Rows seats distance is a key parameter for the comfort on coaches. This distance it is also important for the passenger safety and also for example to extend the use of rearward facing CRS in a safer way. This study analyses what could be the minimum distance (based on comfort from volunteer) and how this comfort distance is affecting the passengers level of protection in R80 frontal impact with respect the minimum distance requested in current Regulations R36/R107. Volunteer testing have been performed to obtain the comfort sitting positions for coach seats geometry. Also CAE software has been used to determine minimum row seats comfort distance for a wider sample of seats geometry. In later phase, R80 sleds tests with two and four Hybrid- III dummies and with two types of seats (2-point and 3-point safety belts) have been performed, to asses the level of protection of the passengers in frontal impact at the current R36/R107 row seats distance and with the proposed one.
This study present a recommendation for a minimum row seat distance to guarantee passengers comfort and how this distance is affecting the passengers safety in frontal impact with the injury assessment criteria of both R80 and R94 for the Hybrid-III dummy. With 3-point safety belts seats, the increment on the row seat distance is beneficial for the passengers safety, except when they are unbelted and if the design of the seat is maintained. With 2-point safety belts seats, the level of protection is similar for both distances. The R94 neck injury criteria and tibia displacement are over exceed even with the lower R80 impact speed (55 kph vs 30 kph). This study shows the status of coaches frontal impact protection levels after the 2003/20/CE Directive has been made compulsory the use of the safety belts in coaches even in the city and road travels.