Even though the listed speed for planes are 951 km/h and the listed speed for maglev trains are 643 km/h, the trains seems to be moving at a much faster speed. In fact, I have a section of track that ran right by the flight path and the train regularly speeds past the planes. Are planes worth the effort since their so high maintenance and are at risk of crashes?
How fast are those planes really moving
openttd
Related Solutions
Shamelessly copying from Jon:
According to the wiki, the "Two-Way" path signal triggers a penalty in the pathfinder algorithm for trains passing through it on it's back side. I'd venture a guess that when a train is trying to find a maintenance depot, there may be a bug (or feature) where the pathfinder rules out that depot due to the path-finding penalty.
Using solution #2
An edge detector in OpenTTD can be constructed via a NOT-gate and inverted detector. Take a look over at the Logic page of openttdCoop. This details various ways you can construct gates. AND and OR gates can be constructed using only signals; but NOT gates and such require 2 trains per gate; so this construction with 3 depots would require 12 trains and 6 gates. Each gate takes up about 3x3 tiles so you're looking at a footprint of about 12x7 tiles with added input/output lines.
Note that you need to disable 90 degree turns for trains for these constructions to function.
Note that these gates do not allow signals to create dangerous situations; such a gate would only serve to 'buffer' a train in your holding pen, not to limit traffic; it will not flash green if the block behind it is unsafe.
In addition, if there is no train at the station platform or buffer at all, then your edge detector will stay red and never turn green (as it sits in front of the station platform). Thus there must always be some trains buffered or the station will deadlock and thus stop working.
I have a simpler suggestion though:
Simply chain combo signals. If there is a row of combo signals from the platform to the holding pen (it is all effectively one signal block) then only one train can be in that whole section of track. Put 7 entry signals near the end of the last buffer; then chain combo signals until you reach the platform. The pathfinder will distribute the trains automatically due to the penalty associated with taking the same route as a previous train.
This means getting rid of the merge and split between the buffer and platforms: give each platform its own buffer. Instead, when wanting to distribute lots of trains between a number of platform groups, use a proper splitter before the buffer instead; not after. There's various types. Probability splitters will get you a roughly even distribution, while a simple gap splitter will fill each line from shortest- to longest-distance (Pathfinder-preferred order) to capacity. Gap splitters are best used for stations as they require no moving parts, and you don't care which platform is used as long as no platform is overwhelmed.
Best Answer
The reason why your planes seem to be slower is because planes fly at a quarter of their listed speed, so sub-sonic planes actually fly at around 240km/h, which is significantly less than maglevs. The quarter speed rule can be adjusted in advanced settings. There are a few other interesting game mechanics surrounding the calculation of vehicle speeds. For the specifics, see the OpenTTD wiki article on vehicle speed.
Whether or not planes are 'worth it' is a purely subjective question, but if your sole goal is making money, then in the absence of competitors, with cities of sufficient size to provide the passengers and enough initial capital to set up the airports and buy the planes, air transport is easily the most lucrative business you can run in the game. It's easy to set up, and require little maintenance, and makes oodles of money compared to the amount you spend maintaining the aircraft. In fact, some players like to set air routes early in the game to make enough money such that they can concentrate on playing with trains later on without worrying about running out of money.
Regarding the risk of crashes, there is one specific case you want to avoid to reduce the likelihood of crashes - large planes landing at small or commuter airports have significantly increased risk of crashing (from 0.07% to 5%), so try to upgrade your airports as soon as you can. A list of 'small' planes that can safely land on small airports can be found on the wiki.