Friday, October 12, 2018

Improving SR 18 safety not a simple task

By Mike Allende

We get plenty of questions about SR 18 over Tiger Mountain, especially following collisions. Unfortunately, there are no simple – or low-cost – solutions to improving the highway.

At first glance, installing a center barrier seems like a straightforward and inexpensive solution. But there’s actually much more to it.

A center barrier requires six feet – at a minimum – down the center of the highway. You need room for the barrier and a few feet of space between the barrier and vehicles. To make that happen, we would need to move traffic to the outside shoulders. OK, so, just do that, right?

Well, again, it’s not that easy.
In many areas, SR 18 would need to be widened to accommodate the barrier, moving traffic to the existing shoulder and rebuilding the shoulder to become a lane. The shoulder as it is now isn’t paved to what is known as “full depth,” meaning it’s not built to handle the weight of traffic thousands of vehicles that would use it each day would present. We would need to excavate the existing shoulders to create a new roadway before traffic could drive on it. Even with this portion, several feet would be needed for a new shoulder for stalled or disabled vehicles to safely pull off the travel lanes.
Sections of SR 18 would need to be widened in order to place a center barrier in the roadway.

There are also several fish barriers – culverts or bridges that don’t allow fish to easily pass through the area -- along that stretch which would need to be replaced during a widening project, and several unstable slopes would need to be addressed. There also is no funding to widen SR 18 between Issaquah-Hobart Road and Deep Creek at this point. The Legislature has provided us $1 million to complete an initial assessment of how much it would cost to design and build a wider SR 18, and those funds become available in the next year. Once that work is done funding would be needed for the design work and construction.
While some funding has been provided to assess the cost of widening SR 18,
no funding has been provided for design or construction.

There are no simple solutions to highway safety. We all play a role in making sure everyone stays safe on the highways. We’ll continue to work within the resources we have to enhance roadway safety and we hope motorists drive safely on the roads. As funding becomes available we’ll look for more ways to improve the highway system for all users.

23 comments:

RobertSeattle said...

Is Highway 18 statistically more dangerous than similar highways in the state?

jputnam said...

There are no simple, inexpensive, popular solutions.

Lower the speed limit to 30-35 mph and you can get by with narrower lanes and less shy distance, and any remaining crashes will have lower severity.

I realize that would require making safety a higher priority than speed, so it's never going to happen, but that doesn't mean it wouldn't work, only that it won't be tried.

WSDOT said...

Hey jputnam,

Appreciate your feedback.

There’s no indication from the Washington State Patrol that speed was a factor in Friday’s collision. They found that one of the drivers was driving while impaired.

During most hours of the day when there is no congestion on SR 18, travel speeds tend to be over 60 mph (the posted speed limit is 55). Reducing the posted speed limit along that stretch will have little effect on reducing overall travel speeds and result in more inconsistent travel speeds between vehicles, leading to increased safety concerns like tailgaiting and risky passing maneuvers. The roadway design is consistent with the existing speed limit. A posted maximum speed limit is just that, and doesn’t replace a driver’s obligation to adjust/reduce their speed appropriately in response to conditions.

Unknown said...

Say..in a perfect world...if you could have the whole of 18 shut down over the Tiger Mt. Summit in order to complete a full widening to satisfy current and future traffic levels, what kind of time frame would we be looking at?

Daniel said...

Ask the destroyed family how much is worth the central barrier.

Unknown said...

SPEED BUMPS.. PLACE SPEED BUMPS AT THE NUMEROUS MVA SITES.. INTENTIONALLY SLOW PEOPLE DOWN

Jon the shooter said...

Great to see traffic planning aware of the 85th percentile speed. So many people think speed limits are magic and can just automatically slow cars. :)

Unknown said...

Highway 18 is in dire need of expansion both to improve traffic flow and improve safety in both directions. It is a main highway out of the Maple Valley and surrounding areas that are growing at a rapid rate. Traffic is getting worse by the day and will only get worse with all the new homes being built. An upgrade to highway 18 is long over due. Not only should it be expanded, but some under and over passes or what is called a clover leaf would open the bottle neck where hwy 18 and I-90 meet. something also needs to be done with an expansion in both directions as semi trucks often create extremely unsafe conditions with the much slower speed they travel and trying to maneuver around each other in two lanes of highway. These improvements should have taken place before all of this new construction was started.

KimmieJoe said...

