Freeways don’t handle a million pounds of aircraft, and cars don’t drive on them at 200 miles per hour. What do you suppose happens when the runway is covered with water or a max-loaded aircraft hits a pothole?
A road can be imperfect for the obvious reason that a car is already on the ground. A runway cannot be. They are built and maintained to higher standards because nobody wants to see what happens when they are not.
On this topic and speaking of Chicago, Midway has been called “the world’s busiest square mile.” Check out the aerial shot of the runways there. Everything outside of that X-shaped pattern is not-airport - regular streets, houses, businesses. As you might guess, when shit hits the fan, things can go very badly. The photo in the linked Wiki article is of a 737 in the middle of an intersection - due to snowy conditions, lack of now-standard runway overrun space (there’s no room to put it at Midway) and insufficient pilot training on the new autobrake system, it plowed right through the wall at the end of the runway and killed a child in a car in that intersection.
I’m thinking the main reason airports don’t have tons of runways is because most were built when flying wasn’t a big thing so nobody had any idea that a ton of runways would be useful by now, and in the meantime the land around the airport was put to other uses.
Interestingly, schiphol (close to Amsterdam) has 6 or 7 runways, the same number as all five airports that serve London together. However, there are many restrictions for environmental reasons so it’s not quite as ideal as you’d think. The newest runway is also extremely far from the terminals and the taxiway is around the formerly newest runway to which it runs parallel, because they decided against crossing it, so you have to taxi for 10 minutes and actually cross a highway.
My thinking is that the ideal airport would have three or four sets of two parallel runways that all begin/end at a big terminal building in the middle, like the hub and spokes in a bicycle wheel.
London Heathrow has two, argument has been going on for many years about building a third. Doing it would require destroying a village. It’s strongly opposed by local residents who don’t want even more flights over West London than is already the case. The Mayor of London favours closing Heathrow and building a new airport East of London
Which only touches on the need for constant vigilance and maintenance. A small metal strap that would be worth only a moment’s notice on a highway was the cause of the crash that killed over 100 people and ended the Concorde’s service.
Knew somebody was gonna jump all over my half-assed runway numbering scheme. :smack:
You mean, a design like LAX? (They can get away with parallel runways because the prevaling winds mostly blow one direction year-round.)
Runways which point directly towards the airport terminal would be an extremely bad idea, for obvious reasons.
OK, so let’s assume that were built. Further assume that the runways were laid out in diagonals so that they form a bisected square like Midway. They would need to be 10,000 feet in length each, and they could only be approached from the perimeter to ensure that the aircraft doesn’t short it into the terminal. However, that means that they are coming toward the terminal when they land, which means that a landing that goes long and has problems stopping might eat the terminal as well. Also, that would take up around the same area as O’Hare, it wouldn’t be as flexible as O’Hare, and it would waste significant space.
Of course, runways are for fashion models. 
Sounds like the 2000-Year-Old Man’s Star of David Factory:
What I have in mind is something like this:
ISTM the closest practical equivalent to iljitsch’s concept would look a lot like the previously mentioned Denver DIA. A wee bit of overkill if you ask me.
Check again that layout for Denver DIA – seems that what you do nowadays* if the climate in the location is prone to periods of sustained wind from different bearings*, as opposed to the ocassional crosswind in a passing storm is put the airport where there’s a very large parcel of cheaper land available so you can build crosswind runways, but separated so they don’t intersect.
OTOH if the prevailing winds are almost constantly from the same direction, then you DO put your runways parallel per your cost-benefit analysis, as in ATL, Paris CDG. It does seem designers now prefer to avoid intersecting runways if possible, though (**)
(** e.g. LEX airport in Kentucky had a deadly disaster due to a confusion between the main commercial runway and a shorter General Aviation runway that intersected right at or near the threshold so a pilot took the latter thinking he was on the former; afterwards the airport was redesigned so the runways do not touch)
On a separate post due to the finite Edit window
Kind of like Denver International only with 6 instead of 4 arms. Except that in most parts of the world you do not need to cover the whole compass at 60 degree intervals. Plus you want to make allowances for the airport complex itself to undergo improvements, expansions and redesigns.
A lot of it has to do with the number of arriving and departing flights an airport has daily. For example, McCarran International in Las Vegas has 4 major runways, 2 sets of 2 parallel runways. (R07/25L and R – and R01/19 L and R respectively IIRC) R09/27 are the larger and preferred runways, which happens to work well with the prevailing winds for the valley.
Vegas has roughly 400 departures and arrivals each day. Generally one runway is used for arrivals and one for departures. So you can figure 400 runway uses per day, 24 hours a day, comes to 16.6 times an hour a runway gets used, or roughly once every 3 1/2 minutes. That is a very comfortable runway usage – We don’t need any more runways here.
Just as a note – traffic patterns do not necessarily follow the 4 leg approach in controlled airspace. In Vegas you can see aircraft lined up 50 miles out to the east later in the evening and at night. Flights from west of Vegas pass the airport and make a single (roughly) 180 degree turn to get in line to land.
Another thing to consider in the big scheme of things is that airport terminals must cater to vehicular traffic as well. By the time you add space for car rental services, passenger drop off, long term parking, short term parking, rail/bus access and various kinds of passenger accessways as well as truck access for deliveries, freight and maintenance requirements you use up a lot of space. And you also want a lot of high volume roads in the area as well.
This means that there is a lot to be said for a model where there is land access on one side of a terminal and runways on the other. A lot of airports are built that way.
And I also submit that there can be a variety of other logistical issues to contend with.
Wellington Airport must be one of the smallest in the world for a nation’s capital. The city is all hills. (Zoom out a little) It is extremely windy on a regular basis and the cross winds can be ferocious. The runway itself is short and much of it is on reclaimed land since that was the only place to put it.
There just aint no six parallel runways going any where near that place.
Note that O’Hare just recently finished a massive rebuilding project which involved yes creating more parallel runways and fewer intersecting ones.
Or we can go with the ever popular airport at Gibraltar that has an operational street crossing it and sits on a damn narrow strip of land.
I’m pretty confident that the slab of concrete used in runways is a lot thicker than what’s used for an interstate.
And part of the expansion involved a 5-year court battle to acquire a cemetery - and reburying about 1500 bodies elsewhere.
I’ve got an even cough better idea–one that will save a whole lot of time and money.
I’ve read that just after American forces captured one of the islands in the Pacific during WWII, there was only one working runway on the island. According to an eyewitness, the bombers came in for a landing from one end, while the fighters were taking off from the other end.
Fighters, of course, don’t need nearly as much runway, so they would zoom up over the bombers just before colliding.
All we need to do is train all the current pilots in similar techniques. What could go wrong? (There would be a strong incentive not to make mistakes, you know.)
