this type of bus is possible to carry up to 55 passenger or more. its a city bus. what do you expect? but if they use for transport people for daily commuter service up hill and downhill , the tear and wear of the parts and component will be much faster. that's why one of the victim mention that the bus move slowly down to the hill and suddenly it want to avoid a lorry in front of them. With the full capacity of passenger plus downhill situation you can imagine to stop the bus in the short period of time because of the momentum. they also had mention that the brake not working normally.