Light Rail on the ROW without killing freight?

So when "subways" get extended often times they'll take a traditional passenger/freight row that is two tracks, and increase it to four tracks. So you'll have two commuter rail tracks and two light rail tracks. If there is still freight on the ROW, that usually means building tunnels and fly-overs (for example, orange line to Oak Grove). Are there any other options? Ways you can add (what I call) subway without killing freight service, or adding many expensive bridges & tunnels? I believe I've read that you can't have "heavy rail" and "light rail" sharing any tracks. Are there any exceptions to this? Like a diamond? Or a very short stretch where you can cross over from heavy rail to light rail, to a freight siding?

l008com wrote:So when "subways" get extended often times they'll take a traditional passenger/freight row that is two tracks, and increase it to four tracks. So you'll have two commuter rail tracks and two light rail tracks. If there is still freight on the ROW, that usually means building tunnels and fly-overs (for example, orange line to Oak Grove). Are there any other options? Ways you can add (what I call) subway without killing freight service, or adding many expensive bridges & tunnels? I believe I've read that you can't have "heavy rail" and "light rail" sharing any tracks. Are there any exceptions to this? Like a diamond? Or a very short stretch where you can cross over from heavy rail to light rail, to a freight siding?

The word "freight" is bantied around this argument without definition. Local, terminal freight operations are different than intermodal stacks and coal drags. Probably it is easier to say local, terminal work can be done between some schedules or after some late night hour and before the early rush. But a dozen stack, intermodal, coal and general merchandise trains zipping through in each directin daily demands a long hard look and careful planning. Seperate rights of way?!

Perhaps I didn't explain my first post clear enough. I'm referring to local business spurs up and down a rail line that currently has commuter, local and through freight. In a situation where they wanna add two tracks of light rail, is there anything that can be done to prevent the need for countless fly-overs and/or tunnels? Other than stopping service to all the freight spurs on the new 'light rail' side of the main tracks? Something to keep the price from going too astronomically high. You know what I'm saying/asking?

If the local traffic isn't that large, you can use "time separation", like the RiverLine in New Jersey -- the light rail line uses the tracks in the daytime and the freight at night. If all the freight for the sidings can be fit into a small time slot when the light rail is shut down, the sidings could be connected to the light rail with the light rail connected to the mainline with a lockable gate.

But the *best* solution is to use FRA-compliant (and we all hope that will become simpler in the future) railcars. In other words, don't make it "light rail", but try to make it as light-rail-like as possible. SEPTA Regional Rail rather than Washington Metro. If you really want to have the light rail feature of street running, you'll have more trouble. Street running with mainline equipment is really severely discouraged these days and I doubt permission could be gotten for new street running of that sort.

What is the reason light rail vehicles cannot run on heavy rails for part of their run? It's the same standard guage isn't it?

It seems feasible to me as a (non-railroad) engineer. I know I must be missing something.

I always assumed it was because a heavy rail vehicle would completely destroy a light rail vehicle in an accident.

l008com wrote:I always assumed it was because a heavy rail vehicle would completely destroy a light rail vehicle in an accident.

Correct, that's the basis of the FRA regulations.

Now, they run trams and freight on the same tracks in Europe all the time. But they have *much better signalling systems*, which enforce block occupancy (non-permissive), enforce speed limits, and force both types of trains to come to a full stop at stop signals. Many of the US light rail systems have signalling systems that good, but they're all incompatible with each other. And worse, almost no freight trains in the US are equipped for that sort of automatic train stop -- and where they are, namely the NEC, it's on yet another signalling system.

The FRA might be willing to consider light rail operation mixed with heavy freight operation if both were running European-quality signalling systems with automatic train control, automatic train stop, cab signals, non-permissive block occupancy rules, and so on. Nobody has actually tried that in this country, yet. (Caltrain is talking about doing so). And the FRA hasn't been pushing in that direction, either.