Two interesting transit resources
Revised in response to follow up of a comment by mattxmal
And in coming up with some links, I came across SEPTA's report, Modern Trolley Station Design Guide, which is relevant to transit stop and station planning beyond streetcars.
2. Free transit. Because some cities in Germany will be testing free transit as a air quality measure ("German cities to trial free public transport to cut pollution," Guardian) there has been a resurgence of interest in the free transit concept. (Separately some communities offer free transit to sub-groups such as youth or seniors, or discounted passes for seniors, low income households, or college students.)
-- Fare Free Public Transport website
For years I've relied ("Is making surface transit free the best transit investment DC can make?") on a series on free transit, No Fares!, published in The Tyee, the alternative weekly in Greater Vancouver. SF considered it, but didn't pursue it because they didn't have the funds to pay for the increased personnel, buses, and storage facilities. Sadly, they never released the study.
An article ("Why can’t public transit be free?") a few years ago in CityLab denigrates the idea because of vandalism and neerdowells, but they rely on very old research and this isn't much of a problem with fareless square transit in Calgary, Pittsburgh, and Salt Lake City.
Tourist towns. Besides various shuttle programs here and there across the country, since then I've learned that a number of resort communities in North America have free transit systems for their communities as a transportation demand management measure. But these places are small and not analogous to a larger city or county. I have referenced a Volpe Transportation Center study on that, which includes a mention of the sub-city free transit in the historic district of Savannah:
-- Visitor Transportation Study: Report on Urban Visitor Transportation Services
College towns. Mattxmal calls our attention to the fact that some college towns have free transit too, usually in combination with the local university. For example, Central Washington University used to do this in Ellensburg, and transit is free in Chapel Hill, North Carolina, although the system is run by the city with some financial support from the University of North Carolina.
It turns out there is a Transit Cooperative Research Project report on the subject:
-- Implementation and Outcomes of Fare-Free Transit Systems (registration required for access)
Railway Technology has a piece on the subject, "Free transport: does opening up the railways make sense?," and it cites a journal article on Talinn, Estonia, the biggest example in the world of a city that offers free transit, which even extends to commuter rail ("The prospects of fare-free public transport: evidence from Tallinn," Transportation, 44:5, September 2017).
From the article:
Cats’s analysis indicated clear benefits. A year in, public transport usage increased by 14%. During the first quarter of 2013, traffic congestion in the city centre was down 15% compared with the end of 2012, while car use throughout had been reduced by 9%.
The criticism is somewhat comparable to a criticism of free transit districts in North America, that the benefits go mostly to people who can afford to pay for transit. Although I think that misses a key point, that congestion management and maintaining the economic relevance of the central business district are important public policy goals.
I never have looked to see if there are good studies on the impact of free transit zones in North America. After the Global Financial Crisis, Portland and Seattle ended theirs, but Salt Lake City and Pittsburgh still have free transit zones in their Downtowns, as does Calgary, Alberta.
The RT article discusses the possibility of extending the free transit experiment to railroad service, and lists some examples of tests, including the Utah Transit Authority's test of "Fridays Free" on their commuter rail. Like SF, they argue that it's not affordable as a regular practice because of the need for more equipment and personnel, and limited funds to pay for such expansion.