The Right Frequency

I got an email from a colleague today asking me if there was “a national standard for transit frequency ranges”. Off the top of my head I wasn’t sure, though I know 15 minute headways are generally seen as “frequent” when it comes to the new mapping standard.

So I did a bit of digging and found a paper from the Transportation Research Board. I skimmed through and as I was looking at some of the charts stumbled upon the exact answer I was looking for…a short simple chart that laid out a pretty simple frequency standard for urban service.

I posted this on twitter and many weren’t happy with this one.

I kind of don’t like this. It’s better for a bus to come every 15 minutes than every 13 or 14.

— alon_levy (@alon_levy) August 25, 2017

Yeah. Plus, this is too generous: I’d replace “desirable/attractive” with “acceptable.” I don’t desire to wait 20 minutes if I miss a train!

— Doug Newman (@donewman) August 25, 2017

For me, 10 min wait is my absolute max, & I’m not happy. 7 is tolerable, but annoyed. 4 is reasonable. 1-2 is ideal.

— Nextransit (@Nextransit) August 25, 2017

So I did some digging to see if I could find more that matched the twitter sentiment. Seems as if the one I had posted was an older version.

There’s a newer version of The Transit Capacity and Quality of Service Manual (TCRP 165) from 2013 that is more comprehensive. The stupid thing is 805 pages but I found what I was looking for…and it wasn’t as simple.  So I took the relevant information and made the chart below. It comes from page 199 to 201 in the PDF.

This made things a bit more detailed and … frequent.