Stop Spacing

“Give Mrs. McG Her Bus Stop”? Reasons to Pause

Here’s some refreshing candor from a local politician, in the context of an effort to speed up express bus services on New York’s Staten Island by removing excessive bus stops and deviations:

Borough President James Oddo added that “people like me” were part of the problem: Requesting new bus stops to help vocal constituents.

“Who doesn’t want to give Mrs. McGillicuddy a bus stop?” Oddo asked.

When bus routes meander, do little squiggles, or make too many stops, the cause is almost always local elected officials who insisted that transit agencies say yes to whatever a noisy constituent demands.  Such officials are always calling the transit managers and saying: “Get Mrs McGillucuddy off my back!”

Of course, Mrs. McGillicuddy rarely calls to advocate the kinds of efficiency that makes transit more attractive and useful for the whole community.  She’s calling to demand something that’s good for her or her friends.

Here, as often, we’re in the presence of the paradox of public outreach.  We want transit to be useful to busy people, but busy people don’t engage much with public outreach processes.  They’re too busy.

So we disproportionately hear from the not-busy people, who have priorities other than speed.  So we hear demands like:  “All those busy people should have 3 minutes added to their trip so that I don’t have to walk three blocks.”

I don’t want to dismiss the concerns of senior and disabled riders, but if a person physically can’t walk three blocks, then the answer may be some kind of paratransit.  Paratransit is expensive, but not as expensive as doing something every hour all day to meet just one person’s needs.  There are some genuinely difficult choices here, but they should be addressed by a policy, rather than a process of just rewarding whoever makes the most noise.

Because if a transit agency establishes a pattern of saying yes to every demand for things that slow down the service, that precedent will only trigger more demands, accelerating a downward spiral in which a resource designed to be used by many becomes micro-designed around the demands of one or two, to everyone else’s detriment.

Arguing against these demands with data is tricky.  The differential impact of adding one bus stop or squiggle may not be much. It’s the cumulative effect of 100 such decisions is devastating, gradually transforming relatively fast and efficient services into slow, meandering scenic tours that only people with lots of spare time to use.

So you really need policy, not just data, to hold the line.  Service design standards about stop spacing and linearity can give staff the backup they need.  These standards should be periodically re-adopted, so that current elected officials feel ownership of them, or at least understand the dangers of not observing them.  And the adoption is the time to have the debate about how to balance some people’s difficulty walking with the need for transit to be fast, direct, and reliable.  Again, the point is not to leave seniors behind but to ensure we’re addressing their needs in a fair and consistent way.

walking in america

Tom Vanderbilt at Slate is doing a series this week at Slate.com on the crisis of walking in America.  He ties it to a range of issues in public health.  It's also an essential part of providing more efficient (and therefore abundant) transit systems.  

The first installment is here, the second here.  

san francisco: winning speed and reliability battles

38 GEARY V A HospMajor San Francisco transit lines take longer than they did a century ago, as they have been obstructed by traffic and slowed by heavy passenger loads using (until recently) inefficient pay-as-you-board methods. A New York Times piece by Zusha Elinson lays out the statistics.  

(It's important to clarify, right away, that this has nothing to do with streetcars as a technology.  You could easily be misled by this subtle bit of anti-bus bias:

In 1920, the F-Stockton streetcar carried passengers from the Financial District at Market and Stockton Streets all the way to the Marina at Chestnut and Scott Streets in a zippy 17 minutes. Today a very similar trip on the 30-Stockton, the successor to the F-Stockton, takes a half-hour if the stars are properly aligned.

In general, streetcars replaced by buses have slowed down more, over the last century, than those that remained streetcars, but that's an expression of how much more was invested in streetcars than in buses.  The main lines that use the Market Street Subway — J through N — have picked up or shed just a couple of minutes from their 1920 times, even though back then they ran on the surface along Market St (about 3 miles) while now they're in a subway, effectively functioning as rapid transit.  No such improvements were made for streetcars that became bus lines, so of course their performance deteriorated more.  In fact, the 30-Stockton relies heavily on maneuverability in unpredictable Chinatown traffic; a streetcar in exactly the same traffic, unable to move around obstacles, would be even slower and less reliable.)

The real message of this story, though, is the need to have a conscious intention about the speed and reliability of transit.  Highway planners ruled the late 20th century with their clearly defined notion of "Level of Service" or cars, which mowed down opposition through its simplistic A-F letter-grades.  Just after 2000, the Transit Capacity and Quality of Service Manual sought, at first, to claim this same authority-through-simplification for transit.  But while the TCQOS is a spectacular reference guide, few in the business believe that a single A-F score can capture the many important ways that transit succeeds and fails.

