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What Causes Runways To "shrink"?  
User currently offlineCross757 From United States of America, joined Jun 2007, 271 posts, RR: 0
Posted (1 year 6 months 3 weeks 3 days 19 hours ago) and read 3366 times:

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!

12 replies: All unread, jump to last
 
User currently offlinerfields5421 From United States of America, joined Jul 2007, 7607 posts, RR: 32
Reply 1, posted (1 year 6 months 3 weeks 3 days 18 hours ago) and read 3333 times:

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]

User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 2, posted (1 year 6 months 3 weeks 3 days 16 hours ago) and read 3196 times:

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.
User currently offlineB6JFKH81 From United States of America, joined Mar 2006, 2881 posts, RR: 7
Reply 3, posted (1 year 6 months 3 weeks 2 days 15 hours ago) and read 2835 times:

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"
User currently offlinespudsmac From United States of America, joined Feb 2008, 298 posts, RR: 0
Reply 4, posted (1 year 6 months 3 weeks 2 days 14 hours ago) and read 2781 times:

Maybe an addition of lights or something like that caused it to be a little bit shorter.

User currently offlinekalvado From United States of America, joined Feb 2006, 491 posts, RR: 0
Reply 5, posted (1 year 6 months 3 weeks 2 days 5 hours ago) and read 2664 times:

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?..


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 6, posted (1 year 6 months 3 weeks 2 days 2 hours ago) and read 2614 times:

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.
User currently offlinerfields5421 From United States of America, joined Jul 2007, 7607 posts, RR: 32
Reply 7, posted (1 year 6 months 3 weeks 2 days 1 hour ago) and read 2588 times:

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.


User currently offlineCross757 From United States of America, joined Jun 2007, 271 posts, RR: 0
Reply 8, posted (1 year 6 months 3 weeks 1 day 22 hours ago) and read 2500 times:

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.


User currently offlineTWA772LR From United States of America, joined Nov 2011, 1869 posts, RR: 1
Reply 9, posted (1 year 6 months 3 weeks 1 day 19 hours ago) and read 2422 times:

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.


Go coogs! \n//
User currently offlinetimz From United States of America, joined Sep 1999, 6813 posts, RR: 7
Reply 10, posted (1 year 6 months 3 weeks 1 day 16 hours ago) and read 2365 times:

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.


User currently offlineMrCazzy From United States of America, joined Oct 2011, 35 posts, RR: 0
Reply 11, posted (1 year 6 months 3 weeks 23 hours ago) and read 2163 times:

Would the distances also vary when the runway thresholds are replaced?

User currently offlinearmitageshanks From UK - England, joined Dec 2003, 3619 posts, RR: 15
Reply 12, posted (1 year 6 months 3 weeks 22 hours ago) and read 2150 times:

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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