So can a modern 747 use a shorter runway than the older 747.
I am trying to figure out if the some of the smaller airports can make use of the 747 so it is not just the JFK's, LAX's or MIA's that can take advantage of the 747 in this day and age.
Probably. The 400's have much more powerful engines than the 100, 200, and 300 models, and it has some aerodynamic improvements. It also depends on how heavily loaded it is. Air Force One supposedly can take off from fairly short runways when it doesn't have the fuel loaded for an intercontinental trip. Nominally it's a 747-200 airframe, but it has the two man digital glass cockpit of the 747-400 and the 747-400's engines.
While engine performance can shorten the amount of runway a 747 needs, it is still restricted by its highly swept wings (37.5°) which is optimized for high cruising speed. The 747 is still the fastest subsonic airliner that has ever existed. The 747 Advanced will cruise at Mach .86 which is faster than the 400 model's and A380's Mach .85. The A380 due to advances in aerodynamics (a supercritical wing) is able to cruise at the same speed as the current generation of 747's while have less wing sweep which gives it better takeoff performance.
The smaller airports don't need the 747. The development of smaller twin engined planes that can fly intercontinental routes means people don't first have to fly to an internatinal gateway airport like JFK or LAX. Airlines can divert lots of the traffic that used to fly from JFK to LHR by offering direct flights from other cities in the US.
British Airways flys three flights per day each way between IAH (George Bush Intercontinental Airport, Houston) and London on 777-200LR's. The reason they don't have a couple of 747's on that route is that they want to have flexible schedules that allow their high yielding business and first class passengers the ability to pick their departure times.
The size of the airport doesn't necessarily correlate to the length of the runways. For example, both Austin, TX and Jackson, MS are fairly small but have long runways. Baton Rouge, in roughly the same size range, has runways so short that 737s have run off the end.
Here's some info on minimun runway lengths for the 747-400.
Fully loaded, 10,800 ft.
90% Max. Takeoff weight, 8,400 ft.
80% Max. Takeoff weight, 6,600 ft.
Note that lengths are longer for 100% weights for either a 767 or a 777, but shorter for 90% and 80%
Surprisingly, the 100% takeoff weight length for a 737 is roughly the same as for the 747 (slightly longer for a -300, slightly shorter for a -700). MD-11 is longer across the board than a 747-400.
Landings at 100% of max are always shorter than take off lengths, but there can be longer at lighter weights.
The page I was using was a PDF. www.san.org/documents/planning/assp/tier_one/Appendix%20B_Aircraft%20Runway%20Length%20Requirements.pdf