Slippery Word Watch: Express

A good post at Greater Greater Washington on Washington DC priority bus corridors reminds me of an old question about the word express:

Metro is working hard to develop “priority bus corridors,” with express buses that run more often, more quickly, and more reliably than existing service

What does express mean in that sentence?  It’s not clear, but it seems to be the everyday meaning: “fast, with a dash of coolness, compared to local-stop service.”

Like a lot of transit planners, I use the word express in a more precise sense, as one of three kinds of stopping pattern that seem to encompass most successful transit services:

Stopping patterns

  • Local means stopping frequently all along the line.  Locals are designed on the principle that if you’re on the line, you should be very close to a stop.  Local stops are usually no more than 1/4 mile (400m) apart, and often much less.  Becuase they stop the most often, these services are characteristically slow.   Local buses and streetcars/trams usually fall in this category.
  • Limited or Rapid means stopping at a regular but widely-spaced pattern.  The spacing is usually at least every 1/2 mile (800m) or sometimes wider, but the point is that the spacing is fairly regular along the line.  These services are meant to link nodes of activity, often activity centers and transfer points, with a reasonably fast service.  They are not trying to be available at every point on the line, although some provide a high-enough quality of service that they’re worth walking some distance to.  Most subways and light rail systems are of this kind.  The new generation of Rapid Bus and Bus Rapid Transit services, which more or less try to duplicate what rail transit does, generally function this way as well.
  • Express, in these terms, really means “serving a very long nonstop segment.”  The classic express bus may run local or limited-stop for a while, but then it has a long segment, perhaps on a freeway, where it doesn’t stop at all.  A common example is the peak express bus routes, which run from a suburban park-and-ride to a worksite or from a neighborhood to a distant school.  Commuter rail lines also often run express segments during the peak period.

The reason I try to use the words this way is that hiding inside this distinction about stopping patterns is a really important distinction about frequency.  Rapid and Express are both ways to be faster than a Local, but Rapid lends itself to high-frequency all-day operation, while Express does not.

During the peaks, masses of people flow in one direction at the same time, and peak express services are often the result.  But if you want service you can build a city around, you want all-day service, and for that, the more versatile “Rapid” stopping pattern is more likely to be useful.
(The stopping pattern distinction, by the way, is also the only meaningful distinction between “streetcars/trams” and “light rail.”  They are virtually the same technology, but “light rail” usually means a Rapid stopping pattern, while “streetcar/tram” means a Local one.)

16 Responses to Slippery Word Watch: Express

  1. Wad June 20, 2009 at 5:31 am #

    You seem to show a fondness for the Los Angeles way of things. Don’t tell us that you are holding us out as a model. ;>
    The local, limited and express definitions you used are the ones operating in L.A. To be more clear on our express buses: They refer to a bus line that run at least 4 miles nonstop, typically on a freeway.
    The stop spacing on the street depends on the line. Some turn to limited stops, others serve as locals off a freeway. There are a few that are limited in one segment and local in another.
    Something else that L.A. has done brilliantly is to have a logical line numbering system. There are both categories and rhythms to how lines are numbered. Lines 1-99 serve downtown L.A. in any direction. Also, the smallest number starts along the Sunset Boulevard service (2) and rotates counterclockwise to 96. Lines 100-199 run east-west outside of downtown. Lines 100-149 are given to routes south of downtown. Lines 150-199 are given to routes north of downtown. However, the logic goes to hell in the San Fernando Valley. Lines 200-299 are north-south locals outside of downtown. Lines 200-249 go from east to west outside of downtown; Lines 250-299 go from west to east.
    Lines 300-399 and 700-799 are limiteds and Rapids respectively, and adopt the underlying local route. Line 720 is the Rapid for local Line 20. The only break of logic is for a 100-299 route with 0 as the second digit. Those are X5X (Line 754 is the Rapid counterpart to Line 204). The official Metro story for this was to differentiate the non-downtown locals with a 35X or 75X, but I think it stemmed from the problem planners had when they had to create the limited line for 204, but the 304 designation was already given to the Santa Monica limited.
    Lines 400-499 are for express buses serving downtown; 500-599 for express not serving downtown.
    Lines 600-699 and 900-999 are more or less grab-bag categories, though with the former for local services and the latter for faster buses.
    Lines 800-899 are internal line codes for Metro Rail.
    This is a brilliant system, and looks even better when comparing it against a system map.
    Other cities should also try to have some form of logical route nomenclature, as it would help orient riders.

