It was ten feet long, fifteen inches wide, covering 12.5
square feet with a surface resembling Swiss cheese stamped out of steel, and it
weighed 66.2 pounds. Locked together, 60,000 of them created a durable
all-weather surface 5,000 feet long and 150 feet wide that routinely accepted
punishment from airplanes weighing up to 60,000 pounds thumping down at speeds
of ninety miles an hour. This is the material that provided the quickly built
platforms from which American combat aviation was projected around the world
during World War II.
During 1941-45, the material was generally known as
"Marston mat." This led many to believe that it was invented by
someone named Marston. Or maybe it was a British invention, manufactured near
Marston Moor, England. The truth is more prosaic. The name comes from a
whistle-stop on the Seaboard Coast Line Railway, thirty-five miles west of Fort
Bragg, N. C.
Here on a low hill a mile east of US Route 1 and two miles
northeast of Marston, N. C., the material was first put to practical use. That
was during the Army's Carolina Maneuvers of November 1941, just before Pearl
Harbor. The novel steel mat gave an eminently satisfactory performance—one
fraught with epochal consequences.
Gen. H. H. "Hap" Arnold, Chief of the Army Air
Forces, visited the "Marston strip" and hailed it as "the year's
greatest achievement in aviation."
The "Marston strip," 150 feet by 3,000 feet, was
operational for only a few weeks. When the maneuvers ended, the runway was
dismantled, loaded into eighteen railroad gondola cars, and hauled away to
Langley Field, Va.—taking with it the name of Marston. Thus, the "Marston
strip," as it was called, entered Army vernacular, and the material became
known as "Marston mat."
Years later, when memories of World War II had faded and
acronyms took charge of military vocabularies, the village of Marston lost its
claim to fame as bureaucrats reduced the material's name to
"PSP"—pierced steel planking. A quarter of a century after 1945, the
generation that laid hundreds of thousands of tons of Marston mat throughout
South Vietnam had no idea who or what Marston might have been or that a Marston
existed. The material was simply "PSP."
In the spring of 1939, the Army Air Corps took note of
operations in Britain and France where air forces were experimenting with steel
grids for unimproved airfields. Unlike the situation in the United States, on
the eve of World War II there were few concrete runways among European
airports, but their turf airfields were among the best in the world. They were
carefully sited, well tiled for drainage, often having collecting points and
pumping stations installed, and were carefully planted with various species of
grass whose root systems absorbed moisture. However, this was a technology not
susceptible to rapid improvement.
With war imminent, the Anglo-French air forces required
hundreds of airfields for dispersal, and the casual pastoral expedients of
World War I could not serve airplane weights of 1939. A Sopwith Camel fighter
of 1918 weighed 1,950 pounds, a Hawker Hurricane of 1939, 6,600. Furthermore,
unlike the flying machines of 1918, the airplanes of 1939 had brakes. Nothing
tears up an airfield's turf like the frequent use of brakes by heavy airplanes.
British runway mat was similar to heavy-duty chicken wire.
Shipped in huge rolls weighing tons, it was difficult to handle. Once in place,
it was difficult to repair, and it seemed inadequate for medium bombers. The
more versatile French type was a heavy steel chevron gridwork similar to that
used in bridge decks or industrial catwalks. But each section weighed more
than a hundred pounds, installation was complex, and much of the runway had to
be taken apart to repair just one section.
The Air Corps required something more versatile, much
lighter, and given to mobility. The specification is summed up by an old
saying of the American aircraft industry: "Simplicate and add a bit of
In 1939, the gross takeoff weight of a typical single-engine
fighter plane was 7,000 pounds; a medium bomber weighed 35,000 pounds. But the
Air Corps required a surface also capable of supporting 55,000-pound heavy
bombers, such as the Boeing B-17 Flying Fortress or the Consolidated B-24
Liberator. Furthermore, in 1939 the Air Corps was already getting ready for
bombers like the B-29 Superfortress weighing more than 125,000 pounds.
Adaptable to Global
Besides being able to support airplanes, the mat had to
occupy minimum space for ocean shipment. This was of small consequence to
Europeans, but everywhere Americans looked they were standing on the water's
One piece of Marston mat fit neatly inside another; a
bundle of thirty pieces stood less than twenty-eight inches high. Packed for
shipping, the mat for a 150-foot by 5,000-foot runway weighed 1,986 tons and occupied
41,600 cubic feet. The lower hold of #3 hatch, the largest space in World War
II's ubiquitous Liberty ship, had a bale capacity of 59,793 cubic feet.
