Sign in to follow this  
Christopher Low

Building AI pathways in Airport Design Editor

Recommended Posts

Posted (edited)

Airport Design Editor is a really useful tool for creating airport AFD files, but I have noticed a handful of issues with AI planes that could easily be avoided.....

 

Multiple nodes on runways between taxiway exits - I have seen so many AI planes make ridiculous turns on the runway after they have landed, and it is usually because they have encountered an extra node between successive taxiway exits. I really do not understand why these nodes are added in AFD files (unless they have simply been overlooked by the developer). As far as I can see they serve no useful purpose whatsoever. Airline pilots (as far as I am aware) rarely make turns of this kind on a runway unless they have no other choice, and it looks really crap in FSX/P3D.

On a similar note.....some taxiways have two or three separate centrelines that connect to the runway centreline (a central one if the taxiway continues on the other side of the runway, and two curved ones either side of this). This is perfectly fine for flight simmers, but it can become a problem if the AFD file includes separate AI pathways for each of these three exits. This is because an AI plane can finish its landing rollout between the three nodes that connect these exits to the runway. If this happens between the middle node and the third node, the AI plane will attempt another one of those awful looking turns on the runway. Now, you could argue that this allows the airliner to exit the runway quicker, but personally I like to see my AI planes move around the airport realistically, and those bizarre turns that (sometimes) involve short excursions on the grass look about as realistic as seeing an Imperial Star Destroyer waiting for departure clearance at the runway threshold. If the AI plane slightly overshoots a taxiway exit, I prefer to see it continue to move down the runway until it reaches the next exit. The simple solution is to have one (central) exit in the AFD file.

A similar situation to the above can occur on taxiways that are nowhere near the runway. The default system for controlling the AI planes seems to be quite intelligent, and simple tweaks can improve AI traffic flow. A good example of this (one that I noticed a few months ago) can be seen at the junction between taxiway Delta and taxiway November in UK2000 Manchester Xtreme (see attached picture). The black circle shows the location of the taxiway junction, and the red line indicates a section of taxiway that I have removed. The reason I removed this is because.....if one AI plane is arriving on taxiway Delta and another one is approaching the junction from the other side, the AI system will see this extra section as an "alternative path". It will therefore allow both planes to approach this junction at the same time, and one of them will end up trying to use that other section as a way to avoid the other plane. Unfortunately, this just ends up looking really silly, and the end result is a "stalemate" bwtween two opposing aircraft (which....I hope you all agree....is not what we want). Removing that section of AI taxiway (which serves no useful purpose in the flight simulation world, because no AI plane needs to use it) results in the AI system instructing one of the two AI planes to wait further back, and in a position that will not interfere with the other aircraft's movement.

 

I just wanted to point these issues out, and I am sure that there are many more. I modify and tweak AFD files all the time, and correct stuff like this whenever I see it :smile:

http://www.mediafire.com/file/fv6exe6u12d10jj/Manchester.jpg/file

 

Edited by Christopher Low

Share this post


Link to post
Help AVSIM continue to serve you!
Please donate today!

There was a time when I would spend hours optimizing AFCADS and applying the correct parking codes, but I gave up a few years ago. I most disappointed in well regarded commercial developers that consider the AFCAD an afterthought. Having incorrect parking codes or poor traffic flow is a sign of sloppy work and we shouldn't accept it as a community. I don't care if a billboard on a parking garage has the correct font. Some developers seem to be more concerned with how things look than how they work. Many of these issue were discovered years ago back in the days of ProjectAI, but developers still don't pay attention to the details.

 

Share this post


Link to post

 Extra nodes on runways are often added to catch the ai into taking a proper exit so as to NOT use the reverse. The AI don't see it as a reverse exit, it's just the closest exit node once they have slowed down enough to exit the runway.

 

Share this post


Link to post

Based on what I have seen recently at airports on my PC, those nodes do more harm than good.

Share this post


Link to post
3 hours ago, duckbilled said:

Some developers seem to be more concerned with how things look than how they work. 

I totally agree, but it's just a general trend in the flight sim industry away from how things work to how things look. With regard to 3rd party airports, I think that it's not so much laziness on the part of developers, but rather the gradual nature of changes that occur in real life airports. Airlines come and go as do gate assignments. Comms and approaches change with each passing AIRAC. It's the same general reason that payware AI aircraft packages eventually fail. The developer is not capable of keeping up with all the short-term changes in models and liveries. Eventually, everything gets so out of date that the developer just gives up.

As to airports, most 3rd party developers use ground polygons to display aprons and taxiways and not the default textures provided in ADE. These polygons are developed from aerial orthoimagery and to modify them in order to match real-world changes requires a lot of work. Sure, one can use ADE and edit a taxiway link but if the ground polygon is unchanged, the AI aircraft will follow the new taxiway link and may wander off onto the grass, etc..

I've become a fine connoisseur of corrected ADE files, but I tend to stick with creating those from the stock airports and I usually don't mess with my 3rd party airports (except to fix gate assignments) unless there's a real gaffe such a major orphan link.

