We’ve got LUDs covered – from Tappan A to Tappan Zee

mageba’s role in the design, fabrication, testing, transport and installation of the Lock-Up Devices (LUDs – a.k.a. Shock Transmission Units, STUs) of the Tappan Zee Bridge’s replacement structure.

The Tappan Zee Bridge across the Hudson River is one of New York metropolitan area’s most important transportation links, with approximately 140,000 vehicles crossing it every day. The structure, which was opened to traffic in 1958, is now being replaced with one of the widest cable-supported bridges in the world; upon completion in 2018, it will have a combined deck width of approx. 184 ft. Its two parallel superstructures, with main spans of 1200 ft supported by 420 ft-tall towers, will carry eight traffic lanes and four breakdown/emergency lanes, achieving a clearance of 138 ft above the shipping channel. The decks will also carry a shared-use bicycle and pedestrian path, and feature space for bus rapid transit, with an allowance for the future construction of a rail line between the two structures. The construction cost is approximately 4 billion dollars.

mageba USA is continuing to play a significant role in the construction of the new bridge. Having already supplied TENSA® MODULAR expansion joints of extraordinary dimensions, as described in the project reference sheet, the company has now also supplied 16 RESTON®STU shock transmission units (also known as lock-up devices) to ensure the deck’s safety in extreme event circumstances. These devices have lock-up capacities of 800 kips (3550 kN) and pressure release valves rated for 1600 kips (7100 kN), with a stroke of +/- 20 inches. Each device weighs 13,500 lbs (6150 kg), and was individually tested prior to delivery in order to ensure that performance meets the required design criteria.

mageba North America Corp. is proud to have been the bridge constructor’s reliable partner in the supply of these critical components – every step of the way from the design office to the bridge construction site.

We would also like to acknowledge the invaluable cooperation of all those who have been working on this project, whose professionalism and expertise has contributed greatly to the project’s success.

Especially, we thank the bridge owner, the New York State Thruway Authority, the design team led by COWI, and the general contractor, the Tappan Zee Constructors, a joint venture comprising of Fluor, American Bridge, Traylor Brothers and Granite.

View of the Tappan Zee Bridge’s replacement structure during construction

3D rendering of a RESTON®STU as designed by mageba USA

Fabrication of a RESTON®STU lock-up device

Attachment of the movable end assembly of the piston rod of one of the bridge’s RESTON®STU devices

Three-coat corrosion protection system on the fixed end assemblies of some RESTON®STU devices

Full scale prototype testing of the RESTON®STU per AASHTO specifications

Assembled RESTON®STUs, packed and ready for shipment

RESTON®STUs as delivered to jobsite

Loading of a RESTON®STU on a barge for transport to the bridge pier

Installation of a RESTON®STU

A RESTON®STU as installed on the Tappan Zee Bridge’s replacement structure