Wednesday, July 4, 2007

Hydraulic boat lifts

When inscribing the Canal du Centre boat lifts in Belgium on its World Heritage List in 1998, UNESCO commented that they “represented the apogee of the application of engineering technology to the construction of canals.” That holds true for each example described here. The boat lifts exemplify the seemingly limitless mechanical ingenuity of the Victorian Age. The Industrial Revolution, first in Britain and then in the rest of Europe and North America, saw the necessarily rapid growth of inland transportation networks. Although they were soon augmented (and often replaced) by railroads, canals were the main arteries of industry and commerce. Differences in water levels along their length and at their junctions with rivers were normally overcome by building locks. In order to save time, creative engineers developed a hydraulic mechanism known as a boat lift, which could replace several conventional locks. Among the most ingenious devices of the machine age, the boat lift continued to be refined into the early twentieth century. The principle was simple: a boat or barge entered a watertight trough that was raised or lowered by filling or emptying a counterbalancing trough.

It is likely that the first commercial boat lift was built in 1838 on the Grand Western Canal in the English county of Devon. The canal, first suggested in 1768, was intended to link the Bristol Channel on the west coast and the English Channel on the east. Construction did not begin until 1810 and four years later an 11-mile (17.6-kilometer) stretch was completed. Extensions were built, and by 1838 the canal reached as far as Taunton in Somerset. A decade later the Great Western Railway linked Bristol and Exeter, and work on the canal was discontinued. But the boat lift served vessels carrying limestone from Tiverton

in Devon. Consisting of a pair of 30-foot-long (9-meter) wooden troughs joined by chains, it was capable of raising nearly 10 tons (8.14 tonnes) through the 47 feet (14 meters) that separated two sections of the canal.

The most important English model for others in Europe was the Anderton Barge Lift, built near the English salt-producing town of Northwich between 1872 and 1875. It lifted barges over 50 feet (15 meters) between the Weaver Navigation and the Trent and Mersey Canal. Designed by the engineers Edward Williams and Edwin Clarke, the mechanism comprised two sets of connected hydraulic cylinders and pistons, each supporting a 76-by-15-foot (23-by-4.7-meter) boat tank. In order to lift a boat, a little water was released from the lower tank; as the then heavier counterbalancing tank moved downward, the hydraulic system was activated to raise the lower tank, boat and all. The process was augmented by a steam-powered hydraulic pump. The mechanism lasted for about thirty years, but corrosion problems in the hydraulic system led to the construction of a replacement (albeit incorporating several parts of the original structure) between 1906 and 1908. The new lift continued to carry commercial traffic until the mid-1960s and recreational boats until 1982.

Early among the European clones was the lift at Les Fontinettes on the Neuffossée Canal in northern France. Built in 1888 to raise 340-ton (305-tonne) canal boats 43 feet (13 meters) from the River Aa to the canal, it replaced no fewer than five eighteenth-century locks, dramatically reducing the time needed to negotiate the network of inland waterways linking Calais and Dunkerque with the industrial center of Lille. It was replaced by a single modern lock in 1967.

Proposed in 1879, the 17-mile (27-kilometer) Canal du Centre in Belgium’s industrial Scheldt-Meuse-Rhiue Delta integrates Europe’s inland waterways. Because they survive in working condition, four lifts near La Louvière, also based on the Anderton model, are unique among their contemporaries. Each lifts boats through 57 feet (17 meters). The first, with a capacity of 450 tons (407 tonnes), was built around 1889; the remaining 340-ton (305-tonne) lifts followed between 1908 and 1917. In 1999, as part of a long-term program to increase the capacity of Belgium’s major waterways, a single hydraulic elevator was completed at Strépy-Thieu on a new section of the Canal du Centre. It is capable of moving barges of 1,500 tons (1.370 tonnes) deadweight vertically though 243 feet (73 meters)—the highest lift in the world—in tanks that weigh almost 9,000 tons (8,150 tonnes).

Because of growing industrialization in the late nineteenth century, Germany’s River Ruhr needed a transport network for raw materials and manufactured goods. In 1899 the Dortmund-Ems Canal was built to connect North Sea harbors to the Ruhr region. The Rhine-Herne Canal, completed in 1914, linked the Rhine with Rotterdam and Amsterdam. The two artificial waterways are joined by the 45-foot (13.5-meter) Henrichenburg boat lift at Waltrop. Constructed between 1894 and 1899 it was replaced in 1958–1962.

Another early hydraulic lift system was built in the New World: the Peterborough Lift Lock on the Trent-Severn Canal, connecting Lake Ontario with the upper Great Lakes and the West. Completed in 1904 it consisted of two ship lifts—each with a mass of 1,900 tons (1,730 tonnes) and rising 49 and 65 feet (14.8 and 19.8 meters), respectively—within the 4-mile (6.5-kilometer) canal, replacing eight conventional locks.

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