MBS/TWC operating rules--a question

[Dayliner]

I am setting up my layout to run by Manual Block System rules, following CP Rail practice ca. 1980. CP's MBS rules were set out in Special Instructions supplemental to Rule 323. According to Special Instruction 323.11(a), "A train authorized by MBS Clearance to "PROCEED" from one point to another, MUST MOVE IN THE DIRECTION SPECIFIED ONLY." That makes sense, but here's my question:

At one point on my layout, I have a branch line joining the main line. There is no wye or siding, just a diverging route. A train running south on the branch line would continue running south on the main line. For southbound trains, an MBS Clearance can be issued before the train enters the main line--no problem there. But what happens when a train entering the main line (i.e., going south) is actually destined for points north? It must then reverse direction on the main. Would a dispatcher have to issue two MBS Clearances, one to get the movement onto the main line, and one to clear it to run north? Or would it make more sense to issue a "Work Between" Clearance (allowing the train to move in either direction), instead of a "Proceed" Clearance?

And a supplemental question: clearing the movement onto the main line obviously requires it to move past the switch, which would normally denote the southern end of the clearance. How would the dispatcher clear movement onto the main without tying up track all the way to the next station? Would he simply designate the next milepost as the limit of the Clearance?

I know these are technical questions, but maybe there is a retired DS out there who has the answers.

Many thanks!

[michealfarley]

Wouldn't the train heading north have to run around his train somewhere? That would easily fix your problem if the train went south to the nearest run-around, reverse direction, and head north. Realistically, a train would not make a reverse move of any distance on the main line.

If the train doesn't reverse itself, then is the train is still technically "Southbound", but making a reverse move on the mainline? If that's the case, then the train would need a "Box 4", or work between, with limits of a mile south of the switch to the northern termination point or next siding for a meet.

If the train runs around itself somewhere, then it would reverse railroad direction and become a northbound train. A "Box 4" would be issued from the junction switch to the next mile post south of the run-around track to the south, then a regular track warrent indicating a new northbound direction from the north siding switch to the northern termination point or next siding for a meet.

[Dayliner]

Thanks Micheal. Actually the run-round move will not be required in most cases because the movements will usually involve RDCs or light engines. After reading your reply and thinking it through a bit more, it seems that the way to go is indeed to issue a "Work Between" clearance. And I will probably deal with the issue of the southern limit of the clearance by simply designating a new station a sufficient distance south of the junction switch to accomodate the equipment making the move.

Thanks again for your input.

[dehusman]

You don't need a work between warrant. All the dispatcher has to do is
give a warrant from a point far enough away to hold the train, give him a
warrant from the point behind the train to where ever its going and then
give verbal permission to make a reverse move to enter the main track.

Switch is at MP 10. Train is going west to MP 100. Give a track warrant
from MP 8 to MP 100. Verbally advise the train they can make a reverse
move to enter the main track. The train shoves out on the main (the rear
end ends up at mp 9), the conductor walks up and then the train heads West.
Way simpler.
Remember, its not that a train CAN'T make a reverse move, they just need
permission.

Dave H

[Dayliner]

Thanks Dave--this is easier still. Does permission to enter the main need to to be recorded or entered on the MBS clearance form, or just given to the crew once the clearance is made "complete"?

[dehusman]

First I am talking track warrants. Don't know anything about MBS. It's not used anywhere that I am familiar with (Western US). With track warrants it would be purely verbal. I would give it after they have authority on the main track, then give them permission to make the reverse move. If you gave the permission to make a reverse move they might act on it before they had authority on the main.

Dave H.

[Dayliner]

Dave,

My understanding is that Manual Block System is simply the Canadian equivalent of TWC. Everything I've read about TWC suggests that it's the same thing.

Thanks for your input--verbal authority to enter the main track after issuing clearance to occupy the main makes sense.

[dehusman]

I was wondering if MBS was similar to DTC (which is different from TWC).

Dave H.

[dehusman]

Don't see anything on MBS or TWC. No special instructions shown on that website.

Dave H.

