SOLARIS BUS & COACH : SOLARIS VACANZA PASSES A DIFFICULT TEST WITH FLYING COLOURS

The stainless-steel construction of the Polish Solaris Vacanza coach is extremely rugged and completely safe. This is the brief, yet very important conclusion drawn by scientists and bus engineers who have just completed an

investigation of an accident-damaged Solaris Vacanza tourst coach.

The incident took place on November 14th of lat year, on the A2 motorway, some 30 kilometres from Hanover. Around 06.40 hours, due to a momentary loss of concentration, the driver, behind the wheel of a coach on a return trip from Paris, lost control of the vehicle and drove over the hard shoulder and onto a steep bank of a side ditch. The driver tried to correct his mistake and fought to regain control of the vehicle over a stretch of over 100 metres, unfortunately to no avail. The Solaris Vacanza, with thirty passengers on board, turned over to the side and landed in a ditch. All the passengers and all crew members escaped major injuries. The coach did not suffer any significant damage either.

The actual accident was very similar to a standard test to which all tourist coaches are subjected as a matter of routine. This test is described in detail in a European Union Directive 2001/85 (formerly known as the R66 regulation). The said test consists in turning the coach over to its side with a concurrent drop from an 80-centimetre bank. The objective of the test is to check whether the coach design is strong enough to guarantee the occupants the required level of safety. Solaris Vacanza came through all the tests during the homologation phase with flying colours, but what is most important, the inherent strength of the structure was 100 per cent confirmed during the actual accident. These extreme circumstances proved that Solaris Vacanza is a vehicle that is up to the standard in every aspect – not only stylish and comfortable, but first and foremost, it is a very safe vehicle. One testimony is the fact that during the accident all windows remained intact. After the coach was stood back on its wheels and cleaned from soil and grass, there was virtually nothing to suggest that the vehicle had been involved in a serious accident. Only a very careful examination could reveal some slight damage to the bodywork. Also, the interior remained virtually intact, as all parts and fittings remained in place without causing any hazard to occupants. As far as safety was concerned, Solaris Vacanza passed this difficult test with full marks.

After the Vacanza was towed back to the factory service workshops in Murowana Goslina, the coach was subjected to detailed examination and tests carried out by specialists from the Solaris Engineering Department, assisted by specialists from the Poznań Technical University. These tests and measurements revealed permanent deformations mainly in the area of the front axle and in the rear section of the coach, at engine mountings. Moreover, on the right side of the vehicle there were slight deformations of the bodywork frame structure.

Careful reconstruction and step-by-step analysis of the accident led to the conclusion that the deformation of the bodywork sustained by the Solaris Vacanza was perfectly natural and justifiable. The damage to the front section can be easily explained in terms of the stresses that occurred around the front steered axle during accident. The deformation observed in the rear section had been caused by inertia forces exerted by the sheer bulk of the powertrain (engine and transmission) the moment the Vacanza was turning over to its side. This system of forces was "unfavourable" to such an extent that it just had to result in plastic deformation of the body structure. The engine mounting sub-frame is designed to provide the necessary strength mainly in vertical direction and not so much in the horizontal direction. This is pretty obvious bearing in mind normal coach and powertrain operation conditions. Turning over of the coach was accompanied by extreme horizontal stresses. However, the damage was so slight that it could only be detected using specialist measuring equipment. As far as the deformation of the right-hand side of the vehicle was concerned, the Solaris Bus & Coach engineers and specialists from the Poznań Technical University agree that most likely it was due to the occurrence of so-called nodal moments.

During detailed examination of the vehicle and available non-destructive tests no cracks have been found in the area of supporting profiles, nor in welded frame truss joints. The material effort and stress levels have been analyzed several times using the finite element method. Moreover, during special tests these findings were subsequently verified by comparing them with stress levels during normal vehicle operation. It is also worth noting that at the development stage, before the Solaris Vacanza entered production, it had been subjected to an extremely severe strength testing programme at DAF‘s proving ground in Holland, with the facility specially prepared to test the Polish-built coach.

"Summing up the tests and analyses carried out in relation to the accident, we can say that the Solaris Vacanza coach proved to be a safe vehicle, with high rigidity of the lateral supporting and load-bearing structure. The Polish-engineered coach owes these attributes mainly to a non-compromise approach to designing all vehicle systems and components. Modern, well thought-out design, high quality of materials used in production and craftsmanship combined to create a Polish tourist coach that is not a only on a par but often superior to the vehicles perceived to be the best on the market," said Professor Wojciech Osmólski from the Poznań Technical University.