Distinct from its cubic dimensions, the weight of this
single runway constituted twenty-one percent of a Liberty ship's payload. The
material was distributed among a ship's lower holds, like flooring. Bulkier
and lighter cargoes were loaded on top of it. With combat loading, such
low-density items as bulldozers, graders, trucks, rollers, and other vehicles
were needed first; the high-density runway mat was the last material required.
For shipping and convenience in the field, five mats were
wired into subbundles; six of these were banded into a full bundle. Each full
bundle contained twenty-nine full-length mats and two half-lengths—a total of
375 square feet. With the mats laid in staggered brickwork fashion, the
half-lengths were used to piece out the edges of a runway.
The material also had to be easy for its installers to
handle. Installation had to be simple, even in darkness. The Air Force
specified a material of no more than seven pounds per square foot; Marston mat
was 5.3 pounds. Its unit weight was 66.2 pounds. One man could handle a section
with ease; two men could pick up a piece and run with it. As a rule, the only tool
necessary for its installation was a sledge to beat it into the earth.
As inventions go, Marston mat ranks among the simplest.
Although its function was to serve motion, it had no moving parts. A single mat
consisted of a steel sheet with two ribs dividing its length into three flat
channels. Each channel had twenty-nine holes punched along its length
—eighty-seven holes per mat. The holes were flared to increase the mat's
These holes not only contributed to strength and reduced
weight but also helped a section adhere to the earth. The holes also served
drainage and helped dry out the terrain on which the mat rested. Vegetation
could grow through the holes, reducing the problem of dust and making a small
contribution to camouflage. The holes also made it possible for backfill to
be poured into small soft spots in the earth.
Along each edge of a mat's length were thirty slots and
thirty L-shaped hooks cut and bent from the mat's edges. Having hooks and holes
in each mat made the mats interchangeable. The hooks of one mat were dropped
through the slots of the adjacent mat, and then shoved forward two inches,
locking the hook into the slot. Mats were further locked together by easily removed
U-shaped steel spring clips that limited vertical motion.
For ease of removing a damaged mat, it was practice to
install one course of mat with its hooks pointed in one direction, and the next
course with its hooks pointed in the other. When a runway was complete, a single
mat could be removed by two men with pry bars.
The Marston mat owes its design to Gerald G. Greulich of the
Carnegie Illinois Steel Co. and to many contributions by the Army Corps of
Engineers. When first tested at Langley Field, Va., in the summer of 1940, the
ribbed steel plank was solid sheet. Later, buttons were pressed into the flat
channels to create a nonskid surface, but they didn't seem to make much difference.
During the winter of 1940-41, it was decided that a solid surface was
unnecessary, and holes were punched along the channels, giving the mat its
distinctive appearance and reducing unit weight by 17.5 percent.
There were five steps in its manufacture: (1) the
longitudinal ribs were pressed or cold-rolled into a blank sheet of 10-gauge
low-carbon steel; (2) the slots and hooks were punched out; (3) the holes were
punched and flared; (4) the hooks were bent ninety degrees to the mat; and (5)
the mat was cleaned, de greased, and painted. By December 1941, two factories
had already manufactured some four million square feet of the material. A year
later, twenty-nine factories were producing Marston mat.
At the dawn of 1944, more than 180,000,000 square feet (some
477,000 tons) had been shipped overseas. This was enough for 240 runways 150 by
5,000 feet. By the end of the war, almost two million tons had been produced,
representing enough steel to build 600 Liberty ships.
Sooner or later it is "General Mud" who commands
too many battle situations. Mud does not occur in nature when rain only wets
the earth; but given intensive use by heavy airplanes and a week of rain, the
best turf airfield will degenerate into a crazy-quilt of badly rutted mud.
Marston mat performed well on soft ground, overcoming most of the problems.
Similarly, Marston mat controlled dust. The airplane is an
incorrigible dust maker, and on a busy airfield dust can be an operational
nightmare. Dust ingested by engines shortens the time between overhauls—never
mind the general wear and tear on an airplane and its interior parts.
