| Summary : The current Whitby Swing Bridge is believed to occupy a crossing point on the River Esk that has been used since the early 14th century by a series of openable bridges (se HOB UID 1495388) designed to allowing the movement of shipping on the river. The current swing bridge dates to 1909 and was built for Whitby Urban District Council as a replacement of an earlier swing bridge of 1834 which had been commissioned by the County Council.The current bridge was designed by J Mitchell Moncrieff, a Newcastle based marine and structural engineer and was built by the engineering company Heenan and Froude Ltd, Manchester, with their works in Worcester undertaking the fabrication. The bridge was electrically operated from the start, with provision for manual operation in case of failure. The steel plate girder bridge is set on masonry piers protected by timber dolphins, it has masonry abutments and a timber framed operator's cabin. The bridge is formed from a pair of cantilevered leaves which rotate independently through 90 degrees on vertical axes centred on the piers, the two leaves meeting in midstream to bridge the river. The structure was assessed for listing in 2012 but failed to meet the required criteria. |
More information : The current Whitby Swing Bridge is believed to occupy a crossing point on the River Esk that has been used since the early 14th century by a series of openable bridges (se HOB UID 1495388) designed to allowing the movement of shipping on the river. The current swing bridge dates to 1909 and was built for Whitby Urban District Council as a replacement of an earlier swing bridge of 1834 which had been commissioned by the County Council.
The current bridge was designed by J Mitchell Moncrieff, a Newcastle based marine and structural engineer and was built by the engineering company Heenan and Froude Ltd, Manchester, with their works in Worcester undertaking the fabrication. The bridge was electrically operated from the start, with provision for manual operation in case of failure.
The steel plate girder bridge is set on masonry piers protected by timber dolphins, it has masonry abutments and a timber framed operator's cabin. The bridge is formed from a pair of cantilevered leaves which rotate independently through 90 degrees on vertical axes centred on the piers, the two leaves meeting in midstream to bridge the river.
The bridge is of steel plate girder construction with the footpaths cantilevered out to either side of the central carriageway giving a total width of about 7m between the parapets. The parapets are formed from diamond set steel lattice, with lamp standards to each one, positioned above the piers. The bases of two of these lamp standards (replaced in 1984) contain the operating equipment to turn each leaf of the bridge; the replacement hydraulic motors being beneath the carriageway, engaging with a ring gear set on each pier. To open the bridge, access by vehicles and pedestrians is first closed with 6-bar gates (also replaced 1984) hung on ornamented gate posts which are sited at each abutment. Closing these gates originally released locking bolts which locked the rotating sections of the bridge into the abutments: this mechanism no longer survives. The rotating sections are locked together and into the abutments with hydraulically controlled locking pins (installed 1984). Once released, the two rotating sections rock backwards (so that the middle of the bridge rises slightly) to disengage from pairs of stools (redesigned 1984) upon which the bridge rests when closed. The two leaves of the bridge then rotate through 90 degrees to point up stream, leaving a clear opening of just over 21m (70 feet). When closing, the original design used a catch between the two swing spans to centre the bridge and prevent over runs. This is now replaced by hydraulic over run buffers and a separate centring mechanism.
The piers and the bridge spans (when open) are protected from collision with shipping by dolphins: timber jetties, mainly lacking decks, formed from piles tided together by horizontal members and cross braces. The current form of the Dolphins are not as originally built, and have been shortened on the seaward side.
Th operator's cabin on the north side of the west abutment there is a small rest shelter for the bridge operator. This is timber framed, with a red tiled, hipped roof. At the northern corner of the building (providing a view of the harbour) is an oriel window topped by a finial in the form of a sunflower.
It had been thought that the only later alteration to the bridge was the replacement of the original pitch covered timber-blocks with tarmac, and slight alterations to the width of the pavements flanking the carriageway. This is now known to be incorrect. Engineering records show that the bridge was modified in the early 1970s with the redesign of hydraulic locking mechanisms, over-run buffers and a centring device. In fact these records indicate that these alterations were to items that were themselves modifications to the original design. Alterations to the bridge in 1984 were even more extensive, including the complete replacement of the original direct current, electrically powered mechanisms with hydraulic powered units. This also entailed modifications to the gearing and the bearings of the bridge (including the rocking pin, roller bearings and support stools). The deck of the bridge was also altered, not only with the replacement of the original timber blocks, but with the replacement of the original buckle plates which formed the deck with flat steel sheets. Since 1984 there have been further repairs and modifications including the replacement of a large section of stonework to the western pier with concrete moulded to match the original.
The bridge was assessed for liting in 2012, but did not meet the criteria required for addition to the list for the following reasons:
Design (Architectural): the gracefulness of the span of the bridge and the overall architectural detailing is fairly typical for the Edwardian period and is not of special interest.
Design (Technical): although an elegant solution to the competing requirements of shipping and land based traffic, the bridge is considered to be fairly ordinary from a technical viewpoint. Alteration: the mechanism and a number of aspects of the bridge's operation have been significantly altered by later 20th century alterations to the bridge, significantly by its conversion from direct electrical operation to hydraulics. (1) |