Canadian signalling - how does it work?

[dave1905]

Just out of curiosity, don't Canadian/American locos have 'Deadman's Handles' to prevent crew from falling asleep at the controls?

 

Only some. For example none of the UP's engines are so equipped. They have been found to be not that effective and easily defeated.

[dave1905]

Once you have a display on every loco telling the crew what their limits and max authorised speed are, and two-way communication between that loco and the dispatching computer to know exactly where it is, what do you need all that other kit for.

 

 

Switch position.

Broken rail protection.

Unauthorized movement (cars rolling free on the main).

Defect detectors.

 

PTC will require about double the current infrastructure that we have out there and requires a completely new layer of radio and communications technology. We are installing thousands of poles to place the radio antennas. Then there are all the communications lines to connect the radios back to the dispatching system.

 

The logical thing at that point would be to expand it to apply it to *all* main tracks anyhow, and use a developed PTC to enable saving yourself the time/cost/effort/disruption of maintaining all that lineside kit.

 

No railroad has ever identified a net benefit to installing it. Every single study done for teh decades this idea has been bouncing around has said it wasn't cost effective. Why would the railroad want to waste money on expanding a system that has no benefit to areas where there is no need? That's not very logical.

[dave1905]

Not trying to be a clever dickey, but why - in this current era of satellites and GPS - is there any such thing as dark area? One would have thought that a central ops centre (like an Air Traffic Control Centre) with radio comms, controller displays, and in-the-cab displays for the engineer, would be the sensible way of runnhing things - and not masts and lights, and miles of wire with employees to have to go out and fix them, - or am I thinking simplistically again?

 

You are thinking simplistically again. 8-)

 

You are just focusing on the pretty lights and not on all the other stuff behind the lights that the railroad uses. Trains aren't the only thing out on the track, there are all sorts of other vehicles for maintaining the track out there too. All the detection systems for track occupancy, weather, defect detection, etc. etc. etc. would all still have to be out there. Plus all the infrastructure for PTC.

 

Using GPS tell an engine where it is is simple (incoming). Using satellites to allow the engine to tell other systems where it is (outgoing) is HUGELY expensive. GPS is sexy, but that doesn't mean its useful. The train dispatcher really has no need to know whether the train is 1000 feet west of switch 1234 or 2000 feet west of switch 1234. He cares which block the train is in. That is the limit of his ability to control. Sure you can spend the money to build it, but there is no real need for it.

 

We have several places where ther are no wayside signals and they use cab signals. Works great until something breaks. If one circuit board in a signal fails you are impacted for 20 min while you run to the next signal at restricted speed. If one circuit board fails on an engine you are screwed for the rest of the trip.

[dave1905]

I don't want y'all to think I don't like technology. North American railroads are awash in technology. Locomotives actually have so many electronic systems on them we are starting to run out of room to chamber the electronics boxes. Those white round "pancakes" on the roofs of engines are covers for a over a half dozen different antennaes to support all the onboard systems. Engines keep track of their health and can be polled for their operating conditin while out on line ("phoning home" when they fail is the next step), the event recorders (speed recorders) auto download when the engine is in a major facility. There record their GPS position and fuel readings every 15 minutes and phone them home. AEI checks trains on the fly and verify consists, check for placement errors and rules exceptions, then automatically notify managers of exceptions. We calculate blowover wind speeds of cars based on weight and loading patterns. Weather forecasts are predicted on specific rail locations and directed to dispatchers and field managers. A tornado that wiped out a town a couple years ago was predicted with enough precision that we were able to stop trains on either side of the path, they both actually saw the tornado pass between them.

 

The part of PTC I like is getting a computer terminal on the engines. Having an interactive terminal on the engine has huge opportunities.

[Glorious NSE]

No railroad has ever identified a net benefit to installing it. Every single study done for teh decades this idea has been bouncing around has said it wasn't cost effective. Why would the railroad want to waste money on expanding a system that has no benefit to areas where there is no need? That's not very logical.

 

With a slightly cynical head on, no US railroad has wanted the cost of installing it either, and they will all have been *very* careful to put out a party line that it's very hard work, very expensive and won't make the slightest bit of difference on their already very safe railways, as that is the position that is in their interest to have up to this point as businesses.

 

But once they have done so, which they will do because they have to, then why would they not use that tech which they *have* to install and *have* to use, and which *has* to be made to work reliably to reduce the reliance on other, mostly much older tech of which this provides largely parrallel functions.

