Justify your choice of bridge design. Please provide research to justify your choice Bridge design has changed dramatically over the years, from a few pieces of logs tied together to massive suspension bridges spanning hundreds of miles. As technology and knowledge have advanced, bridge designs have become larger and stronger. The chosen bridge design uses the Pegram Truss, which is a hybrid of the Warren and Parker truss design. This particular design allows for the recycling of existing bridges, meaning that components from the original bridge can be reused and modified in the design. The Pegram truss can also be reassembled, which allows you to adjust the span of the existing bridge. Since this project is able to use existing components from existing bridges, it will help consumers save more money rather than building a completely new bridge. It will also produce less pollution than building a bridge from scratch. This characteristic is part of the needs and requests of current society in terms of respect for the environment. Since this design is a hybrid of the Warren and Parker truss design, not many of these types of truss bridges have been built. This is also one of the reasons why the design was chosen. The drawing that was made had slight changes to the angles which are supposed to be 60-70 degrees. In the original design the entire bridge is made of iron, however instead of using all the pieces of balsa wood, I replaced the diagonal trusses with ropes, this will allow the bridge to resist the tension given to the supports when the load is present. http://prezi.com/t8-aj6js4s2g/bridges-trusses/ http://www.brighthubengineering.com/structural-engineering/63635-truss-bridge-designs/ h...... middle of the sheet.. ....then it should. Furthermore, some of the balsa wood did not reach the other corresponding side causing the torsional stress of the bridge (shown in diagram 3) causing the torsional bending that was shown in the last seconds before it failed. How could you have made improvements to your bridge? Improvements that could be made are to ensure that the balsa wood is carefully cut into pieces of the same length; this will reduce the amount of shear the deck will face while supporting the load. Other improvements can be things like having a consistent pattern in the way the strings are tied around the bridge (shown in the diagram below); this will allow the voltage to be distributed more evenly across the bridge. The quality of the starting balsa wood should be considered and checked at the beginning to increase the strength of the supports supporting the load.