unfortunately, the RIAT organisers have only so much control over the road system in the surrounding area, they do work very hard with the local authorities to try solutions for this problem, to this end these are some of the things they have done.
Car parks are spread out around the whole southern area of the air base meaning you go to the one on your "side" depending on where you are coming from.
There is a temporary one way system in place from the lechlade side which will reverse in the evening to accommodate the higher flow leaving, unfortunately this does come slightly unstuck because of the road leading up to what is normally the main gate and 'domestic' side of the base, they can't make this one way because it will increase traffic inside the fence line crossing the runway, which is not a good idea.
This year they sacrificed a large area of usable airfield space to incorporate on base car parking to try and ease some of the pressure on the roads by getting the cars off the supplying roads faster, although this doesnt seem to have worked as well as they hoped..... as for the on base parking, well, you cant blame the organisers for peoples stupidity, when it came time to leave, people simply ignored the pedestrian lane marked out for them and walked down the middle of the road next to the car park, next time guys, i WILL run your asses over !!!
Adding the on base parking took away a lot of the area that had been used previously as 'live' taxiway and used to park the flying display aircraft, so unfortunately they had to be on the far side of the airfield this year and not accessible
No on the day ticket sales was i believe another attempt to ease the traffic issue, their limiting factor on attendance is not people but parking, the showground can handle a lot more people but not the associated parking, so by having pre-sales only they can try and control that a little bit.
Participants was down this year on previous years, some of the smaller things that were scheduled to come, simply could not because of the weather on friday when they were due to arrive, although this number was low, the one big, and main reason for what appeared a low turn out is that every country has more and more of it's assets deployed constantly, whilst politicians are constantly cutting budgets and airframe numbers and manning, whilst sending their military to more remote locations... airshows simply become an impossible luxury that they would like to attend but cant.... the RAF C-17 was re-tasked on operational duties both days and was not able to fly it's planned slot.
These aircraft are, with the exception of a few (like the Dutch F16's) fully operational military aircraft with their associated responsibilities/tasks
I think they did a fairly good job overall this year, given the current climate and other things.... dont be put off by one year not meeting what you expected, i am sure the organisers will be looking very closely at the transport arrangements again, and as for park and ride, people just dont like using them.
Private 'Enclosures' at these types of events are pointless, and purely for those that feel the need to appear better than everyone else.... and your not guaranteed a better view as you found out.
RIAT for example, has about a 2 mile runway and crowd line, on the 'front' of that crowd line, you have the FRIAT (Friends of RIAT) stand near the western end, with sloped seating, general grassed area anyone can use, then the 'VIP' tents etc taking up a good sizable chunk of real estate in the middle, then the larger general area to the eastern end with one other enclosure at that end if i remember correctly
Thats a huge crowd line for any display pilot to deal with, many of these show routines are based on smaller crowd lines and much tighter airspace (in many ways they are spoilt for protected airspace at fairford) I am also sure that in the various briefings the crew are reminded to display to as wide an audience as possible, add to this the cloud cover, the Italian display team on the Saturday waited on the runway for 5 minutes, for no other reason than they wanted the clouds to blow over a little before displaying, this was ONLY possible because they were last to go.