Link train from Atomic Taco
Link train from Atomic Taco

Sound Transit has identified a handful of ways to reduce noise from Link light rail, which in sections has exceeded federal standards. To help address the problem, ST is doing or has done the following things:

  • Later this month, ST will be grinding rails along most of the alignment to “create a smoother running service.” This work will take place at night starting on Monday and run through the end of the month, according to a rider alert.While the work is active, headways at night will be reduced from 10 minutes to 15-20 minutes and sometimes you’ll have to board your train at the opposite platform than usual. Sound Transit thinks that this may be related to the high-frequency noise from the trains that some have complained about.
  • Next month (January 2010), track lubricating devices will be installed where Sound Transit has identified that wheel squeal is a problem.
  • Over the next few months, two switch crossings in the Rainer Valley will be modified to have a smoother running surface which ST expected to reduce the “ka-thunk” sounds heard now.
  • The volume of safety bells on trains and at pedestrian crossings on MLK, Jr. Way have been reduced, and train operators will no longer ring bells as long.
  • Station loudspeakers have had their volume lowered, and they are now turned off after 10pm for all stations in the Rainer Valley.

It should be noted that rail grinding will have little effect on “hunting” (the left-right oscillation sometimes noticeable in faster sections in Tukwila). Phoenix’s light rail is experiencing the same issue, and it may be a combination of vehicle maintenance and track alignment.

35 Replies to “Sound Transit to Reduce Light Rail Noise”

  1. I rode Link for the first time this week, just for fun, and really enjoyed it. And during the entire ride I kept thinking to myself, “people actually think this is too loud?”

    I went to school back in Chicago and rode the L daily for the better part of three years. Compared to the L, riding Link is like taking a train in a library (and I loved riding the L). And while I’m sure that there are other systems around the world that run quieter than Link, spending money to “reduce noise” on a system that is already pretty quiet seems very wasteful.

      1. The only real justification for rubber tired trains is if you have grades too steep to handle with steel on steel. You lose a lot of the energy efficiency of a train when you give it rubber wheels.

      2. Except in poor weather when the traction capability of smooth rubber tires is actually worse than for steel-on-steel. You’d never see an above ground system using this tech in any city that gets even occasional snow.

        Add in the increased energy consumption and higher maintenance costs and it’s highly unlikely you’d ever see a system like this in built.

      3. And, in Montrea’s wonderful Metro runs you get that weird smell and black dust from the tyres – the only downsides to a truly marvelous Metro.

      4. Wow, I thought only the Paris Metro used this. Seems from that link it’s pretty wide spread with even a new sky train line in Phoenix under construction. I wonder how much could be saved in tunneling costs on projects like U-Link by being able to use steeper grades? Sounds like it’s not in the cards for Link though:

        Because of the high cost of converting existing rail-based lines, this is no longer done in Paris, nor elsewhere; now rubber-tired metros are used in new systems or lines only,

      5. The “line” in Phoenix is an airport people mover. It connects the terminals, rental car center, parking, and airport Valley Metro station together.

        A huge disadvantage of rubber tired systems is just like monorails and PRT you are usually locked into a single vendor.

      6. Maybe but since these systems are a direct competitor and an underdog to the conventional steel on steel technology I’d expect they have every incentive to provide a cost competitive solution and there’s enough in service that I don’t think you have to worry about it being orphaned. We’re essentially locked into a single vendor anyway because unlike buses the fleet of rolling stock is small enough that you don’t want to try to mix and match. Really there’s not much standard between different rail vendors than track gauge; witness our streetcars, Central Link and Tacoma Link. I wonder if more wheel maintenance is offset some by less track maintenance. Also, if the rubber is akin to changing a tire and steel wheels are grind until replace the lifecycle costs might not be so different.

      7. Bernie, there’s a LOT that’s standard between different LRT vendors’ equipment — witness Portland which runs two-car trains with a Bombardier car coupled to a Siemens car. That’s the kind of flexibility that you want, where the agency is not locked in to a proprietary technology, to a single vendor.

      8. Mmm, looking at it a bit more it seems most systems use a pneumatic tire running either inside or outside an existing steel rail. So, you can still run conventional equipment and in the event of a flat tire the steel wheel takes over. I had thought the rubber wheels would be mearely a solid insert on a steel wheel. Sort of like a traction band on a model train. It seems that would still have the noise reduction and traction advantage without the risk of flat, eliminate the addition of conventional wheels, and less maintainance and less energy loss from the tires. Can’t find any examples of this in practice so there must be some compelling reason to not do it this way.

