Curbstone Presents - the American Road
1823 - First American Macadam Road
Painting by Carl Rakeman
The first macadam surface in the United States was laid on the "Boonsborough
Turnpike Road" between Hagerstown and Boonsboro, Maryland. By 1822, this section
was the last unimproved gap in the great road leading from Baltimore on the
Chesapeake Bay to Wheeling on the Ohio River. Stagecoaches using the road in
winter needed 5 to 7 hours of travel to cover 10 miles.
Construction specifications for the turnpike road incorporated those set forth
by John Loudon McAdam of Scotland. After side ditches were dug, large rocks
were picked and raked, then were broken "so as not to exceed 6 ounces in weight
or to pass a two-inch ring." Compacting work for each of the three layers was
quickened using a cast-iron roller, instead of allowing for compacting under traffic.
In 1830, after 5 years of work, the 73-mile National Pike (or Cumberland Road)
became the second American road to be built on the "McAdam principle."
The wearing surface of a road, street, or sidewalk.
Parts of Babylon and Troy are believed to have been
paved; Roman roads were noted for their durable stone
paving. Roman empire city streets were normally paved
with "basalt slabs". The elevated sidewalks that were
generally built on both sides of the street often took
up as much as half of the total street width and were
paved with "peperino stone". Streets outside of the
city proper were also paved as well, or at the very
least had a gravel surface.
The first road to be paved with
asphalt was in Babylon between 625 and 604 B.C. The
Romans built an impressive road system in Great Britain
during their occupation of the first through fourth
centuries, of which many roads have been used as
templates for modern British roadways.
Credit for modern road construction goes to the Roman
Army, their military road building techniques are the
prototype for the roads of today. Roman city streets,
with their curbstones and elevated sidewalks are the
basis for the modern street designs that we see today.
Early roads in the United States were simply ruts
carved into the ground by the many horses and wagons
that traversed across this great land. Travel was
brutal at best, add to that any inclement weather
conditions and you get the picture. Cobblestones were
common from late medieval times into the 19th cent.
In 1876, President
Grant selected a group of army engineers to study the
use of asphalt on roads. This group suggested that
Pennsylvania Avenue in Washington, D.C., be paved with
sheet asphalt made from Trinidad Lake asphalt. That
pavement remained in excellent condition for 11 years,
despite the traffic at the White House.
Historic Pennsylvania Ave. was first paved with asphalt in 1876. In this photo, taken in 1907, crews repave with the equipment of the time.
qualities in pavements include durability, smoothness,
quietness, ease of cleaning, and a nonslippery surface.
The requirements conflict to a degree, so no one
material is ideal in all respects. The foundation of a
pavement must be crowned, or slightly arched, for rapid
shedding of water; it must be strong enough to
withstand heavy dynamic loads, but capable of
responding to temperature changes. It has been
estimated that some 27,000 tons of water fall annually
on one mile of road.
Early in the 19th century, rock asphalt and natural
asphalt were being used as building products. These
asphalt products had already been used for the past
7,000 years for waterproofing. Hot tar was used in
England as early as 1820 to bind the broken stones
together. This type of mix, known as tarmacadam, was
patented in 1910 by Warren Brothers in Cambridge, Mass.
This company later became APAC, one of the largest
asphalt mix companies in the United States.
highway builders of the late 1800s depended solely on
stone, gravel and sand for road construction. Road
surfaces could be stabilized by adding water to the
surface sand to form a binder, which would support
horsedrawn traffic. Mud and dust did not become a major
problem until the introduction of the automobile.
In 1919, the Washington-Richmond Road near Dumfries, Va.,
about 30 miles (48 km) south of Washington, D.C., claimed this car.
Mud was a serious problem before asphalt paving.
The deplorable conditions of the nations roads became a
great public concern in the late nineteenth century
with the invention of the bicycle and later the motor
car. In the early 1890's bicycle clubs in the United
States pushed hard for road improvements. These efforts
brought about the "National League for Good Roads" in
1892. Continued dissatisfaction with the conditions of
the nations roads resulted in the creation of the
"Office of Road Inquiry" by Congress in 1893.
As the cities and nations continued to grow and expand,
a more cost effective way of building streets was
needed. The complete implementation
of asphalt on roads, however, began with a man named
Metcalfe was born in Scotland in
1717. Although blind from the age of six, Metcalfe
built 180 miles of roads in Yorkshire, England, after
the age of 40. He made sure that his roads drained well
and were built on a firm foundation. He built them with
three layers: the first layer was made up of large
stones, the second contained excavated road material,
and the third was a layer of gravel. The road was also
arched in the center so that water would drain off and
down into the ditches built along each side.
Thomas Telford, who was born in Eskdale, Scotland, in 1757,
perfected the method of building roads with broken
stones. Telford placed the stones at a certain
thickness in accordance with the weight and volume of
traffic on that road. He also took into consideration
road alignment and gradient, which are still important
factors for roadbuilders today.
John Loudon McAdam
Engraving by Charles Turner. By courtesy of the trustees of the British Museum; photograph, J.R. Freeman & Co. Ltd.
