Which joint type is capable of accommodating movement up to about 45 mm?

• A. Medium movement joints
• B. Small movement joints
• C. Bridge expansion joints
• D. Rubber joints

Answer: (B)

Movement joints are chosen based on how much relative movement they must tolerate between bridge segments. The one designed for a limited, modest range of motion—around 40 to 50 millimeters—fits best when the anticipated movement is about 45 mm. That’s exactly what small movement joints are meant to handle: they provide a flexible seal and a simple, economical way to accommodate minor translations without the complexity or capacity of larger expansion or intermediate joints.

Bridge expansion joints, on the other hand, are designed for much larger movements driven by thermal expansion over longer spans, while rubber joints are used for sealing and accommodating moderate movement but aren’t the category intended for the specific modest travel of about 45 mm. Medium movement joints cover a range larger than small movement joints, again intended for greater displacement than the 45 mm figure. So the best fit for movement up to about 45 mm is the small movement joint.