I’ve written a bunch about integrated timed transfer (ITT) scheduling based on Swiss and Dutch principles, developed for intercity and regional trains. Here, for example, is how this schema would work for trains connecting Boston and Worcester. But I’ve also seen interest in how buses can connect to one another, so I feel it’s useful to try to adapt the ITT to this different mode. Two particular places where I’ve seen this interest are a statewide plan for intercity buses in West Virginia, and regional integration around Springfield and the Five Colleges; I’m not going to make specific recommendation for either place, since I don’t know them nearly well enough, but I hope what I write will be helpful there and elsewhere.
The ITT principles for trains
ITT for trains relies on total coordination of all aspects of planning. The centerpiece of this is the triangle of infrastructure, rolling stock, and timetable, all of which must be planned together. Decisions on infrastructure spending should be based on what’s required to run the desired schedule, based on tight turnarounds, maximal utilization rates of equipment, and timed connections.
The even broader principle is to trade state complexity for money. It’s harder to plan everything together – different departments need to talk to one another, planning has to be lean or else the back-and-forth will take too long, regulations may have to be adjusted, government at all levels has to push in the same direction. The reason to do this chore is that it’s far cheaper than the alternative. Organization is cheaper than electronics and concrete at all levels; American households spend around 20% of their income on transportation, mostly cars, whereas households in transit cities like Paris or Berlin or Tokyo spend a fraction of that, even taking into account residual car ownership and operating subsidies to public transit.
On buses, there’s no such thing as electronics…
The Swiss maxim, electronics before concrete, concerns trains exclusively. On buses, no such thing exists. It’s not really possible to get higher-performance buses to make a more aggressive schedule. Acceleration rates depend on passenger safety and comfort and not on the motors (in fact, they’re higher on buses than on trains – rubber tires grip the road better than steel wheels grip rails). The closest analog is that electric buses are lower-maintenance, since the diesel engine is the most failure-prone part on buses as well as trains, but what this leads to, IMC, is not really a strategy for improving timetabling – IMC’s main benefits are less pollution and lower maintenance costs.
…but there is a surplus of organization to be done
All the little things that on trains go in the electronics bucket go in the organization bucket on buses. These include the following operating treatments to improve local bus speeds:
- Off-board fare collection
- Stop consolidation to one every 400-500 meters
- Dedicated lanes in congested areas
- Signal priority at busy intersections
In addition, bus shelter does not increase actual speed but does increase perceived speed, and should be included in every bus redesign in an area that lacks it.
These are all present in Eric’s and my Brooklyn bus redesign proposal, but that doesn’t make that proposal an ITT plan – for one, it’s based on 6-minute frequencies and untimed transfers, whereas ITT is based on half-hour frequencies (for the most part) and timed transfers. Of note, in a 6-minute context signal priority should be conditional to prevent bunching, but if buses run on a 30-minute or even 15-minute timetable then bunching is less likely, especially if buses have prepayment and some dedicated lanes.
That said, it’s important to talk about all of the above in this context, because a bus ITT belongs in areas where public transport ridership is so low that people view a bus every 15 minutes as an aspirational schedule. In such areas, the politics of giving buses more priority over cars are harder than in a city with low car usage like Paris or New York or Barcelona. There are some positive examples, like Rhode Island’s eventual passage of a bill giving six key bus corridors signal priority, but in Tampa I was told that DOT wouldn’t even let the bus agency bump up frequency unless it found money for repaving the street with concrete lanes.
What about intercity buses?
Prepayment, stop consolidation, and dedicated lanes are important for speeding up local buses. But intercity buses already stop sporadically, and often run on highways. There, speedup opportunities are more limited.
But there may still be some room for signal priority. If the bus only runs every hour or every half hour, then driver resistance may be reduced, since the vast majority of stoplight cycles at an intersection will not interact with a bus, and therefore the effect of the change on car speed will be small.
This is especially important if buses are to run on arterial roads and not on freeways. The significance is that highways are noisy, especially freeways, and do not have the concept of a station – freeways have exits but one takes an exit in a car, not on foot. Therefore, development does not cluster near a freeway, but rather wants to be a few minutes away from it, to avoid the noise and pollution. Arterials are better at this, though even then, it’s common for American big box stores and malls to be somewhat set away from those, requiring bus passengers to walk through parking lots and access roads.
Arterial roads, moreover, often do have stoplights, with punishing cycles optimized for auto throughput and not pedestrian-friendliness. In such cases, it’s crucial to give buses the highest priority: if these are intercity buses rather than coverage service to a suburb where nobody uses transit, they’re especially likely to be full of passengers, and then a bus with 40 passengers must receive 40 times the priority at intersections of a car with just a driver. Moreover, if it is at all possible to design stoplights so that passengers getting off the wrong side of the street, say on the east side for a northbound bus if the main development is west of the arterial, can cross the street safely.
Designing for reliability
The principles Eric and I used for the Brooklyn redesign, as I mentioned, are not ITT, because they assume frequency is so high nobody should ever look at a timetable. But the ITT concept goes in the exact opposite direction: it runs service every 15, 20, 30, or even 60 minutes, on a consistent clockface schedule (“takt”) all day, with arrival times at stations given to 1-minute precision.
Doing this on a bus network is not impossible, but is difficult. In Vancouver, the bus I would take to UBC, the 84, came on a 12-minute takt off-peak, and ranged between on time and 2 minutes late each cycle; I knew exactly when to show up at the station to make the bus. When I asked Jarrett Walker in 2017 why his American bus redesigns assume buses would run roughly every 15 minutes but not on such a precise schedule, he explained how American street networks, broken by freeways, have more variable traffic than Vancouver’s intact grid of many parallel east-west arterials.
So what can be done?
Dedicated lanes in congested areas are actually very useful here – if buses get their own lanes in town centers where traffic is the most variable, then they can make a consistent timetable, on top of just generally running faster. Signal priority has the same effect, especially on arterials as noted in the section above. Moreover, if the point is to make sure the noon timetable also works at 8:30 in the morning and 5:30 in the afternoon, then driver resistance is especially likely to be low. At 8:30 in the morning, drivers see a bus packed with passengers, and their ability to argue that nobody uses those bus lanes is more constrained.