Saturday, May 18, 2013

3 Kinds of Blocks

If you were to ask me, the defining characteristic of any TriMet buff is whether or not you can identify the three definitions of 'Block.'

If you are studying TriMet, you will encounter the term 'block' in three different, completely unrelated contexts. This can get confusing, but understanding what they are is essential to any other study of the system.

First, a 'block' is the area inside four intersecting streets, or the distance between one numbered street and another, or the distance between where one numbered street should be and another numbered street, or the equivalent distance overlaid upon a numbered street. I could go on and on, but I think you know what I'm talking about. For example, the stop at 7500 Block SW Canyon would be where 75th Ave would intersect Canyon. However, the stop at 4900 Block SW Barbur would be where a hypothetical 49th Ave would intersect Barbur if the numbered streets were going north/south as well. It is, in effect, 49 blocks south of Burnside.

Now, one interesting point is that when TriMet names bus stops, they may not be named based on the precise address point on the street where the stop is located. Instead, TriMet names them based upon the address sign you see most prominently when standing at the bus stop. This is why the stop at 18200 Block SW Boones Ferry is directly across the street from the 18400 Block SW Boones Ferry: these are the numbers you see most prominently at the bus stop.

Here's an example: if you are standing at the eastbound bus stop on Beaverton-Hillsdale Hwy outside the Raleigh Hills Fred Meyer, the most prominent number you will see on that side of the street is the "7700" above the door on the Fred Meyer. Hence, the stop is 7700 Block SW Beaverton-Hillsdale. This is why there's some strange names, like 21907 SW Sherwood Blvd, 18882-19040 SW Tualatin Valley Hwy, and SW Canyon and Red Robin, because that's the best they could come up with based on what you see from the bus stop.

Second, a 'block' refers to the distance between two ABS signals on the MAX system. While MAXFAQs has a really great explanation here, for simplicity's sake, at each signal, a rail operator waits for clearance to proceed past the signal into the block. That block ends at the next signal. Dividing the system into blocks is what keeps trains from running into each other, because two trains cannot be in the same block at the same time. ABS (Automatic Block Signal) territory is on the westside between Washington/SE 12th and Goose Hollow/SW Jefferson and on the eastside between Lloyd Center/NE 11th and Gateway TC, between Gateway TC and PDX on the Red Line, between Gateway TC and Clackamas Town Center on the Green Line, east of Ruby Junction on the Blue Line, and north of Kenton/N Denver Ave on the Yellow Line. The rest of the system does not use blocks to control train locations.

Third, and most importantly, a 'block' refers to a set of trips a bus or train is scheduled to take each day. You see a timetable for Line 6-MLK; it has 64 outbound trips on a weekday. Some bus has to be assigned to each trip, and the block identifies which bus or train is assigned to the trips. Below is the weekday timetable for Line 6, with the current block assignments for each trip.
6-MLK Jr Blvd to Jantzen Beach, Weekday

Each block is assigned a number. For example the bus that serves the first trip on this timetable is Block 603, also referred to as Line 6, Train 03, meaning it's the third train assigned to Line 6. (Don't be confused by the usage of the term 'train;' it is a term that has been used for many years. the Line/Train designation interchangeable with the Block designation.) All buses, MAX and WES trains, Streetcars, Trams, and Trolleys in the system have a block designation. LIFT shuttles use a different system, but we won't talk about those here.

Weekday schedule (paddle) for 603
I make these for all blocks. This is the style you will see
throughout my blog in the future.
An image of the real paddle the operator of 603 uses. Each operator has a
copy of this in his pouch (bus) or on her clipboard (rail).

For buses, a three or four digit number is used. The first one or two digits represent the line number that block is assigned to, such as Line 6 in our previous example. Block 603 runs only on Line 6, but this is not always the case. Block 2901 runs on both Lines 28-Linwood and 29-Lake/Webster, but it has to be assigned to Line 29.

The last two digits represent the train number, which identifies the specific block of schedules that bus/train covers during the day. The numbers usually are ordered by the time they pull out in the morning (i.e. 601 pulls out before 602) but rare instances do exist where they are not ordered correctly. In our previous example, 603 pulls out after 601 and 602, but because it starts its first trip at SW 18th & Jefferson instead of Jantzen Beach after both 601 and 602 are running inbound, it ends up before 601 in the order all day long. However, 603 did still pull out of the yard third after 601 and 602.

