Safe driving

Safe driving

For years, Mercedes-Benz has pursued its vision of accident-free driving. The integral safety concept covers all phases of automotive safety — safety when driving and in dangerous situations, protection in the event of an accident and minimising the impact of an accident. Safety is also integrated into the eCitaro city buses as standard. The body itself protects the passengers in the event of side impact. In the event of a rear-end collision, the reinforced front end minimises the impact of an accident while protecting the driver.

The Electronic Stability Program (ESP®) is an active system for increasing driving safety and stability. It makes a noticeable contribution to reducing the risk of skidding during cornering or evasive manoeuvres. This is achieved by specifically controlling the braking forces on each individual wheel in critical handling situations, for example if the coach approaches physical limits when cornering. At the same time the engine output is reduced. A possible "breaking-loose" of the bus is thus prevented by the finely metered braking - within the limits of the physical possibilities. ESP® monitors, among other things, the lateral acceleration of the bus. If, on long bends – such as motorway exits – or during rapid lane changes, the bus reaches a critical driving situation, the vehicle speed is automatically reduced to the extent necessary for the bus to return to a stable handling situation. ESP® is similar to the system installed in cars but provides additional functions adapted for use in buses.

ASR prevents the drive wheels from spinning in two ways. On the one hand, ASR minimises wheel spinning through a measured braking intervention. On the other hand, the torque of the engine is regulated via the "electronic accelerator pedal".

Even at full throttle, the engine only provides as much power in critical situations as the drive wheels can transmit – a major advantage for controlled pulling away and driving stability. When starting off, the torques applied and the wheel speeds of the drive wheels are monitored. In this process, torque distribution is controlled in such a way that spinning is prevented. This ensures that optimum power flow is always guaranteed.

ASR helps the driver to minimise the risk of the drive wheels spinning and consequently of the rear of the vehicle (rear-wheel drive) drifting out sideways when accelerating. Especially for high-torque engines, ASR thus provides increased comfort and enhanced safety when pulling away – particularly on roads with varying grip.

The Anti-lock Braking System (ABS) supports driving stability during critical braking operations and ensures that the vehicle remains steerable. The braking forces acting on the individual wheels are distributed by the ABS so that even in an emergency braking situation no wheel is blocked for any length of time, and the steerability of the bus is largely maintained.

The control unit of the brake electronics records the current wheel speed via the pole wheels and wheel sensors. When braking, the system controls the brake pressure at the individual wheel brake cylinders via the control valves. During emergency braking and braking with locking wheels, the system opens and closes the control valves of the wheel brake cylinders fully automatically at very short intervals, thus preventing locking and keeping the vehicle steerable.

During emergency braking and braking with locking wheels, the system opens and closes the control valves of the wheel brake cylinders fully automatically at very short intervals, thus preventing locking and keeping the vehicle steerable.

The Front Collision Guard offers increased safety in the event of a head-on collision by means of a transverse profile behind which crash elements are located. Their absorber structure converts the impact energy into deformation energy. The transverse profile serves as a reliable underride guard. Since the driver’s work space is mounted on a massive frame component, it can be pushed backwards to maintain a protective space for the driver in the case of a frontal impact.

The patented technology includes a multi-part cross section as underride guard behind the bumper with the idea of protecting other road users, e.g. preventing a car from going under the bus. The front-end structure behind this cross section consists of crash elements that can selectively dissipate energy in the event of a collision. In addition, the driver's area, including steering, pedals and seat, is located on a massive frame section that is displaced rearward as a complete unit in the event of a serious head-on collision, thereby increasing the survival space by vital centimetres.

The FCG fulfils the requirements of the underride guard according to ECE-R 93, as well as legal norms for pendulum impact in buses. Moreover, the FCG already meets future statutory standards for pendulum impact tests on buses.

Sideguard Assist is a safety assistance system that supports the driver in critical cornering situations where visibility may be limited. When turning or changing lanes, the system is designed to help avoid critical situations, within its limitations, or reduce the consequences of accidents.

The function of the system and the warning concept were established based on the analysis of accidents while cornering that involved pedestrians and cyclists. In the majority of accident scenarios, the cause is due to the movement of both parties involved (vehicle and pedestrian/cyclist). In these cases, the system provides early information (yellow display) about moving persons or vehicles in a zone alongside and over the entire length of the vehicle and warns the driver as soon as the situation becomes critical (red).

Sideguard Assist provides support in the following situations: -standstill (e.g. at traffic lights, passenger loading/unloading, etc.) -moving from stationary -driving at low speeds -turning when there are stationary objects within the turning curve (up to 22 mph (36 km/h)) -changing lanes (complete speed range) An input variable for the transition from information (yellow) to warning (red) is the detection of the intention to turn. This is done both by evaluating the turn signal on the curbside and by detecting lateral movement (without turn signal). When reversing, the system is automatically disabled and there is no monitoring. At speeds higher than 22 mph (36 km/h), Sideguard Assist assumes the function of a lane change assistant. It informs the driver about any object on the curbside up to the maximum permitted speed. When the turn signal is set to change lanes, the system generates a visual-haptic warning. Sideguard Assist thus supports lane changes, for example when overtaking a cyclist or when changing lanes on multi-lane roads.

