Applying the factor of tailboard occupancy noted in the preceding paragraph and assuming a loading per vehicle of 1.43 tons and a vehicle space 11 ft. wide gives 1.43 60 X X 70 per cent or 0.121 tons per lin. ft. 11 45 of tailboard per hour. This is equivalent to 1.21 tons per 10-hour day or 13.31 tons per vehicle space per day. In the article describing the New York Central freight terminal at Cleveland, it is stated that 131⁄2 tons per door per day were actually being handled prior to its reconstruction, but that for the purpose of design, a value of 15 tons per door per day was used. From the close agreement in the above figures it would appear that from 13 to 15 tons per day can be handled per vehicle space. If the spacing of doors is equal to the assumed vehicle space it follows that a like tonnage can be handled per door per day. Outbound House. The same method of analysis given for the inbound house will now be applied to obtain values for the outbound house: Average time required to actually unload a vehicle... 18 minutes Total per vehicle load.... 16 minutes 34 minutes Assuming a factor of tailboard occupancy of 60 per cent, a loading per vehicle of 1.3 tons and a vehicle space 11 ft. wide gives 1.30 11 60 X 60 per cent or 0.125 tons per lin. ft. of tailboard per hour. 34 This is equivalent to 1.25 tons per lin. ft. of tailboard per 10-hour day or 13.75 tons per vehicle space per day. From a comparison of the values shown above, it would appear that the average daily capacity per lin. ft. of tailboard per day per vehicle space or per door is substantially the same for both inbound and outbound houses. Tailboard Required Per Car. Inbound House. In the foregoing discussion it was shown that 1.21 tons of freight can be handled per lin. ft. of tailboard per 10-hour day. It is important at this time to determine the percentage of inbound freight which is delivered through the doors direct to consignee or connecting lines and that delivered by cars or other means. At the South Water Street inbound house of the Illinois Central Railroad it has been determined that 70 per cent of all inbound freight moves through the doors. Similar data for other houses is not available, therefore this percentage will be used here as a basis for analysis. Assuming one car setting per day and a car loading of 8 tons results in 70 X 85.6 tons of door delivered freight per car and 5.6 1.21 equals 4.64 lin. ft. of tailboard per car. If the house handles 100 per cent door freight, 6.63 lin. ft. of tailboard space is required per car. This value is not susceptible to general application owing to the wide variation in the proportion of freight delivered through the doors and in car loading, but the analysis shown above will serve as a basis and can be modified to suit any particular case. Outbound House. A value for the outbound house can be obtained in a similar manner. At the South Water Street outbound house of the Illinois Central Railroad at Chicago, it has been found that 40 per cent of all outbound freight is received through the doors. Assuming one setting per day and an average car loading of 8 tons results in .40 X 8= 3.2 tons of door freight per car. It was shown under tailboard capacity that 1.25 tons of freight can be handled per lin. ft. of tailboard per 10-hour day. Ap3.2 or 2.56 lin. ft. of tailboard required per plying this value we obtain 1.25 car. If the house handles 100 per cent door freight, 6.4 lin. ft. of tailboard space is required per car. This value is based on specific conditions and should be modified if actual data is available and is found to disagree materially with the assumptions made. Number and Spacing of Scales. Inbound House. There are in general use at the present time two distinct types of freight house scales-the beam scale and the dial scale. For general purposes, the dial scale of 4 to 5 tons capacity has some advantage, owing to the rapidity with which shipments can be weighed. For heavier loads, such as machinery and steel, the beam scale is more generally used. The capacity and style of scale to be used is largely dependent upon the character and volume of freight normally handled through the house. A few scales of greater capacity should be provided to permit weighing of heavy shipments. In recent years there has been a growing tendency to weigh a part or all inbound freight received, or at least such consignments whose billed weight appears suspicious. Admittedly, re-weighing is a heavy item of expense, but it is undoubtedly a profitable operation if exercised judiciously. In numerous cases such re-weighing has doubled and trebled the freight revenue on the shipments in question, thus leaving little doubt as to its desirability. Table No. 4 reflects past practice in re-weighing inbound freight at various freight houses built within recent years. TABLE No. 4-DATA ON SCALES USED AT VARIOUS FREIGHT HOUSES Practically all freight received through the door is weighed upon receipt. To handle the door freight offered during rush periods requires that an ample number of scales be provided. Observations indicate that one scale every 44 ft. is ample, which, based on a door spacing of 11 ft. results in one scale every fourth door. Table No. 5 reflects data in this respect and was secured from a study of a number of the more important outbound houses built throughout the country within recent years. TABLE NO. 5-DATA ON SCALES USED AT VARIOUS FREIGHT HOUSES Careful study of this question would seem to indicate that the door spacing should be a multiple of the vehicle space adopted in determining the tailboard capacity. As previously stated, this width should be between 10 and 12 ft. If two vehicle spaces are provided in each panel of the building, this results in a panel length of 20 to 24 ft. and gives an economic building design from both an operating and a structural standpoint. Another equally important point to observe is the relation between the average car length and panel length of the building. On account of the variation in length of cars commonly used, there is generally some loss of track capacity experienced due to spotting cars opposite door openings and the panel length adopted should be such as will result in a minimum door loss. Where local conditions permit at the inbound house a trucking platform of suitable width between the house and tracks should be provided. With such an arrangement there is no door loss occasioned by spotting cars and transfer of freight from car to house or car to car can be accomplished in a very expeditious manner. Such a platform is also very desirable on the delivery side of inbound houses. At the outbound house there is generally no advantage to be gained in providing such platforms Economic Length of House. Where hand trucking is resorted to, previous investigations of economical operation indicate that the maximum length of house should be about 500 ft. If motor train operation is used, the length of house should not materially exceed 1,200 ft. An excellent reference on this subject may be found in a paper entitled "Notes on LCL Freight Houses," by Mr. E. H. Lee, Vice-President of the Association, Vol. 15, page 364. This paper deals with the economics of handling freight by hand and by motor train and is a valuable contribution to the scant literature on this subject. As a result of the study made in connection with the design of the New York Central freight facilities at Cleveland (Eng. News, Vol. 82-pages 508 to 510), it was decided that 1,250 ft. is the approximate maximum length of house which should be built consistent with economic freight handling, using motor train operation. Floor Live Loads Per Square Foot. The live load per square foot for which Inbound freight house floors should be designed is somewhat dependent upon the character of freight handled. In a previous paragraph it was stated that a ton of inbound freight piled on the floor occupies 76 sq. ft. This gives a load of 263 pounds per sq. ft. of loaded area. Some allowance must be made for impact and for concentrated loads. It is suggested that a live load of 250 to 300 pounds per sq, ft. be used for designing the floor framing unless local conditions dictate otherwise. At the Outbound house, the question of floor load is not so important, as the freight is kept moving, but it seems advisable that framing should be designed to carry about 250 pounds per sq. ft. Summary. In treating a subject so greatly influenced by variables as the design of freight houses, it is extremely difficult to formulate ironclad rules or to set up exact factors of design. A close analytical study should be made |