Mechanical handling the boffins' approach
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THE Cranfield College of Aeronautics is not a name that springs to mind when road hauliers discuss mechanical handling. I cannot recall hearing it mentioned by any RHA or FTA spokesman in any presentation on vehicle productivity. How many people in the industry have ever heard about the Materials Handling Research Unit at Cranfield? Relatively very few, I suspect.
A national Information Centre for Materials Handling in the UK is to be established. Agreement has been reached by the five interested bodies and later this year the Centre is to take over the activities of both the National Joint Council for Materials Handling and the Materials Handling Research Unit at Cranfield.
Many of us tend to decry Government spending—when it is not for our obvious benefit. The Ministry of Technology on behalf of oppressed taxpayers is putting up most of the £45,000 estimated cost of operat ing the Centre for the first year. A director is being sought—the job is worth £4,500 a year—and the establishment is likely to in clude three research officers, two information officers and two technical officers. If the independent management consultants chosen to select the director pick wisely the Cran field Information Centre for Materials Handling should soon be very well known to all road transport operators. The job clearly calls for a blend of technical, administrative, commercial and negotiating skills coupled with a flair for public relations in the widest sense.
Hitherto, Cranfield has been best known in th,e surface transport industries for two major studies in containerization. The research unit is currently investigating code recognition devices for MinTech; there will be sub stantial dividends in transport and warehousing when viable systems permitting the identification and automatic recognition and sorting of cartons, boxes—even containers —are available.
Scepticism Parcels operators may look with scepticism on such projects. The great variety of packages dispatched by mail-order houses, domestic and trade customers, etc., makes electronic sorting sound Utopian. In this field the best hope is for much more "streaming" of goods—carpets and drums and lawnmowers do not mate very happily with standard-sized cartons. The possibility of a range of standardized pack and pallet sizes being introduced in the fairly early future as metrication makes a belated impact in the transport industry lends point to the current Cranfield research.
A recent publication of the Materials Handling Research Unit at Cranfield carries the intriguing title: The Application of Information Theory to Parcels Sorting. Commissioned by British Railways, perhaps with an eye to the more efficient operation of National Carriers Ltd., it was the work of Mr. B. R. Degerlund, a research student, and Mr. A. W. Pemberton, an engineer attached to the research unit. Parcels sorting is such a deadly dull—though vitally important— operation that any help from boffins in its more efficient planning deserves to be considered on its merits. The enormous growth of mail-order traffic lends point to the study.
I understand that one of the largest British mail-order firms handles 100,000 items per day from a catalogue containing 8,000 items, many available in three colour schemes. The warehousing and dispatching problem is formidable, though the transport side is eased by channelling the goods ordered direct to the housewife-agents and not to the individual recipients of the goods.
Infortnation theory Information theory applied to parcels sorting stems partly from the work of Mr. Derek B. Race, of Management Sciences Ltd., whose ideas were applied successfully some four years ago by the Swiss Post Office in letter-sorting operations. The original development in 1948 was in the field of Communications Engineering—the elimination of unwanted noise in a radio channel. One of the aims of the Cranfield research project was to apply the principles involved over a much wider field. As the study says: "There are many situations where a sorting activity takes place in order to reduce a mass of randomly mixed items into discrete categories, and it is likely that many of these could benefit from being examined by the methods suggested in this report."
In the study a parcel was defined generally to mean a box or package of about 2 cu.ft. which could be readily handled by one man. (BR and most road carriers observe this division loosely, treating separately any heavy or unwieldy items.) Three rough divisions into size and "handleability" in parcels traffic are as follows:
(i) Postal parcels accepted by the GPO under stringent size and weight limits.
(ii) Railway and road parcels traffic of almost any size, both parallel with the GPO range and upwards. The upper size/weight limit tends to be set by the pricing structure rather than by imposed physical limitations.
(iii) Larger and generally more irregular packages which usually travel by rail sundries or by road haulage. This category also includes multiple packages to one address.
Boffin territory The study in question was confined to the first two categories. The evaluation of existing procedures for railway parcels, both manual and machine-assisted, to postulate a standard of sorting efficiency made it necessary to look more closely at the theoretical basis of the sorting process. The application of Information Theory using the concept of entropy as a measure of the state of disorder of a given mix of parcels brings us into boffin territory with a vengeance. The many road transport platform workers, past and present, made goggle-eyed by the sorting chore in peak traffic periods may take some comfort from the scientists' concern.
For the relationship between the "entropy index" and the number of bays or divisions into which the parcels are required to be sorted, will enable the amount of sorting per parcel, and hence the most efficient method, to be used.
