The rails for the E line branch of the Green Line subway/streetcar in Boston, Massachusetts, USA occupied the middle of two-lane Centre Street for over 20 years after service was discontinued. There had been a proposal to redo the street and restore streetcar service, but ADA requirements for wheelchair compatibility would have required new tracks to snake over to raised platforms at the curbs for stops. Bicyclists, who already were crashing on the existing rails, would have had to cross the new rails repeatedly. Bus service with the transfer to the Green Line on Huntington Avenue, which runs in the median, is about 2 minutes slower than streetcar service. Reconstructing the street with the new rails also would have been very expensive. Eventually, the proponents for bus service won out and the old tracks were paved over.
The three remaining streetcar lines in Boston all run in the median. A busway also can run in the median. All conflicts can be addressed with signalization. But this solution requires a wide street. If it isn’t wide enough then you lose the bike lane/wide outside lane: here is an example.
A streetcar line on a one-way street allows bicycle traffic to stay on one side and streetcars on the other. Here’s a photo of this treatment in Portland, Oregon. It still has problems described in the caption. Or the streetcar may go contraflow with no other contraflow traffic allowed.
Not so good: Running the bikeway behind the trolley stop. A Copenhagen study found that running a cycle track behind a bus shelter led to 19 times the crash rate and 17 times the injury rate of other installations. Problem with a streetcar line, though, is that the tracks pose the risk of bicyclists’ crashing even when there is no streetcar nearby. That leaves no good solution other than to put the streetcar and bike route on different streets. Here’s an example of a bikeway behind a bus shelter from Portland. Unfortunately, the street here leads to an important river crossing, so a different bike route wasn’t an option.
I have heard that Phoenix’s new light rail system has to skew between stops either side of a one-way street because there is an important trip generator on the left side. A bike lane plays hopscotch with the light rail line and bicyclists must cross the street twice to continue. At least it is possible to transport bicycles in the light rail cars — probably the best way to get through that area with a bicycle!