Total stopping distance for air brakes is longer than that for hydraulic brakes due to:

The total stopping distance for air brakes is longer than that for hydraulic brakes primarily due to brake lag. Brake lag refers to the time it takes for air to travel from the air supply tank through the brake lines to the brake chambers, where the air pressure activates the brakes. This delay is inherent in air brake systems because they operate on the principle of compressing air to engage the brakes, which takes a finite amount of time.

In contrast, hydraulic brake systems are generally more responsive because they operate through the direct transfer of fluid pressure. When a driver presses the brake pedal in a hydraulic system, the brake fluid moves almost instantly to activate the brakes. Therefore, the absence of brake lag in hydraulic systems contributes to shorter stopping distances compared to those in air-braked vehicles.

While reaction time, effective braking, and weather conditions can also influence a vehicle's stopping distance, they are not the primary reason why air brake systems have longer stopping distances compared to hydraulic systems. Reaction time is related to how quickly a driver can respond to a situation, effective braking pertains to how well the brakes perform under certain conditions, and weather conditions can affect traction and braking performance, but these factors do not address the inherent lag in air brake systems that directly increases stopping distances.