That “crack” in the bypass viaduct? It’s built-in, normal, and doing its job

WILLITS, CA., 1/18/17 — In recent days some people have taken to social media to raise the alarm about a “crack” in the viaduct section of the Willits Bypass that crosses Valley Rd. — which is apparently growing. But don’t worry! This supposed “crack,” that has gotten a lot of attention, including some drone footage yesterday, is actually an expansion joint — a normal part of concrete structures.

Concrete, like most things, expands and contracts with heat or cold. Because this expansion can place strains in structural concrete, potentially even causing it to buckle, engineers have long included “expansion joints” to allow the concrete to swell and contract. These have the added benefit of giving bridges and viaducts some sway in a quake.