Western Railroad Discussion > SMART Turns on CTC 01.13.17

SMART (Sonoma Marin Rail Transit) turned on the CTC/ATC system today between Milepost 17 (San Rafael) and Milepost 60 (Santa Rosa Airport). Although signals have been in place for some time, main track authority was previously granted via Track Warrants.

With the new form of dispatching, speeds will gradually be increased across the line. Currently, the maximum authorized speed is 30MPH with a section of "test track" between Petaluma and San Marin good for 59. The ATC/PTC system works in conjuction with the CTC and there are no intermediate signals on the line, just signals at Control Points ie: Sidings, Drawbridge, Gauntlets.

No trains are currently running south of MP 20 (Marin Civic Center) due to the slide(s) at the north end of the Puerto Suelo Tunnel. Hopefully, there will be some rightside up photos posted of the damage in the near future and trains will be running into town and annoying the residents sooner rather than later...

There are cab signals in the DMU although instead of a signal indication inside the cab there is read out of Target Speed and time to penalty, thus no need for lineside signals. The downside, if the ATC goes out, an absolute block must be established for each train. With this system, trains will be allowed a maximum authorized speed 79 MPH.

gonx Wrote:
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> Without intermediate wayside signals, how can
> maimum (high speeds) be obtained?

MTA light rail uses TWC Loops (Train Wayside Communication) receiving data as to signal at interlocker, speed ahead, etc.The loops are spaced as if they were wayside signals.As train passes over the loop, the operator gets a speed indication. If no action is acknowledged, then a penalty stop insues.They can also control grade crossings at nearby staions from the cab such as cancel the crossing and re-start it. This eliminates any undo crossing congestion if the station stop is longer than normal. The loops are positioned at each end of the platform where the leading cab stops over it. 

shortlineer Wrote:
-------------------------------------------------------
> There are cab signals in the DMU although instead
> of a signal indication inside the cab there is
> read out of Target Speed and time to penalty, thus
> no need for lineside signals. The downside, if the
> ATC goes out, an absolute block must be
> established for each train. With this system,
> trains will be allowed a maximum authorized speed
> 79 MPH.
>
> gonx Wrote:
> --------------------------------------------------
> -----
> > Without intermediate wayside signals, how can
> > maimum (high speeds) be obtained?



Edited 2 time(s). Last edit at 01/14/17 01:18 by SP4360.

Conrail (CSX) removed all intermediate signals between Albany and Boston many years ago - and run with cab signals.

If there is occupany ahead, the can signals will conform just like if you were passing a signa. There is a rule in place In conjunction with another (don't recall it) but a "C" light can be illuminated for "clear to the next interlocking.

There is a UP line in Kansas or Oklahoma that is TWC with cab signals and no wayside signals. There are defined points on where cabs can change.

Amtrak's ACESS will display a cab signal plus speed.

CNW ATC essentially only shows three aspects IIRC and most others will display four.

PTC as it is being implemented by a couple of vendors on the locomotive (Wabtec) will show Maximum authorized speed along with stopping and warning distances.

To my knowledge no cab signal system has been replaced or will be replaced (as we have been told) by PTC.

PTC is designed to prevent collisions and similar violations. It's overlayed with the signal system and has not replaced it (yet).

gonx Wrote:
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> Thanks. Let me see if this is right.
>
> So there are coded track signals kicking out track
> speeds based on virtual track blocks?
>
> I think we at TO and other places of foam talk of
> PTC, but I think a lot of specific
> information about the system and how it is to be
> implemented to be vague.

The blocks are not virtual, they are hard-wired blocks, but rather than displaying the signal aspects on wayside equipment it will be displayed in the cab of the DMU on cab signal equipment.  This sounds like ATC with a PTC overlay, similar to what Amtrak has on the NEC, Keystone, and Hudson lines.  If I'm not mistaken, the Hudson line does not have intermediate signals either.  

The signal blocks are hard-wired, with the signal information fed through the rails as electronic pulses.  Depending on the complexity of the system I believe there are two, four, or nine code systems.  The pickup bars pick up the signal code in the rail and display the appropriate signal on the cab signal display in the lead unit.  PTC works in tandem with the ATC system to enforce the signal speeds, as well as permanent speed restrictions and positive stops.

MW810 Wrote:
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> There is a UP line in Kansas or Oklahoma that is
> TWC with cab signals and no wayside signals. There
> are defined points on where cabs can change.

That would be the Hiawatha Sub in Kansas. There are no wayside signals, only signs designating where the cab signals will change, called aspect change points. 

> To my knowledge no cab signal system has been
> replaced or will be replaced (as we have been
> told) by PTC.

I do not believe this to be correct as I have been told that once PTC is implemented, the UP will deactivate the cab signal systems on those territories. 

imrl Wrote:

> I do not believe this to be correct as I have been
> told that once PTC is implemented, the UP will
> deactivate the cab signal systems on those
> territories. 

I am in agreement.  Coded cab signal systems are an antiquated technology that originated back in the 1940's and would serve absolutely zero purpose alongside a working PTC system.  Cab signal systems are expensive to maintain and would undermine the investment in PTC which is far superior in every way.  Keeping the cab signals active would be the functional equivalent of using a CRT computer monitor with a brand new, state of the art HD capable computer.  Yeah, might work, but what are you gaining from it?



Edited 1 time(s). Last edit at 01/18/17 09:00 by HogheadMike.