Direct Traffic Control

I was wondering about DTC. I live close to the UP coastline. During the time SP owned it they used DTC around the L.A. area as well as other places around the system. Since the merger (SP & UP) mosetly the last two years or so UP has replaced DTC with CTC and TWC.

My question is; Do any of the current railroads use DTC?

Thanks ahead of time.

I know CSX does. I know BNSF does not.

What is DTC?

Santa Fe Sucks wrote:I know CSX does. I know BNSF does not.

What is DTC?

The main difference between TWC and DTC is that DTC is based on authority to occupy pre-defined blocks as listed in the timetable. In TWC the Dispatcher can grant authority based on stations or mileposts so it is more flexible than DTC.

BTW - NORAC "Form D" DCS is basically the same as TWC.

clearblock wrote:

Santa Fe Sucks wrote:I know CSX does. I know BNSF does not.

What is DTC?

The main difference between TWC and DTC is that DTC is based on authority to occupy pre-defined blocks as listed in the timetable. In TWC the Dispatcher can grant authority based on stations or mileposts so it is more flexible than DTC.

BTW - NORAC "Form D" DCS is basically the same as TWC.

Ah, so they give blocks instead of mileposts and stations and sidings. Probably speeds things up a bit even though it's less flexible.

If DTC is your authority, then I take it an ABS system governs your movements?

Santa Fe Sucks wrote: If DTC is your authority, then I take it an ABS system governs your movements?

TWC and DTC are for "dark" territory, similar to the old "Train Order" systems where there are no signals. You are correct that DTC blocks are similar to ABS blocks except that movement is by DTC authorization instead of signals. This is probably why DTC was adopted by some railroads when they decided to remove signals from ABS territory.

TWC evolved from DTC to allow more flexibility but it requires careful planning by the Dispatcher to select appropriate limits for the movement. Train crews have to keep alert to remember the location of their authority limit if it is a milepost. There are no fixed Approach Block Limit and Block Limit signs like there were in DTC to remind you where to stop.

Note that UP has some "dark" territories where TWC is in effect and ABS is used, as well, to facilitate the movement of trains. In this case, track warrants convey authority to occupy a main track while automatic block signals keep the trains from running into each other within the authority "blocks."

UP does not use DTC.

ABS Signals by themselves do not have any authority associated with them. You have to have some sort of authority like DTC, TWC or Yard Limits to occupy the main track.

You are correct that DTC blocks are similar to ABS blocks except that movement is by DTC authorization instead of signals. This is probably why DTC was adopted by some railroads when they decided to remove signals from ABS territory.

CN_Hogger wrote:ABS Signals by themselves do not have any authority associated with them. You have to have some sort of authority like DTC, TWC or Yard Limits to occupy the main track.

Under NORAC Rules, ABS signals do "authorize" train movements if DCS Rules are not in effect on the territory. This may not apply on other railroads.

"ABS signals convey to trains the occupancy and/or condition of the track ahead of them. Under normal conditions train movements are authorized by these signals"

The NORAC DCS Rules do provide for both "non-signaled" (dark or against direction of movement) and "signaled" DCS operation (combined DCS and ABS). If DCS Rules apply then, yes, Dispatcher Form D Line 2 permission is required to occupy the track outside of Yard Limits.

It is common to have ABS system operating under TWC/DCS rules to give added flexibility to the operations.

For DTC, most cases I have seen in the past involved the decision to remove an ABS system due to downgrading of a line. The ABS Block Signals were replaced by DTC "Block Limit" signs and operations continued as before except the train got permission to pass the Block Limit from the Dispatcher instead of a clear signal.

Well, I've seen a few places on the CSX where DTC is in effect, but there is some kind of ABS (Signal) system on the line.

Yes, there are a few locations on CSX where a form of DTC is in effect where ABS signalling is operative. These locations are where traffic patterns and/or volumes are such that CSX is using DTC as an additional procedure to ensure a high level of train safety.

An example is the section of double track in the Orlando, FL area (which has an ABS signal system, with CTC systems on both sides of it, extending to Tampa and Jacksonville, and beyond). DTC controls all trains, including the entry and exit of Florida Central RR trains, on this stretch of railroad line.

