25-08-2017, 09:32 PM
Design of Construction Work Zones on High-Speed Highways
Design of Construction Work Zones on High-Speed Highways.pdf (Size: 3.49 MB / Downloads: 310)
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
Systematic, well-designed research provides the most effective
approach to the solution of many problems facing highway
administrators and engineers. Often, highway problems are of local
interest and can best be studied by highway departments individually
or in cooperation with their state universities and others. However, the
accelerating growth of highway transportation develops increasingly
complex problems of wide interest to highway authorities. These
problems are best studied through a coordinated program of
cooperative research.
In recognition of these needs, the highway administrators of the
American Association of State Highway and Transportation Officials
initiated in 1962 an objective national highway research program
employing modern scientific techniques. This program is supported on
a continuing basis by funds from participating member states of the
Association and it receives the full cooperation and support of the
Federal Highway Administration, United States Department of
Transportation.
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Cooperative Research Programs (CRP) grants permission to reproduce material in this
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Introduction
After decades of rapid highway system expansion, construction
of additional capacity has diminished. Increasingly,
capital program resources are being directed to the enhancement
and preservation of existing facilities. However, growth
in highway travel continues unabated. Exhibit 1-1 illustrates
the recent asymmetric growth of travel and basic capacity in
the United States.
Many segments of highway infrastructure constructed
during the system expansion era are approaching or have
exceeded their useful lives. As a result, construction activity on
existing facilities is increasing at a time when the facilities are
of increasing importance to economic efficiency and social
activity. Transportation agencies are challenged with continuous
management of highways, assuring their adequate performance
in the near term and far into the future.
Terminology
Construction and work zone terms are not used consistently
across agencies and disciplines (planning, design, enforcement,
construction, etc.). To facilitate communication, terms used in
this publication are defined here.
50th-percentile speed: the median speed of the observed traffic
at a particular point or segment.
85th-percentile speed: the speed at or below which 85 percent
of all observed traffic is traveling at a particular point or
segment.
Advisory speed: the speed displayed on an advisory speed
plaque and determined on the basis of an engineering
analysis.
Design Controls and Principles
The design of construction work zones involves many of
the same factors that pertain to permanent roads, and much
of the knowledge used for highway design is also relevant to
design of construction work zones on high-speed highways.
Yet there are substantive differences between permanent
roads and roads in construction work zones that should be
reflected in the respective design processes.
Separate design guidance for permanent roads and roadways
in construction work zones is appropriate for two major
reasons. First, construction work zones have short service
lives. Exposure is directly related to service life and is a key
consideration in any design decision involving safety.