Wednesday, December 12, 2018

Changes to the new SR 520 Trail? You decide!

By Steve Peer

UPDATE
Wednesday, Dec. 27 at 8:40 a.m.
We've tied green ribbon on the railing adjacent to the new plate to make it stand out. A sign has been added, and “test” has been spray-painted on the new plate as well.

Thank you for your continued feedback! So far we've heard from more than 220 of you who want us to replace the existing plates, and less than 10 who say you see no difference/the old plates are fine.


State Route 520's new trail across Lake Washington has garnered high praise from more than 300,000 users since its December 2017 opening. Bike riders, runners, dog walkers and folks out for a relaxing stroll tell us they're delighted to have a new, foot-powered trail with scenic lake and mountain views. And many pedal-pushing commuters say the new trail, as an alternative to I-90's cross-lake connection, is cutting significant time off their daily treks between the Eastside and Seattle.

There's one aspect of the path that's not getting rave reviews: the narrow steel plates covering the trail's expansion joints on the bridge. Some bike riders tell us the plates are jolting, especially for road bikes with skinny, highly inflated tires. I've ridden the trail myself, several times, and experienced the thump of each joint cover.

I'm glad to report that we're working on a remedy. Our engineers developed and installed a prototype plate designed to ease the bumps cyclists experience while crossing the floating bridge. The new cover plate design won't completely eliminate the bumps – but it should produce a marked improvement.

That's where you come in. Now that the prototype cover plate is installed, we're asking riders to #RateThePlate. After biking over the replacement plate (located near the east end of the bridge) we're asking riders to text us at (206) 200-9484 to rate their experience with two options:
  • This is an improvement, upgrade all similar plates: text "A"
  • I didn't notice a difference/the old plates are fine: text "B"
We'll solicit feedback through the end of the year. If we hear that the plate provides a better ride, we'll manufacture and install replacements for all 27 existing narrow cover plates.
A side by side comparison of the prototype (left) and the existing expansion joint cover plate (right)

Why the path has cover plates
The roadway on the new, 1.5-mile-long floating bridge has expansion joints on each end of the 23 massive, concrete pontoons supporting the structure. The joints allow the bridge to expand (or contract) horizontally as air and water temperatures change. They also allow the bridge to flex vertically as the lake's water level rises or falls. On the shared-use trail, there's an open gap at each joint that varies in width from about 2 to 4 inches. Left exposed, a gap of that size could be hazardous to someone with a cane, a skateboarder, or other trail users. So we added cover plates over each joint to address the safety risk that open gaps would pose.

The trail's existing steel cover plates are a half-inch thick, with a flat top, beveled edges and a rough, nonskid surface. When designing the bridge, we used federal guidelines to ensure the plates' compliance with the Americans with Disabilities Act.

The plates also play a role in the integrity of the bridge itself. The roadway and shared-use path are elevated 20 feet or more above the lake's surface. This design feature keeps vehicles, bike riders and pedestrians wave-free during windstorms. It also gives our crews ample room for inspection and maintenance of the pontoons below.

Because the bridge deck is elevated – up to 70 feet on the east high-rise near Medina – we use a special truck, equipped with an extendable, hinged arm and crew basket, for inspecting the underside of the bridge. This 3-ton vehicle travels along the trail for these inspections, so the cover plates must be strong enough to support its weight. Moreover, emergency vehicles, including fire trucks, might have to use the trail if a major incident blocked the roadway.
An under-bridge inspection truck

A tale of two trails
A few bicyclists have asked us why the older, narrower shared-use trail on the I-90 floating bridge is smoother than the new SR 520 Trail – without the expansion-joint bumps. The answer, once again, relates to SR 520's elevated roadway.

In the same way traffic moved on the old SR 520 floating bridge, all I-90 traffic crossing Lake Washington – including bicycles – travels directly on the pontoons' concrete surface. That means there are no heavy trucks making under-bridge inspections from I-90's shared-use path – and no need for sturdy cover plates on that path's expansion joints.

The new SR 520 Trail is a wonderful addition to the region's expanding network of trails, and we want your experience of riding the trail to be fabulous as well. Be sure to #RateThePlate after your next ride!

25 comments:

Peter said...

Thank you for the background on this issue. I look forward to trying the new cover, it would be hard to be worse than the current design.

James Webster said...

It would be great to add third option... No new plate isn't an improvement and the old plates still suck.

I rode across yesterday and didn't notice a new plate. Of course it's dark (and hard to see any plate). That itself is a bit nerve wracking. Someone is going to crash because of those plates.

Don T said...

just based on the picture it looks like its going to be way better

Peter said...

I went out to try the new plate last night since it was a pleasant evening for a ride. I didn't notice the prototype cover when going Westbound so I turned around, missed it again, then finally found it on the 3rd pass. The difference from the normal original plate is very subtle. More of a downwards dip instead of a upwards bump. Can you make the edges on the plate have a more gradual ramp angle? That seems the be the main problem with the current covers.

In addition, at night these plates are difficult to see. Some simple reflectors adjacent to the plates on the railings to warn cyclists of the expansion joint would be very helpful.

Geoff in Bellevue said...

I rode the 520 today specifically to see how the new plate feels, and I thought it was a significant improvement. I hope enough people "vote" for the new plate that they change them all out. It was practically a "non event" to ride over.

Daniel Resnik said...

