Website Burkhard Jahnen
 

Railway design - Stations

In the 'Tracks' sub-section, the use of two basic concepts of stations was proposed:

• terminus stations close to the rectangular mesh of intersecting dual tracks and

• through stations lying on the mesh itself.
   

  Picture 1		Picture 2
  Terminus stations around a city		Through station at a factory

In pictures 1 and 2, both concepts are shown again in comparison. Terminus stations are especially well-suited for delivering goods to large cities or for offering passenger services. When placed on the outskirts of a town in the early stages of its development, they are later situated amongst large buildings and accept goods (see the 'Basics' section for details). Since terminus stations allow for a higher density of buildings around them than through stations, it's best to minimize the amount of track tiles further by letting the stations point to the heart of the city (see picture 1, where two of the stations are actually placed like this). Connection to the mesh of dual tracks is then achieved preferably by small intersections. For this, another version of the advanced intersection design proposed in the 'Intersections' sub-section will be presented below. We will deal with this first. In the second part of this sub-section on stations we will then deal with an advanced design for through stations in great detail.

Terminus stations

Well, the need for small intersections to connect terminus stations to the mesh of dual tracks actually implies the risk of traffic jams. Imagine the vast number of trains that potentially arrive at such a station: they transport goods, passengers, mail, valuables. For terminus stations placed on the outskirts of cities, this is quite heavy traffic! In other areas, when dealing with stations at woods or close to mines for instance, heavy traffic should be taken into account by building through stations in the first place. Since we don't like to waste that much space in the vicinity of cities (or perhaps don't have much space at all), such intersections need to be

• as small as possible,
• and reliable even when heavy traffic occurs.

In my experience, the track layout shown in picture 3 should do the trick. It doesn't look particularly small, does it? That's because mandatory servicing depots are included in the example. Without them, and without the additional empty tiles between the dual tracks (see picture 4), some extra tiles for an expanding city (not shown ;-)) are availabe. Besides, the city would be at the far side of the dual tracks. The track tiles extending from the station over to the other side of the intersection usually occupy land that would remain unused anyway.

Both versions make traffic jams less likely by forcing those trains on longer routes that need to turn left to reach their destinations. For trains leaving the station, the respective tracks in the station they have come from work as track blocks where the trains can return to in case of traffic jams. By the way, in both picture 3 and picture 4 some track tiles are shown that will never be used by trains. They have not been removed so that the similarity to the advanced intersections design proposed in the 'Intersections' sub-section becomes evident. You can delete them, of course. However, try to withstand the temptation to take away even more track tiles! Admittedly, the track layout does look strange. That's because, for instance, the dual tracks need to be one tile apart so that signals can be placed on the connecting tracks. When left out, trains just passing by in opposite directions couldn't do this independently: One train would have to wait for the other one to pass by. With the design shown here, in turn, a high degree of protection from other trains is achieved.

Through stations

As mentioned right at the beginning of this sub-section, through stations are situated on the mesh of dual tracks itself. In contrast to terminus stations, traffic doesn't run past it, but through it. Even trains that don't have to stop at a through station have to get through it or around it. So, through stations

• are busy stations where lots of trains have to be taken care of

• occupy more space than terminus stations

• should not be flooded with unnecessary traffic

• are preferably built at factories, saw mills, oil refineries and food processing plants, i.e. where raw materials are delivered to and goods etc. are picked up from.

Any delay of trains delivering raw materials can lead to a total breakdown of such a factory, if all tracks of a station are occupied by trains trying to pick up goods. Thus, the best track layout around stations only works as expected,

• if the goods trains are far outnumbered by those trains that deliver raw materials and

• if there is a regular delivery service to the station.

So use only two or three goods trains with 5 wagons at first and wait until a 'dynamical equilibrium' has developed. If you think there is a steady reserve of crates of goods left at the station (usually about a few hundred is ok), use more goods trains. After all, we don't want to waste money, do we? So let's go to business now and take a look at a trough station with advanced track layout in detail!

