Monument record MDO47227 - Skew Bridge, Norden, Corfe Castle

Cast iron skew bridge with concrete abutments. Built in 1885 for horse drawn ropeway. Later altered for tramway use in the early 1900s, and remodelled in 1938 and 1949.

Ball clay is known to have been extracted in the vicinity of the site since the Roman period and an open cast pit was established to the west of Norden in the 1760s. Prior to 1885 this clay was hauled from the pit by an inclined ropeway system. In 1885, however, the London and South Western Railway branch line to Swanage was constructed dissecting the incline and necessitating the construction of a bridge to carry the ropeway. This bridge consisted of a wrought iron inclined platform supported by concrete abutments. After the pit had become redundant in the early 1900s the area was backfilled and the bridge converted into a tramway for the neighbouring mines and pits. Earthen fill and timber decking was used to raise ground-levels to carry three narrow gauge lines across the bridge. The timber decking decayed and by 1938 the Southern Railway removed the earthen fill and rebuilt the central section of the bridge to be horizontal. Further alterations were made to the gauge of the central section of the structure in 1949.

The structure, which dates from 1885, consists of a disused tramway skew bridge constructed of wrought iron decking with ranking concrete abutments. The decking can be divided into three separated spans comprising two outer sloping sections and a horizontal central section. The outer spans consist of 150 x 400 'I' section beams of 10.7metres in length and sloping at a gradient of 1 in 12.5. The 'I' beams are supported by curved lattice girders and are fixed to the concrete abutments. The outer 'I' beams are surmounted by iron railings. In contrast to the sloping outer sections, the central section of the bridge is horizontal and consists of 'I' section beams supporting timber crossbeams and iron tramway rails.

Given the large number of bridges which survive throughout England, selectivity is required when considering them for designation in a national context. In order to be recommended for listing the structure is required to be of special architectural, planning, engineering and technological interest such as an early example of its type or to be associated with a particular technological innovation of national significance. When examining railway bridges there is a presumption in favour of listing most pre-1840s bridges, where they remain intact, as these structures represent early examples of this type. The 1840s saw a massive expansion in the railway network and structures from the 1860s onwards require rigorous selection in their assessment. Skew bridges became a necessity throughout England after the establishment of canal and railway systems when it became inconvenient to divert the course of the line to ensure a right-angled crossing. Designing arched structures to accommodate the skewed angle required a technological innovation and the first bridges to pioneer these techniques date to the late-18th century and were associated with the canal system. From the mid-19th century, the establishment of the railways resulted in a rise in these bridges popularity. This popularity is evidenced by the sixteen brick and stone skew bridges constructed for the Liverpool and Manchester Railway, opened in 1830. Following the development of iron girder or truss bridges, however, the technological innovation of the skewed arch was superseded and it became considerably easier for an iron deck to span at a skewed angle. The development of cast and wrought iron bridges began in the mid-18th century and the technological advancements progressed rapidly throughout the following century. The design of thinner girders with an 'I' section beam was of particular significance and was patented by Fairburn in 1847. Following the patent, Fairburn became a major supplier of plate girder bridges and by 1870 he alone claimed to have built nearly 1000 bridges with spans ranging from 40 to 300 feet. By 1885, and the construction of the Norden Tramway Skew Bridge, neither the concept or skill required for engineering a skew bridge were pioneering or technologically ground-breaking. The 'I' beam girders were patented nearly 40 years prior to its construction and the technology was commonplace well before the 1880s. In addition the ranking abutments of the Norden Tramway Skew Bridge are constructed of concrete. Techniques for the construction of concrete bridges were pioneered on the continent and in the United States, and were used in Britain from the 1870s onwards. A number of significant bridges have been constructed of concrete and the Axmouth Bridge which is listed at Grade II* is an impressive example of its type. The Axmouth bridge was built in 1877 and, in contrast to the skewed tramway bridge, it is built entirely of concrete with three segmental arches, rusticated piers and a decorated parapet. The limited use of concrete within the Norden Tramway Bridge is not sufficiently early to represent a technological innovation and its functional appearance is not considered to be of any architectural significance. The structure has also been subject to considerable alterations with the central section of the bridge rebuilt in 1938 and further altered in 1949. The Tramway Skew Bridge displays some interesting features of local interest and the structure contributes to the understanding of ball clay extraction which holds significant interest to the local area, as demonstrated by the adjacent Ball Clay Mining Museum. The structure is an important element of the mining landscape and contributes to the setting of the museum. Despite the significant local interest which this structure has it does not meet the very high standards required of a late-19th century bridge to merit designation in a national context. <1>

<1> English Heritage, English Heritage Listing File, Adviser's report on case 166814 (Scheduling record). SDO17502.

<2> National Record of the Historic Environment, 1494549 (Digital archive). SDO14739.

Record last edited

Oct 9 2023 1:14PM