A vehicle barrier system, comprising, a support member having a first side disposed toward an area used by vehicles, a splice plate including a support aperture and a stress concentrator associated with to the support aperture, and a rail assembly including, in one embodiment, a wood rail and a first side, wherein the first side of the rail assembly is coupled to the splice plate and the splice plate is coupled to the support member at the support aperture. In another embodiment the rail assembly includes one or more weakened areas serving as stress concentrators in the rail assembly.