Complex sentence: The Santa Fe Railway offered the use of full-scale crossing signals, but Disney declined as they would be out of scale with the trains, so the railway instead provided scaled-down signals built at their San Bernardino shops as a gift to Disneyland.
Split into simpler sentences: The Santa Fe Railway offered the use of full-scale crossing signals, but Disney declined as they would be out of scale with the trains. These scaled-down replicas were designed and built by the Santa Fe Railway San Bernardino shops as a gift to Disneyland.