2018 FAQ

Question: If I build my bridge such that the loading plane is located on the top surface of the bridge, then is contest rule 2d which requires passing a PVC pipe horizontally across the bridge irrelevant with respect to the minimum width needed for the bridge?

Answer: There is no minimum width requirement in the specifications.  All bridges whether they have portions above the loading plane or not must allow the 1.5 inch schedule 40 PVC pipe to pass horizontally across it.  The passing of the pipe across the bridge has two purposes: (1) to simulate the passage of traffic across a real world bridge and (2) to check that the supports at the loading locations are in the same horizontal plane. If a bridge is entirely below the loading plane then passing the pipe across it should not pose a challenge.  The second check of all supports at the loading locations be in the same horizontal plane is still required.

Question: In the construction portion of the rules, part d states that a PVC pipe has to be passed horizontally across the bridge with the pipes lower surface on the loading plane and the pipe must be touching both loading locations simultaneously. Since I am designing my loading plane to be located at the top of my bridge (90 mm above the base of the bridge), is it required to have some sort of support beams located at the side of my bridge in order to prevent the pipe from rolling off to the sides? Or will the judges move the PVC pipe by hand in a way that the pipe won't be allowed to roll off?

Answer: There is no need for a railing above the support surface to make sure the PVC pipe does not roll off the bridge.  It is the responsibility of the check-in judges to control the PVC pipe while they are using it to check a bridge.

Last update: November 19, 2016
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For further information, contact: Prof. Carlo Segre -, Illinois Institute of Technology
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