Route Building Tutorial 15: Building the Island Platform

In this next series of tutorials, we will start to construct the stations on our route, beginning in this tutorial with the island platform at the second station. Although this station is fictitious, to maintain realism, consideration should be given to the appropriate railway group standards (GI/RT7016 and GI/RT7014) when deciding on aspects such as height, width and clearances. Observations made of prototypical platforms are, as always, very useful.

This route file is based on that from the previous tutorial but with the fence removed after the tunnel exit and the ground restored to the default flat grass after the tunnel. An additional rail (3) object has been added to the right of the tunnel, the ballast from this filling in the gap between the tunnel wall and the ground.

The wall has also been restored to rail 10 after the tunnel entrance and the height of rail 10 gradually reduced as the top of the hill is reached until just the hedge and adjacent ground are visible. This method uses just one object to create a continually varying scene on the right hand side. The disadvantage of using objects in this way is that although not visible, all faces are still being drawn which may result in frame rate reduction if this technique is used excessively.

The final alteration made to the route file has been to decrease the height of the running rail. As the ground on the left hand side of the route should be hidden by another cutting face, it is not necessary to calculate the height in the way that was used to ensure the water surface remained level and the gaps visible in the grass would also be hidden.

Time to get to work…

Our first job is to create a free object file in .CSV format, saved in the objects directory as platform_1.CSV and indexed as free object 60. The platform object will be based loosely on one of the platforms at Cardiff Central station;

The prototype platform at Cardiff Central

The prototype platform at Cardiff Central

The free object can initially be placed in the route file at 2800m (x and y displacements = 0).

Starting off with the main vertical face, code required in the object file is:

Ideally, the bitmap would have been displayed horizontally 2.5 times to maintain an approximately correct aspect (width / height) ratio. However, doing this would have meant the rail height indicator would have appeared rather too frequently.

The next part of the platform construction is to add a support for the coping stones. This requires just one face as the underside will not be visible on the flat platform section:

Here, the stone texture is repeated 64 times in order to maintain an approximately correct aspect ratio.

To add the coping stones, in addition to the main horizontal face, a vertical face is also needed to give an appearance of depth. These two faces have been created separately but using the same texture. This has been done to allow the faces to be illuminated differently should the object subsequently be converted to .x format in the future. It should be noted that it is usually more efficient to create multifaced objects using a single mesh block although (as with the tunnel objects created in the previous tutorial), identical lighting effects would be applied to all faces defined by a single mesh block.

Also needed (to ensure compliance with the disability discrimination act) is a row of tactile paving slabs:

Now we need to add the main surface. In real life, this is often paved in the main passenger circulation areas although for our platform, a tarmac surface will be applied throughout. To allow water to drain, a slight slope will be applied towards the middle of the platform and a drain added. A little thought is required regarding the width of this face; at this point, the distance to rail 1 is 14.73m, therefore the midpoint of the platform will be at 7.365m. Assuming the drain is located centrally and is 20cm wide, allowing for the half width of the drain, the tarmac face will extend to 7.365-0.1 = 7.265m

For the face on the left hand side of the central drain, the following code should be added to the object file:

Now adding the 20cm wide linear drain in the centre of the platform:

Finally, to create the platform on the right hand side of the central drain, we just need to apply the tarmac, tactile surface and coping in reverse order but keeping the same widths:

The texture of the coping stones must be reversed to ensure the white line appears on the platform edge. The sides of the coping stones and platform have not been modelled as they are never in view.

The platform object is now complete – this could be indexed as a .formR object, which has the advantage of being easy to see in the main route code, or left as a free object which can be rotated by 180° for use as a platform on the left hand side.

Because we have built up the platform face by face using different textures, modification of the basic platform structure by changing the textures is also quite straightforward. Additionally, to easily create a single faced platform, the linear drain and everything to the right of it can be omitted and the width of the tarmac face adjusted as necessary.

The length of the platform object we have just constructed is 25.2m, this length was chosen so that if the line is slightly curved or on a gradient, no gaps would be visible between the individual lengths of platform. On the tutorial route, the line is completely straight and level and there is no reason why the platform object should not be 25m long (as in the object included in the download) – the complete absence of overlapping textures will eliminate unwanted ‘flickering’.

Thinking about how long the platform should be, most train carriages are between 18-23m long. If the station was to be able to handle 8 carriage trains, the platform length would need to be about 200m long, requiring 8 of the platform objects. Adding these to the route file:

To position the platform object on the left hand side, use freeobj 0;60;0;0;180,

In this part, we have seen how to build a basic island platform that can easily be modified for use as a single faced platform. In the next part, we will add the ramps at the end of the platform and also examine how to construct curved platforms.

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