| Economics |
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| What are the transportation cost issues? IntroductionHaulage costs are a huge component of aggregate production costs. Aggregates are a heavy, high volume product for which costly equipment and fuel is required at all stages: loading, transportation and unloading. Construction activity is focused in our major conurbations. To be as close to their markets as possible, concrete mixing plants (major consumers of aggregate) are generally located on the fringes of our conurbations - often at great distance from the quarries supplying the raw materials. Aggregates can be transported by road in lorries, by rail, or by water - by sea or inland waterways. Economics are the primary driver in determining the mode of transport used, although environmental considerations are increasingly being taken into consideration. In 2001 about 90% of total aggregate sales from sites in England and Wales were delivered by road, compared with 8% for rail and 2% by water. Road
Rail
A barge being loaded on the River Trent. |
Loading a truck in a quarry. As aggregates are sold by weight, weighing facilities are required. Weighbridges measure the weight of the empty lorry on the way into the quarry (tare weight), then subtract this from the weight of the full lorry before it leaves (gross weight) to calculate the quantity of mineral onboard.A significant proportion of the aggregate extracted from UK quarries is sold in areas located many miles away from the source of supply where transportation by road is economically unsound. For instance, there is a absence of hardrock aggregate deposits in the south-east, supplies are currently brought in by rail from the nearest hardrock sources, the Mendip Hills (limestone) and Leicestershire (granite). Rail transportation is generally preferable to road on environmental grounds: rail haulage is an energy-efficient option, each trainload of aggregates can eliminate up to seventy-five truck trips. Utilising rail transport requires significant capital investment to establish loading and unloading facilities. The quarry must also be linked to the existing rail network. To justify this expenditure the quarry output must be large - several million tonnes per annum. Material is then fed directly into rail wagons from storage silos or bunkers via conveyor belts. The customer - either the final consumer or distribution centre - will be required to accept large unit loads and invest in terminal facilities. Rail transportation is therefore currently limited to supplying large consumers in the larger conurbations such as London and Birmingham. However, a recent development, Self Discharging Trains (SDTs) which do not require sophisticated reception facilities, has increased the feasibility of wider exploitation of the rail network. Self discharging trains now supply certain concrete mixing plants that formerly received supplies by road. Water Where convenient waterways exist, use is made of ships and barges. Again it is environmentally preferable to road haulage on both cost per tonne per mile and environmental grounds. Major rivers such as the Thames and Trent are used by some aggregate transporters. The ships or barges are loaded in a similar fashion to rail wagons and again require significant investment in infrastructure to facilitate loading and unloading. Around 3 million tonnes per year of crushed rock is transported by ship from a few coastal quarries, mainly to London and the south-east. The largest tonnages are shipped from Britain's only coastal quarry at Glensanda on Loch Linnhe in western Scotland, principally to southern and eastern England. Seaborne imports of crushed rock aggregates from Norway, France and Ireland are also landed in the south-east. |
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