and surfacing. Contractors were expected to preserve the natu-
ral landscape through such measures as protecting stream beds
from erosion and felling as few trees as possible. Landscape ar-
chitects and engineers inspected the work regularly.

Construction of the parkway began in September 1935 ona
12.5 mi stretch just south of the Virginia—North Carolina bor-
der. The work progressed quickly in the first several yeats under
the supervision of the BPR engineers Austin, Lee, and Spelman.
By the end of 1937, some 115 mi had been graded, and in April
1939 the first, 50 mi section was opened to the public.

Private contractors did most of the work, but several De-
pression-era public works programs also played a role. The
Works Progress Administration, for example, paid laborers
to perform such tasks as clearing brush and drilling rock.
Crews organized by the Federal Emergency Relief Admin-
istration did landscaping work at recreational areas along
the parkway. The project also employed workers from the

Civilian Conservation Corps, which assigned them to four
camps of approximately 200 men each, including a separate
camp for African-Americans. Because such programs were
intended to create as many jobs as possible, they relied heav-
ily on manual labor.

When World War IT began, approximately 170 mi of the
parkway were open to visitors, and an additional 160 mi were
under construction, But wartime priorities meant fewer dol-
lars for the project, and construction nearly came toa halt, The
war also ended the Works Progress Administration, Federal
Emergency Relief Administration, and Civilian Conservation
Corps programs that had contributed so much to the effort.

By the time the war ended, the project had lost momen-
tum. In fact, major construction did not resume until the mid-
1950s, when the NPS's director, Conrad L. Wirth, launched an
initiative called Mission 66 to invest in the development of
the nation’s parks with an emphasis on attracting automobile
tourists. Thanks to this new infusion of funds, by the end of
1966 the entire parkway was complete and open to the public,
with one notable exception.

The last remaining gap in the parkway wasa single, 7.7 mi
Jong segment near Linville, North Carolina. It remained so for

mote than two decades, forcing drivers to make a 14 mi detour.
The cause of the delay was Grandfather Mountain, a 5,946 ft
peak that belonged to a family-owned corporation. For years,
the route was the subject of negotiations between the NPS
and the Federal Highway Administration, on the one hand,
and the private company, on the other. The parties eventually
reached a compromise, but completing the route would re-
quire the construction of a major viaduct, the funds for which
were not available at the time.

Congress finally funded the project in 1979, making it
possible to build che most significant structure on the park-
way, the 1,243 ft long Linn Cove Viaduct, on the south side
of the mountain. Figg and Muller Engineers, Inc., designed
the eight-span segmental concrete bridge, which was erect-
ed using a unidirectional cantilever construction method to
avoid scarring the landscape. The curvature of the precast,
posttensioned box girder, which follows the contours of the
mountainside, made it the most com-
plex structure of its kind in the world
at the time.

Completed in 1983, the Linn Cove
Viaduct won a merit award in 1984 in
ASCE’s Outstanding Civil Engineer-
ing Achievement Award competition.
In August 1987 the remainder of the
“missing link” was finished, and af-
tet 52 years of construction, the Blue
Ridge Parkway was finally complete.
In 1999 ASCE accorded landmark sta-
tus to the parkway in its Historic Civil
Engineering Landmark Program.

The Blue Ridge Parkway today
winds 469 mi from Rockfish Gap on
Skyline Drive, near Waynesboro, Vir-
Sinia, to its southern terminus at the
entrance to Great Smoky Mountains
National Park near Cherokee, North Carolina. Along the
‘Way, it passes through five major mountain ranges, dipping
to 649 ft above sea level near Lynchburg, Virginia, and rising
to a height of 6,047 ft on North Carolina’s Richland Balsam
Mountain, The scenic corridor includes 14 visitor centers, 26
tunnels, approximately 170 bridges, and neatly 300 over-
looks. In nearly every year since its completion it has been the
most visited place in the National Park Service system, draw-
ing 13.9 million visitors in 2014 alone.

‘The parkway’s historical significance rests on more than sta~
tistics, however. It was the National Park Service's first long-dis-
tance rural parkway and the longest road in the United States
to be planned asa single unit. It was a tri-
umph of large-scale land use planning,
unlocking the recreational potential of a
region spanning two states. Not least, it
demonstrated the value of collaboration
between landscape architects and civil
engineers. —JEFF L. BROWN

Jef Brown is a contributing editor to Civil
Engineering.