 

The railroads are saying this is an 'overlay' - but I would be flabbergasted if 10 years past the deadline for it being in service there are not lines out there relying on largely the same tech to run the whole thing rather than just give a safety overlay.

 

And what is the *potential* above traditional block signalling?

 

Off the top of my head the *potential* could include an easy way to 'signal' and so raise train speeds and potentially increase capacity on any 'dark' territory without the cost of installing a fixed lineside signalling system.

A capacity boost for lines as trains will no longer need to run (for example) 2 miles at 15mph to the next signal if they catch a restricting, they can be braked down to the rear of a standing train safely or even be instructed to run safely just outside the braking distance to the train ahead and following it's speed profile - the former is probably more use in congested area's in clearing trains faster, the latter would make it easier to flight trains closer together on single track routes.

Pertinent to this thread if railroads were to get together on what the display should look like they could even remove the multiple interpretations of the same signal aspect issue altogether as there would not need to be any signal aspects - just a display saying that the engineer has X miles of clear track in front and his safe speed for the moment is Y...

 

You are just focusing on the pretty lights and not on all the other stuff behind the lights that the railroad uses. Trains aren't the only thing out on the track, there are all sorts of other vehicles for maintaining the track out there too. All the detection systems for track occupancy, weather, defect detection, etc. etc. etc. would all still have to be out there. Plus all the infrastructure for PTC.

 

Dave, the logical answer is that just as you give radios to your track gangs now they would have a portable PTC set, then they are 'inside' the dispatching sytem and reporting their presence on track. They don't need track detection and neither do the trains as they are both talking to the signalling system and checking their distances to each other.

 

We know there's other stuff out there too, but we're talking signalling here, some of that other lineside tech would feed into a PTS based signalling system just as easily as it would a block based signalling system...

 

The train dispatcher really has no need to know whether the train is 1000 feet west of switch 1234 or 2000 feet west of switch 1234. He cares which block the train is in. That is the limit of his ability to control. Sure you can spend the money to build it, but there is no real need for it.

 

You're right, the dispatcher does not need to know that. But AIUI that info is required inherently for PTS to operate properly!

 

The dispatcher may not need to know the exact distances (although I suspect at times it may be useful!) - but the train needs to know it's distance to it's limits to correctly identify the correct speed - and that limit may be a slowly moving rear end of the train ahead (see Chicago collision mentioned earlier!) - being a thousand feet out is surely not acceptable, 'somewhere in a block' doesn't let PTS do it's job unless you banned permissive aspects (restricting, or stop & proceed) which are key to keeping things fluid in the US - if PTS cannot tell where a train is in relation to another train or the end of it's limits it will not prevent a collision ( * ) or passing it's limits, which is the fundamental reason for doing it!

 

(*although it will ensure the collision happens at no more than the max speed allowed in the permissive block unlike the Chicago one!)

 

We have several places where ther are no wayside signals and they use cab signals. Works great until something breaks. If one circuit board in a signal fails you are impacted for 20 min while you run to the next signal at restricted speed. If one circuit board fails on an engine you are screwed for the rest of the trip.

 

But if it's a critical safety system Dave, which is what your governments view is, I suspect you won't be allowed to carry on regardless. It's a government mandated safety system, all it would take would be for an accident to take place whilst the system was switched out for what seems like a poor reason and the operator would be hung out to dry.

 

We've been there and done that - I don't reccomend it. http://en.wikipedia.org/wiki/Southall_rail_crash

[dave1905]

Off the top of my head the *potential* could include an easy way to 'signal' and so raise train speeds and potentially increase capacity on any 'dark' territory without the cost of installing a fixed lineside signalling system.

 

It still doesn't give track occupancy detection. I can park a cut of cars on the main track and the PTC system will give a green light maximum speed right into them. In order to protect against that you need a block signal system that PTC doesn't provide.

 

A capacity boost for lines as trains will no longer need to run (for example) 2 miles at 15mph to the next signal if they catch a restricting,

 

Absolutely not. One of the reasons a restricting signal is there is for broken rails or switches open. If you read the rules, you have to maintain restricting to the end of the block. No advantage whatsoever. Its basically a wash with cab signals.

 

The dispatcher may not need to know the exact distances (although I suspect at times it may be useful!) - but the train needs to know it's distance to it's limits to correctly identify the correct speed - and that limit may be a slowly moving rear end of the train ahead (see Chicago collision mentioned earlier!) - being a thousand feet out is surely not acceptable, 'somewhere in a block' doesn't let PTS do it's job unless you banned permissive aspects (restricting, or stop & proceed) which are key to keeping things fluid in the US - if PTS cannot tell where a train is in relation to another train or the end of it's limits it will not prevent a collision ( * ) or passing it's limits, which is the fundamental reason for doing it!

