The I-95 Express Lanes in Southeast Florida (Miami-Dade-Broward County) are showing excellent progress as free-flow speeds are maintained in the express lanes while speeds have improved in the general purpose lanes. The High Occupancy Toll (HOT) Lanes were controversial when they started, but their performance has improved steadily since opening.
According to the October 2011 Monthly Operations Report from Florida Department of Transportation District Six, the two express lanes (both directions) handle about one third of the traffic flowing southbound and about a third of the traffic flowing northbound during peak periods. During peak periods, the express lanes' market share reaches 49 percent of southbound traffic and 50 percent of northbound traffic. Peak period average speeds are 61 mph for southbound traffic in the express lanes and just 48 mph for the general purpose lanes. Northbound drivers in the express lanes average 57 mph during peak periods while travelers on local (general purpose) lanes average 44 mph.
Florida Department of Transportation has also produced a useful introductory video (4:26 minutes) to the project and its performance to date, which would also be useful as a tool for explaining the concept and their performance to those unfamiliar with the HOT Lane idea.
NOTE: This post was updated on December 1, 2011 to delete incorrect calculations on peak period travel on the express lanes from the report.