My own work in this area has always advocated a stronger, more transit-specific approach that begins not with the single delayed line, but rather with the functioning of an entire network.  Don't just ask "how fast should this line be?" which tends to degenerate into "What can we do to make those forlorn buses move a little faster without upsetting anyone?"  Instead, ask "What travel time outcomes do we need across this network?"  Or turn it around: How much of the city needs to be within 30 minutes of most people?  – a question that leads to those compelling Walkscore travel time maps, which are literally maps of individual freedom.

A network speed standard would identify necessary speed standards for each service type, but especially for the Frequent Network, because high frequency means greater impact of delay — both on passenger freedom and the agency's bottom line.  We* used this approach in a Seattle Transit Plan study about 7 years ago:

1.  Define the Frequent Network (every 15 min or better, all day, every day), including any segments that are "Rapid" (faster with fewer stops)

2.  Define the policy operating speed standard for each product (frequent local vs rapid)

3.  Map the existing scheduled speeds on each segment against this standard, creating a map with screaming red segments meaning "deficient."

4.  Prioritize interventions to improve transit speed based on those deficiencies.  

This is quite different from a classic cost-benefit approach in which we count the riders currently on a segment and assign value based on their total travel time saved, because it acknowledges that (a) a dysfunctional segment is probably driving away customers regardless of how many are on it now and (b) the outcome is the network, not just a single line.

We had a lot of success with this in Seattle at the time.  Once the deficiency map was drawn, engineers noticed segments that they hadn't identified as problems before, and went to work on fixing them.  Note too that the method cleanly separates problem from solution.  Don't start with what you think is possible.  Start with what you need.  Define the absence of what you need as a citywide problem that affects the whole network.  Then fix those deficiencies.  If you're going to go to war with three businesses over "their" strip of on-street parking, you're more likely to break through the "big agency attacks struggling small business" frame if you're defending the entire city's transit system.  

Remember: a line is only as reliable as its least reliable point, and a journey through a network is only as reliable as the least reliable of its lines involved.  So one localized problem affecting speed and reliability (such as stops too close together) actually affects a vast area, and drags down public expectations for an entire network product.  If it costs the agency money (as slower service always does) then it's also a direct detriment to the overall abundance of transit service.  That's the frame in which you win battles over three on-street parking spaces, a signal phase, or even an entire tranist lane.

San Francisco's Transit Effectiveness Project is, to a great extent, the culimination of exactly this thought process.  I remember in the 1980s or early 90s a time when Muni proposed to eliminate just one consequential bus stop;  17th & Mission.  The story became: "Big, bad transit agency launches personal attack on the people and businesses at 17th & Mission."  The TEP has worked to change that conversation, emphasizing that on high-frequency services, the speed of every segment is part of the whole city's transit outcomes.  The same process has made it easier to do a range of other locally-hated citywide goods such as removing parallel routes that were too close together.  

Does your city's transit system have a similar project underway, one that moves beyond route-by-route analysis and looks at how every speed/reliabilit deficiency harms the whole city's transit system?

 

*I was with Nelson\Nygaard at the time.  The project was the City of Seattle "Urban Village Transit Network" study of 2004, which became a foundation of the Seattle Transit Plan.

stop spacing: risks of multiple patterns

In a recent post on stop spacing, I quoted an eloquent defense of very closely-spaced stops based on the needs of mobility-limited persons.  This view is unfortunately in tension with the need to move stops as far apart as possible to increase the speed and reliability of operations, and thus attract more passengers.

I was surprised at how many comments suggested that the answer is to provide a mixture of local-stop and limited-stop or "Rapid" services.  This is absolutely the right thing to do on the extremely major streets where you can afford very high frequency (say, every 10 minutes or better) on both patterns.  Most New World cities have just a handful of these streets.  Examples include Mission and Geary in San Francisco, Broadway and 41st Avenue in Vancouver, Western Avenue in Chicago and Wilshire in Los Angeles.  Key features of these streets are (a) very high demand supporting two frequent services and (b) relatively long trips, so that speed advantage of a rapid stopping pattern outweighs the longer walking time it may require. 

But if you can't afford high frequencies, overlaying local-stop (every 200m or less) with Rapid or limited-stop service (every 800m or more) can be really unsatisfying.  Should you wait 11 minutes for a local at your stop, or walk to a Rapid stop 400m away where the next bus comes in 14 minutes but might be faster?  Those are the uninspiring choices presented to a customer when the frequencies are only, say, every 15 minutes but two patterns are being offered. 

When you consider the major streets that support frequent locals plus frequent rapid services, Seattle's long and busy Aurora Avenue might come to mind, but in fact, King County Metro abolished that pattern a few years ago, creating instead a single stopping pattern so that they could run the highest possible frequency.  That's the key.  Especially for trips of under 10 km or so, waiting time easily overwhelms in-vehicle time in determining door-to-door travel time.  So in those cases a reasonable "compromise" stop spacing — not as close as senior/disabled advocates want, nor as far apart as speed advocates want — is actually the fastest at getting everyone where they're going.