Picture 5 shows a typical situation: a trough station between a farm and an oil refinery. Both kinds of 'industry' provide goods for a large number of trains: Oil is delivered to the oil refinery, and goods, grain and livestock are picked up at the station. Since the catchment area of the station itself is too small to fully cover both the farm and the refinery, it is artificially enlarged by the bus station, the lorry station, and the dock. More about the way this is achieved is available in the 'Basic tricks' section. Now, as any through station, this one can be accessed from two directions. In this case via the northern (N) and the southern (S) dual tracks. Contrary to what might be expected, however, the station's tracks are more or less one-way tracks because of the one-way signals on the track tiles just north of the station. The resulting paths of trains actually heading for the station are depicted by yellow arrows:

• When arriving from the north, these trains first run past the station on the western bypass track, then enter it via the two-way signals from the south.

• When arriving from the south, they just enter the station via the same two-way signals.

Trains just passing by, on the other hand, take the following routes:

• When coming from the north, they go all the way down the western bypass track past the station and the farm (green arrow).

• When coming from the south,

  • they run through the station and then past the two consecutive one-way signals (green arrow), when at least one track is free, or

  • past the station close to the refinery on the eastern bypass track (green arrow), when all tracks of the station are occupied.

Trains can leave the station both northbound and southbound, of course:

• When northbound, they first go along the path depicted by the purple arrow, then all the way to the northern exit.

• When southbound, they first run to the north along the path depicted by the blue arrow, then all the way to the southern exit.

If a train that tries to enter the station for loading purposes faces four signals showing 'red', it is directed into a 'holding stack', similar to what planes are forced into when approaching an airport (An application to TTD's trains was first introduced by Mike Metcalf.). In our case, the trains first pass by the station via the eastern bypass track close to the refinery, then enter the actual holding stack (red arrow), and finally try to make it into the station again by taking the same route as trains from the north do. With the design shown, three full-length trains with 6  wagons each fit into the holding stack, a further two trains into the preceding track block and the consecutive one, respectively.

Now that all colours are used up, let's discuss the way track tiles and signals are placed. First, a close-up of the southernmost area, i.e. where trains enter the station (see picture 6): Note the use of consecutive signals. As discussed in the 'Signals' sub-section, two consecutive one-way signals reduce the risk of trains taking wrong routes. Here, trains coming from the north on the western bypass track either proceed southbound (when they don't head for the station) or turn around to the north (for the loading/ unloading procedure at the station). In either case, they will encounter two consecutive one-way signals (yellow rectangles). There is yet a third pair of signals visible in picture 6, viz. a two-way signal followed by a one-way signal at the beginning of the eastern bypass track right next to the bus station (green rectangles). Here, it's save to use a two-way signal as the first signal. In most other situations, however, two one-way signals are needed, as discussed in the 'Signals' sub-section. The following one-way signal, by the way, doesn't seem to be needed for the trains to run as expected. However, it sure doesn't have a negative effect and the track block behind it still is of the full four-tile length. As this is a one-way signal, trains are prevented from turning around and from trying to re-enter the area in front of the station. The two-way signals at the entrance of the station have a nice side-effect: In case of a traffic jam on the rear side of the station,

• northbound trains can leave the area via the eastern bypass track and

• southbound trains can leave the area via the eastern bypass track, the holding stack and the western bypass track!

Similar to the design of intersections therefore (see the 'Intersections' sub-section), trains do not necessarily encounter short routes, but traffic jams are resolved reliably. In addition, most track blocks shown in picture 6 are also capable of taking entire 6-wagon trains, the only exception here being the area in front of the station.

A quick glance on the close-up of the northernmost area, i.e. of the rear side of the station (see picture 7), reveals familiar details: As mentioned above, there are one-way signals at the exit of the four tracks (one of them is marked with a yellow rectangle). Once completely outside the station, i.e. with the last wagon having passed one of these signals, trains are forced to leave the area by going northbound (at least for a couple of track tiles). Again, two consecutive one-way signals are used on each of the two tracks that lead to the north. Where the holding stack crosses the dual tracks, a tunnel has been built. In this particular situation, we could have made use of a bridge just as well, since there are no signals on the respective dual track tiles. Always use high-speed bridges, though, as they don't slow down the trains. For maglevs, bridges should not be used at all, because their maxiumum speed exceeds the speed allowed on any bridge available.

A final hint: Similar to intersections, where 'real' intersections can be turned into T-junctions simply be omitting one branch of dual tracks, a 'real' through station can be turned into a heavy traffic terminus station by cutting off one of the dual tracks serving as entry points.