Bridge Engineering Is Continually Evolving

The consultant engineering partnership Tony Gee is celebrating its 50th anniversary this year – from the Murray River in Australia to the River Exe in Devon the business has always been known for its bridges. Tony Gee’s structures specialist director Riccardo Stroscio looks at where the world of bridge engineering is heading.

Riccardo Stroscio is structures specialist director at Tony Gee & Partners

Bridge engineering is a passion – and it has to be. It’s a discipline where you frequently come up against very testing challenges and you have got to believe in what you are doing to be successful.

Tony Gee has been involved in bridge design from the earliest days of the business 50 years ago and our team has seen major changes in that time. When the company was founded, our former colleagues were doing all their calculations by hand and using slide rules and drawing boards; the technology we have now has transformed the process.

We can optimise solutions and design a lot faster now to deliver more ambitious projects, within budget. Digital is the norm and rather than starting with drawings, we are working with 3D models right from the beginning of our projects.

This technical evolution has changed our relationship with bridge architects and urban planners, which is now closer than it ever was before.

We all have a strong interest in the structural integration into the surrounding environment, because so much of our work is for the public eye and people want to see bridges which look pleasant and interesting.

Engineers will always prioritise safety, buildability and sustainability, while the architect is likely to have an additional degree of focus on the human element and the aesthetics. The collaboration works best when we are consulting each other from the earliest stages of a project.

For example, I worked on a highway bridge to span the River Nene at the University of Northampton’s Waterside campus development in 2016, the  architect’s design was founded on a 50m span flat concrete arch which was going to involve placing a lot of temporary works into the river for support during construction. But, as part of the design and build competition, we wanted to use steel as an alternative – that meant we could build the bridge in two main parts modular style and be able to install components with smaller cranes and a temporary floating pontoon for access, offering minimal intrusion into the river.

University of Northampton by MCW Architects. Copyright Peter Landers / Jim Stephenson 2018

Our approach was significantly more efficient for the client, but understandably, the architect was very interested in how the midspan connection would look and whether the bridge would appear as intended if it was made of steel rather than concrete.

We were able to design the connection to be very discrete and, once painted, the structure looked as in the architect’s concepts. The process went smoothly because the communication between us was good from the start and we were all working towards one desired outcome.

Engineers need to start thinking about their relationship with architects and other construction disciplines from university onwards. Engineering degrees tend to be broader based than they were, and it is an advantage if graduates understand how they are going to be interfacing with architects and other built environment specialists during their careers.

The focus on sustainability is arguably the biggest change we’ve seen in bridge design since the early days of Tony Gee.

Like all parts of the construction industry, bridge construction and design use a lot of energy and a lot of raw materials. We are making progress to reduce both, but it remains a challenging area because, as well as being structurally efficient , our designs also have to withstand the increasingly extreme impacts of climate change.

Disasters like the floods in Valencia in November 2024 will mean bridge designers have to think more about extreme climate events. Some of the flood levels we are considering now would have been unbelievable to people working here at Tony Gee when the company started 50 years ago.

So, at each project stage, as well as keeping in mind structural safety, constructability and durability, we also look at how we can cut the carbon impact of our designs. At Tony Gee we have a brilliant sustainability team – part of their job is to challenge us and make sure we are being as creative as possible when it comes to using renewables and cutting the greenhouse gas emissions linked to our projects.

It’s often true that the most sustainable approach also gives the client best value for money because it involves using fewer resources.

Recycling has got clear benefits, especially with temporary works like haul roads where we can often use materials salvaged after the demolition of a previous structure. But there are limitations. For example, there isn’t enough scrap steel in the world to be recycled and used globally.

Technical authorities around the world are right to be cautious about using new or recycled materials that have not been time-tested; safety and durability are their absolute priorities. But everyone in this industry will need to collaborate to make sure we are working in the most sustainable way.

In some cases, it will make sense to test new approaches and new materials on temporary works rather than on the permanent structure. It is important to use every opportunity for research where we can, so we are able to deliver carbon savings without compromising on durability and safety.

In developed countries, current challenges are how to maintain old infrastructure to ensure safe and economic operation. Some bridges have been deteriorating to a point that they need major strengthening works, or even replacement. Bridge designers have key roles in the decision-making process in finding the solutions that would meet these demands in the most sustainable way.

For example, we adopted innovative temporary works solutions to deliver the complex and challenging Barmouth Viaduct metallic spans replacement in 2023. The unique construction methodology, which was developed by the design and build team, streamlined processes and enhanced the project delivery. It minimised the environmental impact and reduced the carbon footprint through the reuse and refurbishment of the existing substructure.

Barmouth Viaduct

These challenges are affecting us now, and they will dominate the professional lives of people coming into the bridge design world during the next 50 years. We should envy the next generation of bridge designers; they are starting at an exciting time. They will be working in different ways and, quite possibly, with different materials.

But they will have one thing in common with those who went before them: every bridge is different, has its own story (with its unique challenges) and you could say that bridge designers will only continue to design prototypes. There is no repetition, and certainly, no danger of being bored.

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