Since the height of the barrier can only be adjusted through the addition and removal of stoplogs, finding a lighter and stronger material other than wood or concrete became a more desirable choice. Other materials, including steel and composites, can be used as stoplogs as well.
Since the height of the barrier can only be altered with stoplogs, choosing a lighter and stronger material than wood or concrete is now more desirable. Other materials like steel and composites can also function as stoplogs.