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Factory Thinking | Gantry automated design

Flowing lights jpg

On a computer at Ramboll’s London headquarters, a gantry designs itself. At least, it appears to. The road sign structure starts as a few white lines on black screen, then jumps outwards and upwards, growing like a tree, as lines become bolts, ladders and struts.

“It goes off, gets the data. You sit back, make a coffee,” says Ramboll engineer Tom Channell. “We’ve had to move the kettle a bit closer now, the designs come out too quick,” laughs Ramboll director, bridges, Simon Benfield.

Blueprint jpg

Blueprint jpg

Digital models allow for faster design and lower cost

This unique automated software solution for design and modelling of gantries has reduced a task that used to take weeks down to mere hours.

The first steps towards this automation of design were made in the 1970s, when the first set of “modular types” were produced by Ramboll for the Department for Transport. Toward the end of the 1990s, these drawings became standardised into a set of frames and additional parts. These modular solutions became progressively more closely linked through spreadsheet-based analysis.

The final step was full automation. Set the parameters – width, height, location; set the features – signs, lights etcetera; and click. “The product itself links to a database in the backend… containing all the geometrical data to make a gantry. And all this does is ping it, asking it for the data to make it,” explains Channell.

“We’re able to tie all this together, so that this process that would have taken days, using traditional software methods, takes just minutes,” says Benfield.

We’re able to take a longer view on investment, and quite a chunk of the profit gets fed back into R&D

Simon Benfield, Ramboll

It looks simple, but there is a lot going on in the background. The main tools are C# programming language and AutoCad Advanced Steel – Ramboll opted for these after trialling a number of others.

Standard elements of the gantry and a library of structural frames are converted into a library of BIM models. Using C# to tie it all together, the result is a dialog box, where the user can simply click to select the requirements in their design.

After hitting “go”, the complex analysis begins, lines are set and changed, overlapped and offset, all while the computer thinks about Eurocodes and calculates loads, such as likely wind speeds.

“It’s running through all the load cases proposed by the Eurocodes… it gets ridiculous, there’s something like 6,000 cases,” says Channell. “When you’re working with a smaller gantry, it’s fairly simple. But when you’re working to larger sizes, the amount of bolts and every little element grows exponentially.”

Ironing out conservatism

The thousands of lines of programming code iron out the conservatism that would traditionally be built into an engineer’s design.

But once finished, the design must still be tested. First, old designs were run through the new automated system, to ensure it was spitting out the right answers.

Then, for new designs, Highways England stipulates a “Category 2” double-check process, whereby another team, using different methods, effectively “do the design again” and the two sets of answers are compared. “That second check process is the one that takes a bit more time, because they have to use different processes,” says Benfield.

A BIM model pops out at the end, but BIM is not yet used industry-wide and there is a requirement to provide 2D drawings. “Some [fabricators] will just take our 3D models, while others are still very much working off 2D drawings,” adds Benfield.

“There are a number of development ideas,” he adds. “We’re now talking about the potential to generate… the drawings for each individual part that goes out on to the shop floor. Historically they’ve [fabricators] generated those, but with this level of automation, is this a service we can offer?”

Continuous feedback

Benfield says feedback from contractors, the supply chain and roads authorities are fed back into the process again and again to improve speed and quality. “Putting these gantries up takes a lot of motorway space, in some cases it needs to be completely closed. So we tailor the design so they can be erected very quickly, fully fabricated and fitted out offsite,” he says. “So it really is a case of lifting into place and connecting cables. An experienced fabricator can put one of our gantries up in about 10 minutes.”

Fixing existing structures is quick too: a laser scan can be produced, allowing a view of every bolt and plate of a pre-existing gantry. This scan creates a point cloud, generating a 3D model. Then, using Advanced Steel, the model can be retrofitted with additional elements, which are exported to a federated model for the client, connecting all the available data for the ongoing management of the asset.

The driving ideology behind the overall system is a “product-based approach”, says Benfield, who has some experience in this area, as a chartered product designer. He uses an example from car manufacturing: “So if you want to buy a Jaguar, you don’t just get it the way it rolls off the production line, you say ‘I want it green, with certain tyres, stereo…’”

The team is seeking a similar level of customisation and standardisation in gantries.

300 gantries a year

Ramboll designs about 300 gantries a year, and has about 95% of the road gantry market in the UK. Any uptick in speed is crucial, for a few reasons.

The first is profit. “If you were to say the initial design and modelling would account for 50% of the cost of a job, and we’re cutting 80% of that out, so it’s 80% of 50% that is disappearing. That’s the initial cost saving,” says Benfield.

But he says the processes have been driven more by a business ideal, the long-term view. “We’re able to take a longer view on investment, and quite a chunk of the profit gets fed back into research and development.”

Second, being faster makes the team more flexible, and insulates against late changes to programmes. “It’s great that the client can come back and say ‘I don’t really want the sign there…I want it 5mm that way’,” says Channell. “And it’s all done through a quick dialog box entry rather than having to do a traditional CAD modification.”

Exploring the options

Third, Benfield says running the designs quicker through automation allows more options to be explored, and in more depth. The computer can weigh up thousands of options at a time, finding the best way to drive down structural weight and cost. “If you were to look at the gantries we designed in the mid-70s, at today’s prices they’re more than double the cost,” he says.

Finally, an automated process helps to attract and retain talent. “This [automation] isn’t about removing people from the process, it’s about improving people,” says Benfield. “It frees them up from the grind, the repetitive tasks. It allows us to work on a wider range of more interesting projects. It helps us develop people and develop as a business because we have happier people, higher staff retention, business growth.”

In future, the next step for the team will be creating a true automated link between the design and modelling – removing the hoops that separate pieces of software need to jump through. “The ultimate BIM idea is one ‘blob of stuff’, which you can do analysis from, modelling from, and not even blink, it’s just there. That’s where all this is going, reaching that BIM ideal,” says Channell.

But, he admits, this ideal world could either come very soon, or not at all.


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