Explainer | Where’s the safest seat on a double decker? 5 questions from Hong Kong’s tilted bus accident

A double-decker bus in Hong Kong crashed into a concrete divider before coming to a halt tilted to its right on Monday, leaving about 40 people injured. Passengers recalled the traumatic episode, including witnessing people being thrown from their seats. The Post takes a closer look at the accident and overall commuter safety. 1. Why didn’t the bus topple over? To ensure stability, a double decker must withstand a tilt of up to 28 degrees from the horizontal plane on either side without flipping over, according to road traffic construction and vehicle maintenance regulations. This is tested with weights placed on the upper deck to represent a full load of passengers. Lo Kok-keung, a veteran engineer and instructor in traffic accident reconstruction training courses at Hong Kong Metropolitan University, said the bus involved in the crash did not topple over as the tilt was inside the safety range set by the Transport Department. “The speed of the bus was too fast when turning and it deviated from the route, resulting in it crashing into the barrier. If the bus had tilted more than 28 degrees, it would have overturned and caused more injuries to passengers. Luckily, it did not,” Lo told a radio programme on Tuesday. 2. What may have caused the incident? Police arrested the 54-year-old KMB driver on suspicion of dangerous driving after the crash on Ching Cheng Road in Cheung Sha Wan. Officers they would investigate his driving behaviour and mental state at the time, as well as the mechanical condition of the vehicle. Lai Siu-chung, the director of the Motor Transport Workers General Union’s KMB branch, said route 290A from Tseung Kwan O to Tsuen Wan was a long-distance ride with many passengers. “The drivers need to take care on both the 290 and 290A routes. The departure time of each bus is very tight, causing less rest time for them, which may affect driving performance,” Lai told the same radio programme. He highlighted the rest time at the terminus for the driver involved in the crash was only three minutes, which was not ideal, and said that five to seven minutes should be allowed. Passengers describe horror as Hong Kong double-decker crashes, tilts 3. What should passengers do in a similar situation? Lo suggested passengers on the lower deck could swiftly move to the opposite side of the tilt within the vehicle to stabilise the bus. “Passengers on the upper deck could slowly come down one by one and help stabilise the vehicle’s centre of gravity to prevent it from overturning”, Lo said, warning that commuters should not try to exit by themselves. “Once the centre of gravity of the tilted bus changes, the whole vehicle may overturn,” he said. “Passengers should stay calm until the firefighters can stabilise the vehicle.” Lo also said bus drivers should be trained on how to balance a tilted vehicle. “They need to know how to distribute the load inside a bus when an accident happens, and direct passengers on where to stand,” he added. 4. What can passengers do while waiting for rescue? Leung Kin-ming, the commander of Lai Chi Kok Fire Station who joined Monday’s rescue operation, said the passengers on the upper deck were cooperating at the time of the evacuation. “Our colleagues on-site were able to get the phone number from our control centre of a male passenger on the upper deck who called police. We rang him and asked him to put his phone on speaker mode, telling all passengers to stay calm and remain in their seats while comforting them. “Later, we saw them cooperating and in an orderly manner following our instructions to evacuate,” Leung noted. 5. Which seats are safer for passengers in general? Lo told the Post that the middle area of the lower deck of a bus was relatively safe for passengers in a collision. “The area is closer to the centre of gravity of the vehicle, so passengers will absorb less vibration and impact force when the vehicle collides with something,” Lo explained. 2 dead, 10 hurt in Hong Kong as double-decker rams stationary truck and van “When the vehicle brakes suddenly or hits something, the inertia will push people forward. Passengers at the front may be thrown through the windscreen and fall in front of the vehicle. Those in the middle are most likely to hit the seats in front of them but remain in the vehicle,” he said. Lo added the upper deck was definitely not the safest area. “The higher you are away from the ground, the chance of getting injured will be bigger when a vehicle overturns”.

Explainer | Where’s the safest seat on a double decker? 5 questions from Hong Kong’s tilted bus accident

The Post takes a closer look at a harrowing road incident on Monday and comments by experts in the aftermath Among areas explored are how such vehicles are designed not to topple over and what passengers should do to protect themselves

1. Why didn’t the bus topple over?

The Post takes a closer look at a harrowing road incident on Monday and comments by experts in the aftermath

Among areas explored are how such vehicles are designed not to topple over and what passengers should do to protect themselves