past SR 18 to keep left (see right).
Another new sign (NO RIGHT TURN THIS LANE) was also recently installed. It addresses the behavior some drivers call ‘cheating,’ where vehicles turning right onto SR 18 will get in the left turn only lane to make their right, which results in other drivers sitting and waiting longer on I-90.
More Improvements Coming this fall
Drivers should notice new striping on the right eastbound I-90 lane that exits to SR 18. The wide dotted lane striping will be extended farther west to coincide with the 1-mile advance overhead guide sign for the ‘exit only’ right lane to SR 18. WSDOT feels this will provide drivers more advanced warning of the exit only lane that routinely becomes a “waiting lane” for SR 18.
Tired of drivers making u-turns in the interchange? If so, drivers should also notice a new ‘NO U-TURN’ sign installed on the signal mast arm at the entrance to westbound I-90 from northbound SR 18. Currently many drivers avoid the long wait from eastbound I-90 to SR 18 by getting in the left turn lane, heading toward Snoqualmie Ridge and then pulling a u-turn at this light.
As a result, these u-turn taking drivers often create long back ups for westbound I-90 drivers trying to get to SR 18, making overall traffic worse at the interchange. WSDOT says they will do some community outreach to inform drivers of this new restriction and coordinate with WSP to also enforce the new restriction.
Electronic Warning Signs in the Design Phase
Another idea WSDOT design teams are evaluating for this area of eastbound area of I-90 (construction dollars haven’t been identified yet) is Advanced Queue Warning Signs – two blank out signs that turns on when they sense cars waiting in the right lane for SR 18. One sign would be placed about two miles from SR 18 and the second would be about one mile from the exit. The cost of the signs is estimated at $300,000.
WSDOT is also evaluating using these same warning signs on the westbound I-90 approach to SR 18.
Weighing Risk with Interim Improvements, Longterm Solution for 90/18
As WSDOT explores interim options to improve safety around the interchange it has to weigh some risk associated with whether or not the improvement will be compatible with the final interchange design. WSDOT has previously stated a flyover ramp and a lane expansion of SR 18 would be part of the design, and if that ends up being the case, the state doesn’t want to spend millions on temporary fixes that would have to be removed when that works begins.
One idea that had been explored was hardening the shoulder or northbound SR 18 for about a mile at the the merge from eastbound 90 The thought was this peak commute lane would get some cars off of I-90 while they waited to head up Tiger Mountain. Unfortunately the cost of this interim improvement idea came in about double over the earlier $10 million estimate due to environmental impacts and other issues.
5th District Senator Mark Mullet said one idea to achieve the SR 18 lane expansion is to request the state move up $60 million of project funding and start construction of the full 2.5 mile SR 18 expansion as early as next year. A challenge, though, is this new lane would have to be in the precise spot to ensure its future connection to a flyover ramp that could get built later.
Another improvement idea that had been explored was hardening the shoulder of the westbound I-90 exit to SR 18 to make a right turn only lane for drivers heading toward Snoqualmie Parkway – at a cost of about $2.5 – $3 million. The risk to this interim improvement is that this lane wouldn’t be needed when/if flyover ramp is constructed – so it could be like flushing that money down the drain Mullet said.
A bright spot in the 90/18 improvement discussions is that the idea of moving the weigh station has sprung back to life. Washington State Patrol, which operates the truck scales, have been actively working a a redesigned weigh station design could potentially be located close to eastbound I-90 at milepost 33.5 near Truck Town.
WSDOT says while moving the weigh station does remove constraints on the future interchange plans, it won’t significantly affect the interchange operation during congested commute hours. Senator Mullet said if the weigh station is moved and the station is closed by next summer, some of its right-of-way could be used to get Snoqualmie drivers onto westbound I-90 more efficiently and faster.
Funding for some of these identified interim projects would be requested in the next state budget that the legislature will hammer out in January 2017.