I see from some FB posts that Sandown on the Isle of Wight are installing an ‘astroturf’ runway – splitting their existing grass into grass and AstroTurf. Is this a thing? I’ve never heard of it and wouldn’t know where to start with perf calculations (wouldn’t it be dodgy when wet?)
This is the first time I’ve heard of an airport using it and I can’t imagine the cost. This is not cheap stuff to buy and install.
Those who live in wet climates may not be aware, but artificial grass has progressed a lot and is very much a thing nowadays… I hate it but its a thing 
Little real grass is planted in some dry areas where water is in short supply. My water bill avoiding artificial grass is $180/month, roughly double my gas/electric, and that’s the motivation for some.
Airside Applications for Artificial Turf. DOT/FAA/AR-06/23. June 2006. http://www.tc.faa.gov/its/worldpac/techrpt/ar06-23.pdf
Abstract:
A study to investigate the considerations and concerns associated with airside applications of artificial turf was conducted using
input from the artificial turf manufacturers and by administering and discussing questionnaire surveys via site visits to airports.
These site visits were scheduled with some airports that already had installed artificial turf plots and during the installation of
artificial turf plots at other airports.
To address the safety concerns and performance expectations of airside artificial turf installations, several tests were done. The
majority of the tests performed to date were to quantify and qualify the artificial turf product. During the airport surveys, airport
personnel were asked what concerns they had with an artificial turf installation. The results of the surveys and discussions with
airport personnel indicated that the main reasons for considering artificial turf are for safety, soil erosion mitigation, and foreign
object debris reduction. Additional and secondary considerations for the use of artificial turf were found to be abatement of turf
management (i.e., low maintenance), jet blast erosion, wildlife control, and visual enhancements.
The majority of airport concerns for accepting the artificial turf applications concentrated on:
• Jet blast resistance
• Environmental and contaminant (fuel, deicing fluid) resistance
• Safety vehicle load support
• Skid and fire resistance
• Access for lighting and equipment maintenance
Calhan Airport Colorado (5V4) uses artificial turf on part of its runway. Aerial photograph at https://www.codot.gov/programs/aeronautics/colorado-airport-system/general-aviation-airports/ga-airports-c-d/5V4
From a cached Airport Improvement magazine article Air Force Academy Ditches Grass for Synthetic Turf by R Nordstrom. Sep 2012. (link)
The Civilian Side
The same year AvTurf installed a test patch of its synthetic turf at the United States Air Force Academy in Colorado Springs, CO, it also carpeted a 1,240-foot runway at Calhan Airport (5V4), a nearby privately-owned facility.
“It’s been nothing but a good experience,” reports Airport Manager David Glaser of the 2006 installation. Since then, a variety of aircraft, including P-51s, Yaks and a DC-3, have tested the material.
A few years ago, the Army rented the airport for three days of high-altitude assault training with a Cathay, recalls Glaser. “They had 22 people on board and did 12 to 16 landings a day,” he explains. “The pilot locked up the brakes and slid. I had black marks out there that were 20 to 30 feet long, but the turf held up great. I just took my rotary broom out there and dressed it up.”
Glaser has also put the turf through other tests: “I’ve tried to tear it and burn it. I’ve put weed kill on it. It’s held up great.”
He’s similarly pleased with its care routine. Other than brushing some sand into the surface about three years ago, Glaser says the surface has been nearly maintenance free.
From a user’s perspective, a pilot who flies hunters into the airport provided Glaser with glowing feedback about the airport’s synthetic turf: “He told me that it’s better than grass, that it’s the best thing he’s ever landed on.”
Sandown has suffered badly over the years from being waterlogged. I wonder if this helps with that, because waterlogging is AFAIK caused by, ahem, the water table being above the ground Perhaps they mole-drained the runway also, into an adjacent ditch and then have a pump to empty the ditch?
I was in Sandown this afternoon, and the AstroTurf is being installed. R/W 05 threshold is inset by 600m, but no restriction on take-off.
