TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 371: Managing Selected Transportation Assets: Signals, Lighting, Signs, Pavement Markings, Culverts, and Sidewalks explores the state of the practice for managing transportation infrastructure assets other than pavements and bridges, and documents gaps in knowledge and areas in need of potential further study.  The link to the final report is https://trb.org/news/blurb_detail.asp?id=8496