The project design criteria specified a 65-ft minimum vertical clearance from the mean higher high-tide elevation to the low chord of the bridge within the limits of the defined 90-ft navigational channel. The layout of the new bridge was established to satisfy the required vertical clearance over the navigational channel and tie back down to grade using a maximum grade of 4. The bridge design also had to accommodate the environmentally sensitive nature of the salt marshes and address the challenges involved with constructing substructure units within the tidal river. The team selected a superstructure type that could accommodate long spans (modified Florida BT-78 Beams spanning 167.5 ft) to minimize the number of substructure elements required. The team elected to use prestressed beams to eliminate long-term maintenance costs associated with structural steel in a marine environment.
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