German mechanical signalling

[Cricketer8for9]

I’ve been wiling away some hours watching German cab-ride videos. While the sheer extent of the infrastructure continues to impress I remain surprised that mechanical boxes still seem quite prevalent. For example Hanau, east of Frankfurt-am-Main still seemed to have three, maybe four mechanical boxes, and this on a line with regular ICE traffic. Is there a reason why they did not seek to resignal with quite the haste that was seen in the UK. While there are semaphores in third rail areas I can’t immediately think of any on 25kv AC overhead, though maybe Stockport semi counts as Absolute Block but with colour lights.

 

[Gloster]

One reason is that a lot of resignalling took place on the years following World War II, when parts of the rail network got a bit knocked about. Therefore there is not the large amount of ancient equipment that existed here.

 

[Cricketer8for9]

So your argument is that in the UK the mechanical signalling was Edwardian or older, whereas in Germany it was post 1945 and so in less need of replacement. I’m no signalling expert but I kind of had it in mind that the replacement in the UK was to reduce costs, including costs of staffing.

 

[Gloster]

I am not arguing a point as German signalling is not an area on which I am an expert and I cannot get at my books at the moment. However, when they did rebuild after the war the replacement installations were more modern and less labour intensive, both the actual signalling equipment and such things as track layouts.

 

[Cricketer8for9]

Gloster. Sorry if you saw what I wrote as challenging you. It wasn’t meant as such. Perhaps hypothesis would have been better.

 

[duesselmartin]

Not sure about the UK but German mechanical signals can be operated in many cases by a power box many are driven by an electric motor.

 

[P Binnersley]

Germany still has a lot of rail freight, including wagon load so there are several factory sidings that need servicing. Hanau is a centre for the Chemical industry. In the UK a lot of the savings from resignalling come from rationalisation. With the sidings still in use there is a much smaller saving. If the sidings are busy then you would need more than one workstation to cover the three/four boxes and the savings are reduced.

At smaller stations in Austria/Switzerland the signalman used to also cover the booking office so again the possible savings are reduced. I'm not sure how common this was in Germany.

 

[JonathanP]

Not sure about the UK but German mechanical signals can be operated in many cases by a power box many are driven by an electric motor.

Exactly. It's a misconception to think that mechanical signal = mechanical box(although that's not to say there aren't any of those left). Germany went through a phase of building electro-mechanical signalboxes(similar to the Westinghouse miniature power frames) in which the so-called "mechanical" signals were actually all controlled, like the points, by electric motors. I don't think the UK ever did this.

 

[John Webb]

Exactly. It's a misconception to think that mechanical signal = mechanical box(although that's not to say there aren't any of those left). Germany went through a phase of building electro-mechanical signalboxes(similar to the Westinghouse miniature power frames) in which the so-called "mechanical" signals were actually all controlled, like the points, by electric motors. I don't think the UK ever did this.

The nearest to this is possibly the L&SWR's electro-pneumatic system between Woking, Basingstoke and Salisbury at the start of the 1900s?

 

[ac6000cw]

The early (LNWR vintage) power signalling at the south end of Crewe station used electrically-operated semaphore signals, as far as I know - there is a picture of it in one of the signalling history books.

Local to me, another example was the (I think) electro-pneumatic signalling using power operated semaphores in the Cambridge station area (which disappeared with the 1980's re-signalling of the area).

I'm sure there were other examples of the same idea in the UK, but the standardisation of colour-light signal aspects in the early 1920s meant that rapidly became the preferred signal type for power signal installations.

Is there a reason why they did not seek to resignal with quite the haste that was seen in the UK. While there are semaphores in third rail areas I can’t immediately think of any on 25kv AC overhead, though maybe Stockport semi counts as Absolute Block but with colour lights.

I would say taking a 100 years or more to replace most of the manually-operated signalling in the UK with something more modern is not "quite the haste" - the opposite I would say. (And the lack of haste is probably down to railway poverty due to ever-shrinking traffic over most of that period).

 

[duesselmartin]

There are also less electrified lines in the UK compared to Germany and one does find mechanical signalling on UK main lines such as Dundee to Aberdeen.

 

[Bald Rick]

There’s also a difference in German signalling system architecture which made resignalling with electric / electronic systems rather more expensive than over here.

