Glad you found the Forum in its new location.
Self-righting bollards are required to conform to BS 8442:2015, which includes:
13.1.5 Conspicuity panels
Conspicuity panels shall be applied to the front and sides of all RSRB types; rear
conspicuity panels are optional. Conspicuity panels shall be retroreflective,
fluorescent and yellow in colour.
NOTE RSRBs rely on the brightness of retroreflective panels to be conspicuous at
night. Daytime conspicuity of these devices is enhanced by the use of fluorescent
The minimum projected area of the front or side conspicuity panels shall
conform to Table 6. Where both faces display a traffic sign both shall display a
conspicuity panel. The lower edge of the front conspicuity panel shall be a
minimum of 100 mm and a maximum of 200 mm above the ground line.
Table 6 Projected area of the conspicuity panels
Projected area, mm2
Front view Side view
150 000 20 000
BS EN 12899-2:2007 covers normal internally illuminated bollards. It has lots on the dimensions but doesn’t seem to give the minimum size of retrofeflective panels.
So apart from that, I think it’s up to the engineer to design what is safe and sensible.