Although much of the development of prestressed concrete in this country has been in connection with permanent prestressing yards, this challenging field is by no means closed to contractors who are willing to set up facilities for prestressing on their job sites. Indeed, in some cases the cost of transportation alone may tip the economic scales in favor of job-site prestressing. A case in point is a warehouse built recently in Los Angeles. Because of the size of the job, transportation costs would have been very high. The firm that had the lowest bid decided to set up prestressing beds on the job site. By prestressing on site, they were able to build a permanent and fireproof building in the time and for the cost of a temporary make shift structure.