What is a guardrail post?
A guardrail post is the vertical member driven into the verge (or bolted to a bridge deck) every 1.33–4 m to carry the W-beam or thrie-beam rail and transfer the vehicle impact into the ground. Under EN 1317 the post must yield in a controlled way — bend at the ground line rather than snap — so posts are thin-walled cold-formed sections (sigma, omega, C) of defined steel grade and thickness rather than heavy beams. Three families cover the world's roads: the sigma (Σ) post 100 × 55 × 3–4 mm of European EN 1317 systems (Turkey, EU, Balkans, Gulf ministries specifying EN), the C post 125 × 62.5 mm of AASHTO / US-pattern systems (Iraq, Saudi MOT older specs, Africa) and the omega (hat) post, a stiffer variant used in some national standards and for double-sided median barriers; U / UPN 100 posts appear in older and heavy systems.
Post types, sizes and weight
| Post | Section (mm) | Thickness | Length | kg per post (galv.) | System | Note |
|---|---|---|---|---|---|---|
| Sigma post | 100 × 55 (Σ, web 100, flange 55) | 3.0 mm | 1 500 / 1 900 / 2 000 | ≈ 11 / 13.5 / 14.5 | EN 1317 N2 W-beam | most ordered — European standard |
| Sigma post heavy | 100 × 55 | 4.0 mm | 1 900 / 2 000 / 2 200 | ≈ 18 / 19 / 21 | EN 1317 H1 / thrie-beam / median | double-sided, high wind, bridges |
| Omega post | 100 × 50 hat, feet 2 × 25 | 3.0 / 4.0 mm | 1 800 / 2 000 | ≈ 13 / 17.5 | national specs, median barriers | stiffer than sigma, same drive |
| C post (US pattern) | 125 × 62.5 (5" × 2½") | 4.5 / 6.0 mm | 1 830 (6 ft) / 2 000 | ≈ 19 / 25 | AASHTO M180, NCHRP 350 | Iraq, Africa, older KSA specs |
| U post | UPN 100 / 120 | 6.0 / 7.0 mm | 1 800 / 2 000 | ≈ 19 / 27 | heavy / legacy systems | hot-rolled, not roll-formed |
| Base-plated post | sigma 4 mm or IPE 100 on 200 × 200 × 10 plate | — | 600–1 200 | ≈ 12–22 | bridges, parapets, concrete | 4 × M16 anchors |
Standard punching: two slotted holes 18 × 25 mm for the rail bolt and spacer at 550 / 640 mm from the top (EN) or 4 holes (AASHTO); cap holes; custom patterns to drawing. Ground line marked.
Sigma vs C vs omega — which post for which system
| Sigma 100×55×3 | Sigma 100×55×4 | C 125×62.5×6 | Omega 100×4 | |
|---|---|---|---|---|
| Weight | ≈ 14.5 kg | ≈ 19 kg | ≈ 25 kg | ≈ 17.5 kg |
| Standard | EN 1317 N2 | EN 1317 H1 / H2 (with thrie) | AASHTO / NCHRP 350 | National / median |
| Post spacing | 2.0 m (4.0 m light) | 1.33–2.0 m | 1.905 m (6 ft 3 in) | 2.0 m |
| Driving | Pile driver, easy | Pile driver | Pile driver, heavier | Pile driver |
| Behaviour on impact | Yields at ground line | Yields, higher containment | Rigid, more damage to vehicle | Stiffer than sigma |
| Spacer | Sigma spacer 100×55×3 × 350 | Sigma / W spacer | C block or timber | Omega spacer |
| Price index | 1.00 | 1.30 | 1.65 | 1.20 |
| Choose for | EN-spec roads, most exports | Medians, bridges, high wind | US-spec tenders | Where the national spec says omega |
Steel grade and galvanizing
Posts are rolled from S235JR strip (S355JR for 3 mm sigma where the system test used it) to EN 10025-2, punched on the line and hot-dip galvanized after forming to EN ISO 1461 — road authorities specify a minimum of 550 g/m² (≈ 78 µm), and we deliver 600–800 g/m² on 3–4 mm sections; the galvanizing certificate (magnetic-gauge readings per lot) ships with the posts. Zinc-magnesium (ZM310) posts for coastal and de-icing-salt routes on request. Caps: black or yellow polyethylene push-fit, or welded steel caps.
Quantities per kilometre
| Post spacing | Posts per km | Spacers | Post bolts M16 | Caps | Weight (sigma 4 mm, 2 m) |
|---|---|---|---|---|---|
| 4.0 m (light, N1) | 250 | 250 | 250 | 250 | ≈ 4.8 t |
| 2.0 m (standard N2) | 500 | 500 | 500 | 500 | ≈ 9.5 t |
| 1.33 m (H1 / bridges) | 750 | 750 | 750 | 750 | ≈ 14.3 t |
| Double-sided median, 2.0 m | 500 | 1 000 | 1 000 | 500 | ≈ 9.5 t + spacers |
One 20' container carries about 1 400 sigma posts (2 m, 4 mm) or 1 800 posts of 3 mm; one 40' HC about 1 700 / 2 200 posts weight-limited.
