Eric Jaffe at The Atlantic Cities says: Road Fees Don’t Hurt the Poor as Much as You Might Think – :
“Altshuler bases his position on a couple surveys conducted in metro areas that have adopted HOT lanes in the recent past. One was done in San Diego circa 2001. At that time, about 80 percent of low-income respondents agreed with the concept that people should be able to use an express lane on Interstate 15 for a fee — a greater percentage of agreement than people from high-income brackets (70 percent). Additionally, two thirds of people who didn’t even use the lanes still supported them.
A similar survey was done in 2006 in Minnesota. That work showed a 60 percent approval rate for HOT lanes on Interstate 394. A stronger analysis of this corridor, done by Tyler Patterson and David Levinson [PDF], found that income levels did predict use of the express lane (with higher-income drivers using them more often), but that lower-income drivers could also benefit from the shift of traffic out of the free lanes (as well as always having the express option in a time crunch).
(And a far more recent survey, released in April, showed that two-thirds of people making less than $50,000 a year said they’d use express toll lanes — the same percentage as people making more than that.)”
My comprehensive review of the topic is: Levinson, David (2010) Equity Effects of Road Pricing: A Review. Transport Reviews 30(1) 33-57.
The NCHRP had a report on this as well: Equity of Evolving Transportation Finance Mechanisms.
A key point is that HOT lanes also enable freeway BRT where it might otherwise be unaffordable to construct. The express lanes are uncongested and can be used by buses to maintain speed. An example is the I-35W corridor (Orange Line) south of downtown Minneapolis, which is not complete (Lake Street Station is still missing, e.g.), but has a BRT station at 46th.