Passengers are a seated audience with time on their hands, which is why buses, coaches and taxis carry advertising. A screen in a vehicle has a harder life than one on a wall, though. It runs from the vehicle's electrical system, it is shaken all day, and it still has to be readable in a cabin full of daylight.
Bus & Taxi Advertising Displays (view the range) are listed at 10.1, 15.6, 18.5, 21.5, 24, 27 and 32 inch, in Full HD at 350 cd/m², with a DC 8 to 36 V power input, an Android configuration, Wi-Fi and 4G connectivity, and ceiling or pole mounting. The range is described as dust and shock resistant, without a test standard being quoted. For long, narrow spaces such as the strip above a doorway, Stretched Bar Displays (view the range) are an alternative format.
A vehicle screen is only as good as its content supply. Updates can arrive over Wi-Fi at the depot or over a mobile connection on the road, and digital signage content management is scoped separately around your fleet, your routes and who sells the advertising. Mobile data contracts are arranged separately from the hardware.