comments of the week: ideal stop spacing is 400m?
Zoltán:
My experiences in Leeds and Baltimore confirm the validity of a 400m standard for stop spacing. Rarely do you get to experiment with reducing or increasing stop spacing, but we can look at the sum of the experience of the two cities.
In Leeds, there have been a number of routes, normally small single-deck buses running every 30-60 minutes, that have stopped frequently and taken local roads to penetrate various neighbourhoods better than the frequent, relatively fast buses on the main arterials.
These have pretty much all disappeared with time, because people always proved willing to walk about 400m to the main arterials, which is about the furthest you're ever expected to. My experience of occasionally catching one of the slower local routes is that I would be the only passenger.
So, this demonstrates that people really are willing to walk to speed and frequency.
Meanwhile, in Baltimore, buses do stick to the main arterials. But they stop at every corner, just like the streetcars before them, which in Baltimore is about every 120 metres. And hell, are they slow - from Catonsville, MD to downtown Baltimore, I frequently spent 50 minutes to an hour to travel 8 miles that can be driven in about 20 minutes.
What's more, it's an uncomfortable ride, because the bus pulls violently to the corner at every corner, to keep the hell out of the way of traffic. And that's actually the problem with the frequent stops in Baltimore - while boarding time is a bit more complicated (though there's a fixed element to people getting up and making their way out of the bus, and people waiting for the driver's nod to start boarding), you can basically multiply the time spent waiting to pull out back into traffic by the number of stops.
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So what you have is a slow service, and by that virtue, a less frequent service, because one bus can make fewer trips. So, if people will walk to speed and frequency where delivered by different routes, then we can assume that people will also walk to speed and frequency on existing routes when that's achieved by means of widely spaced stops.
In thinking about this sexless but profoundly consequential issue, you may want to refer back to this post, which clarifies the concepts of coverage gaps and duplicate coverage areas. (See that post for more explanation of this figure.)
Balancing these two considerations is the essence of the stop spacing task. Closer stop spacing means smaller coverage gaps but more wasteful duplication of coverage area. So a lot depends on the local land use. If there's more stuff along the transit corridor than in the coverage gaps, that argues for pushing stops wider.
The European HiTrans guides suggest 600m for stop spacing in busy areas where demand is high and local access is the intent. In general, Europeans and Australians are willing to go wider than North Americans in a similar setting.
So why on earth does any transit agency that aims to compete with cars put stops as close as 120m?? Well, these things creep up on you. If ridership is so low that you won't be stopping at every stop anyway, close spacing doesn't present much of a problem. But once ridership reaches the level where you're stopping at every stop, close spacing requires you to stop more, and thus run more slowly, to serve the same number of people.
On the tradition of very-close North American spacing, John offered an interesting speculation:
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"But right now, a lot of transit (in North America especially) seems designed to compete with walking, rather than with the car. Do we have the balance right?"
I think the balance is off, and I think it's largely a legacy of the streetcar era, when transit only needed to be faster than walking to draw a huge mode share. In that situation, minimizing walking distance made sense. Then the competition changed when cars came along and average trip distances increased. The streetcars were removed, but nobody ever bothered to change the stop spacing. Now transit isn't time-competitive, and in most cities it serves only the transit-dependent and niche markets like express routes to the CBD.
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Is very close stop spacing on North American bus systems really so old that it predates the car, and therefore reflects the competitive situation between transit and its alternatives as it was around 1910? That would be some sort of record for failure to adapt: a habit that has survived for an entire century after its obsolescence.
Obviously, too, many North American services aren't trying to compete with the car; they're social services intended only for the transit dependent, and in those cases travel time is presumed to travel less. But be careful about taking that attitude too far.
