When it comes to barrier height, the greatest concern is the barrier being too low as it increases the likelihood of a vehicle vaulting the barrier. Barrier systems have increased in height in recent years to reflect changes in the vehicle fleet, particularly an increase in the prevalence of vehicles with higher centres of gravity such as high utes and SUVs.
The height of the barrier should be measured from the road surface to the top of the rail, with each proprietary product having a specified height and tolerance. Check supplier data sheets for details.