Seconds, at a distance
Roadside posters are read at speed and from far away, usually in a glance. The traditional rule of thumb is seven words or fewer, one image and one message, with the brand obvious without reading. Type must be sized for the viewing distance and set in high contrast. Generated imagery brings a particular risk here: models love fine texture and intricate detail, which turns into visual noise at fifty metres. Simplify the scene, enlarge the product and cut the copy. A common test is to view the design at postage-stamp size; if the idea does not survive that, it will not survive the road.
One master, many shapes
Out-of-home formats span extreme shapes. In the UK, a 48-sheet is 6096x3048 mm, a 96-sheet is twice as wide, and a six-sheet is a 1200x1800 mm portrait; the standard US bulletin is 14 by 48 feet. Digital screens add their own resolutions, set frame by frame by each media owner, from portrait station screens to long roadside panels. A 4:1 landscape and a 2:3 portrait cannot share a crop. The studio adapts one approved key visual to every format in the plan by re-composing each layout, extending scenes sideways or upwards and moving elements, with product-lock keeping the pack exact at billboard scale.
Digital screens: context and dayparting
Digital out-of-home sells time as well as space, so creative can change with context: a breakfast message in the morning and a different one after work, versions triggered by weather or temperature, live data such as scores or countdowns, and location-specific lines naming the nearest store. Programmatic buying can switch versions on those triggers automatically. That turns one poster into a matrix, which generation makes affordable, but screens change with nobody watching, so approve the whole matrix before launch and prepare a default version for when a data feed fails. Audience data comes from Route in the UK and Geopath in the US.
Rules on roads, schools and food
In the UK, planning guidance treats moving or apparently moving displays, and signs bright enough to dazzle, as road-safety hazards, and each roadside screen runs under the consent conditions set for its site. In the US, federal guidance for digital billboards on federal-aid highways rules out flashing and moving displays, and states set their own dwell times. Placement carries rules of its own. Many outdoor media owners will not place ads for alcohol, gambling and other age-restricted products within 100 metres of a school boundary, a practice the ASA has taken into account when judging placement, and Transport for London has restricted ads for food and drink high in fat, salt or sugar across its network since February 2019.
Updated 25 September 2026