Parking Bays

[Guest]

Hi,I've nearly finished a RAFCAD for EGLL.I'm beta testing it at the momemt and everything is fine except for the fact that for example in T1,where planes park park in a "u" or cul-de-sac on opposite sides of the bay, but use a central taxi lane. When one plane wants to depart and one wants to enter they face each other and then dissapear after fifteen minutes.How do I get around this? Do I add a hold short node just outside of the parking "u" and keep getting errors when I run fault finder, or is there another way around it?ChrzPiggin

[Guest]

Thanks Matt,I'll give that a try now.Chris

[Forkboy2 27]

For that situation, the best thing is probably to do what I showed in the one screenshot that shows all the links connected to one single node on the main taxiway, and then overlap them down the corridor. This will usually prevent an aircraft from entering the corridor when another aircraft is already in the corridor.Attached is a simple diagram showing the ideal way to set these up. Unfortunately, it's not always possible if the taxiways aren't set up right, but usually you can do something like this.http://ftp.avsim.com/dcforum/User_files/3e968e2256b75898.jpgIf you look at the diagram, the red dots are the gates and the green dots are the nodes on the main taxiway. The main taxiway is blue and the taxiway down the corridor is yellow. Node number 1 is what I call the Master node. What should happen if you set it up this way is that only one aircraft will go between the gates and node 1 at a time. If another aircraft tries to use the corridor, it will wait for the first aircraft to leave first before entering.If you want you can overlap the yellow taxiways down the corridor so they will use the same taxiway. However you must be carefull not to have any extra nodes in between nodes 1, 2, 3 and 4. It must form a 4 sided figure with one node in each corner (it doesn't have to be square). If you had another node in between 1 and 2 or 1 and 4, it would not work.With this kind of set up the aircraft will almost never get hung on each other. It still doesn't work 100% of the time for some reason, but usually it works. If you try my version of KORD, you should be able to let it run for a very long time and almost never see any hangups, even with full traffic.Also, I drew on your screenshot to show you how it could be done. The second method might have more problems with aircraft getting stuck than the first method, but both should work better than the way you have it set up. The second method has 3 links between the master node and the gate, the first medthod only has 2 links. The yellow lines can be overlapped, I just separated them so you could see them.Matt Fox

[Guest]

Hi Matt,Thanks for all the tips.I like the off set parking to prevent aircraft which want to leave at the same time grinding to a halt, and will amend my file accordingly.Below are a couple of screenshots to show my dilemma.As you can see, the aircraft are supposed to share a common taxi line down the centre of the bay. Would I be wise to create a second taxi line and therefore have two taxi lines? If so wouldn't the aircraft stop anyway when the Radii of the aircraft meets each other and thinks there is going to be a crash?ChrzPiggin

[Forkboy2 27]

One last tip. If you ever see aircraft trying to leave the gates at the same time and get stuck, this will fix that.Notice how all the links that go to the gates are offset very slight amount in the same direction. This will cause all the aircraft to turn in the same direction. If they weren't like this and two aircraft tried to exit adjacent gates at same time they could get stuck on each other if they tried to turn toward each other.Matt

[Forkboy2 27]

Here is another view of the previous overlay. You can see how I took all the parking nodes and connected them to a single node located on the main taxiway. This will usually prevent one aircraft from trying to enter that taxiway when another aircraft is already on the taxiway.Also, notice how the other taxiway to the east, is a two lane taxiway. For two lane taxiways, you don't need to do this because aircraft will taxi around each other in this setup. However, if you have a bunch of extra nodes in there it won't work.Matt

[Forkboy2 27]

Here is one of the other overlays at KORD.In this one all the aircraft land on 27L and depart on 32L. Again, they all loop around in so they are all moving in same direction. Very few, if any, hangups.Matt

[Forkboy2 27]

This is a very common problem and one that most designers pretty much ignore. The designs work great until aircraft start to land and then everything comes to a stand still.The only way to fix it is to design the AFCAD in such a way that aircraft will not go down the same taxiway towards each other. How do you do this? First of all use as few nodes as possible. The more nodes you use the more confused the AI aircraft get and the more likely they are to try and go down the same taxiway towards each other. Some people put a whole bunch of nodes in the corners to try and round off the turns, but that can be part of the problem.Next you have to design it in such a way that aircraft enter one end and exit the other end with all aircraft going in the same direction. Sometimes this is very difficult.If you look at the screenshot attached of KORD that I did you can see that I set it up so all landing aircraft come in on 27R and enter the terminal area at the north. It is designed in such a way that all aircraft loop around the terminal area and depart on 4L. With this design you will get very few, if any, cases of aircraft getting stuck on each other.Matt fox