In dusty North Africa, airplane engines had only half the
life between overhauls compared with those operated from the well-prepared
airfields of England. More frequent overhauls require more spare parts, more
manpower, and more facilities to serve the work. In North Africa, the total
increase in logistics requirements often became horrendous. Meanwhile, aircraft
Dust also creates operational and tactical hazards. After
two or three airplanes take off from an arid, dirt runway, visibility is
reduced to zero. Since airplanes take off into the wind, the dust they generate
blows back among the planes waiting to take off. With each takeoff the dust
becomes thicker. Precious minutes are lost before the next plane can get into
In the worst conditions, it could take half an hour to get a
squadron off the ground, an operation that normally took five minutes. Tank
trucks sprayed water over the runway to hold down dust, but this created only
a thin patina that evaporated quickly. The pressure of airplane tires broke
the thin crust, and prop blasts blew away what remained.
Each hole in a piece of Marston mat provided a small
reservoir for runway watering, retaining its moisture for fifteen minutes or
more. It was soon discovered that if you covered the runway area with local
flora—leaves, small branches, palm fronds, or, if it could be found, hay—and
laid the mat on top, you greatly reduced the dust problem. Even after these
materials dried out, they maintained barriers between the mat and the dust,
retaining hygroscopic qualities that made runway watering more effective.
After experience was gained, it was not unusual to have an
area cleared and graded, the mat down, and airplanes operating within seventy-two
hours. Creating an elevated subgrade was desirable and often necessary before
laying the mat, although it added a few days to the job. The mat ordinarily was
laid lengthwise, across the runway. Laying started from the middle and worked
toward the sides and both ends. By 1943, a technique had been developed for
laying mat from both ends and from the middle simultaneously, and everything
usually came out right. A misalignment was corrected by having bulldozers drag
the runway section into place. Any hundred yards of locked Marston mat always
had some stretch in it.
Marston mat created a universal footprint of Allied airpower
in World War II. Everywhere the mat was laid, Allied airpower was projected
forward—with speed. The Germans and Japanese had nothing remotely similar to
it. Neither did the Russians until they received Marston mat via American
By the end of the war, Marston mat was being manufactured in
an aluminum alloy. Otherwise identical to steel mat, its unit weight was 32.5
pounds. It was intended for special airborne operations, but the war ended
before it saw combat.
Inevitably, Marston mat became damaged by use, but it was
not discarded. Field engineers developed machinery for its rehabilitation. The
diesel-powered unit weighed fourteen tons and reprocessed 250 mats per hour.
The mats were straightened, cleaned, given a chemical bath, repainted, and made
good as new.
This small industrial plant could be broken down for air
transport among units in the field. Six C-47s were needed to move it. This
airlift may seem excessive, but a C-47's cargo space was only 22.5 feet long
within a tube ninety-two inches wide enclosing a usable 1,200 cubic feet. A
C-47's maximum payload was 4,900 pounds. In 1944, a unit operating out of
Australia airlifted its remanufacturing plant throughout the South Pacific,
rehabilitating some fifty million square feet of runway mat.
When the 150-foot-by-3,000-foot pioneer strip was laid at
Marston in November 1941, it took eleven days, including the time to clear and
grade an area 350 feet by 3,800 feet and move some 50,000 cubic yards of earth.
This was regarded as breathtaking speed, but during the war years, it was
exceeded many times and in circumstances beyond any imagination in 1941.
Almost a half century after World War II, a tourist
wandering the back roads of rural Algeria, Italy, Sicily, southern France, the
Philippines, or a host of South Pacific islands may still find evidence of
Marston mat. It is not laid flat, but sometimes stands vertically with one end
buried a few feet in the earth, the other pointing skyward—coincidental
monuments symbolizing an original function.
After 1945, thousands of farmers or rural householders
collected the abandoned runway mat, pressing its hooks and slots together to
create fences and walls that are still standing today. They are the hilt of a
terrible sword that has been transformed into the proverbial plowshare: silent
memorials to an air war of long ago.
Perversely, one place where a sample of Marston mat will not
be found is among the World War II exhibits of any aviation museum. Here will
be found the stuff of "aces" and airplanes and almost no end of
sentimental ephemera. But there is nary a word about, much less a sample of,
this dramatically simple invention that with minimum effort and maximum speed
carried American combat aviation to the ends of the earth.
During 1941-45, Marston mat created the footprint of global
air-power. Although not possessed of glamor or the mystique of "breakthroughs,"
Marston mat nevertheless ranks as one of the most subtle, versatile, and
ultimately devastating "secret weapons" of World War II.
Richard K. Smith is
the author of The Airships Akron and Macon: Flying Aircraft Carriers of the
US Navy and the prizewinning First
Across! The US Navy's Transatlantic Flight of 1919, both published by the US Naval Institute. This is his first article
for AIR FORCE Magazine.
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