The reasoning behind the directional question was based on what UP, BNSF and KSC did here, in Houston.
I live a block away from the the old CB&Q-Rock Island line to Dallas/Fort Worth, now a BNSF main.
Ten years ago, BN ran trains almost every hour, both ways.
There were passing sideings everywhere, and you could count on at least on train every hour.
After the UP/SP merger meltdown, the big three got a brain storm, and formed the Joint Dispatching center, in Spring, a small town just outside Houston.
TD1(train dispatcher one) TD2 and TD3 all work in the same building, all with the same screens, so now, instead of three different diaspatchers in three different locations, all trying to dispatch trains on lines they had never even seen, you have them all in the same place, each one dispatching each others trains in their respective sections.
And they are required to go out and ride the lines they dispatch, once a year, so they know the actual geography of the track they dispatch.
TD1 handles all inbound trains entering the metro complex, TD2 dispatches all outbounds, and TD3 handles all internal dispatching inside the complex.
Each railroad provided the resorces and personel, and the Joint Center
plays no favorites with any one railroads trains.
TD1 has to be able to talk to, and see what TD3 is doing, so he knows if there is a hole he can use to bring a train into the complex.
TD3 has to be able to do the same with TD2, so she knows if she can turn lose a bunch of outbounds from the yards out onto the mains, or if she can use a main for a yard to yard transfer, and TD2 has to know who, what, and where the outbounds TD3 lets lose are going, to make sure he has the space to run them.
You can hear a UP dispatcher raising cain with a KCS crew, for blocking a BN train!
They decided on directional running from the beginning, almost all inbound traffic enters the comp