- Night visibility depends on the grade of retroreflective sheeting, not the paint.
- The supporting structure must be designed for wind on the full sign area.
- Galvanized steel and proper fixings keep signs straight and rust-free.
A road sign has a few seconds to deliver its message to a driver at speed, by day and at night. On motorways and highways, signs are engineered products: the face, the plate and the structure all need to work together for years in sun, rain and dust.
Retroreflective sheeting
Modern sign faces use retroreflective sheeting that sends headlight beams back towards the driver. Sheeting grades are commonly classified under ASTM D4956, from engineering grade with glass beads to high-intensity and microprismatic grades that return much more light. Higher grades are used where signs must be read from a distance or at high speed, such as motorway direction signs and gantries; lower grades can be acceptable on slow urban streets. Always use the sheeting, inks and overlay film from a matched system so the warranty holds.
Sign plates
- Aluminium plates do not rust and are standard for quality signs.
- Galvanized steel plates are an economical option where weight is not an issue.
- Large signs are made from extruded panels or stiffened plates so they stay flat.
Support structures
| Structure | Typical use |
|---|---|
| Single or double post | Warning, regulatory and small information signs |
| Cantilever | Direction signs over one or two lanes |
| Gantry (overhead bridge) | Lane-specific signs across the full carriageway |
Structures are designed for wind load on the whole sign area, plus the foundation to resist overturning. Breakaway or protected posts reduce the danger to vehicles that leave the road.
Other road safety products
- W-beam guard rails with posts and end terminals
- Delineators, cat eyes and road studs
- Kilometre posts and hazard markers
- Street light poles and toll plaza canopies
Durability checklist
- Hot-dip galvanize posts, frames and fixings.
- Use stainless or galvanized bolts with anti-theft fixings in exposed areas.
- Seal sheeting edges and keep the face clean.
- Inspect after storms and replace damaged or faded faces.
Apex Engineers supplied road signs and safety products on the M2 Motorway between 1996 and 1998, and many are still in service today. Explore our road safety and signage work or send your sign schedule.
Written by the Apex Engineers team
Engineers and fabricators at Apex Engineers (Pvt.) Limited, building fuel stations, storage tanks, steel structures, towers and road safety systems from our Lahore manufacturing facility since 1992. About us
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