DECEMBER 2015 Civil Engineering [45]



Road with a View:
The Blue Ridge Parkway

ORE OFTEN than not, a highway is built sim-
ply to facilitate travel from one place to another.
The Blue Ridge Parkway, however, was created
for a different purpose: to offer motorists pleas-
ant views of the Appalachian Mountains. The realization of
that vision involved one of the most successful collaborations
between landscape architects and civil engineers in Ameri-
can history.

The project was born on August 11, 1933, when Senator
Harty Flood Byrd suggested the idea to President Franklin
D. Roosevelt on a visit to Shenandoah National Park. Hav-
ing received the president's blessing, Byrd convened a meet-
ing of officials from the National Park Service (NPS), the Bu-
reau of Public Roads (BPR), the U.S. Forest Service, the Public
Works Administration, and the states of Virginia, Tennes-

[42] Civil Engineering pecemeer 2015

The view from Craggy Gardens, above, is one of many vistas

that the parkway made accessible to the public, Where rock

cuts were necessary, crews typically reduced the gradient
of the back slope for a more natural contour, below,

see, and North Carolina to discuss the proposal. The parkway
quickly gained approval, and in November of that year Har-
old L. Ickes, the US. secretary of the interior, authorized its
construction.

The Public Works Administration's involvement was no
accident, for the Roosevelt administration viewed the parkway
not only as a worthy project in its own right but also as an op-
portunity to create jobs and boost the regional economy—key
goals of the president's New Deal. In fact, several New Deal
agencies funded the project, including the Public Works Ad-
munistration, the Works Progress Administra-
tion, and the Civilian Conservation Corps.

Although the project involved numerous
stakeholders, the NPS took the principal role. To
bring in some badly needed expertise, Thomas
‘Vint, the chief landscape architect of the NPS,
hired Gilmore D. Clarke, of New York’s West-
chester County Parks Commission, as the con-
sulting landscape architect. He also engaged
Clarke's colleague Jay Downer as the consulting
engineer. On Downer and Clarke's recommen-
dation, Vint selected Stanley W. Abbott as the
resident landscape architect.

Clarke was considered an authority because
the system of urban parkways he had buile in
Westchester County between 1913 and 1930

WIKIMEDIA COMMONS/STEPHEN LODY PHOTOGRAPHY, ABOVE; LIBRARY OF CONGRESS, LEFT


epitomized early-20th-century parkway design. The
broad, four-lane roads were located within a landscaped
corridor 200 to 1,700 ft wide to maintain a pleasant
view. Grade crossings were eliminated, and access was
limited to a few entrances and exits. Planners enhanced
the routes by incorporating parks, beaches, and other
recreational amenities along the way.

The pleasant urban parkways of Westchester County
were an inspiration, but replicating them in the rugged
Appalachians must have seemed a distant dream when
Abbott began exploring the area in a Dodge truck in
January 1934. Vint, Clarke, Downer, and BPR engi-
neers William M. Austin, WI. Lee, and Harold J. Spel-
man later joined Abbott in the field. The composition
of the group reflected a partnership between the NPS
and the BPR (and the latter’s successor agencies: the
Public Roads Administration and the Federal High-
way Administration) that would make the Blue Ridge
Parkway a model of roadway design. efits the parkway was expected to bring, and a bitter political

Not long after the project began, Clarke and Downer re- _ battle ensued. The North Carolina highway engineer R. Get-
signed because of a quarrel with Ickes over their pay rate, leav- ty Browning led that state’s lobbying effort, which eventually
ing the 26-year-old Abbott in charge. Abbott assembled his _ prevailed. Ickes approved a Virginia~North Carolina align-
own team, including Edward H. Abbuehl, his ment in November 1934.
chief assistant, and Hendrick van Gelder, an The Linn Cove Viaduct, above, Route planning was a collaborative endeav-
expert on highway location and a veteran of the was the key tofillingthe or. First, an NPS staff member, usually Ab-
Westchester County Parks Commission. A vi- final gap in the parkway. bott, Abbuehl, or van Gelder, staked out a pre-
sionary landscape architect and capable plan- The Linville River Bridge, liminary alignment, proceeding south from
ner, Abbott would lead the project for a decade. befow, is the parkway’s Shenandoah National Park. BPR engineers fol-

The parkway was conceived asa connector _ largest stone-faced bridge. + lowed, surveying and establishing acceptable
between Shenandoah National Park and Great grades while keeping an eye on projected con-
Smoky Mountains National Park, but the initial authoriza- struction and maintenance costs. Once the landscape archi-
tion did not specify a route. The northern portion of the road __ tects and the engineers agreed on an alignment, they prepared
would have to be located in Virginia, but farther south a num- right-of-way maps to guide the states’ land acquisition ef-
ber of possible rouces existed through parts of North Carolina _ forts. The states purchased the land and donated it to the NPS.
and Tennessee. Both of these states wanted the economic ben- Meanwhile, the NPSand the BPR finalized the roadway design.