Installation: driving, concreting, sockets
Posts are driven with a hydraulic post driver to 1.0–1.2 m embedment (2 m post, 750 mm rail height) in soil classes that allow it; where rock, kerbs or utilities prevent driving, posts are set in 300 × 300 × 600 mm concrete footings or in pre-cast sockets (removable posts for medians and toll plazas). On bridge decks and retaining walls base-plated posts are bolted with 4 × M16 chemical or through anchors. Set-out is by post spacing from the system drawing; the rail is bolted through the spacer at the punched slot. A crew with a driver installs 150–250 posts per day. We supply the driving cap and the spacing template on request.
Where the posts are used
- New highway and rural road guardrail lines (with W-beam rails and spacers from the same plant)
- Replacement posts for damaged sections of existing EN 1317 or AASHTO lines
- Median barriers (double-sided, omega or 4 mm sigma)
- Bridge and retaining-wall parapets (base-plated)
- Car parks, logistics yards and plant perimeters (vehicle impact barriers)
- Temporary and removable barriers in sockets (toll plazas, event roads)
Guardrail post price
Posts are priced per piece by section, thickness and length (galvanizing included) or per ton for large lots: as a guide a 2 m sigma post 3 mm sits 15–20 % above the galvanized section band per ton on the galvanized sections page, 4 mm and C posts more; caps and bolts per piece. Firm price per post list within one working day; as part of a full highway guardrail system the posts are included in the price per metre.
Export and packing
Posts bundled 20–40 per bundle (0.3–0.8 t), strapped on bearers with separators against wet-storage stain, caps and bolts boxed on pallets; 20' ≈ 14–18 t, 40' HC ≈ 22–24 t; trucks to Iraq (Habur) and the Caucasus weekly. HS code 7308.90 (parts of structures) / 7216.61 (cold-formed sections) depending on the market.
Certificates
EN 10204 3.1 for the strip (grade, thickness), galvanizing certificate (EN ISO 1461, thickness readings), system test report / CE (EN 1317-5) when supplied as a system, certificate of origin; SONCAP, COC, SASO, EAC arranged.
How to order
Send post type (sigma / omega / C / U), thickness, length, hole pattern (or the system standard), quantity, caps and fasteners, and port. We return the drawing for approval, price per post and per km, container plan and lead time within one working day.
Standards
- EN 1317-2 — containment class N2 / H1 / H2 systems
- AASHTO M180 — W-beam; C post 125 × 62.5 (US pattern)
- EN 10025-2 — S235JR / S355JR strip
- EN ISO 1461 — hot-dip galvanizing ≥ 550 g/m² (road practice)
- EN 10204 3.1
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S235JR · S355JR
Frequently asked questions
What is a sigma post?
A cold-formed Σ-shaped guardrail post 100 × 55 mm, 3 or 4 mm thick, 1.5–2.2 m long, hot-dip galvanized — the standard post of European EN 1317 W-beam and thrie-beam systems, driven at 2 m (or 1.33 m) spacing.
What is the difference between sigma and C guardrail posts?
Sigma is the European EN 1317 post (100 × 55 × 3–4 mm, ≈ 14–19 kg per 2 m); the C post 125 × 62.5 mm is the US AASHTO pattern (≈ 25 kg, 6 mm). Sigma yields at the ground line for lower impact severity; C is heavier and rigid. The system standard decides.
What is an omega post?
A hat-shaped (Ω) guardrail post, 100 mm deep with two 25 mm feet, 3–4 mm thick — stiffer than sigma, used where national specifications call for it and for double-sided median barriers.
How far apart are guardrail posts?
2.0 m for standard EN 1317 N2 W-beam, 1.33 m for H1 / bridges and thrie-beam, 4.0 m for light N1 lines; 1.905 m (6 ft 3 in) on AASHTO systems. Per km at 2 m: 500 posts.
How deep are guardrail posts driven?
About 1.0–1.2 m of a 2 m post, leaving 750 mm rail height (850–900 mm for thrie-beam); in rock or on bridges the post is set in concrete or bolted on a base plate.
What zinc coating do the posts have?
Hot-dip galvanized after forming to EN ISO 1461, minimum 550 g/m² (≈ 78 µm) per road practice, typically 600–800 g/m²; ZM310 on request for coastal routes.
Can I buy posts without the rails?
Yes — posts, spacers, caps and bolts are sold separately as replacement parts for existing lines; state the system (EN / AASHTO) so the hole pattern matches.
Do you manufacture the posts?
Yes — roll-formed and punched on our own line in Dilovası from S235JR / S355JR strip, galvanized with a partner plant, shipped from Derince or Ambarlı.