Designing cabs for drivers of all shapes and sizes

3 MinutesBy NZ Trucking magazineSeptember 11, 2019

Humans come in all shapes and sizes. Scania‘s cabs are designed to fit them: the heavy, slim, tall and short, as well as catering to the diverse body compositions of drivers.

Using anthropometric data from a broad selection of countries around the world, Scania uses its ‘family‘ of virtual mannequins when designing cabs.

“The mannequins are a mix of three or more measurements,” explains Paulo Eduardo Fragoso, anthropometry expert at Scania‘s Vehicle Ergonomics Department. “They may, for example, have short legs with long torsos and vice versa.”

Scania started compiling body composition data in the late 1990s, which has subsequently been expanded and updated as populations evolve. A general trend, which is surprisingly valid for all countries, is the increasing prevalence of overweight and obese drivers requiring, for example, longer seat belts. With growing affluence, men and women also tend to increase in average height, but only up to a population‘s genetic limit.

“Every feature of the truck should be accessible for all of the people contained in the Scania family, which is graded beyond the fifth, 50th and 95th percentile. They include men and women from 1.50 metres tall up to 2.05 metres tall, modelled statistically using the latest science. This is all part of our user insight database.

“If I were to single out one outstanding feature, it would include the greater visibility and cross-cab access,” says Fragoso.

Through simulations, vehicle ergonomists can assess the accessibility for different drivers, without needing a huge number of user tests. The tricky act of reaching out of the window for a toll station ticket will, for example, vary depending not only on the driver‘s height but also on torso and arm length, and can be easily tested by a virtual group of users.

“Since one size clearly does not fit all, we need to provide opportunities for individual adjustments of the steering wheel, seat and side mirrors. If we‘re forced to make compromises, we will ensure that we meet the needs of the vast majority of drivers. But there are also certain things we cannot comprise on, such as comfortably reaching the clutch for those trucks that still have manual clutches.”

The cab design exercise can be compared to a symphony orchestra, according to Fragoso. Each cab feature, like an instrument, constitutes an element in a harmonious and well-sounding musical composition. Nothing should stand out, and changing one feature affects the entirety.

Fragoso continuously collects anthropometric data as well as updating existing data. “The data should always be readily available. It‘s like the woodcutter‘s axe. The blade should always be sharp when called to work.”