A single hairline crack in a bridge deck can seem insignificant. But left undetected, minor cracks and fissures expand, water seeps in, steel corrodes and repair costs start to increase. This risk multiplies across thousands of miles of aging highways and bridges nationwide.

As infrastructure endures increasing strain from heavier traffic, extreme weather and deferred maintenance, engineers are exploring “self-healing” systems, where streets and bridges are built with materials that can repair themselves. Concrete, asphalt and composites capable of detecting and mending microcracks autonomously are moving from laboratory research to pilot projects. But while emerging technology promises longer-lasting infrastructure, it also raises questions about long-term maintenance, performance guarantees, procurement frameworks and risk allocation.