[Dayliner]

Mark,

The main line is unsignalled; the branch line is within yard limits. What is the difference between "permission" and "authority"?

I've looked at the CROR site and am puzzled by the lack of reference to MBS rules. My source for these rules is a CP Rail timetable from 1986--perhaps MBS has been superseded since then, or is (was?) it simply a creation of individual railways?

[Dayliner]

Thanks for the clarification, Mark

[dehusman]

While I would give the same answer as Mr. Hemphill, a FRA acquaintance of mine has informed me when subject came up in another discussion a while back that from a regulatory standpoint there is no difference between permission and authority.

Dave H.

[MACKINACMAC]

Here are two more related questions:

1st, I have a small layout and plan to use DTC. are there any differences between track warrants on DTC vs. CTC systems?

2nd, When a train completes it work on one warrant and is issued a new warrant, is box 1 marked to void the previous warrant or is the next warrant simply issued?

sorry these are neopyhte questions but I'm learning a lot from you fellas.

[dehusman]

The way I like to think about it, TWC evolved from train orders, DTC evolved from manual block. They are two different concepts of how the authority is assigned. In a very general sense its the difference between a layout that operates with a DC toggle block control system and a DCC system. You can operate a model railroad with manual block or DTC with a traditional toggle DC block control just as realistically as the prototype.

Dave H.

[MACKINACMAC]

Thanks for your answers. I have two more questions:

1) What time periods were CTC, TWC, DTC used and are they still being used on today's railroads?

2) On a DTC system, how are the warrants numbered. Sequentially by train, sequentially by block, sequentially by dispatcher?

[Dayliner]

QUOTE: I did some research on Canadian operating methods -- consisting of a few hours conversation with a CPR road foreman and an assistant superintendent over the past few days. Canada hasn't used, to their knowledge, the Manual Block System of operation in some years, at least not on CPR, because it's not in the rule book.

Thanks, Mark, for passing on this information from your friends at CPR. I'm wondering if MBS was perhaps a stage in the evolution from timetable and train order operations to OCS. As I stated in my orginal post, my source for MBS rules is a CP Rail timetable from 1983. I know that just a few years before that, in 1979 and perhaps into 1980/81, the subdivision I model still had agents/operators at key stations and (presumably) was still running by timetable and train order. Other subs in the 1983 timetable were definitely still relying on TT/TO authority. But my trusty Canadian Trackside Guide of 1994 makes no mention of MBS; all the former MBS territory is by then shown as OCS territory. So maybe MBS wasn't around for very long--probably through the 80's and maybe into the early 90's at the outside. I wonder if anyone on this forum has a more detailed knowledge of the history of MBS.

Thanks, everyone, for your continuing input. This has turned into a very interesting and enlightening discussion.

[dehusman]

You might want to get an older timetable 1930's or 1940's that has manual block system rules. For example WM '39 and NYC '56 rule books have manual block system rules. I can't gurantee they will be the same, but it might give you a general idea.

Dave H.

[Dayliner]

QUOTE: I hope this isn't hopelessly confusing.

Confusing? Yes. Hopeless? Not quite!

Your reply suggests that maybe we are talking about two different kinds of MBS. As I read the rules and forms regulating MBS on CP Rail in the 1980s, it quite explicitly conferred on trains "authority" either to "proceed" between or "work between" points named in the clearance. Moreover, it didn't divide the track into fixed blocks at all. A train could be given authority to occupy the entire subdivision if nothing else was running, or it could be cleared just as far as the next siding. On a number of occasions I rode in the cab of passenger trains on the Esquimalt & Nanaimo, and would read the MBS Clearance form. On weekends, when traffic was light, the train would be cleared for the entire line, from Courtenay to Victoria. On weekdays, we would have to stop two or three times to meet opposing freights and receive new authority.

The rules governing MBS were set out in Special Instructions supplemental to Rule 323. Special instruction 323.1(a) read: "The movement of trains will be authorized by MBS Clearances which supersede the superiority of trains for both opposing and following movements on the same track."

Train dispatching--is it an art, or a science? I had no idea it was so complicated.