More on transit's killer app: time
(Another point made by charlie in the argot of the social media generation, is that transit gets riders when it is time-efficient.)
One of the papers you can access at the Urban Studies Journal published by Sage Publications is
"What Really Matters for Increasing Transit Ridership: Understanding theDeterminants of Transit Ridership Demand in Broward County, Florida" by Gregory Thompson, Jeffrey Brown and Torsha Bhattacharya
Urban Stud 2012 49: 3327 originally published online 4 May 2012
In 2004, Broward County Transit, located in Broward County, Florida, had among
the highest ridership per capita and lowest cost per passenger kilometre of all-bus
systems in US metropolitan areas with between 1 million and 5 million people.
Broward County has few land use attributes thought necessary for transit success.
This (2000) study seeks to understand its performance despite its transit-unfriendly
urban environment by estimating a transit ridership demand model that differs
from most by including generalised price of transit travel from origin to destination.
The hypothesis, which the study confirms, is that price (time to reach employment)
is more important than land use variables for explaining transit patronage, at least
for a bus-only transit system with a large number of transit-dependent riders. The
results of this study give further empirical support to recent transit system initiatives
to focus more service on decentralised employment centres using multidestination
transit network structures.
For me the lesson is that the most important element (although tempered somewhat by price) in transit promotion is the time it takes to get to your destination.
While the article says that this is more important than land use variables, recognize that these variables do in fact influence significant how efficient transit can be in getting from and to various destinations.