Providing direct access between Miami’s seaport and highways I-395 and I-95, the Port of Miami Tunnel consists of two parallel tunnels bored beneath Biscayne Bay, connecting the MacArthur Causeway on Watson Island with PortMiami on Dodge Island. During the review phase of the preliminary design, Schnabel provided independent cost estimating services, first for the tunnel and ultimately for the entire project scope.

The $1.6 billion project was developed as a public-private partnership using the design-finance-build-operate-maintain (DFBOM) or “concessionaire” project delivery model. It involved the excavation and support of two tunnels designed to connect major highways as well as ease congestion in downtown Miami by reducing truck and bus traffic. The two 42-foot-diameter tunnels were excavated in extremely permeable oolitic limestone with cover as little as 18 feet.

During the design phase, Schnabel was contacted by Parsons Brinckerhoff and T.Y. LIN International/URS to provide an independent cost estimate for the tunnel (underground heavy civil) portion of the project. We were subsequently asked to join an independent cost estimating team with URS (surface structures, bridges, and roads) and Everett & Gerrish (tunnel systems) to develop a cost estimate for the entire project scope.

In addition to cost estimating services, we performed a constructability review and prepared a report addressing the challenges facing tunnel construction. We prepared an independent statistical risk assessment of 43 potential project risks, and utilized probabilistic cost estimating techniques to establish the range of probable costs associated with the identified risks. Prior to releasing the preliminary design and procurement package, we also reviewed the tunnel-related portions of the project design and construction criteria, the technical specifications, and the geotechnical baseline report (GBR).