Heavy Rail Transit grade crossings

doweling wrote:and yet nobody says "we MUST have Positive Car Control, by Congressional mandate!"

Well, Congress usually at least waits until the technology is feasible before mandating it.
Postive Car Control is not feasible yet as far as I am aware, and certainly Congress doesn't think so.
But you wait, as soon as they think it has, watch them implement a law no matter how expensive it is for us car, truck, bus, and cycle owners.

electricron wrote:

doweling wrote:and yet nobody says "we MUST have Positive Car Control, by Congressional mandate!"

Well, Congress usually at least waits until the technology is feasible before mandating it.

They didn't in 2008; at that time PTC was still only a concept--there was nothing you could order from a supplier. Congress was just in a panic about Chatsworth and was in a Something-Must-Be-Done mood.

Japan, China, and Europe have implemented PTC for decades, having automatic train stopping capabilities.

As I understand it, there's more to PTC than is found in systems that have been around for a while; the NEC has had cab signals and automatic speed control for years, but PTC is supposed to detect the potential overrunning of a stop signal before it happens rather than detecting a failure to stop after it happens. Forcing a train to comply with successive speed reductions in preparation for a stop Is done now, but the critical point has been to predict whether a train proceeding at a speed appropriate for stopping at the next signal is actually going to stop when it gets there. From what I've read, there are complicated procedures built in that examine various actions in real time and set up necessary measures. Surely if it were simple it would have been done by now.

Does anyone here reckon that grade crossing removal, be it closure or grade separation, be prioritised over new extensions given that such crossings aren't allowed on new extensions?

If by prioritized you mean "should be done instead of," I think each case must be judged on its merits; no two situations are alike. For one thing, the volume of traffic (rail and road) over the existing crossing must be considered, as well as accident history. In the U. S., if you want Federal funds to pay for crossing elimination you have to do a study as specified by the Federal Railroad Administration to determine which crossings in an area must be done before others.

I seem to remember that crossings by heavy rail transit systems are actually under regulations set not by the FRA, but under USDOT's highway regulations....

AgentSkelly wrote:I seem to remember that crossings by heavy rail transit systems are actually under regulations set not by the FRA, but under USDOT's highway regulations....

I doubt that. The FHWA regulates traffic control devices, but little else. Apart from interstate highways and the NHS, the FHWA doesn't really care much about roadway geometry, intersections, etc. Those standards are left up to states. For example, here in Massachusetts, the state DOT has a design guide that you must either meet or get an exemption from for projects receiving state money, and a cursory review of the railroad-highway grade crossing section of said manual doesn't show any mention of rapid transit.

The FHWA does publish a grade crossing handbook, but I can't find any mention in it of rapid transit crossings apart from one brief mention of there not being very many of them.

Yeah--when I posted that I was thinking of a project I was involved in years ago that involved a railroad, not a rapid-transit line; the corresponding agency would be the FTA, but I don't know whether they have promulgated anything on heavy-rail rapid-transit crossings. However, I think it still holds true that there are too many variables for a meaningful generalization to be possible.

ExCon90 wrote:As I understand it, there's more to PTC than is found in systems that have been around for a while; the NEC has had cab signals and automatic speed control for years, but PTC is supposed to detect the potential overrunning of a stop signal before it happens rather than detecting a failure to stop after it happens. Forcing a train to comply with successive speed reductions in preparation for a stop Is done now, but the critical point has been to predict whether a train proceeding at a speed appropriate for stopping at the next signal is actually going to stop when it gets there. From what I've read, there are complicated procedures built in that examine various actions in real time and set up necessary measures. Surely if it were simple it would have been done by now.

In other words, LZB, which the Germans have been using since before Ricky Gates?

What is it they say, if all else fails, look it up? I just did, and I didn't realize they had moved beyond the earlier intermittent-inductive system I knew about, but there still seems to be something about PTC that requires more than that; more than adding in civil-speed reductions like ACSES.

deathtopumpkins wrote:

AgentSkelly wrote:I seem to remember that crossings by heavy rail transit systems are actually under regulations set not by the FRA, but under USDOT's highway regulations....

I doubt that. The FHWA regulates traffic control devices, but little else. Apart from interstate highways and the NHS, the FHWA doesn't really care much about roadway geometry, intersections, etc. Those standards are left up to states. For example, here in Massachusetts, the state DOT has a design guide that you must either meet or get an exemption from for projects receiving state money, and a cursory review of the railroad-highway grade crossing section of said manual doesn't show any mention of rapid transit.

The FHWA does publish a grade crossing handbook, but I can't find any mention in it of rapid transit crossings apart from one brief mention of there not being very many of them.

Hmmmm....I'm trying to remember where I heard that from so I can ask that person. I'm going to email a contact I have with NYDOT to see if he knows.

MattW wrote:Perhaps I should have phrased my question better. The question really doesn't have much to do with the electrification. Really I'd just like to know if Heavy Rail is allowed to have grade crossings at all. I only mentioned the electrification because at one time I had heard that it wasn't allowed, but I don't know if that's because most HRT is third rail, or because HRT just can't have grade crossings regardless of power supply.

Your question may be a little too broad for a new system that does not have the money to do either a subway or elevated sections. With some luck the freeway may still have enough width to put in 2 tracks. It may be required to do 4 quadrant gates or other device to keep motor traffic off the rails.