A guardrail crash absorbing assembly comprising: an elongated first rail panel having a first rail panel front portion and a first rail panel rear portion; an elongated second rail panel having a second rail panel front portion and a second rail panel rear portion, said first rail panel rear portion and said second rail panel front portion being in side by side, overlapping relationship at a panel joint; an end impact structure operatively associated with said first rail panel and responsive to vehicle frontal impact on the end impact structure to move said first rail panel rearward lengthwise along said second rail panel; and a braking structure at said panel joint for dissipating kinetic energy during sliding of said first rail panel relative to said second rail panel and absorb impact forces caused by vehicle impact on said end impact structure, said first rail panel defining a rail panel opening and said braking structure including at least one tooth projecting from said second rail panel positioned in and extending through said first rail panel opening, said at least one tooth having a cutting portion for making a longitudinal cut in said first rail panel extending from said first rail panel opening responsive to endwise vehicle impact on said end impact structure, said longitudinal cut extending at least partially through the first rail panel, characterized in that said tooth is one of a plurality of teeth in said guardrail crash assembly, at least one of said teeth having a hook structure and positioned in and extending outwardly through an elongated slot defined by said first rail panel and said second rail panel. an elongated first rail panel having a first rail panel front portion and a first rail panel rear portion; an elongated second rail panel having a second rail panel front portion and a second rail panel rear portion, said first rail panel rear portion and said second rail panel front portion being in side by side, overlapping relationship at a panel joint; an end impact structure operatively associated with said first rail panel and responsive to vehicle frontal impact on the end impact structure to move said first rail panel rearward lengthwise along said second rail panel; and a braking structure at said panel joint for dissipating kinetic energy during sliding of said first rail panel relative to said second rail panel and absorb impact forces caused by vehicle impact on said end impact structure, said first rail panel defining a rail panel opening and said braking structure including at least one tooth projecting from said second rail panel positioned in and extending through said first rail panel opening, said at least one tooth having a cutting portion for making a longitudinal cut in said first rail panel extending from said first rail panel opening responsive to endwise vehicle impact on said end impact structure, said longitudinal cut extending at least partially through the first rail panel, characterized in that said tooth is one of a plurality of teeth in said guardrail crash assembly, at least one of said teeth having a hook structure and positioned in and extending outwardly through an elongated slot defined by said first rail panel and said second rail panel.