ACLfan

ACLfan wrote:An example is the section of double track in the Orlando, FL area (which has an ABS signal system, with CTC systems on both sides of it, extending to Tampa and Jacksonville, and beyond). DTC controls all trains, including the entry and exit of Florida Central RR trains, on this stretch of railroad line.

ACLfan

Why would you need DTC if CTC is in effect?

clearblock wrote:

CN_Hogger wrote:ABS Signals by themselves do not have any authority associated with them. You have to have some sort of authority like DTC, TWC or Yard Limits to occupy the main track.

Under NORAC Rules, ABS signals do "authorize" train movements if DCS Rules are not in effect on the territory. This may not apply on other railroads.

Well, I apologize....I'm not familiar with NORAC rules, only GCOR and USOR rules.

Although the way I read your rule quote I still see nothing about occuping the main track, only authorizing train movement.

I guess what I said previously wasn't exactly clear. Should have been, ABS Signals by themselves have to main track authority associated with them. All this talk has me curious, any online versions of the NORAC?

Santa Fe Sucks wrote:

ACLfan wrote:An example is the section of double track in the Orlando, FL area (which has an ABS signal system, with CTC systems on both sides of it, extending to Tampa and Jacksonville, and beyond). DTC controls all trains, including the entry and exit of Florida Central RR trains, on this stretch of railroad line.

ACLfan

Why would you need DTC if CTC is in effect?

Maybe he means that there is a section of DTC inbetween two sections of CTC. The BNSF has something similar between Savanna, IL and the Twin Cities, TWC/ABS inbetween CTC sections....basically done to save money compared to CTCing the entire line.

CN_Hogger wrote:[
Well, I apologize....I'm not familiar with NORAC rules, only GCOR and USOR rules.

Although the way I read your rule quote I still see nothing about occuping the main track, only authorizing train movement.

I guess what I said previously wasn't exactly clear. Should have been, ABS Signals by themselves have to main track authority associated with them. All this talk has me curious, any online versions of the NORAC?

No need to apologize, you raised a valid point that signals may not authorize track occupancy without specific Dispatcher authority.

But, specific to NORAC, Rule 500 "Occupying or fouling ABS territory"
says:"A train must not enter or foul ABS territory without a proceed indication on a controlled signal OR verbal permission of the Dispatcher.."
So, in this case, IF the track is designated that ABS rules (not DCS) rules apply, the signal indication is equivalent to Dispatcher permission.
Rules 251 and 261 (CTC), when designated in the timetable, also say "signal indication will be the authority for train movement". Only where DCS applies is there a specific NORAC requirement for Dispatcher authorization.

The NORAC ABS Rules may be a moot issue. I am not aware of any territory that has ABS signals that is not now designated "DCS" in the timetable.

I tried to find NORAC Rules online and all I see are some study guides but not the full rules. This is probably due to copyright restrictions.
It will be interesting to see what happens to NORAC now that the former Conrail CSX lines have now abandoned NORAC for a consolidated CSX rulebook.

As someone who operated trains and worked as a manager on an eastern railroad, my first exposure to GCOR terms and procedures was a bit confusing for me.

The concept of "authority" to occupy a main track doesn't (I believe) translate into NORAC terms very well. Basically, in NORAC, if there are track circuit (occupancy detecting) signals in place, "authority" to occupy, as stated above, comes from a controlled signal or verbal dispatcher permision.

Remember, though, that anywhere equipment may be able to enter such a track without a signal, there are track circuit connections for the signals governing other movements, and procedures to follow that ensure the track to be entered does not have a train moving toward the point of entrance (most likely a h/o switch).

In dark main track territory (other than a non-controlled siding, yard, or industrial track) "authority" for occupying and moving is granted by a Form D in NORAC terms.

I was blown away when I had my first exposure to TWC with ABS on UP. It took few minutes of the instructor's time to get my head around the concept because it was so foreign to my experience with NORAC operations.

Track Warrants (with or without ABS) are a great system if everyone knows what their part in the scheme is -- and understands what their "authority" covers. When someone out there doesn't understand that, things get dodgey at times (when two trains try to occupy the same section of track at the same time).