DEMOUNTABLE DUSTCARTS
Page 36
Page 37
If you've noticed an error in this article please click here to report it so we can fix it.
WITH BRITAIN firmly in Europe and an increase allowed in the permissible gvw, the potential for the road haulage of refuse to distant disposal sites is considerable, said Mr P. K. Patrick, general manager of the Greater London Council's refuse disposal branch (department of health engineering), in a paper to 400 members of the Institute of Public Cleansing at their 74th annual conference and vehicle demonstration in Bournemouth this week.
Mr Patrick said he proposed to talk about a refuse transfer station and its associated transport equipment which should be planned as an integrated system. Unless larger-capacity storage space was built into the station design it would be essential to have vehicles available at all times covering the refuse arrival period. For road transport this could best be achieved by use of semi-trailers or containerized units or a combination of the two. Articulated semi-trailer units also allowed a higher payload than rigid chassis vehicles. A drawbar trailer system was another possibility and this kind of truck and trailer was used extensively in the United States for the bulk haulage of refuse.
Mr Patrick said containers could add flexibility to the transport system — and be used with either rigids or semi-trailers — providing storage capacity at transfer stations at a lower cost than built-in storage space. Containers could be designed for top-loading or for end-loading by a compactor, and could be off-loaded at a landfill site for subsequent discharge by a special vehicle which need not be constrained by legislation applying to road-going vehicles.
A debatable point in both transport systems when utilizing landfills was whether to use separate motive units for road and site works. Operating any. road-going vehicle on such sites led to risks of expensive tyre damage and wear and tear on the vehicles. In addition, if articulated vehicles were used it was necessary to specify double-drive tractors to get the necessary adhesion to tip surfaces. As twin-axles were not essential for road use with a 32-ton-gvw unit and had an attendant weight and cost penalty, there were practical advantages in separating the functions of road work and site work, and consequential cost benefits should follow. 'Mr Patrick suggested three ways to operate a separate transport system: CI Special tractor to handle semi-trailers; D Special chassis to handle roll-on containers; O Special chassis in conjunction with a static ramp system of container dernounting.
This latter method merited further examination as it had several potential advantages although it had been used in only one instance for refuse handling in the UK. Fixed ramps were erected at the transfer station and at the disposal site. To demount a container from the chassis the vehicle backed between the ramps. The container was automatically raised on the ramps as these engaged roller arms on each side of the container. In the reverse process, ie picking up a container, the vehicle backed between the ramps, a locking device on the container located on the chassis and as the container was pulled clear it engaged back on chassis.
This system allowed considerable flexibility both at the transfer station and at the disposal site. At the transfer station containers could either remain on the chassis for loading or be demounted on to ramps at the loading positions. Additional ramps could be installed to hold spare containers, thus providing storage capacity.
At the disposal site ramps were installed to receive containers from the road vehicles to be handled later by the special site chassis. Other advantages of this system were the elimination of sub-frames and hydraulics on the road vehicles, thus reducing tare weight, simplicity of operation and low cost, and reduced licensing duty as the container was not included in the unladen weight.
GLC experiments Mr Patrick said GLC experiments had assessed the practicability of the system for payloads of up to 17 tons on 32-ton-gtw artics. A container 30ft long, 8ft wide and weighing 2 tons, built for the trials, was loaded with baled tins in excess of the per-. mined gross weight. Tests were carried out using a standard 32-ton outfit with skeletal semi-trailer, and no problems were experienced in mounting or demounting the loading container. As a result of the test the system had now been introduced at one of the.GLC's transfer station and landfill sites. Another decision facing the designer of a refuse transfer station, said Mr Patrick, was choosing the method of load discharge from the transfer vehicle. Tipping gear, although favoured by many operators, had disadvantages. For instance, tippers up to 70 cu yd capacity were unstable on soft surfaces and apart from risk of capsize had severe stress imposed on chassis. If large tippers were used, tip management should where practicable be arranged to allow vehicles to discharge at the base of the tip where the ground was more stable, rather than on the soft surface of freshly topped refuse.
Horizontal discharge was preferred — being safer, it put less strain on the chassis and created less disturbance of the refuse on discharge. However, when carried out by multiple hydraulic ram and end plate equipment the method carried a substantial weight and cost penalty if each vehicle was to be fitted with the necessary equipment.
Hydraulic discharge gear could be dispensed with altogether by adopting a system of cable discharge as used in the United States. At the transfer station, cables were laid along each side of the floor of the vehicle, crossed at the front end and carried up at the top of the body. After the refuse had been loaded the cables were laid along the top of the load to the back of the vehicle in one quick operation. The method was effective and minimized unladen weight. However, it occupied additional bulldozer time on the disposal site and labour in handling the cables at the transfer station and the landfill site.
Californian system A site in California had two specially designed tipping platforms mounted on tracked platforms which then tipped the whole vehicle to discharge the load. This system also minimized vehicle tare weight and cost, but money spent on the special tipping machines would only be justified in a large-scale operation. The capital and operating costs of transfer and transport systems he had described depended, he said, very much on local conditions. Bulk transport systems might be council operated or contracted out to individual hauliers. The choice depended on council policy and the availability and competitiveness of suitable contract transport. One important factor vas that all disposal systems with a large oad transport cost element were likely to ise substantially in the future quite apart rom inflationary increases. New legislation low affecting local authority vehicle iperation and maintenance was certain to ead to higher overall costs. Ideally, ransport from road transfer refuse stations .hould operate at times when road transport vas at a minimum, ie outside normal lay-work hours.