I rode it today. I had to go back and forth 3 times so that I could make sure that it was the new improved bump. It is still a bump, a bump is a bump weather it is big or small. If you guys had asked any cyclists in your 40 years of planning this new bridge about whether they liked to ride over bumpy roads you would have gotten an answer. You didn't make bumps for the cars but you did for the cyclists. Shame on you.

Michele said...

The new plate is an improvement--it's not nearly as bone rattling as the existing plates. That said an equally large safety issue is that the plates are not very visible on grey days, at night, and especially on a rainy night. The yellow paint preceding the plates--which I assume is intended to give some warning about the plates--does not appear to be at all reflective (the plates and the paint aren't very obvious or easily seen even on a clear bright day). Can the plates and the warning paint be improved to be brighter and reflective?

Lisa said...

I rode the bridge this weekend and like others, I didn't notice the plate at first. I wasn't sure if it was because the difference wasn't significant or because it was significant enough that I didn't realize I was going over the plate. So I went back and rode it again to find the joint. Without a doubt new cover is better. My question is what is the cost to replace all of them? For me The question is now is the improvement significant enough for the cost?

Yuri & Steph said...

It's WAY better!

Without a doubt new cover is better.

WSDOT said...

Hi James, thanks for the feedback. Option B was intended to capture feedback like yours – either you don’t like the new plate, or you thought the old plate was fine, but regardless, you don’t think this is an improvement. Thanks as well for the feedback about the visibility, we’ll pass that along.

WSDOT said...

Hi Peter, We’ll pass the visibility comment along. Additionally, our engineers made the ramp angle more gradual (from a 2:1 ratio to a 6:1 ratio) on the replacement plate, and we appreciate your feedback if it doesn’t feel that way. Thanks for your help with #RateThePlate!

WSDOT said...

Hi Daniel, As the blog post lays out, there are many reasons why we need this plate, and there’s likely no perfect solution out there. Additionally, cars experience a slight bump as they pass over the expansion joint. There are many engineering difficulties associated with building a floating bridge and we hope this new plate, while not a perfect solution, improves your experience.

WSDOT said...

Hi Michele, We'll pass this along to our crews and see about adding a reflective element.

WSDOT said...

Hi Lisa, we're glad you like the new plate! We're still gathering feedback from the public to determine if this is a satisfactory improvement, and we haven't priced out a full replacement yet. At the end of the year we'll compile the comments we've received and if the public likes it we'll look at a cost.

Erik said...

Your post explained why the I-90 bridge doesn't have thick plates (it's not elevated with trucks driving on it), but does the path have plates at all? Wouldn't it need to have gaps between pontoons just like 520? Maybe it has them and I've never noticed it.

Daniel Resnik said...

Having ridden the old bridge for as long as it's been there I have never had to slow down for any of it's bumps and gaps. Unlike the new bridge which has bumps that you do slow down for. Nobody even gave it a thought. All they worried about was complying to some regulations that were on a piece of paper. I am not an engineer but they could have shown me the plans and when I saw raised bumps that were higher then the pavement I would have said nooooooooo. Other then speed bumps on residential streets they don't build roads with bumps, but for bicycles, then it's ok because have no idea that some of us travel at speeds of 10 to 25mph. They failed. Any comments from people who think the bumps are ok are from people who don't ride very fast so the bumps don't feel like bumps to them. And next I suppose that the bureaucrats will read this and enact speed limit signs for bicycles on the bridge. Yeah, that will fix the problem.

Unknown said...

It was difficult to discern which was the new plate...it is not well marked. I ride the 520 every day and I did not notice it until I looked for it after a friend sent me this blog. I think I know which one it is now. It seems smooth heading west and the same heading east. So I guess that is an improvement. It would be great to have a nice smooth plate over both sides of the exp joints. Thanks for caring tho.

Brigitte said...

The new plate is improvement, but not a significant one. I wonder if there wouldn't be another material (other than metal) that could be used to protect us from those gaps. Something softer maybe, more rubbery...

robert said...

New plate feels like an improvement over the existing. But is there any way to not have any "bump" and just the equal plane of grooves similar to I-90?

WSDOT said...

Hey robert, unfortunately not. The cover plates span an opening that exists because, unlike I-90, the 520 roadway/trail is elevated from the pontoons. The I-90 trail travels directly on the pontoons' concrete surface. That means there are no heavy trucks making under-bridge inspections from I-90's shared-use path – and no need for cover plates on that path's expansion joints.

Midgen said...

The test plate is a *slight* improvement in terms of the jolt you get going over it. It's still jarring, but it should help reduce pinch flats. Visibility at night is still a serious concern though. It's *VERY* hard to see!

WSDOT said...

Hey, thanks for the insight! We’ve heard the same feedback from others so were working on a plan make the expansion plates more visible. We evaluating painting reflective warning strips and potentially adding reflective road markers on the outer edges of the expansion joints to make them more visible.

Mark Follmer said...

Why does the pedestrian/bike path have these joint covers when the roadway does not?

Unknown said...

The first couple times I rode the bridge with the test plate it was hard to find. However, after more than a month now, it's clearly discernable from the other plates and a significant improvement. When traveling westbound, the second cover plate after the test plate is especially tall on the right (near the railing) to the point where I now veer to the left to avoid the right side of that plate. The contrast between the test plate and that one is stark and I look forward to an improved solution across the whole bridge... On the plus side the bumps do remind me to look up, which prevented me from hitting joggers without bright clothing on dark nights and mornings.

CJ said...

The test plate is a slight improvement, so I texted A to the listed phone number. However, I am disappointed that it is not a bigger improvement. I hope WSDOT will continue to tweak the design to get a smoother bump.

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