I focused on construction this time and not on trying to complete the scenario. So I think I only have completed 10% or so of the goal. But I think a couple of the stations turned out pretty cool.
Here's a screenshot zoomed out a bit:
http://www.punar.net/games/loco/60track2.PNG
Closeup of the center 60 platform station.
http://www.punar.net/games/loco/60track1.PNG
I think I saw a post of someone who made a 67 tiles long station. That may be the limit or at least extremely close. My platform is 60 tiles wide. It wasn't very hard, but took sooo long to build so I'm not going to try to beat 67.
Closeup of one of the chemical lines.
http://www.punar.net/games/loco/60track3.PNG
There are three lines coming from the left and a train on any of those can go to any of the four stations. This network took even longer time than the 60 tiles wide platform. It doesn't look like much now (spent a lot of time optimising it) but I wanted it to be so that trains from any line could go to any station, the trains had as few slopes as possible, no joining intersections before they arrive at the stations, and no waypoints because that will save me time when I replace the trains. Yes, I probably saved one or two minutes by not needing waypoints, but it took me way longer to construct this

Savegame here:
http://www.punar.net/games/loco/60track.rar
Oh btw, nobody has commented on the scenario design. What do you think of the look of the scenario?