Rule 9.2.11:  Clearance must be provided under the bridge.  The clearance must be at least 5.1/2" over every surface outside the footings.

Common Error:  It appears to be more common to violate the vertical clearance requirement than the longitudinal extent of the rule.  The clearance is typically measured with a template.  Alternatively, the judges may measure from a taunt string line if there is a question of the flatness of the floor.   A major change in the rules this year reduces this clearance more than was required in previous years so the image shown is not exactly like this year's requirement.