David, I'm assuming this is private? If so, can you tell me how long, how thick, what you did for base, & finally mas importante, que dinero?
It is private. The finished product is 2170'x25'.
I've learned much, mostly from the asphalt company co-owner who has taken a personal interest in the project. The key to a satisfactory, smooth runway is base preparation.
We have an excavated area of 27' wide by some 11" deep on average considering leveling some high spots and filling some low spots. The final cut of the excavated area is made with a road trimmer (also called planer) at a specific depth and gradient angle referenced to a string line attached to metal posts along the side of the runway. That string reference is adjusted every 50' to smooth gradient variations and is set considering where we want the runway elevation to end up.
Then 8" is base material is filled in and spread over a stabilization fabric with a high lift and rolled with a 10 ton roller. This base material packs like concrete, it is 1" rock mixed with much smaller particles of varying size. Then the trimmer comes back in again and makes another pass leveling and setting the grade. On top of the fill goes 3" of road asphalt, the grade is BP-1 or 2. The actual amount of asphalt is greater than 3" as it is rolled to end up at 3".
A runway can be built using a high lift and standard grader, but even the most expert grader operator can not match the precision of the trimmer machine. The trimmer machine has a 16' rotary cutter that is controlled by a hydraulic system referenced to the guide line. There are various rotary cutters for dirt or asphalt cutting.
I learned that the price of asphalt is controlled by state government in most states. They set what is know as an asphalt index each month. This was started some years ago when the price of oil was making huge swings and no one knew what a project would end up costing. Now the price is set for at least 30 days.
The cost - we have a contract that includes filling, rolling and trimming a grass landing area adjacent to the hard surface with a smooth transition from grass to asphalt and vice-versa. The final bid number is based on square yards of asphalt and came in at $25.55/yrd, or approximately $155,000. (The included grass area prep is about $14,000 but does not include seeding.) The final cost will be determined by actual yardage of asphalt installed and the state index. As a friend commented, you can not get good carpet installed in your home for $25.55/yard, what a deal!
The price of the project could have been reduced without using the trimmer and without grass area preparation. But a primary objective here was to end up with a smooth runway, not a repeat of what we had. We considered a complete redo of the grass landing strip but that would have cost $80,000-90,000 and we still would have a mess over the winter months.
It will take about a year to get the new grass area seeded, growing and settled but it will be much better than it was.
As of right now, local residents are quite satisfied how this is turning out.
