Cross757
Topic Author
Posts: 233
Joined: Thu Jun 28, 2007 1:32 pm

What Causes Runways To "shrink"?

Mon Jan 28, 2013 9:58 pm

Hello,

I have been curious about this for awhile and finally decided to ask the question: why are runways at some airports that were once a certain length seem to have "shrunk", i.e. are now shorter than they were before? And I don't mean runways that were purposely shortened, such as runway 03-21 at PDX (was formerly 7,000 feet long and was shortened to 6,000 feet when runway 10L-28R was extended), but runways that are listed as being, in most cases, just a few feet shorter than they once were. Here are some examples, and they are all airports that I have flown into/out of and I know for a fact the runways were longer than they are now "officially" listed on FAA approach plates/airfield diagrams:

TUL: Runway 18L-36R, used to be 10,000 feet, now listed at 9,999 feet (a whopping 1 foot shorter, but still...)

HDN: Runway 10-28, used to be 10,000 feet, now listed as 9,998 feet (were the other 2 feet stolen?)

AEG: Runway 04-22, used to be 7,400 feet, now 7,398 (a difference of 2 feet), and Runway 17-35, previously 6,000 feet, now "only" 5,993 (seems that 7 feet of runway have disappeared).

I know the FAA conducts periodic safety/operational inspections on airports, and during the process, do they go out and measure the length of runways to validate the charts/airport diagrams? Is is possible a runway is now officially a few feet shorter because of deterioration of the pavement at the ends and therefore a foot or two of that pavement is no longer considered load bearing, and therefore is unusable? Any information is appreciated.

Thank you!
 
rfields5421
Posts: 5773
Joined: Thu Jul 19, 2007 12:45 am

RE: What Causes Runways To "shrink"?

Mon Jan 28, 2013 10:31 pm

I would suspect it is due to better accuracy with laser survey measurement.

Quoting Cross757 (Thread starter):
TUL: Runway 18L-36R, used to be 10,000 feet, now listed at 9,999 feet (a whopping 1 foot shorter, but still...)

This runway could have been spec'd at 10,000 ft and actually be 9,999 ft 7 inches in the original 'build' but now measures 9,999 ft 5 inches with the more accurate laser devices.

Or there might be a requirement to list the runway as the last full foot in length rather than rounding up to the next complete foot.

[Edited 2013-01-28 14:31:48]
 
IAHFLYR
Posts: 3945
Joined: Sat Jun 25, 2005 12:56 am

RE: What Causes Runways To "shrink"?

Tue Jan 29, 2013 1:20 am

Most changed as you refer are due to new airport surveys and for what ever reason lose or again a small amount of real estate,
Any views shared are strictly my own and do not a represent those of any former employer.
 
B6JFKH81
Posts: 1987
Joined: Thu Mar 16, 2006 6:35 am

RE: What Causes Runways To "shrink"?

Wed Jan 30, 2013 1:32 am

George Costanza would tell you it's the cold water causing the shrinkage  

 
"If you do not learn from history, you are doomed to repeat it"
 
spudsmac
Posts: 245
Joined: Tue Feb 19, 2008 10:36 pm

RE: What Causes Runways To "shrink"?

Wed Jan 30, 2013 3:22 am

Maybe an addition of lights or something like that caused it to be a little bit shorter.
 
kalvado
Posts: 524
Joined: Wed Mar 01, 2006 4:29 am

RE: What Causes Runways To "shrink"?

Wed Jan 30, 2013 11:31 am

If shrinkage is mostly result of new surveys - then there should be similar number of expansions, to 6001 feet or so,
Are there such examples as well?..
 
IAHFLYR
Posts: 3945
Joined: Sat Jun 25, 2005 12:56 am

RE: What Causes Runways To "shrink"?

Wed Jan 30, 2013 2:56 pm

Quoting kalvado (Reply 5):
If shrinkage is mostly result of new surveys - then there should be similar number of expansions, to 6001 feet or so,
Are there such examples as well?..


With shrinking are you referring to George above?   

Yes there are examples of some increases in length however: I can't think of any at this time. I know from my work in ATC there have been in the Houston area during the last year just not sure where they happened. I want to say Houston Southwest (AXH) had a slight increase in length but not sure why I remember that one specifically.
Any views shared are strictly my own and do not a represent those of any former employer.
 
rfields5421
Posts: 5773
Joined: Thu Jul 19, 2007 12:45 am

RE: What Causes Runways To "shrink"?

Wed Jan 30, 2013 3:50 pm

Sometimes shrinkage is due to a change in how runways are measured over uneven terrain.

I remember a discussion about the length change for KADS while I was taking training there.

KADS has a slight elevation change from 636 ft on both ends to 644 ft at the 'hump' near the 2/3 mark on Rwy 15.

The length of the runway based on measuring the centerline is 7,210 ft long. However the straight line distance from one end of the runway to the other measured with a very accurate laser device held 12 ft above the runway at each end is 7,202 ft - a 'shortage' of 8 feet.
 
Cross757
Topic Author
Posts: 233
Joined: Thu Jun 28, 2007 1:32 pm

RE: What Causes Runways To "shrink"?

Wed Jan 30, 2013 6:51 pm

Quoting rfields5421 (Reply 1):
I would suspect it is due to better accuracy with laser survey measurement.



That seems to make the most sense...thank you!

Quoting B6JFKH81 (Reply 3):



Classic!

Quoting kalvado (Reply 5):
If shrinkage is mostly result of new surveys - then there should be similar number of expansions, to 6001 feet or so,
Are there such examples as well?..



As a matter of fact, after I posted the original message, I did a little more research and I believe I found an example of where one did: DTW, runway 04R-22L was for a long time listed as 12,000 feet, and is now reported as 12,003 feet.
 
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TWA772LR
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Joined: Thu Nov 17, 2011 6:12 am

RE: What Causes Runways To "shrink"?

Wed Jan 30, 2013 10:06 pm

It could be a seasonal thing. Concrete and asphalt expand in the summer, and contract in the winter. Which is why your tiles may pop up in the winter if your house is built on a slab.
And for my next miracle, I'm gonna turn water into funk!
 
timz
Posts: 6198
Joined: Fri Sep 17, 1999 7:43 am

RE: What Causes Runways To "shrink"?

Thu Jan 31, 2013 12:33 am

Quoting rfields5421 (Reply 7):
The length of the runway based on measuring the centerline is 7,210 ft long. However the straight line distance from one end of the runway to the other measured with a very accurate laser device held 12 ft above the runway at each end is 7,202 ft - a 'shortage' of 8 feet.

If you calculate it you'll see the difference between straight-line and on-the-surface couldn't be that much, unless the runway has a bunch of other lumps.
 
mrcazzy
Posts: 33
Joined: Tue Oct 25, 2011 8:44 pm

RE: What Causes Runways To "shrink"?

Thu Jan 31, 2013 6:05 pm

Would the distances also vary when the runway thresholds are replaced?
 
ArmitageShanks
Posts: 3780
Joined: Tue Dec 30, 2003 5:30 am

RE: What Causes Runways To "shrink"?

Thu Jan 31, 2013 6:28 pm

Could it have something to do with insurance, regulations or something similar if a runway is 10,000 feet versus 9,999 feet so they change the length to avoid costs or regulation?

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