Until recently, all new German electric signalling had to be hard wired back to the interlocking. That means a LOT of cables. (Over here we often use vital telecoms links between signalboxes / interlockings / ground equipment - exchanging what would be hundreds of signalling & power cables for a pair of comms cables).

Hence the economics of resignalling was perhaps not as attractive as over here.

 

[Fireless]

The Reichsbahn (the first one) was quite quick on deciding on standardised equipment with the type "Einheit" (Unity or Standard) double wire system and the Siemens & Halske type 1912 (which later saw some further developments right until colour light signals and three-phase point machines) power frames (mostly semaphore signals with a very slow shift to colour light signals after the second world war) and also rather conservative (they insisted on mechanical interlocking for train movements for quite a long time).

After the second world war, the proven and still quite modern technolgy was used to rebuild the infrastructure like in Hanau which got the, at that time, modern type E43 (slightly improved S&H type 1912 which was turned into a railway standard in 1943) power frames.

As the situation improved, the railways could continue the development of relay interlocking from the early 1940s and spent the 1950s perfecting it ending up with the "Spurplan" (the relay interlocking is set up like the track layout and picks the elements needed for a route instead of working with pre defined fixed routes) technology.
That new technology was then put into the SpDr60 standard in the early 1960s which was then rolled out rather quickly over western Germany.
The Bundesbahn then reused some of the still far from life expired equipment made redundand by the new relay-based signal boxes for budget resignalling projects usually replacing even older technology with relatively modern standard equipment well into the 1980s.

The eastern german industry on the other hand could not deliver enough of the modern relay interlocking so they just kept building new power frames with the latest revision of the type 1912 (known as E12/78) dating from the late 1970s and being capable of working three-phase AC point machines.

So most of our mechanical and electromechanical signal boxes feature relatively modern and relatively standard technology that is sometimes a lot younger than you may think at first and second glance (one particular box in my area has a pre-WWI building with a 1933 vintage power frame inside that was only installed in 1977).

 

[Cricketer8for9]

Thanks all. Really interesting.

 

[MarkyT]

There’s also a difference in German signalling system architecture which made resignalling with electric / electronic systems rather more expensive than over here.

Until recently, all new German electric signalling had to be hard wired back to the interlocking. That means a LOT of cables. (Over here we often use vital telecoms links between signalboxes / interlockings / ground equipment - exchanging what would be hundreds of signalling & power cables for a pair of comms cables).

Hence the economics of resignalling was perhaps not as attractive as over here.

Up until the early 2000s that was all that was on offer from Siemens, the main signalling supplier in West Germany, and under Railtrack/early NR, the UK purchased a small number of installations based on the same technology, for Bournemouth and Portsmouth resignalling. In terms of cabling, the Siemens 'SIMIS' processor-based product line was little different to 1960s and 70s era UK relay-based signalling with large remote equipment rooms each covering a major junction or station and every trackside function hardwired directly from the input/output stages in those rooms. Starting with SSI in the 1980s, BR processor-based systems could be engineered with a far more distributed input/output architecture housed in smaller cabinets located much closer to the controlled trackside objects, linked by trackside datalink cables instead and requiring far less cabling in total than previous relay-based solutions and the contemporary Siemens offering. Sometime after the rather unsuccessful Portsmouth project, Siemens lost their framework contracts for UK signalling renewals using the German technology, but later successfully re-entered the UK market by acquiring the former Westinghouse signalling businesses and product lines from Invensys, and were then able to offer SSI-based solutions and much local UK legacy project expertise. They also updated their German products to offer a more distributed input/output paradigm.

While this concern may have some bearing on the early digital era from the 1980s, it doesn't really explain why more centralised electrical signalling wasn't provided in Germany in the 1960s and 70s, when there was little difference conceptually between the relay-based solutions available in Germany and UK, although it is interesting to note that the UK, while on the one hand having some of the most centralised signalling control installations anywhere in Europe today, simultaneously also retains some of the smallest signal box control areas as well, mostly in rural areas clearly! There are even some sizable mechanical installations remaining on main lines, albeit not always with semaphores. While most people know about Shrewsbury and Worcester due to their obvious semaphores, few realise the Stockport area colour lights are still operated from a series of mechanical lever boxes. Stafford was until recently also mechanically controlled colour lights. Both of these areas were legacies of repeated WCML modernisation programmes running into problems!

 

[Cricketer8for9]

Thanks again. I was aware of Stockport, but not Stafford.