Transit Temperatures of Heavy Loads of California Lettuce Shipped in Several Types of Rail Equipment

Excerpts from the report: Mechanically refrigerated rail cars and Ice Tempco cars have become readily available to western lettuce shippers in recent years. The Ice Tempco car is a modified RS car in which one bunker has been removed and the other enlarged to hold 7,400 pounds of ice. This increases the inside length of an ice bunker car by about 3-1/4 feet and thus permits larger loads. The larger loads result in reduced freight charges per carton because of the new per-car rates and incentive rates for heavy loads. Heavy loads also are used in mechanical cars and in the conventional RS cars to take advantage of the per-car rates and incentive rates for heavy loads. The mechanical cars used were of the semienvelope type with openings in the ceiling to permit the cold air to circulate directly through the load compartment. The effectiveness of the Ice Tempco and mechanical cars was compared with that of the RS car in providing satisfactory transit temperatures for heavy loads of California naked-pack lettuce shipped during the warm season of the year. Thermostat settings and percentages of salt were varied in the Ice Tempco cars to determine the conditions providing optimum temperatures during transit in this equipment.