Design once, use often

Structures required for HS2 Phases 1 and 2A, London to Crewe

• 132 bridges
• 10 viaducts
• 5 flyovers
• 150 access and maintenance staircases
• 25 culverts

With 225km of new high speed rail line already under construction between London and Crewe in the first phases of HS2, Europe’s largest infrastructure project, the sheer number of bridges, viaducts, flyovers, access and maintenance staircases, and culverts needed presents a rare opportunity. This is to develop standardised design solutions that can be optimised and used repeatedly, bringing time, cost and also the quality benefits that come with factory manufacture.

HS2 will ultimately connect London with Glasgow and Edinburgh. Construction is under way on phases 1 and 2a

Efficiencies of scale

While no two of these types of structure are typically the same – dimensions vary – each class of asset is capable of being built using shared standard elements, such as beams, deck slabs and parapets. A ‘kit of parts’ can be designed for manufacture and assembly (DfMA). DfMA alone provides quality, safety, time and cost benefits, which we saw the opportunity to push further.

Other industries, such as petrochemicals, have benefited from using object libraries for several years, where common elements are standardised and reused. While this innovation is not new in construction, this is first time it has been used on a project of this scale.

500 designers collaborated on Phase 1

Across the first phase of HS2 we had some 500 designers, representing 10 disciplines. With so many of them tackling fundamentally the same challenges it made sense to enable a ‘design once, use often’ approach to common elements. We had developed smart object libraries for projects in other sectors, including the water sector, and saw the opportunity to bring the same innovation to a major rail project.

We created a library of ‘smart objects’ designed using building information modelling (BIM), that are virtual representations of real components, tagged with metadata describing all their physical and operational properties. Designers can simply ‘select and place’ required components into their engineering models.

The time efficiencies meant that hundreds of hours were saved across multiple structures.

Smart object library

We created the HS2 Smart Object Library – a resource of more than 600 standardised BIM objects for common design elements. Objects include beams, slabs and panels, culverts, parapets, and mechanical, electrical and plumbing (MEP) elements such as pumps and switches. These are all hosted on Moata, our digital solutions platform, using a tool called Moata Intelligent Content.

600 standardised BIM objects

Standard construction components proposed by the engineers were transformed into 3D BIM objects to which we applied parametric modelling functionality. This meant that modellers could meet different design requirements, such as the length or skew angle of a viaduct span, using the standardised objects. The necessary algorithm was built into every variable object, triggering an automatic update of all the other object parameters. It saved designers time and reduced the chance of human error causing delays further down the line.

A sample of the parametric objects in the Smart Object Library, all of which have unique ID references and attributed information

To ensure use of standardised components, we developed a checking tool that queries every model to see if it includes appropriate objects from our smart object library. This encouraged uptake and drove consistency across the design team. This effectively reduced design risk, as the standardised components had already been quality assured and checked to ensure they met all engineering requirements. This in turn saved time spent on checking designs and carrying out modifications.

There were further benefits at the interface between design and construction. All objects have unique ID references and attributed information (dimensions, geometry, weight and material properties) that had to be added to construction drawings. Given the scale of the project – with beams alone numbering more than 5000 – it was clear we had to automate this process. The reporting tool we developed extracts information directly from the model and adds it to the drawings. Information is also fed into Power BI to create dashboards that help our client, joint venture contractor Balfour Beatty-Vinci (BBV), to package batches of work for their precast manufacturers, who can rationalise production by grouping together elements of similar size.

A £3M cost saving in two years

Using the HS2 Smart Object Library to create 3D models for bridges, structures and MEP components led to savings of between £100,000 and £150,000 each month – worth approximately £3M over two years.  

Looking ahead, we are expanding the smart object library to assist the rest of the HS2 programme of works, bringing efficiencies right through to completion and then maintenance. Our information-rich models will form part of the project digital twin, ultimately handed over by BBV to HS2. This will aid asset management, as when assets or elements need to be replaced, the client will have all the reference information needed to easily procure replacement parts when needed.

£100,000 minimum savings each month

We have also started to add generative design as a powerful feature of the smart object library, starting with staircase design. Engineers would have input values to modify a standard staircase design to site specific requirements. But now they can specify the requirement and an algorithm loaded with the necessary values will produce the design. With over 100 access and maintenance staircases across the first phase, generative design has already saved many engineering hours. As the number of generatively designed objects increases, the benefits of the smart object library will grow.

Our smart object library approach can be applied to any project, anywhere in the world, regardless of discipline, design codes or ways of working. So long as the project can be broken down into regularly repeating elements, then developing a library of smart construction components will help bring efficiencies to modelling – cutting costs as well as boosting quality and consistency.