This is my information how the bridge are developed by the engineer's .Now a day many things are developing by Hus.So i proved to be an civil engineer.I'm doing my engineer.
36. All bridges held generally the same amount of weight. The
arch bridges held a little more than the other bridges.
They were in the 1400-1500 gram range. The other bridges
were in the 1000-1200 gram range.
The bridges would not stand up on their own, so a support
at each end had to be constructed. Balancing the
weights on the bridges required patience. Clamps were
used to hold the bridges during gluing.
The bridges supported different amounts of weights
because each type has different construction. The arch
bridges supported the most weight because of the great
natural strength of the arch. The pier bridges supported
the least weight because the supporting piers broke
during construction.