True but all that is train centric information. I totally agree the train needs to know that for PTC to work and never said otherwise.

 

But if it's a critical safety system Dave, which is what your governments view is, I suspect you won't be allowed to carry on regardless. It's a government mandated safety system, all it would take would be for an accident to take place whilst the system was switched out for what seems like a poor reason and the operator would be hung out to dry.

 

There are always contingencies for equipment failure. We have them now (absolute block in cab signal territory, flagging past a stop signal, etc) and we will have them in the future. PTC is an extraordinarily complex system, failures are inevitable.

[BR60103]

Chris:

If you mean the east-west line north of Bloor street (actually near Dupont), this is the main Canadian Pacific line across Toronto and always was. I think CP has abandoned the line from West Toronto to Union (sold to GO); I'm not sure about their line northeast from Union.

CN's bypass line is north of Steeles Ave -- outside of Toronto.

[shortliner]

Thanks Dave - I thought I might be being simplistic - My background is in Air Traffic Control rather than Rail Traffic Control

[Glorious NSE]

It still doesn't give track occupancy detection. I can park a cut of cars on the main track and the PTC system will give a green light maximum speed right into them. In order to protect against that you need a block signal system that PTC doesn't provide.

 

But in that currently dark territory there may well be no existing block signal system or track occupancy detection - so you use the same protection methods you would in that environment, except delivered via PTC instead of delivered verbally and copied to a track warrant. The same protections, but delivered quicker, quickly updateable as events unfold, and much harder for crews to make an error with.

 

Absolutely not. One of the reasons a restricting signal is there is for broken rails or switches open. If you read the rules, you have to maintain restricting to the end of the block. No advantage whatsoever. Its basically a wash with cab signals.

 

Switches left open is covered as they need to be detected.

 

Broken rails to my eye is the only scenario where a PTC based system would be incapable of doing the same thing, we've had the same question come up over here over the use of axle counters versus track circuits on UK block signalling - we now have 125mph running controlled by axle counters, make of that what you will...I have my doubts that if that's the only thing the track circuits are providing that can't be done another way that they would be retained.

 

Yes I agree you have to currently maintain that restricting response to the end of the block, and that's my point exactly - but with a PTC based system there does not need to be such a thing as a block, once you are past the location causing the restriction, or once the train ahead causing it clears then the restriction can clear.

 

True but all that is train centric information. I totally agree the train needs to know that for PTC to work and never said otherwise.

 

Sorry Dave, you were saying it was too expensive to install a system to get that info and share it - but the system that *has* to be installed needs to share that info to work. Once it's doing that you've done the hard bit - not using that info in other ways such as allowing dispatchers access seems somewhat perverse to me.

 

There are always contingencies for equipment failure. We have them now (absolute block in cab signal territory, flagging past a stop signal, etc) and we will have them in the future. PTC is an extraordinarily complex system, failures are inevitable.

 

Absolutely

[The Stationmaster]

Switches left open is covered as they need to be detected.

This is of course one are where we come up against a fundamental difference in the US approach from the way we have managed things for a long time as there is no way we would permit a train to approach points which are open, it's a very basic principle in Britain (and most of Europe and many other countries.

Broken rails to my eye is the only scenario where a PTC based system would be incapable of doing the same thing, we've had the same question come up over here over the use of axle counters versus track circuits on UK block signalling - we now have 125mph running controlled by axle counters, make of that what you will...I have my doubts that if that's the only thing the track circuits are providing that can't be done another way that they would be retained.

Broken rails was one of the biggest arguments against use of axle counters in Britain for a long time, second only to doubts about the reliability of an axle counter (the latter being overcome by technology and extended trials). But somebody I think lighted upon an important point - a singe rail track circuit only give a 50% chance of detecting a broken rail and I've an idea some statistical work was done on that basis. Equally delay analysis on the WCML showed that a large percentage of minor delays were down to right side track circuit failures and part of the axle counter investment case was based on reduced delays and the csts arising therefrom.

