Road salt corrosion is not limited to the bus exterior. During the winter months, passenger shoes bring the road salt into the bus. Frozen slush on boots often melts during the ride and the deicer in fluid form is able to seep into the smallest cracks and crevices. The result is fastener and flooring corrosion from the inside of the vehicle, as well as accelerated wear on floor runners and interior fabrics.
The most concerning area of corrosion from road salts is the underbody of the bus. Corrosion from chlorides attacks the under-carriage metal, engine components, brakes and electrical systems. The damage to vehicle systems is not only a cost burden to a bus owner, it can result in a vehicle safety issue for drivers and passengers. Rust/corrosion on load-bearing metal structures makes the vehicle unsafe for driving.
What is the transit industry solution?
Transit industry suppliers are working on many approaches, such as metal plating and better coatings on new structural components. Some manufacturers are even replacing underbody carbon steel with stainless steel — a very expensive alternative. In addition, many transit companies are adding after-market permanent coatings to the underside of existing vehicles. All of these new technologies will help, but for the foreseeable future it is not possible to protect all the potential corrosion points on vehicles. Are there alternatives to corrosion-resistant materials and specialized, permanent coatings that will help prevent deicer-related corrosion? One approach is to thoroughly clean the vehicle by integrating the proper methods and detergents into the routine cleaning cycle.
Integrate corrosion control into transit wash systems
Effectively cleaning road salts from vehicles requires a different approach from conventional vehicle washing. The focus needs to be on cleaning the inside and outside of the vehicle, including the underbody. It is vitally important to use a detergent with the right chemistry to break the road film and neutralize the corrosive effects of the deicers. Using a detergent with the wrong chemistry can aggravate the road salt problem. Most conventional transit wash detergents are either neutral detergents or alkaline cleaners. These traditional detergents are not capable of breaking and “neutralizing” the impacted salt deposits; the wrong detergent will react with the road salts and make them more difficult to remove from the vehicle.
Surprisingly, some (not all) low pH detergents have proven to be especially effective at neutralizing the corrosive effects of the deicers. These low pH detergents will make the road salts soluble allowing for easier removal in the wash process. In a touchless wash, an alkaline detergent must be used in conjunction with the low pH detergent in order to get a clean vehicle. Magnesium and calcium chloride increase the effective hardness of the water, as the deicers add additional magnesium and calcium ions to the cleaning cycle. Transit wash operators will most likely need to increase the hardness control of alkaline products.
These same low pH detergents should be used to clean the inside of the buses, as well as luggage compartments. It is important to get the detergent under floor mats to remove road salts that may have seeped beneath it. If these deicers are not removed during interior cleaning, corrosion will be just as bad from the inside out.
Most transit washes focus on cleaning the exterior painted surfaces and glass of the vehicle, despite the fact that most of the road salt-caused corrosion occurs on the underside of the vehicle. At best, these washes might have a high-pressure rinse or flush applying water to the underside of bus. To clean the undercarriage, spraying high-pressure water on the underside of the vehicle as it enters the wash is not sufficient. Low pH detergent must be applied to the underside of the vehicle as well to remove the road salts. Applying the detergent with foaming nozzles as the bus drives through the wash is an effective way to ensure adequate detergent coverage on the undercarriage. Adding the equipment for an underbody wash is a relatively simple and inexpensive addition to an existing wash.