That’s a great question! Some of the strongest bridges that I have worked on are on the railway. The bridges need to be strong to support the weight of heavy goods trains that travel over them. The strongest railway bridges can support trains with a mass of up to 285 tonnes (that’s 285,000 kg!).
Someone else once asked me how many elephants could my strongest bridge support. The average adult African elephant has a mass of 5,433 kg (that’s about 90 times the mass of an average adult human, which is 62kg!).
So to work out how many elephants a railway bridge can support, we do 285,000 / 5,433 = 52.5 elephants (Or 52 adult elephants and 1 baby elephant!)