 

As far as GPS style systems are concerned I was at a small presentation made to the OC I worked for when the big push was on to introduce it to the WCML as part of the route modernisation. The two US gentlemen who came to talk to us were very easily stumped when asked some very basic questions like 'how would it work in Kilsby Tunnel?' or 'what happens if solar activity interferes with the satellite signals?'. But the best bit was when they explained how 'compact' the on-train 'black box would be - about the size of a coffin in terms of length and maximum width but slightly shallower; they apparently expected this to be installed, somehow, within a few feet of the driving cab and their schematic in fact suggested that a nose end would be the ideal location (so all you need is a nose end). Some of it was a long way removed from 'operational railway practical'

[dave1905]

The US railroads will install PTC and we will make it work. Guaranteed

 

My point is that it isn't as simple as people think it is. It doesn't decrease infrastructure and wires on the ground, it hugely increases them.

 

I managed a 36 mile unsignalled branch in an industrial area with 125 main track switches. Prior to PTC the track itself had (discounting grade crossing warning devices) zero signal appliance, zero electrical power requirements, zero signal maintenance.

 

After PTC each main track switch will have to have an appliance to detect if the switch is open. It will require a pole installed for the radio antenna and a radio. If there are multiple switches within a 1/4 mile radius they can be ganged together to used the same radio. Since we have electrical equipment we now need power run to the installation. Since we want the system to work even if there is a momentary interruption in power, it will require a battery backup system for reliability. A battery backup system requires a charging system. Every mile or two there will be a hub with a base radio that communicates with the trains. It will need power, back up power, radios to communicate with the satellite switch installations and trains, signal equipment to do the logic, plus a communications link with the railroad's information systems to access data about the train (length, tonnage, etc). Since this branch is along the Gulf Coast, the railroad will have to buy a portable generator for each of the base station locations to get it working in the event of a hurricane. Each of these devices will have to be maintained and tested, so the railroad will have to hire signal maintainers and communictions technicians to perform that work.

 

So my simple branch went from zero appliances and zero wire to hundreds of appliances and miles of wire, from zero maintenance to thousands of dollars per year in mainenance.

 

A lot of this equipment will also have to be installed on signalled lines also. In a conventional block system all the system needs to know is that in the block between mp 100 and milepost 102 there is a switch open. With PTC it will need to know which switch and exactly where that switch is located. There will also have to be the same radio infrastructure to communicate with the trains.

 

Its a lot more complicated than putting a GPS reciever in an engine.

[dave1905]

Interesting to read the various remarks re route indicators. If I understand it right the signals indicate a requirement to reduce speed so that a diverging route can be taken but the route is not actually indicated? How does the engineer know that the correct route has been set? For example in the UK if there are 2 routes diverging off a mainline the approach signal will have 2 sets of route indicators one for each route, the driver will know through his route knowledge which route should be indicated and can bring the train to a stand if an incorrect route is set (if he sees the signal in time!!).

 

Your last comment is a critical element.

 

The short answer is we expect the dispatcher or control operator to line the proper route.

 

If the train is moving at any speed above restricted speed, with the size and weight trains we operate, the train is unlikely to be able to safely stop prior to passing the signals and entering the route anyway. If there is a 19,000 ton coal train running 40 mph and a mile from the signal they see the route is wrong, the chances of them getting safely stopped before passing the signal is slim. Its not a major problem, that is, it is fairly rare.

 

You also have to realize that we tend to have fewer routes that are that critical. In the vast majority of cases its pretty binary. The train either goes straight or diverges. The train either gets a diverging signal or it doesn't.

[The Stationmaster]

Your last comment is a critical element.

 

The short answer is we expect the dispatcher or control operator to line the proper route.

 

If the train is moving at any speed above restricted speed, with the size and weight trains we operate, the train is unlikely to be able to safely stop prior to passing the signals and entering the route anyway. If there is a 19,000 ton coal train running 40 mph and a mile from the signal they see the route is wrong, the chances of them getting safely stopped before passing the signal is slim. Its not a major problem, that is, it is fairly rare.

You also have to realize that we tend to have fewer routes that are that critical. In the vast majority of cases its pretty binary. The train either goes straight or diverges. The train either gets a diverging signal or it doesn't.

 

In reality it is no different here Dave - Signalmen (or Signallers to use the daft modern term) are exoected to set the correct route as are Automatic Route Setting (ARS) systems but occasionally errors happen or things are changed so the Driver acts as - again as so often in British practice - belt & braces.

 

But if you have 5,000 tons of train moving at 60 mph, as we do on some routes in this country, then good advance warning of route settings is essential if they are going to be able to respond to incorrectly set routes. But incorrect setting is pretty rare and, I understand, increasingly so. Incidentally most trains in this country can stop safely from their maximum speed in one mile - on level track.