Bus 2635, with the digital block display

Now, for buses, the train digits also distinguish which garage the bus pulled out of and will return to. Buses out of Center Garage will feature numbers 01-32; buses out of Powell Garage will feature numbers 34-65; buses out of Merlo Garage will feature numbers 67-89. A bus will never pull out of one garage and end up at another under normal scheduled circumstances (this can be different in the case of a bus trade or a mechanical failure).

The three or four digit block number is always clearly visible in the bottom left of the front window of the bus. Older buses (through 2500-series) have manual signs; newer buses (2600-3000s) have electronic signs.

Bus 1904, with the manual block display

All MAX trains have block numbers assigned under Line 90, and the train number designates which actual MAX line the train is assigned to. Trains 01-19 are Blue Lines out of Ruby Junction Yard; trains 20-39 are Blue Lines out of Elmonica Yard; trains 40-59 are Red Lines (all out of Elmonica); trains 60-79 are Green and Yellow Lines (always out of Ruby), which change colors at PSU. Trains may run as different colors, and all trains run as Blue sometime each day as both yards are only served by the Blue Line. In example, 9021 is the second Blue Line train out of Elmonica Yard (although strange numerical exceptions do occur, as in the fact that 9006 pulls out before 9005). For MAX, the number is most commonly referred to without the '90,' usually just called "Train 21." This two digit number shows up in the bottom right window on each end of the coupled or uncoupled trains (not the cabs facing each other where they are coupled).
Car 217 with manual block display (left); Car 404 with digital display (right)

NS-line Streetcars have block numbers 9380-9389, but they are not seen on the train. Likewise, CL-line streetcars are numbered 9470-9479. WES has 2840-2849. For all these cases, not all numbers are used (i.e. WES only runs three trains currently, 2840-2842).

In review, here is a list of numbers and what they mean:

  • 804: the fourth bus out of Center Garage on Line 8-Jackson Park/NE 15th
  • 2235: the second bus out of Powell Garage on Line 22-Parkrose, which also serves Lines 23 and 25 weekdays
  • 5272: the sixth bus out of Merlo Garage on Line 52-Farmington/185th, also serving one outbound trip on line 36 from downtown weekday afternoons
  • 9004: the fourth Blue Line train out of Ruby Junction Yard.
  • 9071: the twelfth Green & Yellow Line train out of Ruby Junction Yard, serving Blue stations from Gateway to Ruby Junction on pullout and pullin trips.
  • 9473: the fourth (not necessarily consecutive) Streetcar on the CL-line.
Three last considerations:
  1. A bus may pull out and pull back in the morning, and then pull back out in the afternoon. These are called "split-shift buses," and are usually pulled back out in the order of the number available. The actual bus assigned to the second pullout will likely be different than the first pullout. However, MAX trains that return to the yard in the morning will not pull back out in the afternoon. Any new pullouts would be assigned a new block number.
  2. Three-digit Line numbers (152-156) are assigned Line/Train numbers using the last two digits. For example, 5534 is the first bus out of Powell Garage on Line 155-Sunnyside (also on 156). This is not to be confused with 5567, which is the sole bus on Line 55-Hamilton. Buses like this will never pull from the same yard, because that would be too confusing. They would be assigned to a different line.
  3. Sometimes when writing block numbers, a slash is used between the line and train numbers (i.e. 52/72). This helps (1) note the difference between which numbers are line and which are train, and (2) distinguish between Block ID and Bus ID (i.e. there is a block 20/02 and a bus 2002, and there's only a slight chance that that bus would be running on that block, although I have seen it).
TriMet Scanner tweet using the slash to differentiate block from bus

This is a very exhaustive breakdown of the three types of blocks, although there are even details I left out. I will be talking more about these as I write, but this is a good introduction to three concepts that make up the backbone of the study of transit. If you have any questions or your mind is exploding trying to figure this information out, email me at; I would be happy to try to answer any questions.

(Block graphic from, via Google Images)


  1. A few things -

    1) Sometimes a block doesn't not match its line, such as 904 which starts out life on line 75.

    2) If someone is interested researching this sort of stuff, my site is a good resource --

    1. Max,
      That is a good point that I may not have made clear in the post. The line and block numbers don't have to match, although it is guaranteed that the block will run on its assigned line at least one trip.

      I'm glad to see you got your GTFS site back up. I have created paddles that include deadheads, but I don't release that info for everyone to see except to use as examples. I will do a post about interlining soon, and I will definitely link to your site in the post.


Please keep it clean! Thank you.