Safety at Daimler Buses: Vision of accident-free driving

As a bus pioneer, Daimler Buses has traditionally stood for safety in city, travel and intercity buses. With state-of-the-art driver assistance systems and on-board protection systems, we aim to significantly increase road safety and, ultimately, drive accident-free. With this objective we are contributing to achieving the European Union's goal of reducing the number of road deaths to nearly zero by 2050. We’re also contributing to increasing the quality of life in cities. The goal of our integral safety concept is ambitious: It is the implementation of the vision of accident-free driving.

The key to success: an integral security concept

At Daimler Buses safety does not consist of individual measures. There’s much more of a comprehensive integral safety concept behind it. The integral safety concept is made up of several components. The focus is on a wide range of innovative vehicle and application-specific safety equipment, with the goal of continuously increasing active and passive safety. This is further supported by measures such as driver training.

Drivers should recognize dangers in a timely manner and avoid them. Likewise, they should react properly in the event of an accident. Passenger informed in the use of on-board safety equipment – beginning with fastening their seatbelts - is also part of the concept. However, the concept goes far beyond this to include responsible vehicle maintenance and the use of proven original replacement parts. The goal of the integral safety concept is the implementation of the vision of accident-free driving.

Safety and assistance systems at a glance

Active Brake Assist 4 (ABA 4) brakes for pedestrians

The exceptional feature of Active Brake Assist 4 (ABA 4): As the world's first system of its kind it warns the driver prior to a possible collision with moving pedestrians and simultaneously initiates automatic partial braking. This makes it possible for the driver to avoid the collision by means of full braking or steering.

ABA 4 with pedestrian detection is based on a new generation of radar technology. It is an electronically scanning multi-mode radar composed of a far- and near-range radar.

Active Brake Assist 4 is standard on all touring coaches from Mercedes Benz and Setra: Mercedes Benz Tourismo RHD, Setra ComfortClass and TopClass, including the Setra S 531 DT double-decker coach.

Electronic Stability Program (ESP) introduced early in the series

Back in April of 2002 Daimler became the first bus manufacturer to introduce the Electronic Stability Program (ESP) as an option. In October of 2003 ESP was adopted as standard equipment. The driving dynamic control ESP considerably reduces the risk of skidding within the realm of physical possibilities. A sensor detects impending driving-dynamic, critical situations from information such as the steering angle of the front wheels, the speed of the vehicle and lateral acceleration. In order to avoid danger engine torque is reduced and, in the next step, the individual wheels are deliberately braked to prevent dangerous instability.

At the same time, Daimler also introduced Brake Assist (BA). It detects an emergency braking situation based on the operating speed of the brake pedal and can directly apply significantly increased brake pressure. This shortens the braking distance and helps to avoid accidents.

Autonomous Intelligent Cruise Control keeps the correct distance

The Autonomous Intelligent Cruise Control (AICC) assists the driver on highways and highways. When AICC anticipates a slower vehicle it will automatically decelerate the bus until it reaches a separation distance preselected by the driver, which AICC will then maintain. For this purpose AICC employs a multimode radar with a near-range opening angle of 120 degrees and far-range angle of 18 degrees.

When there is no vehicle driving ahead AICC works like cruise control. Autonomous Intelligent Cruise Control particularly supports the driver in medium to dense traffic on highways by largely taking on the burden of adjusting speed by braking. It limited to approximately 20 percent of maximum braking power. Should higher brake pressure be required Active Brake Assist will activate.

Cruise control with the added function of "stop and go"

Autonomous Intelligent Cruise Control (AICC) with Stop Assist (AHA) assists the driver in traffic jams or slowing traffic. The added "stop and go" function is an extension of the regulation range of the cruise control.

If the vehicle is not stationary for more than two seconds, the distance control remains active in slowing traffic at a speed of up to 15 km/h and brings the coach from a standstill back to the set speed.

Lane Assist warns of lane departure

Lane Assist (LA) uses a camera system behind the windshield to detect when the vehicle is about to leave the lane. LA constantly checks the distance of the bus to the lane marking lines. If the vehicle threatens to cross the line, the driver is warned by vibration in the corresponding side of the seat. LA becomes active at a speed of 60 km/h and is switched off, for example, by pressing the turn signal to initiate a desired lane change

Constant and safe downhill with Continuous Braking Limiter

The endurance limiter brakes the vehicle via a retarder when the legally permitted maximum speed of 100 km/h is exceeded. Accidental speeding down grades is practically impossible.

Preventive Brake Assist, the brake assistant for city buses

With Preventive Brake Assist Daimler Buses introduced the world's first active brake assistant for city bus buses. This new assistance system warns of a collision with moving pedestrians, as well as with stationary or moving objects, and automatically initiates partial braking in the event of an acute collision hazard. A series of warnings and braking interventions are designed for use in city traffic.

