A Guardrail is a longitudinal barrier used to protect motorists from roadside hazards. The purpose of a guardrail is to reduce the severity of collisions by preventing a vehicle from veering off the roadway into an embankment or fixed object.

Many public spaces are fitted with guard rails as a means of protection against accidental falls. Any abrupt change in elevation where the higher portion is accessible makes a fall possible. Due to this responsibility and liability, rails are placed to protect people using the premises.

The most common type of guardrail in use today is the Blocked-Out W-beam (Strong Post). Strong-post W-beam guardrail consists of steel posts and steel Blocks. The posts’ primary purpose is to maintain the height of the guardrail during the initial stages of post deflection. Maintaining guardrail height also reduces the potential for a vehicle to vault over the guardrail upon initial impact.

The posts also play a role in the amount of resistance and deflection a guardrail may experience during impact. Resistance in a strong post system results from a combination of tensile and flexural stiffness of the rail and the bending and shearing resistance of the posts.