Another approach, which I advocate looking at, is to accept that the constituency for very closely-spaced stops may also accept poorer frequency.  If you look at the part of a route that is halfway between two Rapid stops, and thus most dependent on the local stops, and you then subtract all the people there who are willing to walk 400m to the rapid stop, you end up with a fairly small number of people.  So perhaps locals should be less frequent than rapids.  Transit agencies sometimes try to be neutral about this, carefully calibrating local vs rapid service based solely on current ridership.  But in fact, transit agencies have a strong reason to prefer rapids: faster service is cheaper service to operate, because transit vehicles complete their cycles is less time, and we pay drivers by time, not distance.

But it's definitely not adequate to say that we can resolve the conflict between close and wide stop spacing simply by running two separate lines on the same street.  We can in a few places, and if public transit had a lot more money we'd do it in a few more.  But transit agencies need a stop spacing policy that works for the more ordinary street, where you can afford maybe 10-15 minute frequency on just one line.  That means just one stopping pattern, so we have to pick one. 

 

dissent of the week: impact of wider stop spacing

Moving bus stops further apart achieves a range of benefits in speed and potentially frequency, as I've argued here and here.  Zef Wagner at Portland Transport recently laid out a similar case in the Portland context.  The post and most comments are worth reading, but I wanted to quote this dissent from commenter Cora Potter. 

Please keep in mind that you have to weigh any time/cost savings of stop consolidation with providing adequate mitigation for people with barriers to accessing transit stops (disabilities, cognitive barriers that require clear landmarks, etc).

Shuffling these riders off to LIFT [demand responsive paratransit for disabled persons] is not a cost effective solution. The average LIFT ride costs nearly $30 (one way). Even with a conditional eligibility system, you run the risk of increasing costs to the point that you might actually end up with more operating funding deficits than gains. In addition, while LIFT is a complimentary service, meant to be comparable in timing and experience for the consumer, there are tolerances to the system built in and a LIFT trip is usually longer, less direct and less convenient in that it requires an advance reservation. The ability to access the fixed route system is usually the least restrictive and most convenient means of travel for people with disabilities who can reasonably access a transit stop.

When you raise the bar for reasonable access by spacing stops at .25 mile, or 4 blocks or greater, you start significantly limiting what a person with barriers to walking or cognitive barriers can accomplish and make it far more of a challenge for them to reach a stop in a reasonable amount of time, or with a reasonable amount of challenge. The difference between walking one block in the cold and rain vs. walking three blocks in the cold and rain can present a huge challenge to a person who can not walk at a 3 mile per hour pace, and is more sensitive to cold temperatures due to normal aging.

So – just keep in mind that wider stop placement, particularly for bus service, will exclude a segment of the population from accessing fixed route. You need to weigh the gains in convenience for people who have few or no barriers to accessing transit with the social and financial costs of excluding the people who do experience barriers to access. My personal opinion is that everyone loses when older adults and people with disabilities are excluded from fixed route by design. You might gain 3 minutes and the sense that you're getting somewhere faster – is that really worth service cuts on other bus lines to offset the increased costs for ADA paratransit? Is it really worth socially isolating people with disabilities? And, with the aging of the population, we really need to start taking the needs of older adults seriously and not constantly tune our system to serve just the needs of commuters.

A quibble: I disagree with dividing the population into "older adults" with "commuters," as Cora does in the last sentence.  The consituency for larger stop spacing is basically anyone who wants to get where they're going as soon as possible, and who is open to walking a bit further in order to achieve that.  This is not everyone, but it's a larger group than "commuters," who are people making rigidly scheduled trips to or from work or school. 

But I agree with both the practical and ethical dimensions of the comment.  The mobility issues faced by older and disabled people are real and the costs of serving them with paratransit are high.  I also believe that allowing older people to become socially isolated is both economically and ethically unacceptable.

On the other hand, it's very, very hard to organize the mobility limitations of small, scattered numbers of people into facts.  In the early 1990s, when US transit agencies were struggling to implement the Americans with Disabilities Act, no issue was more vexed and emotional than eligibility for expensive paratransit services.  For example, ADA is clear that age, by itself, is not a disability — an important insight because people are not only living longer but remaining able-bodied longer.  The process by which a local government assesses people's disabilities is obviously highly emotional for the individual in question and challenging for all concerned. 

A similar issue applies to bus stops.  When we move bus stops further apart, lots of people complain, and people with mobility limitations complain bitterly.  But given the high cost of the close stop spacing, how should those claims be assessed?  In some transit agencies, the default policy has been: "If anybody complains, cave in."  I'm not ashamed of suggesting that transit agencies be more forceful in articulating the tradeoffs, which requires educating their elected officials about what's at stake.  Cora's done an excellent job of articulating one side of that tradeoff.