Additional wage costs of shift work could te more than offset by the additional loads arried as a result of less-congested roads. kn operation of this kind would involve ;torage at the refuse transfer station where ;ollection vehicles usually arrived between 8 nn and 4 pm and special arrangements at he disposal site to receive transfer vehicles )ut of normal hours. Mr Patrick said he felt ;ertain that some system such as this would )ecorne necessary in the very near future as raffle density grew.
Mr W. Jenkinson, a district secretary of he TGWU, in a paper on management in sublic cleansing work said that he had :xamined the present costs and working wactices of a large city cleansing lepartment in the North of England which iossessed a mixed fleet of 265 vehicles from efuse collectors to gulley empties and now-clearance machinery. The cost of iperation of vehicles had averaged £1400 Ind the total cost of vehicle operation for his authority in one year had amounted to to less than £371,000. However, more ffective use of vehicles and manpower ould have provided a much improved ;ervice of refuse collection and disposal to he public. He felt that by working a hree-day week on bin emptying and ubbish disposal, but more hours in each lay at least 12 the continuity of lervice would increase by a more regular Ind sustained effort by the employees.
Vehicles, often terminated a shift, he said, )y travelling to the tip with only a part load. 3y virtually doubling the working day the ncidence of part loads would be reduced with a subsequent increase in the number of )ins emptied each day.
The maintenance and cleaning of nunicipal authority vehicles, he urged, ;hould be done outside the working shift tnd therefore should be carried out by an wening and all-night staff in the same nanner so effectively used by the passenger .ransport industry.
In his presidential address the new )resident of the Institute, Mr R. E. Bevan, iirector of public cleansing to the City of Vianchester, said the Institute had been )articipating in the inhprovement of the )nvironment for well over 70 years. —We .herefore welcome the increasing interest )eing shown in this sphere. We would very
much like to see an increasing eMphasis on obtaining sufficient funds and facilities to provide and maintain the basic services, clean water, sewage disposal and refuse collection and disposal services, which will always form the very foundation of environmental improvement."
Mr Bevan said the future reorganization of local government held out the hope of creating a more comprehensive and integrated management of solid wastes with more imaginative and positive use of neglected sites for land reclamation. The site on which the vehicle demonstration and exhibition of the Institute was held, at Kings Valley, Bournemouth, had been reclaimed many years ago by controlled tipping.
Mr Bevan said that during his term of office he would like to see a concentration of effort by the central Government in sponsoring a Controlled Research Development Project which would include the building of a full-size refuse handling plant with access to some large sources of refuse of all kinds, including toxic wastes, and with access to suitable land for final disposal. This would enable experimental work on types of vehicles to carry waste and toxic materials and other methods of disposal and collection of refuse.
It was unfortunate that the schedule of refuse sites now being examined by various working groups in preliminary work for 1974 and beyond was based on lists prepared with an out-of-date attitude in mind. Mr Bevan told delegates: "We are not likely to see much change until the new Solid Waste Authorities are established and have the opportunity to practise the new thinking suggested by the working party on refuse disposal."
These long-term policies, he explained, could not be properly determined until the land survey had progressed. Enough scientific and technical knowledge was currently available to solve all refuse and waste disposal problems including toxic waste. What was needed was the improvement of the managerial and administrative machine to organize and implement control. At present it seemed that any attempt at maintaining, let alone improving, municipal and city services depended on stamina, patience and appreciation of human nature plus a thick skin rather than new types of vehicles and new technical processes.
Mr G. Staples, of Urwick, Orr and Partners Ltd. in a paper on management and its application to public cleansing, said 'no one could be in any doubt that changes in local government structure would bring problems. New technical skills would be required and the enlargement of authorities would call for an increasing application of managerial expertise and knowledge of vehicle use and care. However, with technical advance and a greater awareness of the need to give more attention to improving the environment, increasing satisfaction would be gained from the tasks to be encompassed within the public cleansing sphere.
Mr I. L. Cooper, a fellow of the Institute of Public Cleansing, speaking on refuse storage and collection, said the original 1+ Cu yd capacity container weighing about 2cwt was frequently loaded with 5cwt of refuse during the immediate post-war years. Today, however, the average payload was less than 2cwt. To suit present needs, he felt a system should be introduced utilizing an existing 1+ cu yd capacity container but incorporating a system of refuse compression which included in the design some form of self-cleansing. This would go a long way toward reducing costs.
Mr Cooper said that another system being developed used the standard 11 cu yd container to store compressed refuse. This embodied the use of a refuse shredder /compactor which could be sited beneath a refuse shute and the refuse fed into a standard lf cu yd container. This machine could, it was claimed, shred, crush or flatten all types of glass, metal and plastic containers including aerosal cans, glass bottles and metal drums and also allow non-compressible objects such as telephone books, to pass through a shredding chamber without damage to the mechanism of the vehicle involved.
Maintenance standards -Mr P. M. Shepherd, division manager of H.B. Maynard and Co Ltd, of London, speaking on maintenance standards in public cleansing said that through the entire development period of British industry vehicle engineering maintenance had been considered "a sort of fire brigade". It had trailed other functions in terms of control, management technique and the measurement and planning of work. It was always regarded as a necessary, but increasingly expensive force to correct faults on commercial and municipal vehicles and equipment. However, with the everincreasing cost of labour and downtime of vehicles plus new and coming legislation managements' interests in maintenance had become more critical and necessary. Engineering work should be planned and controlled, producing increasing vehicle availability despite the additional costs.
The four-day conference included a parade of more than 100 vehicles used by municipal and city authorities (CM May 19). Hundreds of delegates also attended a demonstration of earth-moving machinery and heavy plant and an exhibition of vehicle appliances and equipment.