 As environmental awareness increased through the 1960s and 1970s, gritting once again came under criticism due to its environmental impact, leading to the development of alternative de-icing chemicals and more efficient spreading systems.Winter service vehicles are usually based on a dump truck chassis, which are then converted into winter service vehicles either by the manufacturer or an aftermarket third-party.A typical modification involves the replacement of steel components of the vehicle with corrosion resistant aluminium or fibreglass, waterproofing any exposed electronic components, replacement of the stock hopper with a specially designed gritting body, the addition of a plow frame, reinforcement of the wheels, bumpers to support the heavy blade, and the addition of extra headlamps, a light bar, and retroreflectors for visibility.