Sand barrels in work zones
Typically, Virginia recommends a conservative design (NCHRP 350 TL-3) if there is adequate clearance, usually consisting of twelve barrels for a narrow hazard (see link below for an example array). If the clearances are too tight to accommodate the 12-barrel array in the work zone, then the design will be based on the manufacturer’s recommendations and engineering judgment.
The amount of sand placed in each barrel varies according to barrel size/type and in accordance with the manufacturer’s recommendations. Typically the heaviest barrels are placed adjacent to the hazard and the lighter barrels are placed at the nose of the array to soften the impact and to provide deceleration prior to the fixed object.