[davknigh]

One thing not mentioned but a big factor in accidents over here is unprotected level crossings. Even gated crossings are no sure thing but there are far too many places for trains and traffic to meet that depend on nothing more than a tin crossbuck to warn off dump trucks, semis and the ubiquitous SUV.

 

Cheers,

 

David

[dave1905]

(or Signallers to use the daft modern term)

 

I'd hold out for "Signaleers" (rhymes with musketeers), if you are going to go, go large. 8-).

 

But if you have 5,000 tons of train moving at 60 mph, as we do on some routes in this country, then good advance warning of route settings is essential if they are going to be able to respond to incorrectly set routes. But incorrect setting is pretty rare and, I understand, increasingly so. Incidentally most trains in this country can stop safely from their maximum speed in one mile - on level track.

 

With the speed set by the signals or the type of track , the crew will know the safe speed whatever the route is. If the signal is a "medium' signal then they know the route, whatever it is, is safe for 30 mph. If its route signaling and the CP is good for 30 mph per the time table then any diverging route is good for 30 mph. Either way the train is at a safe speed.

 

With PTC, if the wrong route is lined, the GPS will know the train is leaving the approved route, just like your auto GPS knows you made a wrong turn, and if the train is above restricted speed, will stop the train. If the train is at low speed, it won't stop it because the train could be making a switching move.

[dave1905]

One thing not mentioned but a big factor in accidents over here is unprotected level crossings. Even gated crossings are no sure thing but there are far too many places for trains and traffic to meet that depend on nothing more than a tin crossbuck to warn off dump trucks, semis and the ubiquitous SUV.

 

You would be suprised at the number of people killed at crossings with active warning devices (bells and lights). It is also amazing the number of people who drive into the side of a train after it occupies a crossing. Lights, bells and steel wall 15 ft high and a mile long and they still try and plow through it. You might beat the 50th car in a train, but the 49th car will get you every time.

[dibber25]

This whole thing has got a long way off topic about how CANADIAN signalling works but its a very interesting debate nevertheless. Thinking about it this morning it does seem that it is a good illustration of how two different countries choose to spend their money:

In the UK we spent large amounts of money on sophisticated signalling technology so that we can save the cost of an extra man in the cab and have safe single manning.

Canada seems happy not to spend out on fancy modern systems but to employ two men in the cab. Both systems have created pretty safe railways, it seems.

CHRIS LEIGH

[dave1905]

In the UK we spent large amounts of money on sophisticated signalling technology so that we can save the cost of an extra man in the cab and have safe single manning.

 

The big split occurred almost a century ago when the N America went down the path of automatic block signal systems and centralized control and the UK chose to stay with the manual block systems. That's why NA has centralized dispatchers and UK has signal boxes. There are fundamentally divergent schools of thought between a tower operator and a dispatcher. It also depends on how you measure "sophistication". I know your railroads are automating more systems and consolidating signal boxes into facilities that control more territory. NA railroads have been doing the same things since the 1930's, to the point now that we operate the equivalent of the entire UK railroad network from one or two centralized dispatching centers.

 

So its not an apples to oranges comparison. The railroad systems have different in purposes and grew up along diverging paths. Ranking "sophistication" can be somewhat subjective.

 

Canada seems happy not to spend out on fancy modern systems but to employ two men in the cab. Both systems have created pretty safe railways, it seems.

 

You are missing a major point here, the railroads are designed to do different things. In most NA commuter and passenger operations there is one man in the cab, just like in the UK. The reason for the 2nd man in the cab of a NA freight train is because our freight trains do switching, so you need a ground man to couple and uncouple cars, and line switches. I would be willing to bet that your freight trains that couple and uncouple freight cars, set out and pick up cars, spot and pull industries have more than one man on the crew (or assigned to assist trains doing so).

 

I would also hesitate to say that NA roads "seem happy not to spend out on fancy modern systems". Remember some of the "modern systems" that UK roads are installing now, NA roads installed in the 1930's. NA roads have spent billions of dollars on new technology in the last several decades. Virtually every major railroad in the US has made a major upgrade to its dispatching systems in the last decade (or is in the process of upgrading systems). Several roads have or are in the process of completely re-writing their computer business operating systems. In 2012, the UP alone will spend over $3 billion dollars on capital improvements. That's just one railroad in one year. Just something to think about, NA sells more railroad equipment and technology to the UK than the UK sells to NA. There are way more EMD and GE engines running in the UK than there are UK built engines running in NA.

