Here in central New Jersey, there's several railroad lines that had competed to provide service to New York. I believe the Reading/B&O line must have started as single-track, became double-track and is now single-track. The Pennsylvania RR line, now the Northeast Corridor is still more than double track, serving Acela and freight.
i'm hoping someone can explain the history why some lines expand then contract, as well as why other didn't. Some of this may be obvious, but i'm looking for someone to explain the less than obvious, providing a complete explanation.
greg - Philadelphia & Reading / Reading
greg,
Answering your question would be facilitated by your explaining why you ask the question. Note that you're asking for "a complete explanation". That sounds like you need an analysis of every railroad's history. 'Cause after all, every railroad is different.
Ed
I agree with Ed. You could write a sizeable book on the subject, and use it to earn your doctorate in transportation history.
However, speaking in generalities, MOST railroads started off with one track and added additional tracks as traffic warranted - two, three, four or sometimes more. The exceptions designed for anticipated traffic - and a lot of New Jersey's railroads anticipated a lot of traffic. After all, they were building in a developed area, not pushing out into uncharted wilderness.
Then, as they began to feel competition from trucks (short-distance high-value freight) busses and private automobiles (passenger) they reduced the number of trains, which reduced the need for multiple track. Development of CTC allowed more efficient use of tracks, so busy lines installed the new technology and pulled out tracks.
In some places, traffic faded away altogether, or became totally uneconomical - and rights-of-way went from rails to trails. In other places, traffic came back, and second tracks that had been pulled have been replaced. In the late 1970s Wyoming's Powder River route was a single track, not heavily used. Today there are stretches of triple, the whole thing is at least double track and it is BUSY!
Since part of New Jersey is in Super-New York (Or the coming metropolis of Boswash) don't be surprised if passenger loads/frequencies increase - and some of those single track branches take on characteristics of the New York subway system.
Chuck (Modeling Central Japan in September, 1964 - with LOTS of traffic)
The fact that trains today do run safely on single track in both directions fulfills the vision of early RR pioneers. But even today, it appears that the expense of multi-track mainlines is still desired.
My limited understanding is that miscommunication (pre-1900) forced RRs to invest in double track to avoid accidents, not necessarily because of greater traffic. I think the answer to my query is really aboutRR communication and rules. My limited understanding is that early rules were based solely on schedules. Telegraph eliminated dependence solely on time. But if this approach were fool-proof, trackside signals wouldn't have been developed. Presumably these signals were developed to provide more direct communication with trains between stations to confirm schedules and to handle delays and other unforeseen events.
Direct communication between CTC and trains today has satisfactorily addressed these shortcomings, allowing more trains to runs in both directions over single track. I'm guessing that multi-track avoids waiting for slower passenger and local freight trains.But I think my understanding is far from complete, and partially incorrect.
In the 1970s, when the future of railroading was looked grim, a lot of railroads reduced multiple track. Changing traffic patterns, the introduction of commuter routes on formerly freight-only lines, container traffic, and economic recovery in the 1980s-1990s caused a number of lines to reinstall pulled-up track. In some cases, where track was improved to accommodate new commuter operations, transportation authorities (RTA, Metra, etc.) contributed funding for the improvements.
It should also be remembered that in some juristictions, railroads have to pay taxes on track, even if it is not currently in use, and often have to ask permission to remove unneeded trackage. This led to the removal of a lot of trackage during the cash-strapped 1970s.
Dan
The abandonment of passenger service in the late 1960's-early 1970's, plus reduced freight traffic, negated the need for double track mainlines.
The Illinois Central line from Chicago southward to New Orleans, for example, was double track most of the way when the IC was running their streamlined passenger trains. When they abandoned passenger operations, there was no need for a double mainline to handle only the freight traffic, so much of the second main was removed, leaving only strategically placed passing sidings.
Centralized Traffic Control, improved signalling systems, and radio communications also negated the need for much of the double track lines throughout the country.
As others have stated, railroads pay local property taxes on their trackage, so eliminating track miles saves them money. Maintanance costs are also a factor.
I like to compare it to the road system. When you're in or near a city the highways are 4 lanes or more wide to absorb the heavy traffic. As you move away from the city the roads drop a land then 2 etc depending on the traffic density . Railroads are no different. They set up based on the needs of the road.
Springfield PA
One example:
Before CTC (Centralized Traffic Control), the best way to add capacity was to double-track a segment of railroad.
With CTC, many of these same lines could be reduced back to single track (often with longer sidings) and handle all the required traffic. Single track is less costly to maintain.
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I can give you a quick history on one line in my area that might answer your question. The B&O through northern Indiana built in the mid 1870s started as single track as that was enough to handle capacity at the time. Sometime in the early 1900s it went to double track for more capacity (read more and faster trains). Then, (I think in the late 50s) it single tracked again but with CTC, sidings and some short sections of double track. This was because CTC style signaling provided cost savings in track, control and property taxes.