    1. Matt,

      It’s the external noise, not internal, that they’re addressing.

      The noise problem is overstated, but there is some screeching in the elevated turns, and some operators were out of control with the bells at the wee hours of the night.

      1. And please could they turn down the PA in the tunnel at night, too? I was at the ID station Thursday evening at about 2200 and the volume was waaaay too high for that hour and the number of vehicles and transit users. Surely this can be aon a timer in this modern age, no? And yes, it is past time to limit bell ringing to two pops at the entry to the station; use the horn for emergencies.

  2. “Over the next few minutes, two switch crossings in the Rainer Valley will be modified to have a smoother running surface which ST expected to reduce the “ka-thunk” sounds heard now.”

    Now that’s just in time reporting!

    1. I think it was supposed to be months, so I changed it – but I’m not positive. Hopefully John will appear and make a modification.

      1. From Sound Transit’s notice (

        Sound Transit is modifying the two switch crossings in the Rainier Valley so train wheels have a
        smooth running surface through the switches. This will reduce the ka-thunk sounds now heard.
        This work involves rail welding and will occur in the evening and at night, when rail service can
        be operated at a reduced level.
        This work is located at the switch crossings near S. Walden St. and at S. Willow St. The work is
        scheduled to begin no earlier than 7 p.m. and end no later than 4 a.m. and will occur over eight
        weekends beginning Friday, Dec. 11th. A more detailed work schedule will be available later.

  3. Ya, living in Chicago, we live with deafeningly loud trains. So loud you can feel and hear them at the top of 30 story buildings.

    About 6 years ago, CTA bought a fleet of 100 buses from Metro of the articulating variety (for $10K) and used them to supplement a number of routes. Talk about luxury such padded leather seats and quiet. Unfortunately, they only lasted a about 3 years in service until CTA could put their newly purchased buses in service. But it was fun to see the old Metro brown and yellow buses coming down the street.

    1. Wait 100 buses for $10k? I’m hoping there’s a typo in there, but if there’s not, I’ma call up Metro and see if they’ll take $100 for an old artic!

      1. CTA definitely got their moneys’ worth – I vaguely remember a picture of a bunch of them rolling along on either a train or flatbed trailers on I-90 .

  4. Things I’ve noticed:
    -The hunting is worse going northbound to Rainier Beach than than going south to Tukwila.
    -Some cars appear to hunt less than others and the ride is noticeably smoother.

    Is this something easily fixable, no matter if it’s the track, cars, or a combination?

    1. I’ve also noticed a lot of hunting in the Northbound turn entering Westlake station. Even with the low speed the Link trains take the turn, they seem to jerk back and forth a lot.

    2. I’ve noticed that the trains don’t seem to hunt as much when there are a lot of people on board. When I rode the train last Saturday it was standing room only and the train didn’t seem to hunt at all northbound. I even commented to my wife that it seemed really smooth.

      Could the weight of the train be a factor? I could see how a light train could tend to hunt more with no enertia behind it, and a heavier train would be more stable.

    3. Three things can fix this problem:
      -Grinding the rail. It does help since it changes the rail’s profile and thus how the train rides on the rail. Think of it like regrinding I5.
      -Installing different shaped tires on the LRV’s.
      -Adjust the track’s profile. I went out a month before opening to watch ST adjust the profile. Its EXTREMELY labor intensive and time consuming. They only could do about 500′ of the worst stuff in an 8-hour window.

      This problem didn’t exist when the Link first started operating (well before opening), so it has appeared over time.

  5. Do these changes include getting drivers to stop ringing their bells in the underground stations? I only ride Link infrequently, so I’m not sure if that’s still been a problem.

  6. The squealing track noise in the Beacon Hill tunnel has been getting progressively worse. I hope these measures will fix that.

  7. If you want to see one in person, there is one at Holgate Street next to the Amtrak coach yard.

  8. With complaints already of Link’s communication when there are problems, I find the idea of turning the loudspeakers all the way off at night concerning… I hope that this does not mean that important service announcements don’t play either. Especially during the track work in the evenings.

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