  2. Jarrett at June 20, 2009 at 6:14 am #

    Wad. I’m glad you agree with me transit in Los Angeles does a lot of things right! But no, I’m not promoting LA in particular, just good planning and nomenclature wherever I see it. The terms I discuss in this post are widely used among professionals all over the industry. Cheers, Jarrett

  3. anonymouse June 20, 2009 at 9:35 pm #

    Santa Clara County also has a semi-logical system, though not as good as LA’s: two-digit routes are local, 1xx are express, 3xx are limited, and the 522 is Rapid. In the two-digit series, 2x are the main east-west routes (numbered from north to south), 3x are secondary east-west lines, and 5x, 6x, 7x are north-south lines (numbered from west to east). 4x and 8x are miscellaneous routes in the main part of the county, while 1x are mostly South County routes, except for the 11 and 13, and the 10 Airport Shuttle.
    Meanwhile, I think Oslo the ultimate route numbering system, with subway, trams, buses, and possibly even ferries all part of a logical and unified scheme.

  4. dale June 21, 2009 at 11:22 am #

    I always wish there were about a third as many stops on the local lines here, but I realize (grudgingly) that you also have to serve people for whom a half-mile walk is an ordeal, rather than something pleasant.

  5. Rob June 22, 2009 at 9:30 am #

    Your clarification at the end is well stated and exactly why I think it’s confusing for SoundTransit to have Tacoma Link (really a streetcar) but also brand the new light rail as Link.

  6. Alon Levy June 24, 2009 at 3:43 am #

    The New York City Subway has a mixture of all three service patterns. There are local trains that stop at all stations, and express trains that stop only at some stations. The express stop pattern depends on the line: the older lines, inherited from the IRT (1-7) and BMT (J-Q), have regularly spaced express stops – every third or fourth station is express; this is what you call limited stop. For example, the 4 stops at 125th Street, 86, 59, 42, 14, and City Hall (about -20). On the newer lines, inherited from the IND (A-G), the express trains have the stopping pattern you call express: they stop at every second or third station in neighborhoods close to the termini, like Harlem, and at almost every station in Midtown, but then can skip 7 stops in between. For example, the A stops at 168, 145, 125, 59, 42, 34, 14, 4, Canal (-7), and Chambers (-20).
    To complicate matters, some trains run on multiple lines, with different stopping patterns. For example, the 2 runs local on the White Plains Line in the Bronx, but then runs express on the Broadway-7th Avenue Line in Manhattan.

  7. Jonathan July 9, 2009 at 12:00 pm #

    I always wanted to know what the difference between “Limited” and “Express” was. Thanks!

  8. Aaron Priven July 9, 2009 at 3:55 pm #

    The problem with “logical” numbering patterns is that they only make sense from the 30,000 foot level. The problem faced by somebody on the ground is remembering which line to take. If you are told you need bus #94 and then go out to the street and are faced with lines 93, 94, 95, and 96, it’s harder to remember which line you want than if the lines you faced were 25, 38, 94, and 145.
    A system that makes it easier to understand the entirety of the system is something that benefits planners and enthusiasts, not typical riders.

  9. EngineerScotty August 4, 2009 at 2:02 pm #

    I’d argue that there is a bit more distinction between streetcar and LRT than stopping patterns… while the fundamental vehicle technology is the same (generally caternary-powered steel-wheeled trains), there are these issues:
    * Mixed traffic operation vs exclusive (or least semi-exclusive ROW)
    * Vehicle weight–LRT vehicles aren’t really “light” at all, and require sturdier railbeds
    * Entraining–most streetcars are single-car trains; most LRT services run multiple cars coupled together.
    But, yeah… I’m probably splitting hairs. 🙂
    At any rate, how do you define a “special”? 🙂

  10. Brent Palmer November 14, 2009 at 7:17 am #

    Brisbane used to have a clear distinction between local and limited-stops routes in its numbering system – local services were numbered in the 1-199 range, whilst the regular limited-stops routes were numbered in the 5xx range (and enjoyed their own distinct livery). Alas, they did away with this more than ten years ago, in favour of allocating number ranges by region, regardless of service type. Plus these limited-stops routes have had several stops added, reducing the express-running distances. Ironically, the advertising for the new route numbering arrangements boasted about “introducing something new: Logic!”

