u201d beam constructed side rails herein base rail 130 and fly rail 140 are so constructed as to receive center u201c i u201d beam rail tongue 152 and center rail groove 154 of center rail 150 respectively fig4 c illustrates the manner in which base u201c i u201d beam rail 130 center u201c i u201d beam rail 150 and fly u201c i u201d beam rail 140 are assembled again it can be appreciated that the arrangement of tongues and grooves may be varied without affecting the basic concept of interlocking tongues and grooves fig5 a illustrates a tongue and groove assembly that incorporates additional tongues added to the outer edges of each side rail and an abrasion resistant strip attached to one of the outer tongues although only tongues are herein added it will be appreciated that the substitution of grooved sections in place of the illustrated outer tongues is equivalent in both function and purpose the configuration of tongue 32 creates baffle 36 that functions as a shock absorber when the ladder is dropped upon a localized area such as a curb or large rock as a force is directed against tongue 32 tongue recesses 38 enable tongue 32 to flex inward toward the main body of fly rail 30 thereby employing the flexural properties of the glass and matrix binder as the force is released the flexural properties of the glass and matrix binder return the tongue to its relaxed position in similar fashion the ridged.