P1070842I'd also note that in Europe and Australia, stop spacing is wider than in North America.  In Europe, many stops also have major infrastructure that signals their permanence.  Everyone, whatever their mobility limitation, works with that.  The result is that service runs faster and more reliably.  So from that perspective, this is partly a question about how to transition to that outcome.  It could be done most peacefully if it happened over decades, but ours is an impatient age, and transit agencies are under too much pressure to wait that long.

Part of why this is less of a problem in Europe, I'm guessing, is that the permanence and infrastructure of many stops signals clearly that you should take them into account when deciding where to live.  If an older adult can anticipate becoming dependent on public transit in the future, the location of transit stops should be part of their location decision.  This, to me, fits into a much larger agenda of insisting that everyone who makes a location choice — especially about where to live — should be required to acknowledge the transit impacts of that choice.  Today it's still common to encounter the other sequence, in which someone (a) signs a lease or deed of sale or development agreement and then (b) yells at the transit agency because the service isn't what they desire. 

So as usual, I don't have an answer, but I do think the question needs to be seen as geometrically inevitable, which means that those who disagree with us have a rational and ethical basis for doing so. 

basics: walking distance to transit

The question of walking distance in transit is much bigger than it seems.  A huge range of consequential decisions — including stop spacing, network structure, travel time, reliability standards, frequency and even mode choice — depend on assumptions about how far customers will be willing to walk.  The same issue also governs the amount of money an agency will have to spend on predictably low-ridership services that exist purely for social-service or “equity” reasons. Continue Reading →

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.

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.)

Slide2

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:

"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.

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.

dissent of the week: stop spacing and transit’s multiple goals

Ben Smith from Toronto defends closely-spaced stops, on my post on imagining cities without mobility, which suggests the need to focus more on widely-spaced "rapid transit" stops. 

I'd like to be the devil's advocate for a minute and defend somewhat tighter stop spacing. Think of transit as an elevator: You're on the 7th floor and decide to walk up to the 8th floor, and feel that having the elevator stop there is a waste. However, someone who is getting on at the ground floor may also want to get off at the 8th floor, so having a stop there isn't a waste.

I'm not trying to say that transit should stop at everyone's doorstop, but there is a case for having a more local oriented transit with SOMEWHAT frequent stops. However, if demand and density is having your transit vehicle stop every 100m with a large number of passengers boarding at each stop, then it makes sense to use a higher-order transit vehicle with wider stops.

The easy answer to this is that if you can walk from the 7th floor to the 8th floor to get from one to the other, you can take the same walk from an express elevator that stops only at the 7th.  But that may be too easy. 

I personally am willing to walk as far to useful rapid transit (for a long trip across the region) as I will to a final destination.   My personal mode choice algorithm (as far as I understand it) is that I want to (a) minimize total travel time and also (b) get exercise and (c) avoid waiting and especially passive uncertainty.   So I'm as willing to walk the same distance to a place regardless of whether that place is my destination or I'm planning to catch rapid transit there.

Does my philosphical viewpoint on this depend too much on my own abilities and preferences?  In other words, am I assuming that secretly everyone wants to be just like me?  And if so, am I doing this more than anyone else does?

Obviously, as always, we need to recognize a portion of the population that can't walk far, but at the same time we have two widely articulated policy goals that push the other way:

  1. health goals that support encouraging people to walk if they can. 
  2. sustainability goals that require transit with highways rather than with walking and cycling, which means competing for the trip that is well beyond most people's walking distance

Those considerations lead me to a provisional view that the main prioirty for public transit investment needs to be rapid transit that's worth walking to, not slow transit that stops near everyone's door and that looks intimate and friendly in a New Urbanist mainstreet.  That was the core of my argument with Patrick Condon.

Obviously, there need to be mobility options for senior and disabled persons who have greater need for short-distance transit.  There are also other logical markets for short-distance trips where very high frequency is possible (recalling that waiting time is often the disincentive for short trips) such as downtown shuttles. 

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?

UPDATE!  Ben Smith, the author of the dissent, has had an epiphany!

Basics: The Spacing of Stops and Stations

The unglamorous but essential struggle over the spacing of consecutive stops or stations on a transit line is an area where there’s a huge difference in practice between North American and Australian agencies, for reasons that have never been explained to me as anything other than a difference in bureaucratic habit.  In Australia, and in most parts of Europe that I’ve observed, local-stop services generally stop every 400m (1/4 mile, 1320 feet).  Some North American agencies stop as frequently as every 100m (about 330 ft). Continue Reading →