How to run two LEGO electric trains at the same time? I have a LEGO city built with a train encircling it. The track is the classic style with metal railings running through it. I have a switch track as well that is connected to an NXT robot to switch the track each time a train comes by. 

The problem is, there are areas where the trains run into each other because there isn't enough power running through certain areas of the track or too much power. I have 2 of those power consoles connected to the tracks. 

Does anyone know how I can have these two running at the same speed without slowing down and crashing into each other?
This probably isn't going to be solved without either changing to remote controlled PF trains or creating a complex control system.

Even if you were able to supply the exact same constant voltage to both trains, they'd both need to have precisely the same motor characteristics, weight, and aerodynamic properties. That's going to be difficult.

One way to address this is to create track blocks that are electrically isolated and can be controlled independently. You can isolate the track sections using tape at the joints, or you can physically cut the metal rails. You could then connect these blocks up to your NXT and build some sensors to determine what speed the trains need to run in these sections in order to not hit each other.