ICE Bridge Month: Bridge #13 – Firth of Forth Bridge
One of the most iconic and spectacular bridges in the world is the Firth of Forth Bridge, north west of Edinburgh in Scotland. The bridge carries rail traffic and has been open and operating since 1890. An amazing feat of engineering. Nowadays, approximately 200 trains use the bridge every day, carrying 3 million passengers each year.
Designed by Sir John Fowler and Sir Benjamin Baker, the bridge including main spans and approaches is approximately 2.5 km long. The main spans measure 1.6 km. I looked up some statistics from the book “The Forth Bridge; A Picture History” by Sheila Mackay. Over 53,000 tonnes of steel was used to construct the bridge with over 6.5 million rivets.
Large caissons founded on rock supports the pylons. Once the pylons were constructed, the balanced cantilever method of construction was used to reach out from each pylon until the cantilevers met. A lighter bridge section between cantilevers was used to give the bridge its distinctive shape.
The principle of the balanced cantilever was beautifully illustrated by Sir Benjamin Baker in 1887. I have tried to recreate his demonstration in the below sketch.
My personal story with this bridge is from July 2016 when my family and I visited Edinburgh. We stayed at North Queensferry in a bed and breakfast (B&B), right under the northern approach span! My wife knows me too well and this was the perfect placed to stay. The bridge was built over the top of B&B. You can see the house in the historic photos of the bridge construction.
When you walk up the stairs, the skylight frames the actual approach viaducts overhead (see below). Walking out the front door, I could see the Forth Road bridge, the new Queensferry crossing and to my left and over my head, the old rail bridge. Three eras of amazing bridge engineering in one place.
This is a place I will return to. It is a magical place for Bridge Engineers. Even non-bridge engineers would have to stand back and admire the amazing work the designers and construction workers left as their legacy. I hope the B&B is still there when I go back.
Legal Counsel at Ventora Group
6 年Missed my chance to visit this bridge last year during my Scottish travels. However, another site to visit are the bridges that cross along the river Clyde in Glasgow, Scotland - Over 20 bridges representing different eras of civil engineering design and technology!
Technical Director and Business Leader at CaSE & PIKE Design
6 年I mean the B&B next to the bridge abutment.
National Engineering Manager - Infrastructure driving steel growth in key projects
6 年Ken time for one of those big lovely coloured steel ones in Australia (RedCor Weathering Steel ) results in potentially Zero Maintenace of the steel structure!
Consulting civil structural engineer/manager for rail/road infrastructure, resource and energy, wastewater industry, and advocate of social justice (Sustainability and ESG) FIEAust NER CPEng RPEQ RPEV
6 年Highly recommended to visit, especially if you are a bridge engineer !!, three bridges at different era !! heavy, highly damped trusses to modern day, lightly damp, slender, susceptible to various wind-induced oscillation, modern day material marvellous cable suspended bridges.
Engineering Leader at RKF ES
6 年What an accommodation (hope they don’t increase their prices after this post) Was it noisy when the train passes?