Speed signalling

BTW, could SimSig handle areas with speed signalling?

Route signalling and speed signalling

Signalling of British origin generally conforms to the principle of route signalling. Most railway systems around the world, however, use what is known as speed signalling.

Under route signalling, a driver is informed which route the train will take beyond each signal (unless only one route is possible). This is achieved by a route indicator attached to the signal. The driver uses his route knowledge, reinforced by speed restriction signs fixed at the lineside, to drive the train at the correct speed for the route to be taken. This method has the disadvantage that the driver may be unfamiliar with a route onto which he has been diverted due to some emergency condition. Several accidents have been caused by this alone.[3] For this reason, in the UK drivers are only allowed to drive on routes that they have been trained on and must regularly travel over the lesser used diversionary routes to keep their route knowledge up to date.

Under speed signalling, the signal aspect informs the driver at what speed he may proceed, but not necessarily the route the train will take. Speed signalling requires a far greater range of signal aspects than route signalling, but less dependence is placed on drivers' route knowledge. (Wikipedia - Route signalling and speed signalling)

There are two main types of signaling aspect systems found in North America, Speed Signaling and Weak Route Signaling.[2] Speed signaling transmits information regarding how fast the train must be going in the upcoming segment of track, weak route signaling transmits information related to the route a train will be taking through a junction and it is incumbent upon the engineer to govern the train's speed accordingly. Weak Route Signaling is applied with the term "Weak" because some speed signal aspects may be used in the system and also because exact route information is not typically conveyed, only the fact of a diverging or straight route, each having a predictable range of known speeds.

Typically railroads in the Eastern United States ran speed signaling, while railroads in the west used route signaling, with some mixing of systems in the Midwest and South. This was due to the lower train density in the west combined with generally simpler track layouts. Over time, the route signaling railroads have incorporated segments of speed signaling through merger and have also adopted more speed based aspects into their systems. Of the five major Class 1 railroads in the United States, CSX uses speed signaling, Union Pacific and BNSF use speed enhanced route signaling and Norfolk Southern uses a mix of speed and route signaling based on the original owner of the line. Commuter railroads and Amtrak all use speed signaling where they own or maintain the tracks they run on. Canadian railroads all use a strong system of speed signaling in Canada, but have some segments of route signaling on lines they have acquired in the United States. (Wikipedia - North American railroad signals)

The railways of Victoria use a mix of railway signalling practices: British route signalling with home and distant signals (2 position signalling) and American speed signalling (3 position signalling)... (Wikipedia - Australian railway signalling)

I've always wondered - presumably in speed signalling, the signallers have to be even more careful of a wrong route, as it's much more likely for a driver to accept a wrong route. What additional mitigation, if any, against wrong routes do they have?

" said:

BTW, could SimSig handle areas with speed signalling?

Yes, to a certain degree. It could handle a handful of different speeds but not a wide range. Again, to a certain degree, US and (US-style) Australian signalling.

I've always wondered - presumably in speed signalling, the signallers have to be even more careful of a wrong route

Thank you for the explanation of what is being discussed here.
For a time there I thought perhaps this was a discussion regarding certain areas already available being enabled for super-quick mouse clicks or similar, for those with nimble enough reflexes to set routes with the sim running on the fastest setting. :doh

So, no German or East European (OSShD*) signalling is possible?

I suspect you could probably simulate the West German signalling system, which is still widely used, by using the defensive driving rules, as the West German system only really has "line speed" or "restricted" speeds.

" said:

I suspect you could probably simulate the West German signalling system, which is still widely used, by using the defensive driving rules, as the West German system only really has "line speed" or "restricted" speeds.

I wouldn't say so. Yes, there is a dedicated aspect for restricted speed (40 km/h), but with the help of theatre indicators any other speed (as long as it's a multiple of ten) can be shown as well. In that regard it is actually even more flexible than the OSShD derived signalling systems, including the East German variety, which can only show a certain number of fixed speed steps and don't use any theatre indicators at all.

The West German signalling system - the "Hp" system, which distinguished stop signals and distant signals by head shape - didn't include theatre indicators as far as I'm aware.