Falkirk Wheel
A grand engineering statement, the Falkirk Wheel is the only rotating boat lift (boat elevator) in the world. Since the opening in 2002, the Falkirk Wheel became undoubtedly one of the most important thing that happened in the region and is located near the town Falkirk in Central Scotland.
The Falkirk Wheel connects Forth & Clyde Canal and Union Canal, providing a corridor of regenerative activity through central Scotland. The Wheel makes it possible to travel between Edinburgh and Glasgow – Scotland’s two largest cities – by boat. Originally, a series of 11 canal locks connected these two canals, but they fell into disrepair and were dismantled in 1933. The Falkirk Wheel re-crearted this a major link and undoubtedly in a much more efficient way.
The original concept of a wheel is set back to 19th century but it started to be a solution for Falkirk only in 1994. Dundee Architects, Nicoll Russel Studios presented a Ferris Wheel type design that was used to establish a project called Millennium Link.
In the beginning of the construction, there was one serious problem that had to be overcome as & Clyde Canal was 35 m (115 ft) below the level of the Union Canal. The British Waterways (Scottish Canals) had a breakthrough idea of the world’s first and only rotating boat lift – the Falkirk Wheel as we know it now.
Wheel Mechanism
Each boat enters the Roughcastle tunnel to the Union Canal. The upper trolley is lowered with water that they float in, to the basin below and at the same time, an equal weight rises up, lifted in the other trolley.
Each trolley runs on small wheels that ft into a single curved rail fixed on the inner edge of the opening on each arm. In theory, this should be sufficient to ensure that they always remain horizontal, but any friction or sudden movement could cause the trolley to stick or tilt.
To ensure that this never happens and that the water and boats always remain perfectly level throughout the whole cycle, a series of linked cogs acts as a back-up. At each end are two, in diameter 8 m cogs, to which one end of each trolley is attached. The wheel is closed down for approximately three weeks each year for essential maintenance routines on major components, such as pumps and valves. During shutdown, engineers are able to thoroughly examine the wheel and inspect the structure and make any necessary improvements.
The uniqueness of the structure required innovative and unconventional design methods. UK design codes for bridges, buildings and floating vessels were utilised, as well as Norwegian, German and American codes for such criteria as thin-walled cylinder behaviour, barge impact and constrained ice loading. The Wheel was analysed using finite element techniques including non-linear solid continuum modelling for movement sensitive connections. The rotation of the wheel undergoes full directional reversal up to 40 times per day. This constant wearout became the compelling influence over the design of the structure.
Wind effects and thermal movements became the principal “live” loads on the wheel (it is designed to resist a 120-year return period Scottish Storm and operate in Beaufort 6 speeds) and placed it beyond the scope of codified recommendations. So, a 1:50 scale model was built and wind-tunnel tested to provide fortitude that the assumed loads and behaviour were reasonable.
Construction
Designed to last 120 Years, the Falkirk Wheel project was taken over by 1000 people who took part in construction, including several ICE members. Early challenges included tar and mercury contamination as the ground had previously been used as a mine and tar works. Other early stage work included laying 600 m of access to roads to get plant and materials to the site.
Once the area was cleared, engineers dug deep foundations for the structure and used 22 m concrete piles socketed onto the bedrock for support. The wheel was constructed and fully assembled at the Butterley Engineering plant in Derbyshire. It was then dismantled and driven to Falkirk in 35 lorry loads. Workers reassembled it into 5 sections which were lifted into place. As the wheel rotates in alternate directions, the changing load can cause stress to parts of the structure. To avoid fatigue – weakening caused by repeatedly applied loads – engineers bolted sections together instead of welding them.
Vital Stats
With an overall diameter of 35 m the Falkirk Wheel consists of two opposing arms extending 15 m beyond the central axle. The design is that of a Celtic double headed axe. Two sets of these axe-shaped arms are connected to a 3.8 m (12 ft) diameter central axle of length 28 m (92 ft). Two diametrically opposed water-filed caissons or trolleys, are fitted between the ends of the arms. These trolleys each have an impressive capacity of 250,000 litres.
The design takes advantage of the Archimedes principle to maintain water levels and thus balance the weight of the gondolas. It maintains the water levels on each side to within a difference of 37 mm (1.5 in) using a site-wide computer control system comprising water level sensors, automated sluices and pumps. It takes 22.5 kW (30.2 hp) to power ten hydraulic motors. This consumes 1.5 kW-hours (5,100 BTU) per half-turn, roughly the same as boiling eight kettles of water. Each of the two trolleys is 6.5 m (21 ft) wide and can hold up to four 20 m long (66 ft) canal boats.
Facts
The final design is claimed to have been inspired by a Celtic double headed spear, a vast turning propeller of a Clydebank built ship, the ribcage of a whale and the spine of a fish.
1998 -Work started on the ambitious £84.5million Millennium Link projects to re-join the two canals.
Parts were constructed and assembled, in Derbyshire, then dismantled and transported to Falkirk in 35 lorry loads before being bolted back together and craned into position.
1,200 tonnes of steel was used to create The Wheel and over 1,000 construction staff helped to build it.
The structure contains over 15,000 bolts which are matched with 45,000 bolts holes. Each of these bolts was hand tightened.
The 600 tonne gondolas hold 500,000 litres of water.
The Wheel only uses 1.5kWh of energy to turn, the same amount as it would take to boil 8 household kettles.
Reference
https://www.scottishconstructionnow.com/articles/and-finally-engineering-secrets-of-falkirk-wheel-to-be-revealed-to-public
https://blog.wor-con.com/tuesdays-marvels-of-engineering-the-falkirk-wheel/?lang=en
https://www.tonygee.com/our-work/falkirk-wheel
https://www.ice.org.uk/what-is-civil-engineering/what-do-civil-engineers-do/ falkirk-wheel 5. https://www.mamasmiles.com/falkirk-wheel/
By -
Tuhina Chatterjee, Associate Editor Civil Engineering and Construction Review
