TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 425: Waterproofing Membranes for Concrete Bridge Decks documents information on materials, specification requirements, design details, application methods, system performance, and costs of waterproofing membranes used on new and existing bridge decks since 1995.

The synthesis focuses on North American practices with some information provided about systems used in Europe and Asia.

NCHRP Synthesis 425 is an update to NCHRP Synthesis 220: Waterproofing Membranes for Concrete Bridge Decks that was published in 1995.