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Additional Rail & Highway Tunnel Projects
Little Switzerland Tunnel
Inspection Rehabilitation
Blue Ridge Parkway, North Carolina
Project Description
The Little Switzerland Tunnel, a two-lane highway tunnel about 600-ft-long, was
constructed in the 1950's in metamorphic rock, mostly gneiss with some schistose
zones. Most of the tunnel was supported only with rockbolts, and is in good
condition. One section, about 100-ft-long, required initial support by means of
steel ribs, and has an 18-inch-thick concrete liner for permanent support.
Scope of Services
The concrete-lined section has experienced significant cracking in one location,
and the cracks, as well as two construction joints, are the source of troublesome
water inflows. The water, in conjunction with freeze-thaw action, has resulted in
some concrete damage; and causes major icing problems in the winter, sometimes
forcing closure of a section of the Parkway.
LACHEL & Associates, Inc. (LFA), working as subconsultants to HDR Engineering,
Inc., conducted an inspection and damage survey of the tunnel. This included mapping
all cracks and deterioration using the full perimeter mapping method and conducting a
visual survey inside and outside the tunnel.
A system of drainage chases was designed for the cracks and construction joints, aimed
to intercept water inflow and conduct it to the drain at the tunnel invert.
Client
HDR Engineering, Inc.
Federal Highway Administration
Eastern Federal Lands Division
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Los Bronces to Santiago Highway
Santiago, Chile
Project Description
In 1980, LACHEL & Associates, Inc. (LFA) was selected to perform the
geotechnical analyses for 150 miles of two-lane highway alternatives in mountainous
terrain near Santiago, Chile. The terminus of the road is the Disputada Mine,
which has historically been closed by landslides and debris flows for a significant
portion of the operating year.
Scope of Services
LFA was also responsible for the evaluation of the geologic and geotechnical
characteristics on a regional and local scale and for the identification of potential
problem areas such as landslide zones, soft foundation material areas, and highly
erodible soils. Route examination included locating, designing, and cost estimating
seven twin-lane tunnels varying in length from 600 to 2500 feet. The tunnels were
supported with rock bolts and shotcrete through sedimentary and metasediment
formations.
Client
Ralph M. Parsons Company
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Wycliff Avenue Highway Design
Dallas, Texas
Project Description
The City of Dallas investigated the possibility of eliminating a very congested,
major at-grade intersection. LACHEL & Associates, Inc. (LFA) served as a
geotechnical and tunneling subcontractor, and was retained for over a year to
evaluate the possibility of developing a sub-surface alternative which still
permitted the construction and operation of a large surface parking facility.
LFA was responsible for the development of the geotechnical investigation and
supervised the exploratory drilling.
Scope of Services
Thereafter, LFA provided feasibility level designs for a cut-and-cover project
and detailed construction costs which permitted an evaluation of other considered
alternatives. Estimates were prepared for two construction methods. The construction
cost using a slurry wall structure, was roughly $19 million for two lanes, and
approximately $20 million for three lanes. The cut-and-cover method construction was
roughly $26 million for two lanes, and close to $29 million for the three lane design.
Client
City of Dallas
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