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3.6 New Curve and Mountain Handling

curves, -c

mountains, -m

TTD does not take into account the differences in the various train technologies. For example, the real Maglev trains do not have the same problems in curves and on hills as the traditional trains do; they can have a much smaller curve radius or pass the same curve at a much higher speed. When travelling across hills, they can have more power than on flat land, so that their speed decrease is often negligible. This is why I created this switch to correct that. In fact, this is why I started making TTDPatch, because otherwise you need too many bridges and tunnels and other normally unnecessary stuff to create an efficient network.

It also circumvents another bug, namely that there can be no signals inside tunnels. This makes larger tunnels rather useless, because it interrupts the flow of trains that have to wait until a train has completely left a tunnel. Thus, one has to either level the mountain (if there's no way around) which is ugly and costly, or lay the tracks on top of the mountain, which considerably slows down the trains as well. Until now that is, because now you can set it so that trains have no disadvantage when going over the mountain.

This switch also allows you to enable realistic acceleration of trains. Regular TTD uses a constant acceleration of trains, which is not realistic. In reality, acceleration of trains decreases with their speed. This switch can make trains use a more realistic model of acceleration. For more info on how it works, please see Realistic Acceleration.

The mountain and curve switches allow to select which type of trains will use a higher speed on mountains and in curves, and which ones use realistic acceleration. There are two steps of acceleration; the first one being simply higher speed and the second one doesn't slow down the train at all. This can be especially useful if you have many "clover-leaf" type crossings, where you have to have a few bridges.

The argument to mountain and curve is a four-digit number, one digit for each of the four land-based vehicle types: railroad, monorail, maglev and road vehicles. For each, you specify one digit from 0 to 3 with the following meanings:

For example, you might specify mountains 3320, which means: railroad and monorail are realistic (3), maglev is "full speed" (2) and road vehicles are normal (0).

If the electrifiedrailway switch is on (see Electrified Railways), the meaning of the argument slightly changes: the second digit controls electrified railroad instead of monorail, and the third digit controls the combined monorail/maglev system.

For curves, setting 3 ("realistic") is implemented by limiting the speed of trains in a curve. It's slower the more curving segments the train is on currently. For road vehicles, the speed is limited to 75% of the top speed.

Note that if you're using realistic train acceleration, it is possible to make a train that is too heavy. If the engine is not powerful enough to overcome the initial friction, the train will not be able to leave the depot. What's even worse is that the engine may be powerful enough for an empty train, but as soon as the train is full, the increased weight may mean that it'll be unable to leave the station.

In addition, it may happen that a train gets stuck on a mountain, again because the engine is not powerful to pull the train's weight uphill. If this happens, you will either have to remove some waggons, or add more heads to the train using the multihead feature. Note that if the engine is too weak to move the train at all, it will still be able to move exceptionally slowly. This will allow you to send it to a depot to rearrange the train even if it really shouldn't be able to move at all.

Finally, note that realistic acceleration assumes trains propelled by wheels. That means it's not appropriate for maglev systems, for which you should use either the "faster" or "fastest" settings.