Route Building Tutorial 9: Basic Signalling Related Objects

Following the previous tutorials, we now have a fully working route. Except for gradients (which will be covered in a future tutorial), the work still needed on the route can really be considered cosmetic, making the route look good but not actually affecting the way it drives.

In this tutorial, we will concentrate on adding various items of lineside furniture (by simply placing objects on the route), before having a look at creating some of the scenic elements, including platforms, grounds, walls and dikes. Although it was not originally my intention to cover object building, I will include how some of the objects which are going to be used were built. However, it is suggested that the BVE object construction guide http://bve.altervista.org/guide.html by Luigi Cartello is read beforehand.

Time to open the route file and get coding…

Although our route is entirely fictional, it is worth studying real railways to get an idea of the type of objects which might be found lineside. These include TPWS loops, relay cabinets, cable channels, point motors, cable troughing, axle counters, hot box detectors, flange lubricators, bags of ballast, rails – the list is endless. The more of these which can be included at appropriate locations, the greater the realism of the route.

Our first job is to add signals on the opposite track. Considering the positioning of these, the first signals we need to install are those on the approach to the junction at the second station. To add the these, we can use the same signal pole object as was used for the facing signals (this is not ideal and some modifications to the object would be desirable).

For the brachline track, to position the signal at 3200 metres we need to add

Notice how this object has been associated with the adjacent track and positioned 0.5m to the right (not left as with the facing signals) as a consequence of rotating the object by 180 degrees.

We can similarly position a signal next to the mainline track by adding this:

These signals may seem a bit close to the junction they are protecting but as the line speed is only 20mph a short distance after the signals, overruns should be minimal. Guidance on exact signal positioning may be found at RGSonline.

The only other locations where we might want to add signals on the adjacent track are where the ‘distant’ signal is located and also at the third station. These may be included in the route by adding;

and

We will also need to add AWS ramps 185m in front of these signals by adding this code:

TPWS loops are positioned as free objects (included in the objects download – © A. Bowden) and as usual we must first index the object file in the ‘with structure’ section of the route:

We also need to remove the grey rectangles which are visible where the TPWS beacons are situated. This can be done by including this at the start of our beacon section:

Recalling from previous tutorials the requirement for TPWS loops at the signal (for the train stop function) and some distance in front of the signal (to act as a speed trap). Dealing firstly with the train stop function, this needs a pair of loops (arming and triggering loops) situated 1m in front of the signal and at the signal respectively. For the signals on the running track, these can be included in our route by adding the following;

Signal at the first station;

Signal at the second station:

TPWS fitment is not required at the ‘distant’ signal, so the only remaining signal which requires fitment is at the third station:

And that’s all the TPWS train stop loops fitted on the running line. You will notice that the actual TPWS beacons have been fitted 4m in front of the signals – a conseuence of using conficting sources of information! If this were found to cause a problem, the beacon command may be moved forward 3 or 4 metres.

The next job is to fit the loops associated with the speed trap (overspeed sensor). The triggering loop may be fitted at the same location as the beacon command with the arming loop situated between 4 and 36m before the the triggering loop. The time taken to pass over the two loops at the maximum permissible speed should be 974ms for passenger trains and 1218ms for freight trains. To simplify our calculations, we will assume 1000ms (1 second) is the time required to pass between the arming and triggering loops.

Considering the speed trap at the second station, the speed at which this will be activated was set at 16kmh = 0.444metres per second and it is this distance which should separate the two loops. In practice, the minimum distance between the OSS loops is 3.5metres; this would require a much higher activation speed and demonstrates that the setup we are modelling at this signal is in practice completely unrealistic. However, we will leave it at as it is and consider it a lesson learnt!. Placing the loops at the minimum possible distance apart we need to add this:

For the signal at the third station, we previously set the TPWS OSS to activate at 60kmh. This equates to 16.666 metres per second so our arming and triggering loops can (correctly this time!) be positioned by adding this code:

Now all of the signals on the running line have TPWS loops installed. We must not forget that a pair of trainstop loops is also required at the buffer stops. The can be added in the same way as was used for the signal trainstops:

TPWS loops also require fitting on non-running tracks. Trainstop loops being required at the same location as the signal objects positioned earlier in this tutorial and 1metre further along the route. So for the signals just after the junction, add this:

For the signal at the third station, the train stop loops are positioned in the same manner:

TPWS loops also need to be fitted for the speed traps – at the signal near the junction, these may be fitted 175metres in front of the signal with a separation between the arming and triggering loops of 17metres:

Similarly, for the signal at the third station,

That’s now all the TPWS loops added.

That’s enough of simply placing free objects on the route; next time, we will create a tunnel, introducing the wall, pitch (gradient) and brightness commands in the process. In the meantime, I have included in the object downloads a couple of different relay cabinets to dot around the route as you see fit. If you choose to include these, index the objects as free objects 33-35 to avoid any possible future confusion.

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