However, with the Conrail break-up and more traffic, CSX double tracked it again. So: single-double-single-double!
Double track isn't/wasn't used for increased safety, it is/was used for increased capacity. That is also the reason for "fancier and fancier" signaling. ALL the various track/signal systems you described can be operated safely; it's just that, while doing so, there are different levels of throughput for each of them. And concurrent possibilities for increased profit. After paying for the improvements.
Just remember running a railroad is all about $$$$. But in general terms:
Single - to get to customers to make $$$.
Double track (Pre-CTC) expansion because traffic was so heavy they could run more trains and make more $$$.
Double to single because CTC allowed running the same number of trains allowing less physical plant (i.e. less track to maintain ($$), stations, etc)
Any expansion now is the same as it was before, if it looks like traffic needs double (triple, quadruple) track then the railroad will spend $$$ to make $$$.
Chris
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Some railroads that went back to single track in the seventies are now looking at going back to double track, since the longer trains and longer cars of today don't fit on single track passing sidings as well.
tomikawaTTDevelopment of CTC allowed more efficient use of tracks, so busy lines installed the new technology and pulled out tracks.
cuyamaWith CTC, many of these same lines could be reduced back to single track (often with longer sidings) and handle all the required traffic.
wabash2800Then, (I think in the late 50s) it single tracked again but with CTC, sidings and some short sections of double track. This was because CTC style signaling provided cost savings in track, control and property taxes.
stilson4283Double to single because CTC allowed running the same number of trains allowing less physical plant (i.e. less track to maintain ($$), stations, etc)
what exactly did ctc do that earlier systems did not do? (anything to do with safety)?
wjstixSome railroads that went back to single track in the seventies are now looking at going back to double track, since the longer trains and longer cars of today don't fit on single track passing sidings as well.
why not just lengthen the sidings?
gregc what exactly did ctc do that earlier systems did not do? (anything to do with safety)?
CTC provides a nearly real-time mechanism for the dispatcher to control traffic. It also eliminates much of the individual crew decision-making (which inevitably involves a certain amount of guess work) that comes with train order authority. It's an extra margin of both safety and capacity.
wjstix: Some railroads that went back to single track in the seventies are now looking at going back to double track, since the longer trains and longer cars of today don't fit on single track passing sidings as well. why not just lengthen the sidings?
Extending sidings is how it's done if capacity doesn't warrant a full double track installation. If revenues from a given route don't justify the cost to extend sidings, or the money isn't in the budget, shorter trains are still run. One of the reasons the former WP main across Utah and Nevada isn't as well used by UP as it could be after the SP merger is due to the short sidings, forcing shorter trains to be used and/or restricting meet/pass locations to the longer sidings that do exist. It's now often easier to send long trains onto the former SP instead.
Rob Spangler
Lengthening the sidings isn't always feasible. Over time, the right of way can be encroached by new buildings and such that make it hard to clear the space. In some cases it's more feasible to take over a parallel railroad. That's what Canadian National did in northeastern Minnesota when they bought the Missabe Road. The Missabe and CN's Duluth Winnipeg and Pacific mainlines ran roughly parallel, so CN bought DMIR and now uses one railroad's mainline as the 'northbound' and the other as the 'southbound'.
And sometimes there are other headaches like grade crossings that trains can't be parked for very long while in the hole...
CTC is remote control too and another savings in that much of the infrastructure and people can be eliminated: block stations, towers, operators.... The dispatcher can sit at his panel and see the whole section he governs for miles at a time with all the trains at a given time and efficiently maneuver trains around each other. The signaling is automatic unless the dispatcher wants to override it but will provide interlocking safety at every place where two routes could conflict, even at the entrance and exist of sidings.
On some sections of the Wabash they had what they called a poor man's CTC. The signals were controlled by the dispatcher but the switches (turnouts) were operated by the train crews on the ground.
wabash2800The signaling is automatic unless the dispatcher wants to override it but will provide interlocking safety at every place where two routes could conflict, even at the entrance and exist of sidings.
Under typical CTC, the dispatcher controls the turnouts and signals at places like entrances to controlled sidings, crossovers or other interlockings. At such locations, the signal is considered to be "absolute," i.e. cannot be passed unless authorized by the dispatcher, either through the route being lined or through some form of verbal or other authority that allows the signal to be passed despite displaying "stop." The remaining signals between control points work off detection only, on the APB principle (absolute permissive block), where a red means "stop and proceed," and the dispatcher does not normally have the option to override them. In some cases other absolute signals may exist to hold trains at specified locations outside of interlocking limits.
The presence of absolute signals under sole control of the dispatcher is key to the extra safety provided by CTC.
That's my understanding anyway.