Though I can see WSDOT's argument, the deaths have to stop and they're working on other projects that aren't designed to stop the deaths. Where's the urgency, the care for the loss of human lives, the concern over frustration of those of us who use Hwy 18 and/or are impacted by the I-90 backup and the lane jumpers that cause so many accidents on I-90 when people are driving 70+ mph.

Shannon Robinson said...

So you need a million dollars to study exactly what you just published? I understand the need to stabilize some of the slopes but the fish that don't exist need an expanded path? Innocent people are dying and the state wants to spend money on a study that everyone knows the answers to. Congrats on wasting money.

Unknown said...

Have the state quit spending money on I-5 and 405 and use it ti fux Hwy 18. Its rediulous that hey 18 cant get fixed. Pretty sad!!!

Mark Sogge said...

Slightly different topic but what would it take to extend the second eastbound lane from the top of the hill east of the Raging River bridge to the interchange with I-90? It seems to me it would relieve all that congestion of the traffic having to merge back to one lane.

Candi Smith said...

If WADOT would build roads to 20 yrs down the line capacity...we would have had a 4 lane all the way from I90/Hwy18 to Auburn but no you guys never look to the future. I hate that road, it scares the hell out of me so I usually drive to Issaquah and take the back road to Hwy 18...takes much longer but makes me feel a bit safer too!

Ardella said...

My friends died in the accident yesterday and something has to be done to save lives!!! I myself have almost died several times due to semi trucks crossing the line in that very spot my friends died!!! Please do something!!!!!!

Unknown said...

Our region would be served better by coming up with solutions to the 30+ min trip from the base of tiger mountain to I-90 from 5am-830am every weekeday morning commute. How about extending the truck lane north of Raging River all the way to the I90 Eastbound on ramp?

fred bowman said...

one of the choke points on 18 is at the I-90 intersection. Why cannot the truck lane on north/eastbound 18 be extentended to the east bound on ramp to I-90. That would relieve some of the back up. The shoulder is there and just needs to be graded and paved. We were promised over ten years ago that hiway18 would be completely 4 laned but the project keeps getting delayed and money wasted on another study. We passed a tax increase on our fuel to build better hi
ways but are not seeing any improvement. Hobart Issaquah rd. is another place that needs attention and a huge amount of money was spent on a study that just told us what we already know. There is to much traffic on a small road that whould have been inlarged years ago. STOP STUDYING, TRY ENGINEERING.

Nojwerel said...

I'm surprised that WSDOT would mention that there is no indication from the Washington State Patrol that speed was a factor. They shouldn't need to. Even if both vehicles were going the speed limit (55 mph), the force caused by that collision alone guarantee's less than 50% survivability.

Additionally, have you done a study to determine whether a reduced travel speed would increase tailgating and risky passing maneuvers? Or is that a theory? How can you claim that reducing the posted speed limit along that stretch will have little effect on reducing the overall travel speed? That's what the WSP is for. I'm sure they would love to write some tickets in a speed reduction zone, just as they did when WSDOT lowered the speed on the SR101 approach to I5.

Unknown said...

People are dying, find a way. What I read in your blog is this: “Our job is hard, and the state doesn’t really value all the lives that have been lost, and that will be lost. Except the fish - we all work to save the fish.” Traffic congestion alone warrants the work to finishing improving and widening this road, but the deaths (two more this past week!) must make this a state priority. In this case, patience is not a virtue, it is a death sentence for some unknown family or families. Mitch Reinitz, Issaquah.

WSDOT said...

Thanks for your message. It’s not a matter of valuing lives. No one wants to see anyone get hurt on the highways. We would love to do every project that is on our list to do. The bottom line is we can’t do projects that don’t have funding. Like any other project, the legislature has to earmark funding for the work. If you want to see SR 18 widened, barriers installed, etc., your best bet is to let your elected representatives know that you’d like to see funding provided for that project.

WSDOT said...

We are in the process of designing and planning improvements to the I-90/SR 18 interchange area and will pass your suggestion along to that group. Construction on that project is expected to begin in 2021.

WSDOT said...

We're in the process of designing and planning improvements to the I-90/SR 18 interchange area and will be sure to pass this along to that project team. Construction on that is tentatively scheduled to begin in 2021. More info here: https://www.wsdot.wa.gov/Projects/I90/SR18ICImprove/default.htm

WSDOT said...

In response to the fourth comment, by Unknown: Is this also assuming that the project has been fully funded?

Unknown said...

prohibit large trucks/semi trucks, vehicles over so many pounds, and lower the speed limit

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