Revision as of 16:44, 26 October 2009

Our networks usually have a single drop station for every cargo type or even one for multiple cargo types combined. With thousand or more trains running you can figure these stations have to be efficient and high capacity. Over the years we developed many types of main stations, each suitable for another purpose. First we'll look into the function of main stations and the standards they should meet for different purposes, then we will look into some common designs more deeply.

Drop & Pickup seperation

One of the most important jam-preventing measurements we take is to keep drop and pickup stations separated. If we would not do this the situation could appear where all platforms are taken by secondary goods trains waiting to fully load, which will obviously never happen when there is no platform left for primary trains to unload.

Breaking & Accelerating space

You should keep this in mind when building any mainline station. Trains slow down when they enter a station, if trains are very close to each other one might be stopped when the train before it enters a station. This can be solved by having a few empty tiles in front of the station. The amount of empty tiles you need depends on both trainlength and train speed, the longer the length and the higher the speed, the more tiles you need. For long maglevs the number of tiles needed will be close to the actual length of the train. For long steamers a third of the trainlength will do. For maximum efficiency you'll also want a few empty tiles after the station to allow the train to accelerate before merging with the other trains. It is advisable to make this at least as long as the actual train; this way a train will never block the platform it just left when it has to wait to merge in with the other trains.

Different styles

As said, there are many different styles of main stations. Below I'll introduce them and name some pros and cons and when to use them. Each station can be categorized in one of two main categories: RoRo or Terminus. RoRo stands for Roll-on-Roll-off, which means a train enters a platform at one side, loads/unloads and leaves the platform at the other side. Terminus stations terminate a line; a train leaves a platform at the same side it entered. RoRo stations have a higher capacity than terminus stations; even though terminus stations' capacity is dramatically increased thanks to some clever designs, RoRo stations will always have a higher capacity. That said, the increased capacity for RoRo stations sometimes doesn't weigh up against the extra space it consumes. In practice you'll often find that RoRo stations are used mostly in cargo games and termini are most common in pax games.

RoRo with dedicated platforms per track

This type of station has the highest capacity. Period. No need to argue; there is no way you'll ever create something more efficient than a station that has a dedicated set of platforms for every incoming track. This station will be the best design when you have dense traffic and plenty of space to build your station.

However, there are some downsides to this design. The most important one is that it does not use its platforms efficiently; most of the platforms will be empty most of the time, only at surge times all platforms for a single track might be taken.This can be greatly reduced by introducing all-to-all acces for the incoming tracks.

All-to-all RoRo

All-to-all means that trains coming in from any track will be able to chose from any platform. As it is unlikely that all tracks will experience their peak traffic levels at the same time this approach requires less platforms, however, the construction becomes more complex.

Pre-balancing

This is a technique that basically combines the two designs above. It is rarely seen, but deserves more attention. This technique allows you to dramatically decrease the complexity of the all-to-all construction. As long as the amount of tracks during the pre-balancing process is never less than the amount of input tracks you should not get into bottleneck issues.

Pre-signal bypass station

This is an entry-style that bypasses the gaps pre-signalling can cause, especially on bigger drop stations with short, fast trains. The article dedicated to PBS (not to be confused with Path-Based Signalling) provides more in-depth information about this style.

Regular Terminus

You'll probably know this station style; it's one of the most basic in OpenTTD.

WIP --Mark 16:44, 26 October 2009 (UTC)