John Loudon McAdam,
born in Scotland in 1757, and the general
surveyor for the city of Bristol, England, designed roads using broken
stones that were laid evenly and tightly so that they
covered the soil and formed a hard surface. These
macadam roads, as they were called, served
the purpose of providing a somewhat stable pathway for
pedestrians and horsedrawn traffic.
While Telford and
McAdam were contemporaries, they each had different
ideas of how to build the best road. Telfords
designs were more expensive than McAdams, but
some scholars say they were superior in quality.
Macadam construction diagram.
Macadam consists basically of compacted layers
of small stones cemented into a hard surface by means
of stone dust and water (water-bound macadam). However,
the main pavement surfaces in use today are
bituminous/asphalt coverings and concrete.
The macadam method of road building uses a layer of
well drained and compacted subsoil to support the load
weight of the roadway, while the top layer acts as a
wearing surface built only to shed water. Modern day
macadam road construction is based on this practice and
is used worldwide.
The top layer of a macadam road is mostly made of
asphalt and rocks, now some builders use other
ingredients to help deter road wear and add traction to
the surface. Nowadays asphalt is made synthetically,
but true asphalt in its natural state was originally found in only
one place in the world, in a pitch lake on Trinidad
Sir Walter Raleigh, in his third voyage in 1498, discovered the
still-famous pitch lake of asphalt on the Island of
Trinidad, the largest natural asphalt lake in the
world. "Trinidad Asphalt" as it was known, was much
prefered over the manmade variety, because it had a
good record for standing up to time and the elements.
Trinidad was the first source of asphalt made
available in America; the second source was the
Bermudez Lake in Venezuela.
Macadam construction with asphalt.
By 1910, refined petroleum asphalt had
gained its permanent market supremacy over the
producers of rock, natural and sheet asphalt. The oil
companies could manufacture asphalt superior to that
mined from the natural deposits in Trinidad Lake and
Bermudez Lake. This supremacy even threatened
diplomatic relations between the United States and
In the bituminous
macadam pavement, the foundation is macadam, upon which
a bituminous material that penetrates at least 2 in (5
cm) into the foundation is poured, forming an
impervious binder. In the bituminous-mixed macadam
pavement, a mixture of crushed rock, ground glass and
other additives, and bituminous binder is spread over a
macadam foundation and rolled into a compact mass.
Key Dates of Interest in United States Road Building
1625 - Earliest known paved American road - Colonial city street - Pemaquid, Maine
1795 - First engineered American road - Philadelphia to Lancaster toll turnpikee
1823 - First macadam road constructed in America - State of Marylande
1877 - First asphalt paving in N. America - Pennsylvania Avenue - Washington, DC
1893 - First rural brick road - Ohioe
1906 - First Bituminous macadam road constructed - Rhode Islande
The two other pavement types use a concrete road slab as a
foundation. In the sheet asphalt pavement, a binder
course and a wearing course are laid over a concrete
foundation. The binder course, whose function is to
prevent creepage of the upper course, is composed of
broken stone and asphalt cement. The wearing surface is
a mixture of fine sand, filler, and asphalt.
By far the
most common type of pavement for heavy use is rigid
concrete. The first concrete pavement was laid in
Bellefontaine, Ohio, in 1894. A modern highway will
have a 6 in (15 cm) base of concrete, on top of which 3
in (7.5 cm) of steel-reinforced concrete will be laid.
Pavements that must withstand only pedestrian traffic
may use brick or wood-blocks, set in a 1 in. (2.5 cm)
bedding of sand, cement mortar, or mastic.
1910 - Spreading asphalt Macadam on crushed rock base, State Aid Road No.59 - 85, Yakima County. Washington State.
1912 - Steam roller compacting macadam. Washington State.
1910 - Auto-truck spreading asphalt Macadam, Walla Walla County, Washington State.
1911 - Crushing plant and hauling machinery used in building permanent highway, Yakima County. Washington State.
The U.S. Corps of Engineers, which
had not previously been involved in pavement matters
prior to World War II, was charged with military road
and runway construction. Faced with the production of
larger, heavier airplanes, the Corps needed to come up
with pavement thickness design methods for runways that
could handle wheel loads greater than 12,500 pounds
(5,670 kg). Not only did they meet the huge military
demand for heavy-duty pavements, but they would
continue to influence all aspects of asphalt paving
long after the war was over.
In 1956, the Federal-
Aid Highway Act was established, creating an
infrastructure highway program unmatched by any other
in the world. President Dwight D. Eisenhower stated
that the Interstate System would establish a
grand plan for the rebuilding of our obsolete road and
street system. The basis of the system was a
41,000-mile (65,983-km) highway network connecting
major cities in the Unites States. One component of this plan was
that for every five miles of road, one mile would be straight
for use as an airplane landing strip in time of need.
The network design
task was given to the U.S. Bureau of Public Roads and
the State Highway Departments. While many state highway
departments requested asphalt for their part of the
interstate system, concrete was also used despite its
higher cost of construction.
Besides cost, another
feature that makes asphalt superior to concrete is
flexibility. Maintaining asphalt is also typically less
expensive than maintaining concrete.
Curbstone is a SOFTWARE company, please do not inquire about paving.