Monthly Archives: August 2010

Happy anniversary

At the Mall/SW 5th Ave platform, watching workers laying down the tracks for the transit mall about 3 years ago

Today marks 1 year since trains began operating on the transit mall in downtown Portland – originally just the Yellow Line with operators running out of service on their Green Line trips since that didn’t officially open until September.

Mass detectors

As mentioned in the call loop post, although call loops are used on almost all of the alignment, most of Burnside does not use them. Instead, on Burnside you will find mass detectors.

Mass detector

These look a little similar to call loops, but they’re smaller and they function differently. While a call loop requires interaction from the operator to select a signal, a mass detector works automatically when a train passes over it. The mass detector detects the mass of the train (I love the things that are intuitively named) which will automatically call the pre-empt and bring it up when the train reaches the intersection – no button pressing on the part of the operator is required.

Most of Burnside works on mass detection rather than call loops, but that only works when the train is running normal traffic (east in the eastbound and west in the westbound). There aren’t mass detectors set up for trains running reverse traffic (west in the eastbound or east in the westbound) so operators have to call Control for permission to get through the intersections (aka SOP the intersection) if they are running reverse.

Mass detectors can also be found elsewhere in the alignment, such as at 12th & Washington westbound, where the mass detector will automatically bring the crossing gates down when a train arrives at the platform.


Question: Can trains get flat tires?

Someone apparently found their way here searching for the answer to this question. I hadn’t answered it yet, so here it is now. The answer is yes, sort of – a train will not get flat tires like a car can, but train wheels can develop flat spots. You’ll know if you’re on a train with a flat because it will sound like this:

Westbound into Sunset TC, sitting over the C truck of a Type 4 that had a flat

The trains should run pretty quietly – a “chugging” sound like that is indicative of a flat.

Flats can form on slippery rails or when the train makes a sudden hard stop, and bad flats on a train will get it pulled out of service so the wheels can be repaired.

Push button

Another reader question!

When going eastbound off the Steel Bridge into Old Town/China Town there is a box with a button at cab height… what does this do?

There are a few of these on the alignment – I knew I had a picture of this particular one somewhere:

push buttonOld Town/Chinatown, looking towards the Steel Bridge along the westbound alignment

A lot of areas of the alignment, such as the transit mall on 5th and 6th, Interstate, and Washington Street in Hillsboro have secondary call loops that a train can stop over to re-call their pre-empt if it times out. Another way an operator can get their pre-empt is at push buttons like this one (also seen in other places on the alignment such on Burnside near 97th Ave before Gateway and at 197th by Ruby Junction). They work kind of like a crosswalk button where an operator can reach out of the cab window and hit the button to get their signal. This one was put there for an operator to recall the pre-empt if they came over the Steel Bridge and their leader was still in the Old Town/Chinatown platform.

At intersections that don’t have a secondary call loop or push button, an operator will have to call Control for permission to proceed through an intersection, also known as “SOP an intersection” when they don’t have a permissive pre-empt to continue.

Blogs and safety

A post doesn’t feel right to me unless it has a picture of something, even if it’s a total non sequitur like this one.

I’m still working my way through reader questions I’ve gotten. If you’ve sent stuff to me and are waiting on an answer, I am not ignoring you. It’s just that a combination of working a lot of hours plus having drafts that I’ve wanted to post on other topics and my obsessiveness with trying to have accurate posts that are understandable for people who don’t have a rail background (WordPress tells me that I made 25 revisions to the recent Time Lock Switch post within the 6 hour period before I posted it) means that it takes a while to move through the drafts that I have partially written.

So while I can’t claim that any of this is official, TriMet-approved information, please understand that I am doing my best to make sure that what I post is complete and correct and easy to understand. I like rail, I like writing about it, and while I know that a topic like light rail has a small following – especially when compared to, say, all of the cooking or parenting blogs out there – I know it’s a very dedicated following and I like the interaction this blog has with the people who read it out of a shared interest in the MAX light rail system.

Which brings up something interesting I saw recently – I watched the video recording of the last TriMet Safety & Service Excellence Committee meeting that Al M posted, because although I’m not personally involved with that committee, I like knowing what’s going on. Anyway, at about the 77 minute mark, the consultant that was hired to do a safety review of TriMet’s practices discusses the role of blogs and blogging. He mentions how blogs can be used to get system information and safety information out to the public. At about 79 minutes, one of the committee members asks if that sort of thing falls under the previously mentioned recommendation of expanding TriMet’s safety department. The consultant agrees, and again mentions the blogging community and how TriMet’s public information officer should be interfacing with the blogs. He discussed the importance of getting positive messages out to the riding public because there are a lot of positive things about TriMet (with regard to safety) but he said that TriMet doesn’t do a very good job of broadcasting that.

I’m curious what “blogging community” the consultant was referring to – as far as I know TriMet has no official blogs, though there is an official Twitter. There have been a number of unofficial blogs, such as EMS‘s which was one of the first that talked about safety at both rail and bus. And in mine, I write about safety (especially the details of the rail system that keep things safe but aren’t publicly recognized), but I am not officially endorsed/approved/authorized/recognized by TriMet and nothing I write can be considered official information. But I absolutely agree that TriMet does not promote a lot of the things that make the system safe – at rail alone there are ground inspections and ATS magnets and fit checks and so many mechanical failsafes that no one knows about because TriMet doesn’t make that information officially available. It’d be pretty great now if they did.