What’s the theoretical best spot for a bus barn for transit? From a land use perspective it has many light-industrial type qualities - but is an existing industrial park actually the best place to put one?
I'd imagine one key objectives is a location that minimizes non-revenue time for as many routes as possible. Put another way, you want the garage as close to the start of as many routes as you can. With so many routes that might be difficult to meaningfully balance - but central, well connected locations are likely still your best sites. Availability of land is another one of course, these facilities are never small.
First the practical parts - it has to be in an industrial area. A bus barn is a maintenance facility and a fuelling station, meaning inevitably fuel spills and various other chemicals. It also needs roads engineered to handle substantial heavy traffic, and it makes a bad neighbour; who would want 200 buses driving past their house every morning at 5 AM?
Buses need a fair amount of maintenance; certainly nightly fuelling and cleaning, but they travel a lot. A good rule of thumb is an in-service bus travels at 20 km/h; between stops, traffic, time points etc. So a bus in service for 18 hours a day will travel 130K km per year; it travels in 6 weeks what a typical personal car travels in a year. And almost every inch of that is hard city mileage with more stops and starts than normal cars in traffic. Obviously, they're designed for this, but they do need preventative maintenance pretty frequently.
There is a certain minimum size of facility you want; for example, a bus might get a level A inspection every month, a level B inspection (which also includes all of A) that covers more systems in more depth every second month, and a level C inspection (including A and B) every four months. In that case, a bus gets a C inspection every 80 weekdays. Or in other words, your level C inspection station and mechanic will be idle if they don't have at least 80 buses in the garage. You can move buses to a different garage for heavy maintenance, but that adds more complexity and there's still the portion of mechanical work that begins unexpectedly with the driver reporting the steering seems stiff when they drop it at the end of service.
One thing that is instructive is that CT runs all of their community shuttles out of Spring Gardens; the efficiency of having all the maintenance for this vehicle type in a single location presumably outweighs the inefficiency of some of them travelling a little further to start service.
Even most buses that run in the central part of the city have routes that extend into the middle suburbs, and bus routes usually start at the suburban ends, rather than the downtown middle. So suburban locations near major roadways are actually a pretty good location for the majority of bus routes.
To get an order-of-magnitude for the time savings on reducing deadheading -- the time while the bus travels from the garage to the start of service -- consider the proposed garage in Bearspaw; it's as far as you can get from other garages, about 20 minutes. (Literally the drive time to all four existing garages are all 18-22 mins, and the 22 minute garage is Vic Park.) The most time a bus could save would be about 20 minutes.
If you assume bus route starts are roughly evenly distributed, then the average time savings would be 1/2 that, around 10 minutes per bus. (A bus starting at Crowfoot would save 10 minutes with a Bearspaw garage vs Stoney; a bus at Sage Hill would save 3 mins; etc.)
At $120 per hour, that would work out to roughly $3M per year in saved operating costs for 200 buses. (Stoney has 400 bus capacity.) Roughly 2% of the cost of construction. Building another garage halfway in between (e.g. near Stoney/Shaganappi) would then have half the savings again. It's pretty quickly diminishing.
One thing that's assuming is only one deadhead per day at start and end of service; we run a lot of buses peak only and there's two deadhead round trips -- but the best thing to do about that is to provide more midday service.
