There’s a lot of ways to visualize frequency; I’m hoping this is relatively intuitive. Here is the service offered by the light rail networks in Canada and the US. The grid represents a station at the edge of the downtown during the 7 to 8 AM weekday time period; each cell is a minute, and if it has a colour and letter then that’s the train that arrives in that minute.
The two rows for a city represent the two directions; some cities with more complex situations have four rows — in Portland and Houston, the trains run in two different directions, and in Denver, the trains go to two different stations in the downtown area.
What’s Interesting Here
One thing to note is that rail service doesn’t mean rail service; you can have a 15 minute wait between trains, or a 5 minute wait. Almost all of the services rise to the level of 15 minute “frequent” service, but only a quarter are in the 10 minute headway range that I think of as true frequent service — remember this is rush hour!
While I hate to be a local booster — seriously, look at Calgary. 26 trains per hour in a single direction. This is on 7th Avenue, which runs at street level, mixed with other transit vehicles and crossing roads at lights. This is a frequency even subway systems have a hard time matching. The next busiest stations are Union Station in Denver and 12th and Imperial in San Diego and both are multi-platform stations. Dallas is the next busiest simple two-track configuration, with 70% of the trains Calgary has, and they’re working on building a downtown tunnel to relieve congestion.
Not much to say for methodology; it was just a matter of looking up the schedules on 18 different websites. All schedules are current as of Jan 5/2019 (Denver is as of the Jan 13/2019 service update).
The chart is sorted by increasing frequency, with ties broken by the fewest number of services — Seattle, Sacramento and St. Louis all have 10 trains per hour but Seattle has all that service on a single line, where Sacramento spreads it out over three different services.
I’ve only included light rail focused cities; I’ve left out streetcar and commuter rail service (Denver is an interesting hybrid, and I’ve included the A and B there), and I’ve left out cities where there is also a major heavy rail component — the light rail service in Boston or San Francisco are only a portion of the transit picture.