Each year in California, approximately 23,000 small signs supported by single 89mm x 89mm (4" x 4") or 89mm x 140mm (4" x 6") wood post set in auger-made dirt holes are knocked down by errant motorists. Roadside sign replacement along California's highways is a dangerous daily routine for Caltrans sign maintenance crews. During the last four years, 11 Caltrans employees have been killed while working on foot. Some of whom were in the process of replacing sign posts that had been found by errant vehicles. Each year, Caltrans maintenance crews are subjected to hundreds of hours of hazardous traffic exposure while replacing these sign posts.
Replacing a typical knocked down sign takes a two-person crew approximately 40 minutes if a lane closure is not required. A typical non-lane closure replacement job requires removal of the broken wooden stub using a pick, pry bar, or shovel, cleaning of the hole using a manual post hole digger or power auger, mounting a sign panel on the sign post, cutting the new sign post to the required length, making sure the post is plumb, and finally backfilling and tamping the soil.
A few tubular steel sockets have been proposed in the past but had a common problem. The dimensions of the wooden posts vary considerably because they are either surfaced or rough sawn. The hole cavities in the steel sockets proposed thus far have had parallel sides with large radius corners and a fixed internal dimension that must be large enough to accept a wide dimensional variation in both surfaced or rough sawn standard wood posts.
Recognizing the high risk of serious injury to maintenance personnel due to errant traffic while replacing these downed sign posts, the Caltrans Design for Safety Concept Action Group requested that the Structural Materials Branch of Materials Engineering and Testing Services (METS) design, build, install and evaluate a new type of reusable foundation for the two smallest sizes of wooden posts which would reduce time needed for replacing small wood sign posts and hence exposure time of workers to traffic. This task was later handed over to the New Technology & Research Program, Office of Research. The goal of this project was to develop a foundation that would enable sign maintenance crews to complete stub removal and sign replacement in 10 minutes or less, with common tools that crews already carry.