Comments on: Signaling on MLK (I)

By: Chris

Chris — Tue, 16 Mar 2010 02:55:21 +0000

NEVER SKIP A PEDESTRIAN SIGNAL!

There is no way to communicate to the ped what is happening, and you’ll just encourage jaywalking, despite the engineering opinion. Two minutes is an eternity–four minutes is ridiculous.

By: Nathanael

Nathanael — Fri, 12 Mar 2010 05:38:18 +0000

What’s “recent”?

Most of the major subway systems dating from the 1900s were explicitly replacements for surface streetcar lines or elevateds, and most of the elevateds were replacements for streetcar lines. Boston’s Green Line is mostly streetcar routes with tunnels built to replace surface running.

A number of commuter railroads have been grade-separated through various cities in recent decades (too many to mention, including Boston), as have some freight railroads. (e.g. Alameda Corridor.) Cascades is getting some grade separations.

*Light rail*? It’s too new as a concept, and there hasn’t been enough of it built yet, for it to reach the point where it’s worth conversion from at-grade to grade-separated.

You wouldn’t expect it to happen until the infrastructure was at least 20 years old, probably a lot more. SF’s Market Street Subway is a good “recent” example, however.

By: Nathanael

Nathanael — Fri, 12 Mar 2010 05:25:57 +0000

“The only reason I can think of why this might happen is if the train is too close to the intersection to stop before entering that intersection. Otherwise, emergencey vehicles should always have priority over Link trains, obviously.”

I’m pretty sure this is why Link can get priority. Trains take a LONG time to stop.

By: Chris Stefan

Chris Stefan — Tue, 09 Mar 2010 20:57:01 +0000

FWIW I’m told that Bellevue has one of the most sophisticated traffic light control systems in the region. I don’t know if it is up to full ITS standards as seen in Asia and Europe, but at the very least the building blocks are there.

Given the 8 years that is likely to elapse between making a decision on the downtown Bellevue alignment for Link and when it actually opens I suspect there probably won’t be an issue with the City of Bellevue refusing to grant Link signal priority. The City Council very likely won’t have the same members. Besides as East Link nears completion the prospect of a ribbon cutting and the large transportation investment Link represents provides a powerful incentive to make it a success.

Look at Tukwilla who fought the SR-99 alignment of Central Link as well as the 599/I-5 alignment that was ultimately chosen tooth and nail. Years later when it came time for Link’s grand opening Tukwilla city officials were all crowing about what a great thing it was.

By: Mickymse

Mickymse — Tue, 09 Mar 2010 20:51:09 +0000

Not 100% applicable, because they changed modes, but the Canada Line up in Vancouver is elevated in Richmond, and replaced an at-grade BRT line that had been built just a few years before to run separate from regular traffic in the median with signal priority.

By: Michael Arnold

Michael Arnold — Tue, 09 Mar 2010 20:17:21 +0000

Would love to have a Granham Street station built someday. I don’t mean underground as in the old diagram, but at-grade with the rest of the existing system.

By: Signaling on MLK (II) - Seattle Transit Blog

Signaling on MLK (II) - Seattle Transit Blog — Tue, 09 Mar 2010 18:27:48 +0000

[...] SDOT Senior Engineer Darlene Pahlman. For the most part, these words are paraphrases. See also Part I of this [...]

By: Matt

Matt — Tue, 09 Mar 2010 16:49:52 +0000

I guess my question was more about why ST can’t put the official clock, service bulletins, etc. at Union Station, or somewhere like that.

By: Matt

Matt — Tue, 09 Mar 2010 16:46:58 +0000

I can’t think of any heavy rail running in a similar alignment, except maybe the Ballard Terminal Railway. And that goes way slower than the speed limit for cars!

By: Lloyd

Lloyd — Tue, 09 Mar 2010 15:49:09 +0000

Thanks, Chris, for this oft forgotten sobering reminder.

By: kwakiudl

kwakiudl — Tue, 09 Mar 2010 08:25:47 +0000

Rule book – R 2.5 EMERGENCY VEHICLES – When obseving emergency vehicles, with lights and sirens, operators shall stop their train clear of intersections, if safe to do so, until emergency vehicles have passed.

Link operators are to yield to emergency vehicles when it is safe to do so, even if we have a priorty light. This is another reason we might lose the cascade.

By: kwakiudl

kwakiudl — Tue, 09 Mar 2010 08:19:10 +0000

Matt, as a Link Rail Operator, the offical clock is right next to the sign in window so all us operators can set their watches within 20 seconds of that clock before we leave the building and go to the trains. (rule book R1.21.1) We have 20 minutes from our sign in time to read all the new operation notices, get our train orders, and proceed out the building to the relief shack on the elevated track near Forest Street.

And psf, driver changes were not the reason you were let off at Beacon Hill, the train and operator were going into the yard at OMF and done for the day. That problem has been solved by running those trains empty and out of service from SeaTac or the Pine Street Stub Tunnel

The reason we make road reliefs at the shack is simple…money. ST doen’t want to pay us for travel time pay to go between Sodo and OMF, or any other station.

By: Chris Stefan

Chris Stefan — Tue, 09 Mar 2010 06:06:38 +0000

The only example I can think of is Muni moving from at grade on Market to the upper level of the shared tunnel with BART.

Past that there are some examples way back when and some examples of elevated lines moving to subways.

I believe Calgary is talking about putting their downtown segment in a tunnel, but so far I think it is only talk.

But the safe way to bet is to assume if something gets built at-grade we’re going to be stuck with it for a while.

By: Seattle Greg

Seattle Greg — Tue, 09 Mar 2010 05:47:21 +0000

Heavy rail with WSDOT has done this at several points in Kent, running roads under or over existing grades… but just at some key major intersections

By: Cyclist Mike

Cyclist Mike — Tue, 09 Mar 2010 05:19:42 +0000

In Philadelphia, parts of the elevated line was turned into a subway line. It probably wasn’t cheap to do this, but it has been done before.

By: Chris

Chris — Tue, 09 Mar 2010 04:37:50 +0000

Yet another reason we shouldn’t have built it at-grade.

By: Chris Stefan

Chris Stefan — Tue, 09 Mar 2010 04:23:19 +0000

I hate to break it to you but the vast majority of light rail lines around the world have at least some or all portions at-grade. If you’re going to take the trouble to build a 100% grade separated system you might as well go for high floors, third rail, automated operation, and 75 mph top speeds. That is usually called a “metro” or “heavy-rail” system though.

The problem is such beasts are incredibly expensive.

By: Chris Stefan

Chris Stefan — Tue, 09 Mar 2010 04:09:54 +0000

Are the trains really limited to the speed limit by state law? Does that apply to heavy rail running in a similar sort of alignment? What about if all of the intersections had lights and 4 quadrant gates? I know with lights and gates the FTA and AASHTO rules/guidelines allow higher speeds for the rail line.

By: Matt

Matt — Tue, 09 Mar 2010 04:07:38 +0000

Wow. Don’t get me wrong. I love Link. But dang, some of that stuff in the EIS is sweet.

By: Anandakos

Anandakos — Tue, 09 Mar 2010 03:27:08 +0000

That Cute Little Surrey With The Fringies All About….