Seat Design: An Important Consideration for Occupant Safety in Public Transit Buses

BC Transit, a crown corporation in the province of British Columbia, has reported injuries resulting from passengers sliding off seats during extreme braking and/or turning maneuvers. The corporation was eager to determine whether seat design could help minimize the likelihood of passengers sliding off seats and initiated a review of existing forward facing seats. The review examined seats of different designs within the corporate fleet plus a prototype seat. Without the advantage of seat compartmentalization, passive restraints or seat belts to reduce occupant movement during harsh maneuvers or in a collision, seat design in the first forward facing position should consider characteristics that provide passive restraint for the occupant. Tests using a weighted body form and three common clothing fabrics set against each seat cushion found a surprisingly wide range of friction values. The results show that both friction and seat base angle can be optimized to reduce the potential for rider injuries during turning and braking decelerations up to 0.5 g.