 

There are fundamental differences between the two systems. It will never be an even up comparison, each system will always excel in its area of concentration and will lag in the areas it hasn't concentrated on. NA railroads will beat UK roads on moving freight every time and UK roads will beat NA roads on passenger operations every time. Viva la' difference.

[The Stationmaster]

The big split occurred almost a century ago when the N America went down the path of automatic block signal systems and centralized control and the UK chose to stay with the manual block systems. That's why NA has centralized dispatchers and UK has signal boxes. There are fundamentally divergent schools of thought between a tower operator and a dispatcher. It also depends on how you measure "sophistication". I know your railroads are automating more systems and consolidating signal boxes into facilities that control more territory. NA railroads have been doing the same things since the 1930's, to the point now that we operate the equivalent of the entire UK railroad network from one or two centralized dispatching centers.

And the UK has been doing it for just as long (in fact minor consolidation dates back even further in the UK and power signalling, originally with kit of US origin, has been used in Britain for well over 100 years. Schemes covering larger areas emerged here in the 1930s but WWII and subsequent political and financial considerations delayed major introduction of such things until the 1960s and that period of modernisation extended into the 1970s covering most of the mainline routes by the end of that decade. What is happening now is that those schemes are due for renewal and further technological change has allowed control to be extended over even larger areas - arguably with some loss of resilience in failure conditions (a considerable loss at times judging by several examples).

 

But we are talking about very differently trafficked railways - as you say - and we are operating in some places with a density of trains which exceeds the designed headway capacity of the signalling.

 

There is really no direct comparison between the US despatcher system and the British signalbox - the latter was there basically to ensure space separation between successive trains and to comply with the law in respect of controlling points in running lines. The idea of an individually controlled switch in a running line was basically dead in Britain by 1889 (although it took a few years longer to complete the job) and train control and arrangement is a Control Office job, not something the Signalmen usually do.

 

So its not an apples to oranges comparison. The railroad systems have different in purposes and grew up along diverging paths. Ranking "sophistication" can be somewhat subjective.

Not so much originally different in purpose but their purpose has tended to develop in different ways because of distance - the larger percentage of British freight traffic is relatively short haul in small quantities and the railway is really only in the market for bulk hauland longer distance traffic (preferably in reasonable bulk).

 

 

You are missing a major point here, the railroads are designed to do different things. In most NA commuter and passenger operations there is one man in the cab, just like in the UK. The reason for the 2nd man in the cab of a NA freight train is because our freight trains do switching, so you need a ground man to couple and uncouple cars, and line switches. I would be willing to bet that your freight trains that couple and uncouple freight cars, set out and pick up cars, spot and pull industries have more than one man on the crew (or assigned to assist trains doing so).

We had got rid of a large amount of double manning on freights by the 1980s and even if they are required to shunt I doubt very much if there are any double-manned freights in this country now. The introduction of secure channel back-to-back radios with a continuous 'safety' tone allowed the elimination of a second person on a loco for shunting purposes but there is, for obvious reasons, a man on the ground working with him except in the simplest of jobs such as attaching loco to train etc. And of course in some places the person doing the work is dual role and can either drive or do the groundwork depending on what is need at any particular time (or do both).

 

I would also hesitate to say that NA roads "seem happy not to spend out on fancy modern systems". Remember some of the "modern systems" that UK roads are installing now, NA roads installed in the 1930's. NA roads have spent billions of dollars on new technology in the last several decades. Virtually every major railroad in the US has made a major upgrade to its dispatching systems in the last decade (or is in the process of upgrading systems). Several roads have or are in the process of completely re-writing their computer business operating systems. In 2012, the UP alone will spend over $3 billion dollars on capital improvements. That's just one railroad in one year. Just something to think about, NA sells more railroad equipment and technology to the UK than the UK sells to NA. There are way more EMD and GE engines running in the UK than there are UK built engines running in NA.

I don't think there's anything being installed in the UK now that the US was installing in the 1930s, the only new things are different forms of long distance remote control equipment (which didn't even exist in the 1990s let alone 60 years before that) and such developments, again new, as ERTMS.

 

CTC on the US model was totally unsuited to British operating conditions as they once were with lots of local freight trip workings mixed among relatively frequent passenger trains of some sort or several sorts. That could be handled by more centralised control methods but the investment required usually wasn't there and by the time the 1960s came along a lot of the major power 'box schemes - covering as much as 800 track miles in some cases but with massive rationalisation at the same time.