Responsibility and commitment. More than almost any other manufacturer, Mercedes-Benz has advanced safety in touring coaches. This is also the case for the Mercedes-Benz Tourrider. An extensive crash test was therefore carried out specifically for the market launch in North America.

The Mercedes-Benz Tourrider had to pass numerous tests before the start of series production. It is even one of the few touring coaches in the world to have undergone a crash test. In a conversation with the Omnibus Magazine publication, project manager Orhan Dönmez, test engineer Peter Schmutz and Exterior Team Leader Recep Karakiş look back on the development phase of the Tourrider and report on exactly how the crash test went and which findings were obtained.

No one knows the Mercedes-Benz Tourrider better than Orhan Dönmez. As the responsible project manager, he led the development and testing of the touring coach model for the North American market – from the creation of the requirement specifications to the construction of the first series-production vehicles. When asked about the greatest challenges during the project phase, which lasted around four years, the experienced engineer quickly brings up an event that was almost at the end of the development phase: a crash test at 25 km/h head-on against a solid concrete wall.

“It is not mandatory to carry out real crash tests on buses/touring coaches in Europe or the USA,” explains Dönmez. "Daimler Buses is one of the few manufacturers in the world that nevertheless voluntarily carries out real crash tests on such new designs as the Mercedes-Benz Tourrider. We want to ensure maximum safety for drivers and passengers, which is why we used the Tourrider crash test to verify our simulations in practical tests."

One of the few crash test centres specialising in commercial vehicles in Europe is located in Neumünster, north of Hamburg. Here, on the DEKRA Automobil GmbH crash test track, a prototype model of the Mercedes-Benz Tourrider was subjected to a full head-on collision against a rigid barrier. Or to put it another way: the vehicle's front end collided with a solid concrete wall across its entire width. This is a Daimler Buses' internal crash load test.

Because there is no legally prescribed test specification for crash tests of buses/touring coaches, unlike for passenger cars, the developers of Daimler Buses defined the criteria and parameters for such a test themselves years ago. For example, the impact speed: the head-on collision at a speed of 25 km/h against a concrete wall corresponds to a real situation in which the driver can still intervene by braking at travelling speed, but can no longer prevent the impact.

Many days of preparation were blocked in the calendar before the actual crash test. There was only one attempt possible and therefore it had to be successful. Installing sensors, aligning cameras, conscientiously checking the flawless function of the cable for the acceleration of the test vehicle, placing the crash test dummy on the driver’s seat, aligning it with the exact angle and fixing the hands to the steering wheel with adhesive tape. Specialists at DEKRA had their work cut out before the crash.

“During the test, high-speed cameras recorded what was happening inside and outside in super slow motion,” reports Orhan Dönmez. Special sensors measured the accelerations acting on the driver and passengers. The measurement values from the sensors placed on the dummy provide additional information on potential injury risks for the driver in the event of a head-on collision.

The evaluations of the crash sensors, which are distributed over the entire length of the vehicle, show that in the event of an impact at an apparently low speed of 25 km/h, the vehicle and thus the driver and passengers are already subjected to considerable forces.

As expected, the highest forces occur only milliseconds after the impact in the front section around the driver’s seat. Daimler Buses has equipped the Tourrider with the Front Collision Guard safety system to take this into account. In the event of an impact, a rigid substructure, to which the driver’s seat is attached, can move backwards in a targeted manner. The aim is for the driver to gain space for survival. The kinetic energy is absorbed by absorber structures in and behind the bumper as well as in the underbody.

The measured values of the sensors in the crash test dummy prove it: despite the severe impact, the acceleration values were well below the limit values. The images from the high-speed cameras also show that the three-point seat belt fulfils its purpose perfectly. It reliably restrains the dummy's body thereby preventing an impact with the steering wheel or the instrument panel.

Test engineer Peter Schmutz is very satisfied with the results of the crash test: "The evaluations confirm what our simulations have already shown. Based on our evaluations, we can say that Front Collision Guard is very likely to contribute significantly to the protection of the driver in the event of head-on impact. Hardly any damage can be identified in the passenger compartment." This shows that the Tourrider is not only a genuine Mercedes-Benz in terms of ride comfort and drive, but also in particular in terms of safety.