Share this post


Link to post
2 hours ago, Christopher Low said:

Based on what I have seen recently at airports on my PC, those nodes do more harm than good.

It all depends on where you put the extra catch nodes not to mention your AI FDE's. What works on my setup may not work so well on yours and so on. Too many variables in there.

Share this post


Link to post
7 hours ago, Christopher Low said:

Based on what I have seen recently at airports on my PC, those nodes do more harm than good.

Chris,

The great thing about ADE it gives us a tool to fix these issues.  I have built a lot of airports using ADE and don't have any problems.  Look at all the airports Ray Smith has built using ADE and his AI seem to work without any problem.  It takes a lot of work to build a runway and taxiway system to get the AI aircraft to turn around correctly.  I've had UNNT finished for a week, but I am struggling to get the AI to work correctly.  The only reason I'm fixing the AI paths is that I am going to upload the file. If it was going to keep it for personal use only I wouldn't care since I don't use AI aircraft except with Real Traffic.

Not being critical, just another view. 🙂

Share this post


Link to post

It seems that each airport is unique where the AI system is concerned. I have only really looked at airports and airfields in the UK and Ireland, and these may be relatively "standardised" in format.when compared to the huge variety of airports around the world. Maybe those "inter taxiway exit nodes" work well elsewhere. I just know that "aircraft turning around on the runway" problems on my PC have effectively been resolved by removing those nodes, and reducing taxiway exits to a single node. Of course, adding sections of taxiway/apron pathway can also work well in controlling the movements of AI planes on the runway (effectively stopping them from turning off at departure exits for example), but I guess this needs to be done carefully, and on an "airport by airport" basis :smile:

Share this post


Link to post

There are too many glitches at airports as described above and some more issues come into my mind. Airports with non-parallel runways are difficult to program correctly if this possible at all. AI traffic design for seaplane bases is a nightmare. Not to speak about sloped runways, which cannot be used for ai traffic until now. IMO, the ai engine of P3D needs a complete overhaul/redesign.

Share this post


Link to post
Posted (edited)
Quote

IMO, the ai engine of P3D needs a complete overhaul/redesign.

I am reasonably sure that a lot of flight simmers have been asking LM to do this for P3D, but there does not seem to be any sign of this happening to date. If LM really are interested in listening to home user requirements, then you would think that this is one area where they could make significant improvements to the base product. Getting the AI planes to approach and land more realistically (touchdown speed/flare/realistic rollout etc), and solving problems like landing well short of the runway threshold/endless "stop/start" messages when following user planes etc. would be a massive step forward with respect to realism and immersion at major airports.

Edited by Christopher Low

Share this post


Link to post

A major fix for me would be if Laminar would allow AI traffic to use sloped runway/taxiways. Frustrating with such nice 3rd party airports like Svolvaer in Norway that looks amazing but the only other traffic around the airport has to be static.

and while at it I would love them to improve ATC, especially IFR. Back and forth, back and forth vectoring :)

I always improve my 3rd party airports. Always something that can be improved. Since Fsaerodata however the com freq is one less thing to have to update with ADE. I use VoxATC as well so the AI traffic is even more sensitive to a correct airport structure. I gave up airports where tawiways dont align to end of runways beacause VoxATC generated traffic cant backtrack and turn 180 degrees for takeoff

Share this post


Link to post

I don't think we'll ever see the AI using sloped runways in XP any time soon. AI traffic is probably one of the reasons that MS left out sloped runways in FSX. Despite some statements made on AVSim to the contrary, it is possible  to make an airport in FSX with a sloped runway. There is a perfectly good example of one in the AVSim library.

I also get annoyed how finicky the VOXATC AI aircraft are with some airports. But when I take a look at the offending ADE file, I realize that the airport's geometry is modeled inaccurately. With ADE, given both an accurate aerial orthoimage and the airport chart, it doesn't take much to fix most runway and taxiway errors. 

Share this post


Link to post
10 hours ago, Christopher Low said:

I just know that "aircraft turning around on the runway"

Chris,

To get this to work I build a special path slightly offset from the center line that will take the aircraft to the end of the runway and reverse the course as it would in the real world.  Ray Smith is very good at this.  🙂

 

 

Share this post


Link to post

Getting AI planes to turn at the end of a runway (where there is usually a wider turning area) is easy. I am referring to AI planes turning halfway down a runway when there are additional taxiway exits beyond that point. Of course, the AI planes have no choice but to turn on the runway at some airports. A good example of this in the UK would be EGNJ Humberside, where aircraft landing on runway 20 have no option but to turn around and backtrack up the runway. In this case, I have multiple turning points along the runway that are all connected to the exit by taxiway links that are on the runway itself.

Share this post


Link to post
4 hours ago, Christopher Low said:

I am referring to AI planes turning halfway down a runway when there are additional taxiway exits beyond that point.

I must admit I struggle with AI aircraft, that's why it has taken me over a week to get the AI aircraft to work correctly with an airport as simple as UNNT.  I just work with it until it works correctly, for me it's just "trial and error." 

  • Upvote 1

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this