I need assets to HOLD airplanes on taxiway at runway entrance automatically.

[stagecoach]

My Heathrow layout has full control of planes landing and taking off. You wont be able to have planes flying around without stopping somewhere as there will always be a point where timings get to tight. I set aircraft on a loop someway out on base boards placed a long way from the airport itself and they will often wait time. Once they enter the approach path they have control of the runway and all aircraft wait to enter the runway or cross the runway. this means that they may wait for more than one plane to land if the second plane is on the approach path. Paul_r has used my layout and updated some items to make a full day's operation. Push back is available on some parking bays but due to the size and number of bays it was limited to a small area.

 

[Robert3a0]

I have done what you want to do by using invisible signals, the plane will not enter a junction against a red signal. Put a signal on short finals, about 1 km out, which should give runway clearance to the landing aircraft; use invisible speed signs in conjunction with those signals so that the incoming aircraft slows on descent. At the runway/taxiway entry point make sure you have an invisible signal also. So, if a landing aircraft is within 1 km, the departing aircraft will receive a red signal at the junction and won't proceed onto the runway until the landing aircraft has moved past the next junction, which will be at half-way down the runway onto the taxiway. You can run as many AI aircraft as you like in that fashion, just use plenty of invisible signals on the departure tarmac and the aircraft will stack up nicely. You can also make plenty of use of one way direction markers with parallel taxiways to separate departures from arrivals. Just experiment a bit. You have to set up the AI functions using the navigate to track-mark function; so you need to install track-marks also for this to work.
Regards
Bob