Gantry crane carrying girder for new lane in April (NYSDOT)

Widening two 640m-long elevated highway sections over wetlands and an active rail yard in De Witt, about 370km north-west of New York, called for an innovative construction approach. Using traditional cranes would have required large ground space and risked disrupting rail traffic and the sensitive ecosystems below the work zone. Instead, contractors deployed twin gantry cranes configured to run along the existing bridges, with wheels riding each structure.

Crews are using the custom cranes to lift 60 steel girders, each weighing 30.8t, for 15 new spans of bridge deck between the existing structures. The equipment also helps transport deck forming materials and reinforcement bars. To avoid disrupting the area below, the cranes were delivered, assembled, and calibrated on-site within a single week in February.

The bridge widening is a key part of the I-81 Viaduct Project – considered to be the largest infrastructure initiative ever undertaken by the New York State Department of Transportation. It includes removing Interstate 81 and rerouting traffic through an upgraded I-481 corridor, aiming to ease congestion for 60,000 daily drivers.

The widening is being delivered under a design-build contract by CNY Alliance, a joint venture of Rifenburg Companies, A. Servidone/B. Anthony Construction and Economy Paving.

Currently, beam installation is advancing, with project completion expected by the end of 2025.