Houston’s light rail system was stymied for a long time because of Tom (“I can’t believe he isn’t in prison”) Delay. But we’ve now got one very busy line running & two secondary lines. More growth is expected as the economy allows.
Houston light rail stops at traffic lights. In a few areas it shares the street with wheeled traffic. It would love it if both situations were fixed–but the train is still faster & more comfortable than the bus. (But Metro *did *improve bus service significantly last year–with new routes & more buses.)
Here in The Hague we’re too small for a metro/subway network so the tram (streetcar) system has grown over the years and now also has some light rail lines. There are parts where the trams / light rail run on elevated or completely separated tracks, especially a part that used to be regular heavy rail but was converted. There’s also tram lines that run through regular traffic. But a good part of the city has the trams run separated from other traffic, usually in the middle of a wide road where there used to be a canal. However, as they run on street level they have to cross other traffic at intersections. What happens here is that the trams get priority, so they get a green light pretty quickly (but not immediately) as they approach or when they want to leave a stop. This works reasonably well although I live close to a big intersection where there’s two tram lines at pretty much the same time and it can take a very long time to get a green light.
The main advantage of trams is not speed, busses can go pretty fast, too. But trams have much higher passenger capacity.
This is more of an IMHO thing, because the decisions were made as opinions of someone who specified these things when building the system…
Light rail getting priority at road crossings is more like the way its done with heavy rail…
Best not to have a stop near the crossing, and then the train is detected a minute away and the crossing is brought to a stop… the train picks up speed and blasts across the road… if the road traffic blocks the way, the train can stop in time and have the road cleared.
Now if there is a rail stop near the crossing,and the crossing gives rail priority, the road might be stopped for 5 minutes while the passengers get in and off the train and waits for the time to go per the timetable, and stuff like that. However with light rail , the stop time is shorter and it makes sense that it comes to a stop near the road and the passengers get on and off, sitting there for a minute at a red light and then it gets the green light.
There’s no one numeric guide for these things, because there’s opinions to deal with…risk (not objectively determinable)…feelings (of drivers being scared…)
Many of the stations are located immediately adjacent to where the tracks cross major arterial roads. When the locomotive is stopped at some stations (including mine) it’s only about 1-1/2 loco-lengths short of impinging on the roadway.
The solution is NOT, as you suggest, to stop road traffic for the whole time the train occupies the station.
Instead the road crossing remains open the whole time the train is approaching the station, slowing to a stop, and sitting while loading / unloading. When the train is ready to leave, the loco creeps forward a few more feet which triggers the crossing lights, gates, etc. Once the gates are down (and the last of the gate-evaders zoom through; morons!) the train accelerates away from the station. The gates are fully down for maybe 30 seconds total.
There are also periodic through trains going 50-60 mph on the same tracks. For them the gates drop much earlier in both time and distance. With modern control systems it isn’t magic to know which kind of train is approaching and how to best operate the gates for minimum impact on road traffic.
Bottom line: the tradeoff you’re talking about need not be a factor. It might be in some areas with truly primitive control systems. But if our obsolete, cash-starved, politically orphaned local railway can do it, I’d imagine any competent modern commuter railway, light or heavy, could do it too.
There are also places outside of downtown Portland where the lightrail runs on streets. The Blue Line runs on some streets in Hillsboro and (I think) Gresham. The Yellow line runs on Interstate Avenue in north Portland and the Orange Line runs on several different streets, especially McLoughlin Boulevard, going to and within Milwaukie.
One thing about running on Portland city streets is that it limits the trains to only two cars. Portland has fairly short blocks and a three car train would be too long to fit between intersections. There’ve been suggestions that they put the downtown routes underground to avoid this problem and also to speed it up through downtown. It would be expensive, and they’d also have to reroute or do something about these other areas where it runs on streets.
It was definitely Old School, but I liked his diäereses.