They are planning for another section to be installed Autumn’19.
Does anyone know about the surface preparation?
The stuff isn’t stiff enough to support aircraft weight, so you still need a good solid surface underneath, and a “good solid” (hard packed) soil won’t drain well, unless you do some other stuff…
Whereas the rigid green plastic stuff (discussed here before) which is buried in the surface and allows grass to grow through it, can support a certain amount of point load.
One of the directors at Act Global, Daniel McSwain, emailed some technical reports on the AvTurf aviation synthetic turf system. The dry and wet (saturated) coefficients of friction evaluated using ASTM C1028-07 (now withdrawn), for CA 1201 Aviation Turf with 5 lb per square foot of sand infill, are reported as 0.7 and 0.51 respectively. Similar results from standard methods of evaluating runway friction coefficients—see for example EASA RuFAB reports at SKYbrary (link) —weren’t provided. Data recorded for normal acceleration and strain, for trial landings on grass, AvTurf, and a paved surface, indicate that AvTurf is more similar to a paved surface.
Peter wrote:
Does anyone know about the surface preparation?
The section Detailed Description of the Invention in US patent 7,901,753 (Synthetic runway surface system) (link) covers this question. Behaviour in rain is addressed n paras 5 and 6 of the section Summary of the Invention in US patent 6,620,482 (Safety system for airports and airfields) (link):
The present invention further includes a plurality of water drainage mechanisms to produce a target area near airport and airfield runways or taxiways substantially free from standing water or wet areas. Specifically, the present invention provides a layer of infill, which is primarily sand, between the synthetic fibers, that sufficiently absorbs water and provides a first line of defense against standing water. For heavy rains, the present invention enables water to drain through the artificial turf of the present invention into a sub-surface retention area. The system includes additionally grading the soil surface, creating the positive drainage necessary to eliminate standing water. The sub-surface of the present invention includes water sheeting layers or mechanisms, such as a waterproof membrane, to enable water to drain across the top of the turf leading into pipes or larger drains.
Removing standing water eliminates muddy or dead areas that currently proliferate at airports, resulting in a uniform, year round surface. The lack of available water eliminates another attraction for birds and other animals. A substantially dry surface in combination with a stable, compacted base also enables any type of airport vehicle to reach any part of the runway or taxiway at any time of the year, if necessary, subject only to extraneous conditions. The lack of mud around standing water reduces the likelihood of mud reaching the runway or taxiway and becoming a FOD.
Base material and drainage is further discussed in US patent 9,157,196 (Adhesively secured artificial turfs for airports and methods of installing such artificial turfs) (link).
A bit more information about the Sandown astroturf runway was included in an interview with the owner Dan Subhani posted on the 4th edition of the Two Thousand Feet podcast:
- Acquired a discarded 6,000 sq metre hockey pitch (at what sounds like minimal cost)
- This is because 100+ sports pitches get dug up every year, only one recycling plant in the country, difficult to dispose of.
- First 200m already installed, drainage pipes + 2000 tons of crunched concrete and 700 tons of sand, then glued and stitched astroturf
- No water pooling, no tyre wear but braking resistance all a lot better than concrete
- Split existing 50m grass runway in two, so one half remains grass, the other half will become completely astroturf – a winter and a summer strip.
- Clearly much cheaper than concrete
- It’s very bright and can be seen from miles away on a murky day
It was said that there are a lot of airfield managers looking at this experiment to see if its worthwhile.
It certainly is novel and appears to be an excellent way to recycle old Astroturf pitches.
I wanted to ask if anyone has good or bad experiences with the various types of reinforcements that can be used on grass runways. I understand that good drainage is the first step, but we’re looking for a way to make the grass more resilient to the repeated landing cycles. Since we will be redoing the grass, I figured we might at least consider something more. I didn’t get much about this specific subject from the various “grass field” threads I was able to find. Thank you!
