~ The existing bridge is relatively short with a causeway over the surrounding wetlands.
~There were questions regarding the length of the replacement bridge, foundation types and size, and the span arrangements.
~ The site geometry especially at the bridge landing, where there is a roadway intersection and some businesses, presented a significant challenge in providing sufficient under-clearance for the navigable waterway.
~~ Deeper girders would have required raising the grade, but it would have been difficult to tie back in to the approaches.
~~ Predicted scour resulted in waterline footings on piles.
~~ Relatively shallow layer of hard material resulted in A-frame interior bents
~~ There were several other concerns that were raised, but each discipline had cogent reasons for the resulting layout and design of the structure.
~ It was suggested that use of FB-Pier on projects with numerous challenges, such as this one, might allow the Department to design interior bents that are a lot less imposing.
~ Therefore on long coastal projects with waterline footings and lateral stability concerns the Department should consider alternate analysis approaches.
~ There were still questions as to who throws the flag for alternative analyses.
~ The group was in agreement that project schedules should not drive engineering decisions / designs.
~ FHWA inquired if this was a suitable location for jetting piles.
~~ It was noted that jetting is most suitable for Divisions 1 & 2 (coastal counties).
~~ Problems encountered when jetting for the Virginia Dare Bridge (Manteo) have been unduly generalized for all sites.
~~ However, the Department is still pursuing jetting. A Special Provision, which specifies limits on containment for the contractor, is currently being developed. This will provide a starting point.
~~ The Department has proposed to perform jetting demonstrations/tests, which will be the basis for new jetting models for the certain/various soil types.
~~ Regulatory Agencies don't qualify zones in which jetting is not acceptable. In general they view jetting favorably, but they want to know how jetting will be implemented.
~~ FHWA recommends making jetting a priority.