Hi
A TCB will only indicate to an Enhanced Interlocking Tower that the track is occupied and will prevent the tower from setting paths into the section if it is. As far as I'm aware there is no way yet for two trains to enter the same section when it is controlled by an EIT with TCBs.
The only way that I know of having trains travelling in the same direction follow one another into a single line section is to use two variables, one to act as a token to indicate if the section is occupied and the second to indicate the direction of travel of any train already in the section. This will only work though if the single line section is divided by signals into blocks in both directions otherwise the entry signal will stay red until the train clears the whole of the section. A train approaching the section will check the value in the token variable. If it is 0 it will then enter the section incrementing the token variable by 1. I use increment to count the total number of trains in a section. It will then set the direction variable. On an East - West route for example I would set the variable to 1 for Eastbound and 2 for Westbound.
If the token variable is greater than 0 then the train will then check the direction variable. If the train already in the section is travelling in the same direction the second train will increment the token variable by 1 and set the direction variable to the correct one for the direction of travel before entering the section following the first train.
When a train exits the section it will decrement the token variable by 1 to keep the count of trains in the section accurate. There is no need to reset the direction variable because a train will only check the direction if the section is already occupied.
It needs a trackmark placing just before the entry signal at each end where the train will be held if the section is occupied by a train coming the other way. When using EITs to set the path, the path setting for the entry path is set to manual and the path set when needed by the IT SetPath command.
Regards
Brian