On July 18, 1996, about 1200 Alaska daylight time, a wheel equipped Cessna 170B airplane, N2813C, sustained substantial damage while landing at an off airport site located approximately 8 miles northwest of Tyonek, Alaska. The airline transport certificated pilot, and the sole passenger aboard, were not injured. The local, 14 CFR Part 91 flight departed Lake Hood Strip, Anchorage, Alaska, about 1130, and operated in visual meteorological conditions without a flight plan. During a telephone conversation with the NTSB investigator-in-charge on July 23, 1996, the pilot stated he was attempting to land the airplane on a narrow, gravel surfaced road that was formerly used to provide access to oil well drilling sites. The pilot said he lost directional control during the landing roll, the airplane swerved to the left, went off the roadway, and subsequently damaged the right wing.