Vibration characterisation of strollers and cargo bicycles for transporting infants over different road surfaces

The objective of this study was to comprehensively evaluate vibrations with dummies representing infants aged 0, 3, and 9 months lying or sitting in five strollers and two cargo bicycles with dedicated baby seats on six common road surfaces using the ISO standard for whole-body vibration. Strollers induced on average 0.4 ms${}^{-2}$ on tarmac and up to 5.0 ms${}^{-2}$ on cobblestones at a mean walking speed of 5.3 km h${}^{-1}$. Cargo bicycles induced on average 0.6 ms${}^{-2}$ on tarmac and up to 10.7 ms${}^{-2}$ at 25 km h${}^{-1}$ on paver bricks. The standard suggests the highest accelerations for strollers and cargo bicycles are extremely uncomfortable and continuous exposure should be limited to less than 10 min. Vintage strollers have reduced vibrations compared to modern strollers, indicating benefits of compliant suspensions. We recommend that designers systematically consider vibration, users avoid prolonged exposure to surfaces rougher than tarmac, and researchers pursue scientifically founded test procedures and standards for infant vibration.