When does rainfall have the greatest impact on the start-up and braking of the tram?

In the initial phase of rainfall, water mixes with contaminants accumulated on the rails (dust, oils, dirt), forming a very slippery sludge. This layer drastically reduces the adhesion of the steel wheels to the rails, which significantly hinders moving off and increases the braking distance. Continued, heavy rainfall washes away this dangerous layer, slightly improving the conditions.