A car deck on a bridge is fastened by a hinge on one end and is resting on rollers on the other end. The deflection of the bridge when subject to the static weight of a car is to be estimated. A scaled physical model of the system is set up in a laboratory. The system is also modeled as a simply supported Euler-Bernoulli beam. Measurements on the physical model are carried out and the behavior of the analytical model is computed by a numerical method. Exemplify, explain, and motivate at least six types of errors that can be expected to get involved in these estimates of the bridge deflection.