One of the big problems with the “test” red painted transit only lanes running on Church St. between 16th and Market Streets is the barrier effect. They don’t let cars headed North turn left at several key intersections. Cars are forced into the far right lane and the arrows on the pavement direct them to go forward or take a right.
To legally turn left they would have to use the red lane which has signs prohibiting all access at all times to regular cars. Even at midnight drivers are afraid to use the red lane.
These turn restrictions interfere with the flow of vehicles rolling through the Castro forcing many to use 17th Street to get to Sanchez Street so they can cross Market Street and keep going North on Steiner Street. It’s crazy but Sanchez and Noe Streets are the most viable crossings for drivers passing through the Castro toward the North of Market neighborhoods.
Actually the red lane on Church Street plays a double role in diverting automobiles to tiny little 17th St. It has much to do with that huge host of cars coming from San Mateo County and headed for the Northern neighborhoods. They have to cross Market Street.
Anyone that drives knows that Dolores Street doesn’t cross Market Street at all. Guerrero Street barely crosses and Valencia shunts you East over to Franklin Street. Church Street does cross Market Street historically carrying a good chunk of that North/South load but the red lane killed 50% of its capacity creating a choke point at Market St.
So drivers headed North detour up 17th Street to Sanchez and in some cases all the way to Noe Streets contributing negatively to 17th Street and two already very dangerous Market Street intersections.
This goes far in explaining why at certain times of the day 17th Street is seeing hundreds of cars per hour blasting through at high rates of speed.
How do they do bus-only lanes in New York City?
New York City doesn’t bother with all the expensive red carpet treatment. And they don’t have confusing signs. What they do is they run their buses on the right hand lane of the street and they label that lane with paint and with hanging signs as “bus-only” and they are specific about when drivers have to stay out.
But what about the parking? This is Fifth Avenue in the very heart of Manhattan. They need parking more than most people on earth but they have the wisdom to use their streets in an intelligent manner that prioritizes transportation of people over publicly subsidized parking. 
I humbly suggest that San Francisco should adopt New York City’s approach to bus only lanes and spend our money on resurfacing and repairing the pavement instead of repainting the streets.
I further suggest that San Francisco’s Most Troubled Agency (SFMTA) should stop experimenting with our lives. They don’t have any special ability or funding for these sort of “tests.” In fact their lack of data regarding vehicle counts and speeds in this specific area is scandalous. If this is a test show us the before and after data for the test zone.
When their poor traffic engineering and deferred street maintenance kill people SFMTA doesn’t even apologize. In light of the moral turpitude of their staff I suggest that they be limited to using designs that have been proven to work in the big world. Using the Fifth Avenue method of facilitating buses on Church Street would be a good way to start.
UPDATE: Jan 5, 2017: The SFMTA released their own report on the Church Street Red Lanes. “Church Street Transit Lanes Final Report” February, 2015.
There were two recent articles in the news media of interest to anyone who wants to learn a bit more about this red lane test program.
“SF red transit lane beloved by riders, but merchants unhappy” – San Francisco Chronicle 12/28/2016
“Mission red lanes crushed in online popularity contest” – Curbed SF, 12/28/2016
offtracksanfrancisco 
I realize this is an old article, but it mis-states New York’s bus only lane description. Red lanes were first found in New York, not San Francisco. They do not use them everywhere, but they use them in a LOT of areas.
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