Mk1 Inglis Portable Military Bridge (Light Type) over the Basingstoke Canal, , Hampshire

Summary

A Mk1 Inglis Portable Military Bridge (Light Type) from around 1916, also known as the Inglis Pyramid Bridge, now used to carry services across the Basingstoke Canal.

Description

A Mk1 Inglis Portable Military Bridge (Light Type) from around 1916, also known as the Inglis Pyramid Bridge, now bridging the Basingstoke Canal.

MATERIALS: metal tubes, and pre-cast, angled junction box fittings.

PLAN: the bridge spans the Basingstoke Canal, running from north to south.

DESCRIPTION: the bridge is pyramidal in section with three sets of 'W' trusses forming the sides which are attached via angled fittings to a single run of tubes, forming the apex. The walkway floor has regularly spaced angled fittings for a walkway and diagonally-tensioned, wire braces.

Each end of the bridge is located on a later-C20, brick wall; these are integral to the buildings structure but have lesser interest. At walkway level, timber planks* and one metal beam have been added, along with a sewer pipe*.

* Pursuant to s1 (5A) of the Planning (Listed Buildings and Conservation Areas) Act 1990 (‘the Act’) it is declared that these aforementioned features are not of special architectural or historic interest. However any works which have the potential to affect the character of the listed building as a building of special architectural or historic interest may still require listed building consent and this is a matter for the LPA to determine.

History

The First World War led to a rapid development of all forms of military bridging. In 1914, Charles Inglis (1875-1952) was commissioned into the Royal Engineers and appointed to the War Office where he was in charge of bridge design and supply.

During the First World War he invented the Inglis bridge, a lightweight, portable and reusable steel bridge, designed for rapid erection and deployment in combat conditions. It was also known as the Inglis Pyramid Bridge, so named because of its triangular construction. This bridge type was effective in the field, being easily transported and requiring little specialist training to erect. The construction members were 8ft long steel tubes connected by specially designed fittings. The 'W' profile of the girders was called a Warren Truss, after a captain of the Royal Engineers of the same name. Although the transoms were heavy at 198 pounds, the tension tubes were very light and this, coupled with the simple construction technique, enabled a 108 foot long bridge to be completed in around 15 minutes. They were usually assembled by a team of 12 men using a turntable and counterweight on the home bank side, allowing the pre-erected structure to be swung across the river to the far bank. It was intended for use by infantry although it was also able to carry 3 ton vehicles by pairing two bridges and keeping the centres less than 16 feet apart.

The tubes were fabricated at the Round Oak steelworks in Brierley Hill, West Midlands. The junction box angled fittings were manufactured by Kryn & Lahy, a company established by Belgian refugees. 10 sets were ordered and delivered to France for use during the First World War.

The Inglis bridges were an important precursor to the Second World War Bailey bridge and all later, C20 portable bridges.

In 1918, Inglis retired with the rank of Major and was awarded the Order of the British Empire (Military Division). Returning to Cambridge he was knighted and became Professor of Engineering, a post he held until his retirement in 1943.

An example of an Inglis bridge is known to have been located across a waterway in Belton, North Lincolnshire. This was later broken up into components for restoration at Chetwynd Barracks, Chilwell. Two sections are known to be in the Royal Engineers Museum at Gillingham.

A listed example of a Mk2 bridge, which used longer tubes and heavier construction to support vehicles over longer spans, is located in Monmouth, Wales, and is listed at Grade II by CADW (reference 87635).

The bridge across the Basingstoke Canal at Aldershot, appears to be the only complete Mk1 Inglis Pyramid Bridge remaining in situ, in England, although it was relocated here from France, to allow pedestrian and services to connect between the various barracks in the area. It is first shown on the 1963 edition of the Ordnance Survey map, however a canal crossing is shown on 1944 aerial images.

Adjacent and on the north bank, there is a Second World War pillbox which was part of Aldershot’s General Headquarters Line (GHQ Line), designed as part of a wider ring of defence, built to fight a German invasion. The pillbox was restored in 2016 by The Land Trust.

Reasons for Listing

The Mk1 Inglis Portable Military Bridge (Light Type) from around 1916, also known as the Inglis Pyramid Bridge, which crosses the Basingstoke Canal at Aldershot, is listed at Grade II for the following principal reasons:

Historic interest:

* as the first portable bridge by Charles Inglis (1875-1952), which was used effectively on the battlefield during the First World War and was hugely influential in the development of future military bridges;

* it is a rare example of a Mk1 Inglis bridge, which is only one of ten known to have been manufactured during the First World War and probably the only example in use as a bridge in England;

* as one of the relatively few military structures in England that date from the First World War.

Architectural interest:

* for the innovative lightweight and component based design, which allowed a team of 12 soldiers to erect the structure in around 15 minutes.

External Links

Historic England Listing

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