The theoretical sorting method developed by the Cranfield boffins can be applied to both manual and mechanical sorting. It indicates which method is likely to be most efficient in a given situation as regards costs.
Speed The speed of parcels sorting depends upon the number of categories into which the items must be sorted and the number of sorts necessary to separate them to destinations. With letter sorting there is little actual movement of the letter at the sorting point; speed in identifying the destination is crucial. With parcels sorting the greater length of time is spent in carrying the parcel from the sorting point to the sorting destination.
But sorting speed is not the only factor for optimal sorting. Increased sorting speed, due to the smaller number of sorts, is offset by the number of times a parcel must be sorted and the increased handling time between sorts. Total sorting efficiency, therefore, depends on the speed of sorting and the average number of sorts.
With 100 destinations to be sorted to and an equal number of parcels for each, then two sorts into 10 bays each can be used. At the first sort the parcels are placed into 10 bays each having 10 destinations allotted to it.
The parcels in each bay are then sorted into a further 10 bays, one bay per destination.
Given that the volume for each destination has been equal, sorting for 100 destinations only requires twice the number of sorts needed for 10 destinations. Sorting for 1,000 destinations only requires three sorts of 10 bays each. Expressed in mathematical terms this means that the effective work done in sorting can be related to the logarithm of the number of bays. This logarithm can be called the Index of Effectiveness and allows for the effect of varying number of handlings occurring with different numbers of bays.
Interesting examples of practical depot sorting problems are given in the report, such as the area of platform needed, handling time per parcel, etc., of great relevance in the replanning of any parcels depot. At one BR depot mentioned 26,813 parcels were handled of which 10,748 were collected for forwarding, 14,023 were received for tran shipment and 2,042 for delivery. The number of possible destinations was 176 and the number of parcels per destination varied between 2,851 and 1.
In the foregoing example the entropy per parcel calculated for the whole section came to 1.81. (For an equal number of parcels per destination the entropy would have been log. 176, i.e. 2.245). The method used was to sort to 57 destinations, the traffic being resorted to the 176 at the various transhipment points.
Theoretical method
Using the theoretical method of optimal sorting, the parcels could be sorted with an average number of 1.8 handlings per parcel into 10 bays. Alternatively, if 15 bays were used, the parcels could be sorted with an average of 1.54 handlings per parcel.
Of course, the numbers of parcels received daily and their destinations fl ictuate widely but the report stresses that over a period of
time a representative number of parcels per depot per day can be obtained and this figure can be used for determining the allocation of sorting bays. As traffic trends alter rearrangements will be called for, fixed area bays with immovable partitions are not recommended.
Much of the report is concerned with a cost-evaluation of mechanical sorting methods which are by no means a panacea for all parcels operators because of their cost. It is interesting to know that of all possible destinations BR parcels are liable to be forwarded to, 75 per cent receive less than 100 parcels per day each. Hence the greater practicality of mechanical/manual sorting systems in which the primary sorting is by machine followed by a manual secondary sort.
With mechanical sorting 40 discharge points is the maximum the operator can key to efficiently and it is pointed out that though this number of discharges reduces the number of secondary sorts it means a fair increase in the cost capital of the equipment and a much larger area of platform is occupied.
Useful
There is a useful summary of the performance characteristics of various types of sorting machine all based on the use of a conveyor with the possibility of using logic memory units, photo-electric cells and other devices. Tilt-tray systems used as a recirculating loop or as a simple over-andunder circuit are discussed. Much experience and local knowledge of the operators of such machines may be called for until address codes become standard throughout the country. It is stressed that whatever system is used a small proportion of traffic would have to be handled manually owing to excess length. (The point might have been made that out-of-gauge traffic should bear such a high premium that it would be cleared out of any mechanized sorting system. When will parcels operators grasp this nettle?) I have deliberately refrained from any discussion of the mathematics—way above my head—included in the report. Its conclusion that entropy can be applied to parcels sorting, thus giving the amount of uncertainty in the collection a finite value, enabling comparisons to be made between various collections and giving an indication of the amount of sorting required, seems to me to be valuable to parcels traffic managers. Even if the savings possible are only marginal, it is in the margins that profits must be sought.
A recent visit I paid to C ranfield convinces me that the road transport industry has not made nearly enough use of its experts and facilities in the past. Research projects are welcomed and consultancy services can sometimes be arranged. I hope that when the National Information Centre opens it will succeed in widely disseminating expertise in materials handling and warehousing design and operation. The energizing, of the road transport industry to appreciate what Cranfield can offer is perhaps a task for the operators' associations, aided by the technical Press.