59.12. How does the braking distance of a passenger car change when driving with a trailer that does not have a braking system?
UAЯк змінюється довжина гальмівного шляху легкового автомобіля при русі з причепом, що не має гальмівної системи?
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This exam question from the Traffic Rules of Ukraine concerns road safety during braking and the correct assessment of a vehicle's stopping ability. In the theoretical exam, it checks whether the driver understands how the braking characteristics of a car change in real operating conditions, particularly when driving as part of a road train. Such knowledge directly affects the choice of speed, distance, and timely reaction in a dangerous situation.
According to the traffic rules, specifically the definitions in point 1.10 (braking distance, trailer, road train) and the requirements of section 12 regarding safe speed and actions in case of danger, the driver must take into account the condition of the vehicle and the peculiarities of driving with a trailer. If the trailer does not have a braking system, only the car actually brakes, while the total mass of the combination increases. Due to greater inertia and the "pushing" effect of the trailer during deceleration, a longer distance is needed for a complete stop, meaning the braking distance increases.
The explanation of the answer options is based on physics and driving practice. The statement about reduction due to additional resistance is incorrect: the resistance to movement does not compensate for the sharp increase in inertia and load on the braking system, especially during intensive braking. The option "does not change" is also incorrect, because the mass and operating conditions of the brakes change, and a trailer without brakes continues to roll by inertia. That is why the correct conclusion within this exam question and the requirements of the Traffic Rules of Ukraine is: the braking distance when driving with a trailer without brakes becomes longer, and therefore a greater distance (point 13.1) and earlier braking are required.
Clause 1.10 (term "Braking distance")
Braking distance — the distance a vehicle travels from the moment braking begins until it comes to a complete stop.
Clause 1.10 (term "Trailer")
Trailer — a vehicle designed to move in conjunction with a motor vehicle.
Clause 1.10 (term "Road train (vehicle combination)")
Road train (vehicle combination) — a motor vehicle connected to one or more trailers.
Clause 12.1
When choosing a safe speed within the established limits, the driver must take into account the road situation, the characteristics of the cargo being transported, and the condition of the vehicle in order to constantly control its movement and drive it safely.
Brief application: driving with a trailer (especially without brakes) changes the condition/capabilities of the vehicle regarding braking, so the driver must take into account the increase in braking distance when choosing speed.
Clause 12.3
If a danger to traffic or an obstacle that the driver can objectively detect arises, he must immediately take measures to reduce speed up to stopping the vehicle or safely bypassing the obstacle for other road users.
Brief application: the actual ability to "reduce speed up to stopping" depends on the braking distance, which increases when driving with a trailer without brakes.
Clause 13.1
Depending on the speed, road situation, characteristics of the cargo being transported, and the condition of the vehicle, the driver must maintain a safe distance and a safe interval.
Brief application: an increase in braking distance when driving with a trailer without brakes requires a greater safe distance.
That is, the correct answer is "Increases.", given that according to the definition of the Traffic Rules, the braking distance is the distance to a complete stop, and driving a road train (a car with a trailer without a braking system) impairs braking capabilities and must be taken into account by the driver when choosing speed and distance.
During braking, the vehicle must reduce its speed to zero due to the operation of the braking system and the grip of the tires on the road. According to the Traffic Rules, the driver is required to choose a safe speed and distance, taking into account the condition of the road and the characteristics of the vehicle, in particular the presence of a trailer. This means that with a trailer, stopping requires a greater safety margin.
When a passenger car is moving with a trailer that does not have its own brakes, only the car actually brakes. In this case, the total mass of the “car + trailer” becomes greater, and therefore the inertia of the entire combination increases. When pressing the brakes, it is necessary to “dissipate” more kinetic energy, so it takes more time and a longer distance to come to a complete stop.
Additionally, a trailer without brakes continues to move by inertia during deceleration and transmits a pushing force through the coupling device to the car. As a result, it is more difficult for the car to decelerate intensively, and the driver feels that the vehicle combination is “pushing” forward, especially during sudden braking.
In practice, this looks like the following: at the same speed and on the same road, a car without a trailer will stop sooner than a car with a loaded trailer without brakes. That is why the driver needs to start braking earlier and keep a greater distance, as the braking distance will be longer.
Therefore, the correct answer is "It increases," because a trailer without brakes adds mass and inertia, and only the car brakes, so a greater distance is required to stop.