  11. Ben November 17, 2009 at 8:44 pm #

    I agree with everything here, except that rapid transit has to keep stop spacing equal. I think it should be fairly equal in the environment it is in, but not necessarily along the entire route.
    For example, in the central business district you can have the train stop very frequently since there is a lot of activity in the area. Once outside of downtown and in the inner suburbs, the stops can space themselves out to make travel quicker; but not too far apart as to leave those in between stops behind. Depending on the geography, every 1000m +- 200m (800-1200 meters, or 1/2 to 3/4 of a mile) should be the target. Longer gaps can be used when connecting areas which are separated by low activity environments, such as parkland or a highway.
    Also remember that unlike a bus, most rapid transit stops at every stop regardless if people are getting on or off. Therefore stops should also be spaced out enough to ensure a large number of people are boarding and unloading the train.

  12. Jarrett at November 17, 2009 at 9:12 pm #


  13. Garlynn Woodsong November 19, 2009 at 3:55 pm #

    Actually, there are very real technological differences between streetcars and light rail. You can OPERATE a light rail as a streetcar (ala MUNI in SF or the Green Line in Boston), but it is still technologically a light rail.
    One, as mentioned above, is that light rail trains can be and generally are linked together as sets. Streetcars in the U.S. don’t usually do this.
    Two, as mentioned above, is vehicle weight. Streetcars weigh a lot less than light rail trains. While you can run a streetcar on a light rail line, you can’t run a light rail train on a streetcar line (or, at least, you shouldn’t). As a result, the streetcar line can be installed with only a quick removal of the top layer of pavement, installation of the tracks and poles and stations, and surface repaving. Light rail, OTOH, requires a complete rebuild of the streetbed as well as utility relocation. Witness the time difference in Portland between installation of the streetcar on 10th/11th, vs. the installation of the light rail on the transit mall or on N. Interstate Ave, or in downtown Hillsboro.
    Three, and this is critical, is vehicle width. A streetcar is about 8 feet wide; a light rail vehicle is generally another 6 to 8 inches wide. This allows the streetcar to more nimbly move through mixed-traffic operations.
    Four, and this is critical for a different reason, is cost. A streetcar system costs less per mile and per vehicle than a light rail system.
    Sorry to split hairs, but as a Portlander, I know these things and like to make the distinction.

  14. EngineerScotty November 19, 2009 at 4:53 pm #

    One other important technical difference between the streetcars in Portland, and Tri-Met’s fleet of LRT vehicles, is top speed–the Streetcars max out around 40MPH (65km/h) or so; wherease LRT trains can hit 60MPH (100km/h) fairly easily. Right now, Streetcars and LRT trackage is distinct, though there are several points of intersection (near PSU, and around 11th and Yamhill). In the future, it is expected that the two vehicle types will share the proposed transit bridge (along with busses). However, the speed difference essentially keeps Streetcars from moving (on their own power) to Tri-Met’s main maintenance yards at Elmonica and Ruby Junction–at least unless done at night when the trains are out of service. (Streetcars are stored at their own yard; but some maintenance tasks can’t be done there).

  15. Jarrett at November 19, 2009 at 5:36 pm #

    True enough in Portland. Fact is, streetcar technology is really diverse, and the differences Garlynn and Scotty site are differences of degree where different cars perform differently.

  16. Ivy February 22, 2012 at 10:21 pm #

    Interestingly, the light rail line (known as the Norristown High-Speed Line, formerly Route 100) in my region, Philadelphia, Pennsylvania, actually has your express & limited designations reversed, with Limited being the runs with the fewest stops & Express being 2nd-fewest.
    It’s odd if you ask me. To me, the word express conveys a better idea of the fastest possible service and limited conveys something in between express & standard local service – perhaps a Sunday or night run where certain stops wouldn’t be made (where people would never go due to business closings, etc) but most of the route is still covered.