With the Preventive Brake Assist feature, Mercedes-Benz is offering the first Active Brake Assist for city line buses worldwide. The assistance system warns of a potential collision with moving pedestrians as well as stationary or moving objects and automatically initiates a braking manoeuvre with partial braking in the event of an acute collision hazard.

Warning cascade and braking intervention are designed for use in city traffic. In the event of an imminent collision with pedestrians and with moving or stationary objects, the Preventive Brake Assist warns the driver visually by a red illuminated triangle with a vehicle symbol in the central display as well as acoustically, while initiating partial braking. This is held until either the driver intervenes or the bus comes to a stop.

The platform for the Preventive Brake Assist is a new generation of radar technology: the radar system continuously scans an area of up to 250 metres in the lane in front of the bus and works reliably even at night and adverse weather conditions.

The Acoustic Vehicle Alerting System (AVAS) is a sound generator that generates a noise similar to that of a combustion engine in a speed range of up to 30 km/h when driving forwards and up to 6 km/h when reversing. A pleasant sound alerts those in the vicinity of the fully electric bus.

The system increases the volume up to a speed of 20 km/h, and from this speed it reduces the volume again up to 30 km/h. In this way, it communicates the speed and any acceleration. At speeds above approx. 15 km/h, the rolling of the tyres makes a louder sound than the system itself. The system does not generate any noise emissions when the vehicle is stationary and cannot be switched off by the driver.

The sound generator is mounted behind the front panel on the left-hand side of the vehicle. With the AVAS, the sound level of the electric bus is approx. 5–6 dB above the required minimum noise according to UNECE-R 138.01.

The cornering light function provides even more safety through better visibility conditions at night-time when cornering at intersections and roundabouts and when manoeuvring in forward driving and backing up.

The cornering light function is activated automatically at speeds of up to approx. 35 km/h if the main headlamps are on, the turn indicator is actuated or the steering wheel is turned. One of the two front fog lamps then cuts in to illuminate an area on the side in front of the vehicle that is not being illuminated by the main headlamps.

The intelligent electronic system switches the cornering lights on or off progressively in the same way as a dimmer switch. This gives the driver's eyes a chance to adapt to the change in light.

Both agile and robust. The Articulation Turntable Controller (ATC) developed by Mercedes-Benz is a sophisticated anti-jackknife system for articulated buses. This swivel joint and its control system form one of the core components of the vehicle.

Articulated bus joints usually have high levels of basic damping. This invokes a strong inclination for the driver to understeer when cornering and increases tyre wear on the front axle. This is where the driving dynamics control system Articulation Turntable Controller (ATC) comes in.

The dynamic ATC regulates the hydraulic dampening of the articulation joint quickly and above all when and where it is needed, depending on the steering angle, the angle of the articulation joint, the speed and the load, among other factors. To this end the ATC falls back on the data from the CAN bus.

The otherwise usual high damping of the joint leads to a strong tendency to understeer in curves and increased tire wear on the front axle, this vehicle’s joint runs freely under normal running conditions and is attenuated only by the friction of the elements.

The wireless tyre pressure monitoring with indication in the multifunctional display is an electronic safety system that permanently monitors the air pressure of all tyres. Tyre pressure losses are displayed within the system limits.

The right tyre pressure contributes to driving safety and significantly reduced fuel consumption. Even a tyre pressure set 0.5 bar too low can increase fuel consumption by up to 5%. The wheel electronics are positioned on the valve on the inside of the rim. The sensors record the data relevant to the tyre pressure and transmit it to the display instrument.

The tyre pressure is recorded both when the vehicle is stationary and when it is moving. Caution! A sudden loss of pressure, for example due to the penetration of a foreign body, is not immediately indicated by the tyre pressure monitoring system. Damage to the tyres that does not lead to acute pressure loss is also not detected by the monitoring system. Here, visual inspection by the driver is and remains essential.

Installed video monitoring cameras can monitor events in the bus. A video monitoring system can not only improve the perceived safety for the bus driver and passengers, it can also deter hooligans committing acts of vandalism in the vehicle and record acts of violence.

The data is transmitted to the monitor in the bus driver's workstation. The bus driver can then better discern and assess certain situations and events occurring in the passenger compartment and if necessary react to any threat. The vehicle is labelled with pictograms to inform passengers that the vehicle is video-monitored. Together with the video monitoring, they increase the perceived safety for your driver and the passengers and thereby enhance the attractiveness of public transport. The video monitoring system is special equipment.

For more information on the functioning of the video monitoring and data storage, contact our bus sales advisor.

* Optional equipment

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