What is an Expansion Joint of the aqueduct?

Bridge expansion joints are structural components used in bridge construction to allow for the expansion and contraction of bridge components due to temperature variations, seismic activity, and other factors. These joints are installed between adjacent segments of the bridge deck or between the bridge deck and its supporting structure.
Expansion joints serve several important functions:
1. Accommodate Thermal Movements: Bridge materials expand and contract with changes in temperature. Expansion joints provide a gap between bridge segments to accommodate these thermal movements, preventing the buildup of stress that could lead to structural damage.
2. Absorb Seismic Movements: In seismic-prone areas, expansion joints help absorb the horizontal movements caused by seismic activity, reducing the risk of damage to the bridge structure.
3. Seal Against Water and Debris: Expansion joints often include seals or gaskets to prevent water, debris, and other contaminants from infiltrating the gap between bridge segments. This helps protect the bridge’s substructure and prolong its lifespan.
4. Provide Smooth Riding Surface: Expansion joints are designed to maintain a smooth riding surface for vehicles crossing the bridge, minimizing discomfort and wear on vehicles and improving safety.
Expansion joints come in various types, including modular expansion joints, finger joints, strip seals, and elastomeric joints, each suited to different bridge configurations and requirements. The selection of the appropriate expansion joint depends on factors such as bridge design, expected movements, and environmental conditions.