A barrier movement operator moves a barrier between open and closed positions. The operator receives a first request to move the barrier. The actual force required to move the barrier is measured. An obstruction to barrier movement is determined by comparing the measured actual force to a first predetermined force threshold. Responsive to the detection of an obstruction, the direction of travel of the barrier is reversed. The operation of the barrier movement operator is modified, by permitting the use of a higher force threshold in future measurements. A second request to move the barrier is received. The actual force required to move the barrier is measured a second time. An obstruction to barrier movement is detected by comparing the measured actual force with the new, higher force threshold.