How Are Travel Lift Piers Designed for Busy Working Boatyards?

The runway slab is the most heavily loaded concrete most engineers will ever design. I start with the travel lift manufacturer's wheel load diagrams — axle spacings, tire footprints, and maximum wheel loads with the rated vessel — and design the slab for punching shear at each wheel, flexure between supports, and fatigue from cyclic loading. The slab sits on pile caps or grade beams on piles driven to bearing, with the pile layout verified against both vertical loads and the lateral push of a loaded lift turning. The piers themselves are designed as marine structures: reinforced concrete or steel on piles, with fendering where vessels come alongside and corrosion protection for the splash zone. Expansion joints are placed to control cracking without creating bumps the lift feels on every pass.

The basin between the piers is dredged to serve the yard's vessel mix at the lowest expected water level, with side slopes or bulkheads designed for the surcharge of the loaded piers beside them. I coordinate the dredge depth with the maintenance plan, because a basin designed without a siltation allowance becomes a recurring emergency. On the yard side, the runway extends into maneuvering aprons where the lift positions vessels onto stands — these aprons carry the same wheel loads and get the same structural treatment. The yard layout keeps the travel path clear of stored boats, provides washdown stations where hulls get cleaned after haul-out, and stages the work stands so the lift never has to thread a needle with a boat in the slings.

A travel lift pier is a machine foundation as much as a marine structure, and the design has to satisfy both roles. I verify the manufacturer's load data against the structural design, the basin depth against the vessel mix, and the yard layout against the lift's turning and maneuvering needs. Commissioning includes a survey of the finished runway for levelness — a lift that crabs sideways on its first run tells you the runway is not true. Here is the checklist I use to close out the design. • Runway slab designed for manufacturer wheel loads, punching shear, and fatigue cycling • Pile foundations carried to competent bearing for vertical and lateral loads • Haul-out basin dredged for the deepest vessel plus siltation allowance at low water • Maneuvering aprons and work-stand areas built to the same load standard as the runway • Utilities routed alongside — never across — the wheel paths, with washdown collection • Finished runway surveyed for levelness before the lift makes its first loaded run