LIBRARY OF CONGRESS, BOTH



The Blue Ridge Parkway was similar to Skyline Drive, a
scenic roadway then under construction in Shenandoah Na-
tional Park, but the two roads differed in significant ways. For
example, Skyline Drive followed the crest of the mountains,
but Abbott sought a route that would pass through a variety
of terrain and give motorists a sense of the diversity of the land-
scape. Moreover, Skyline Drive was restricted to a telatively
narrow right-of-way. In contrast, Abbott wanted a cottidor
that would vary in width, widening at times to include large
tracts seen as having special scenic or recreational value. Even
areas beyond the actual right-of-way were to be protected by
easements in order to keep entire vistas free of development. In
1935 Abbott directed the states to acquire an average of 100
acres of right-of-way for every linear mile of roadway, plus 50
actes of easements.

One innovative feature of the road involved its curvature.
Prior to the development of the Blue Ridge and other park-
ways of the 1920s and 1930s, American highway engineers
tended to view the horizontal alignment of a road as a series of
straight lines called tangents. When a change in direction was
required, they made the transition ftom one tangent to another
using a “circular” curve, that is, a segment ofa circle.

Railroad engineers had once taken a similar approach, but
as trains became faster, they realized that curves would have
to be more gradual to counteract the centrifugal
force and keep trains moving at relatively con-
stant speeds. They adapted by making more fre-
quent use of “spiral,” or transition, curves. Here
the radius of curvature is not constant but rather
decreases at a uniform rate. Because spiral curves
are flatter than circular ones, they ease the transi-
tion from travel in one direction to travel in another.

Clarke, Downer, and another landscape architect, Wilbur
Simonson, were among the first to borrow the spiral curve con-
cept from the railroads and apply it to parkways, most notably
Virginia's 15 mi long Mount Vernon Memorial Parkway (later
renamed the George Washington Memorial Parkway), which
opened in 1932. The designers of the Blue Ridge Parkway ad-
opted the same approach on a grander scale.

Spiral curves benefited the Blue Ridge Parkway
in that they enhanced safety by enabling motorists to
maintain a constant speed. They also made it possible
for the roadway to conform more closely to the ter-
rain, promoting a sense of connection to che natural
landscape. Each gentle curve opens a new vista to the
motorist, making the drive a pleasant and memorable
experience.

The parkway’s cross section too was designed with
aesthetics in mind. Where hillside cuts were required,
plans typically called for excavation crews to reduce the
gradient of the back slope (on the inside edge of the
roadbed) and extend the fill slope (on the outside edge).
Flattening the slope in this way resulted ih a stream-
lined cross section that appeared to follow the natural
contour of the land.

The toadway is typically 21 ft wide and has 4.5 ft
shoulders of stabilized turf. Its base consists of com-
pacted stone. For most of its length the road has an

[44] Civil Engineering vecemBer 2015

‘Tunnels, above, bridges,
opposite, and the curv-
ing roadway itself, below,
were all designed with
a rustic look in mind.

asphalt surface, although some sections in Virginia are paved
with bituminous concrete. The parkway was designed for trav-
elat 50 mph, but in many places the grades and curves prevent
drivers from attaining even the posted 45 mph speed limit.

‘The two-lane, undivided road was designed to be unobtru-
sive. Its planners generated land use maps to indicate the in-
tended appearance of each segment of the parkway, including
such details as plantings, drainage lines, and views to be pre-
served. They even omitted outer edge stripes to help the park-
way blend into its surroundings.

‘The patkway’s early bridges and grade sepata-
tion structures reflect a similar attention to detail.
Many are rigid-frame, reinforced-concrete arches,
although they are often mistaken for stone arches
because they were faced in native stone ina rustic
style. Even the three-span, 309 ft long Linville
River Bridge, the largest of the eatly crossings, is barely no-
ticed by motorists, although a trail beneath it offers hikers a
close look at the impressive stonework.

For construction purposes, the alignment was divided into
45 segments, and separate contracts were awarded for various
phases of the work on each segment. For example, an initial
contract might include clearing, rough grading, and drain-
age, while a subsequent contract would entail final grading

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