The New NY Bridge project is installing new expansion joints in the twin-span roadway.
Motorists on the Tappan Zee Bridge may be familiar with the rhythmic bumps in the existing bridge’s roadway. These interruptions are the result of nearly 200 expansion joints, which are designed to absorb the slight expansion and contraction of the bridge’s steel and concrete. While these elements are a necessity, drivers can expect a much smoother ride in the future thanks to the dramatic reduction of expansion joints on the new bridge.
The twin-span crossing will utilize a mere 12 expansion joints on the westbound span, and 11 on the eastbound. The significant change is the result of the bridge’s efficient design and the advancement of expansion joint technology, which can now provide a greater amount of movement than their 1950’s counterparts. Tappan Zee Constructors has installed eight expansion joints on the new bridge to date.
Expansion joints can be found on bridges, sidewalks, railway tracks and even some buildings. However they are all designed to address the same issue. Warming and cooling alters the shape of concrete and steel, and without periodic gaps, these materials could crack under the stress. Expansion joints provide a release for these stressors, allowing structures to maintain their shape even in extreme conditions.
The new bridge’s expansion joints are designed to compensate for the larger movement created by the longer bridge spans. By utilizing a combination of molded rubber and small steel beams, the joints can expand and contract for these movements. In addition, the joints interlock with the ends of the road deck with additional steel reinforcement, creating a tighter connection and a more continuous driving surface.
Drivers can expect a quieter and smoother ride when the new bridge’s first span opens to traffic next year.
