This report describes a study, conducted jointly by Bethenergy Mines Inc. and the U.S. Bureau of Mines, to assess the effects of longwall front abutment loading on various supplemental support materials utilized in a predriven recovery room. The purpose of the predriven recovery room is to reduce longwall equipment transfer time by eliminating the premove preparation associated with conventional recovery methods. In addition, the room provides a large area in which face salvage equipment can maneuver. Results of four recovery- room study areas show the progression and influence of the front abutment on the longwall panel and supports and their subsequent behavior. The best performance (i.e., the support that most facilitated recovery) of support material was achieved through the use of a concrete mixture that had a sand content of 35 vol pct. The longwall transfer time was reduced by 30 pct, which translates to a production advantage of 37,000 raw tons of coal per panel. Note.--The paper was presented at the 1989 session of longwall usa under the title "optimization of supplementary support for open entry longwall equipment recovery" and was published as pages 20-27 of the proceedings.