Last edited 18 Jun 2021

Swing bridge

BartonSwingRoad.jpg
The Barton Swing Road Bridge (pictured on the right) is controlled from a brick tower situated on an adjacent island. The Barton Swing Aqueduct (pictured on the left) is controlled from the same tower. Both were designed and built to pivot open for ships that needed to travel through the Manchester Shipping Canal.

Contents

[edit] Introduction

Bridges are a common feature of the built environment and one of the key elements of civil engineering. The basic principles of bridge design are dependent on the load-bearing structure. These are generally beam, arch or suspension structures.

[edit] Movable bridges

Movable bridges are designed in a way that allows them to accommodate different situations and the flow of different types of traffic. One kind of movable bridge is a swing bridge.

While a swing bridge in England is defined under Section 329 of the Highways Act 1980 as, “...any opening bridge operated by mechanical means”, this broad interpretation would include other mechanised opening bridges, such as certain types of drawbridges, lift bridges, retractable bridges and so on. For clarification, a swing bridge is a movable bridge with a deck that rotates around a fixed point, in some instances working in a similar way to a gate.

[edit] How do swing bridges work?

Some swing bridges have two moving parts that swing to the sides. This clears a central channel. Others pivot on a central support, which opens one (or sometimes two) waterway channels.

MovableBridge swing.gif

Swing bridges generally make a one-quarter turn to pivot 90°. However, some may open to smaller angles, depending on the orientation of the bridge and the waterway.

[edit] What do swing bridges do?

These structures are typically used to manage road or rail traffic above busy waterways. When the swing bridge is closed, road or rail traffic can travel freely over the waterway. For busy roads, this is often the default position.

When water traffic needs to pass through, traffic signals or barriers are activated to prevent road traffic from crossing. The bridge is then mechanically activated so it swings or pivots into place, allowing sufficient space and time for boats, barges and other watercrafts to pass through the channel (or channels) safely.

Swing bridges are considered beneficial in certain circumstances, but they can cause issues when controlling the flow of traffic in busy areas. They can also create navigational concerns for large water vessels or inexperienced boat operators.

[edit] Oldest and newest swing bridges in the UK

The oldest swing bridge in the world is the hydraulic Swing Bridge over the River Tyne. This Grade II listed structure is believed to be one of the few remaining 19th century swing bridges still in operation in the UK.

SwingBridgeTyne.jpg
Photo of the Swing Bridge, the Tyne Bridge and the Millennium Bridge in the distance taken from NZ2563, The High Level Bridge.

Initial designs for the Swing Bridge were drawn up in the 1860s by John Ure, the resident engineer of the Tyne Improvement Commission. These designs would be further developed and financed by the engineer and inventor Sir George R Armstrong (whose company would later devise the mechanisation required to operate London’s Tower Bridge). An earlier bridge on the site was demolished in 1868 and construction of the new bridge was completed in 1876.

The bridge, which requires approximately six minutes to complete a full rotation, underwent a significant renovation in 2018. However, Armstrong’s hydroelectric powered engineering mechanisms have been kept in working order and still operate as originally designed.

The Gateshead Millennium Bridge designed by WilkinsonEyre, is unusual in that it tilts to allow shipping to pass underneath.

In March 2021, plans were announced for a new swing bridge over the River Clyde. The bridge will be designed for vehicles, pedestrians and cyclists and will open at regular intervals to accommodate shipping. The bridge will span from Renfrew to the boundary between Glasgow and West Dunbartonshire. It will have a twin-leaf design - making it a double swing bridge - with each leaf opening and closing horizontally.

[edit] Other noteworthy swing bridges

There are many examples of swing bridges all over the world.

AlFerdan.jpg
The El Ferdan railway bridge is no longer functional, due to the expansion of the Suez Canal.

The longest swing bridge in the world is the El Ferdan Bridge in Egypt. This railway bridge has a span of 340 m and crosses the western shipping lanes of the Suez Canal.

Some of the other noteworthy swing bridges in the UK include:

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[edit] External resources

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