A road sign is four decisions. Three of them are usually made correctly by default and one of them is usually not made at all.

Here is the order, and what goes wrong in each.

Shape carries meaning before the legend does

Drivers read shape and colour before they resolve any text. An octagon means stop. An inverted triangle means yield. A yellow diamond means warning. A white vertical rectangle means a regulatory instruction.

That is why a warning message on a rectangle underperforms the same message on a diamond, and why regulatory shapes are prescribed on public roads. On private property you have latitude — but the conventions still do the work, so it is worth following them.

Size follows approach speed, not preference

24 inch is for car parks and low-speed private roads. 30 inch is the general-purpose size and the safe default for most public applications. 36 inch and larger belong on higher-speed approaches and anywhere sight lines are poor.

Undersizing is the most common mistake on private sites, because signs are bought by eye from a catalogue rather than by approach speed. The cost difference between 24 and 30 inch is small; the difference in how early it is read is not.

Sheeting grade is the decision nobody makes

Retroreflective sheeting returns headlight light to the driver’s eye. Engineer grade is the entry specification, with a service life around seven years, and it is adequate for car parks and low-speed private roads.

High-intensity prismatic is the general-purpose choice for public roads — longer life and far better wet-night performance. Diamond grade is the top specification and earns its cost on high-speed approaches, overhead mounting and complex junctions.

If a quote does not name the grade, assume it is the cheapest one and ask.

Mounting is half the job

U-channel is the workhorse: galvanised, punched on one-inch centres, driven straight in. Telescoping square tube is tidier and lets a damaged post be swapped without excavating.

Where a post stands in the clear zone of a road carrying traffic at speed, a breakaway base is not optional — it shears on impact so the post does not become the hazard.

Get the hardware quoted with the signs. A pallet of signs and no posts is a very common and entirely avoidable delay.

What to send when you ask for a quote

The legend, the road or approach speed, the quantity, and whether you need posts. That is enough for a real quote and a mockup the same day.

If you do not know what the road warrants, describe it — speed, lighting, whether pedestrians cross — and the specification will pick itself.