THE CHALLENGE: The Chart House Bridge Project involved
replacing a bridge that provided the sole vehicular access for patrons to the restaurant.
Since the restaurant was open seven days a week, a design was needed that could be constructed
as quickly as possible to limit restaurant closure time.
THE S0LUTION: The new bridge consisted of an AASHTO HS20 designed,
pressure treated 18 inch thick transversely dowel laminated timber superstructure on the
existing concrete substructure. The clear span was 36.5 feet and the road width was 15.3 feet.
A 4.1 foot wide sidewalk was included, designed to span over and conceal existing utilities which
could not be easily relocated.
The sidewalk curb height selected was such that a vehicle would not be
able to place a wheel load on the sidewalk. Therefore a pedestrian rail system was provided on the
sidewalk side of the superstructure, and a vehicular and pedestrian rail system was provided
on the opposite side. Preservative treatment was coal-tar creosote, except that pentachlorophenol
was used in areas subject to direct human contact. The deck was left unpaved. Metal beam
approach guide rails were included, made of weathering steel for aesthetics.
The project was bid to be constructed during a 16 consecutive hour period, with an hourly
liquidated damages clause included in the contract to ensure an on-time completion. A deductive
alternative in the bid was selected by the client, for construction during a 40 consecutive
hour period.
The client based this decision on anticipated lost revenues versus the premium they
would have to pay for a quicker construction period. The prefabricated superstructure was erected
in the component form off-site the day before the bridge closure, to speed final erection.
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The bridge was completed during a 24 consecutive hour period in 1997. Final construction cost
was approximately $112,000.
Complete bridge engineering design services were provided by Nathan L. Jacobson and Associates, Inc.
Project management was directed by an associate of the firm, specializing in bridge design.
Services included everything from preliminary design, final design, bidding phase, and
round-the-clock construction administration and inspection, through project close-out.
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