Preventive Brake Assist is similar to Active Brake Assist 4 in its mode of action. However, it is designed for the very high dynamics of city traffic with a large number of varied road users and directions of movement. In the event of an imminent collision with pedestrians, as well as moving or stationary objects, Preventive Brake Assist visually warns the driver by a red flashing triangle with vehicle symbol in the central display and acoustic warning while simultaneously initiating partial braking. It continues until either the driver intervenes or the bus comes to a halt. The driver can override an intervention at any time by stepping on the brake, evasive steering or by pressing the accelerator pedal. In addition, he or she can also warn pedestrians or other road users with the horn.

Preventive Brake Assist deliberately does not perform automatic full braking. This reduces the risk of injury for standing passengers on the bus, as well as for unbelted seated passengers. The driver can always initiate full braking.

Warning and braking reactions to stationary and moving obstacles occur over the entire speed range of the bus. Pedestrian detection is active up to a speed of 50 km/h.

Preventive Brake Assist is available as an option for the entire Mercedes-Benz Citaro model series, including the Citaro G articulated bus, the Citaro LE low-entry bus, the Citaro G/GÜ intercity bus and the CapaCity large-capacity bus. Preventive Brake Assist is also offered as an option for the Mercedes-Benz Conecto city bus.

Attention Assist for the driver

The Attention Assist (AS) safety system continuously monitors information on the driver's activities based on certain criteria including steering and braking activity, turn indicator actuation, vehicle speed and time of day. From the correlation of the data it obtains and the adapted driver profile, Attention Assist determines the responsiveness or fatigue level of the driver. If a defined model value is exceeded, an electronic signal - unnoticed by the passengers - will trigger a vibration in the driver's seat.

Front Collision Guard, the passive safety system

Front Collision Guard (FCG) is a unique passive safety system designed to protect the driver and front-seat occupant in a frontal impact. Front Collision Guard is made up of a complex security system. It begins with a transverse structural section, which can, in the event of an accident, prevent driving under a passenger car. The frame behind this section consists of crash elements that selectively absorb energy in the event of an impact

In addition, the driver's seat of the bus, including steering, pedals and seat, is arranged on a massive frame component. This structure can completely move backward in the event of a serious frontal accident and thus increase the crumple zone or survival space by critical centimetres. Our engineers both calculated the effects of Front Collision Guard, as well as testing it in in several crash tests. The FCG already meets future legal standards for swing-bob impact tests on buses.

More safety with LED headlights

On request, Mercedes-Benz and Setra buses come equipped with the world's first integrated LED headlights. Drivers benefit from light that does less to fatigue their eyes, as the color temperature of the light from LED headlamps is approximately equivalent to daylight. This innovative lighting technology increases active safety and ensures good visibility even under poor weather conditions. Another safety feature: The luminous flux of an LED lamp remains almost constant throughout its lifetime. Therefore its lifetime reaches a multiple of that of halogen or xenon lamps. This eliminates several lamp changes and therefore the associated costs and downtime - companies benefit both from LED headlamp performance and significantly lower maintenance costs.

Sideguard Assist: first turn Assistant for city buses and coaches

Turning maneuvers in city traffic are among the most unpleasant tasks for drivers. The must -- at the same time -- pay attention in front of the vehicle and to traffic lights, signage, counter- and cross-traffic, all while looking to the side and keeping pedestrians and cyclists in view. Meanwhile, the traffic situation can change in seconds. In addition, cyclists and pedestrians are not always aware that a bus driver may not be able to see them. As the world's first bus brands, Mercedes Benz and Setra now offer the turn assistant Sideguard Assist with passenger recognition. Mercedes Benz will supply it in all versions of the Citaro city bus, including the CapaCity large capacity bus and the Tourismo; Setra touring coaches; and in the Setra ComfortClass 500 and TopClass 500 coaches, as well as the Setra S 531 DT double-decker coach.

Sideguard Assist works in a multi-level manner: It first informs the driver when a relevant object is in the warning zone. It next warns the driver if he or she initiates or continues an action where there is a risk of a collision.

If the sensors detect a stationary obstacle, such as a traffic light or a bollard in the turning radius of the bus, a visual and haptic warning is issued. This helps to avoid collisions and expensive repairs. The turn warning works starting at a walking speed and up to 36 km/h. Other functions of the Sideguard Assist are available starting at walking speed and up to 100 km/h.

Sideguard Assist can do more still: It warns the driver at speeds higher than 36 km/h when changing lanes to the right. In this case the driver is also informed of any object on the passenger side and warned when actuating the turn signal.

Brake Assist for coaches

Brake Assist (BA) is standard equipment in coaches from Mercedes-Benz. It detects an emergency braking situation based on the operating speed of the brake pedal and provides direct control with significantly increased brake pressure. This shortens the braking distance and helps to avoid accidents.

Crash element: Collision protection for the Citaro driver

A safety feature in the front of the Citaro city bus is a crash element that provides collision protection. Together with reinforced A-zero columns and a defined frame construction, which directs forces into the substructure in the event of an impact, the new Citaro complies with the swing-bob impact test for touring coaches in accordance with the European regulation ECE R 29.

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