Highway guardrail components are the rail panels, posts, spacers, splice bolts, post bolts, terminal ends, transitions, base plates and post caps of one barrier system. A guardrail BOQ lists each of these by drawing reference, size, coating and quantity, so nothing is missing at installation.
Use the approved drawing and BOQ as the controlling documents. This page shows each part, gives typical sizes and offers a free BOQ template.
Guardrail Components at a Glance
| No. | Component | Main job | Our typical size (W-beam) |
|---|---|---|---|
| 1 | W-beam rail panel | Contains and redirects the vehicle | 4130 × 310 × 82 mm, 2.5–4.0 mm, Q235B / Q345B |
| 2 | Splice bolt set | Joins rail panels into one line | M16, class 4.8 or 8.8, with nut and washer |
| 3 | Post | Carries the load into the ground | H post W150 × 13.5 × 1830 mm; Sigma, U, C or round |
| 4 | Spacer / blockout | Holds the rail away from the post | W150 × 13.5 × 360 mm |
| 5 | Post bolt set | Fixes rail and spacer to the post | M16 bolt, nut and rectangular washer |
| 6 | Terminal end | Finishes each end of the run | Buffer or flared end, per drawing |
| 7 | Base plate and anchors | Fixes posts to bridges or concrete | Plate and anchor bolts per drawing |
| 8 | Post cap | Covers the top of the post | To suit the post profile |
For thrie-beam, the rail is 4130 × 510 × 82 × 2.8 mm with 1100 g/m² zinc. It uses W150 × 13.5 × 1980 mm H posts and 554 mm spacers.
Download the Guardrail BOQ Template
The Excel template lists all eight highway guardrail components, plus transitions and spares. Each line has columns for drawing reference, unit, rule, quantity and coating.
Download the guardrail BOQ template (Excel)
How to Build a Guardrail BOQ in Four Steps
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Identify: confirm the installed or planned system.
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Match: match every component to the drawing.
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Quantify: measure by BOQ item, not by appearance.
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Verify: check the full assembly before release.
Important: parts that look alike are not always interchangeable. Rail profile, post type, spacer, hole pattern, coating, hardware and terminal details must match the approved system.
1. Start with the Barrier System, Not One Part
A steel guardrail works as a connected system. First confirm whether the site uses W-beam guardrail, thrie-beam guardrail, a bridge or transition layout, or another approved design.
Then collect the current drawing, the BOQ lines, clear site photos and the location. With these, the supplier can match a full set of parts without relying on a name or photo alone.
2. Core Components to List in a Guardrail BOQ
| Component group | What to confirm | Useful supporting information |
|---|---|---|
| Rail panels | Profile, thickness, overlap direction, hole pattern and finish | Drawing detail, panel mark, quantity and a photo of the splice area |
| Posts | Profile, steel grade, length or embedment, hole position and coating | Post drawing, ground or foundation condition and spacing |
| Spacers / blockouts | Type, orientation, material and fit with the chosen post | Cross-section showing the rail-to-post offset |
| Fasteners | Bolt set, nut, washer, coating and install direction | Hardware schedule or close-up photo of the joint |
| Terminals and transitions | Full approved layout, adjacent barrier, ground level and anchorage | End or transition drawing; do not order only the visible panel |
3. How the Parts Fit Together
Rail and splice connection
The beam panels form a continuous line. Confirm the profile, the joint layout and the hardware for that joint.
Spacer and post connection
The spacer is chosen with the post and rail. Do not swap in a different shape just because the length looks similar.
Terminal and transition
End and transition details are assemblies. Their BOQ must include every rail, post, plate, anchor and connector on the approved drawing.
4. Rail Panel: Seven Details for the Enquiry
"W-beam" or "thrie-beam" alone is not a purchase specification. Both come in more than one configuration. Give the supplier enough to check the beam against your drawing before production.
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Profile: W-beam or thrie-beam, with the section drawing.
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Steel grade: the project standard, for example Q235B or Q355B (comparable to S355JR).
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Thickness: base-metal thickness and tolerance, for example 2.67 mm (AASHTO Class A).
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Panel geometry: overall length, effective length and overlap, for example 4130 / 3810 mm.
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Hole pattern: hole type, position and quantity.
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Coating: for example 550 g/m² (Type I) or 1100 g/m² (Type II), plus the inspection method.
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Installation side: overlap direction and side of the road, where the layout needs it.
5. Post and Spacer Checks
Post profiles vary with the layout and site. In the BOQ, link each post to its spacer, rail connection and foundation or embedment detail.
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For an H post, confirm the rail and spacer connection detail.
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For a Sigma post, confirm its profile, layout and connection points.
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For U, C or round posts, check the system drawing instead of matching by eye.
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State the finish and any inspection or packing needs in the BOQ.
Compare profiles in our post types guide, or see our H, Sigma, U, C and round posts.
6. Fasteners Are BOQ Items, Not Extras
List bolts, nuts and washers by their job: rail splice, rail-to-spacer, spacer-to-post, terminal or transition. A full hardware schedule prevents missing parts on site and wrong substitutions during repair.
Our standard range covers M16 bolts, spacers and delineators in class 4.8 or 8.8, hot-dip galvanized.
A general "bolt" line is not enough. Head style, shank length, washer shape and use can differ. List each set against its drawing reference.
Procurement note: give the part description, drawing reference, coating, quantity, packing and destination port. For repairs, add photos of the damaged run and nearby parts.
7. Coating, Packing and Delivery
A part is not fully specified until its finish and delivery terms are clear. Check the corrosion protection against the project specification. A photo of a coated part does not prove the coating mass or test standard.
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Finish: state the finish, standard, test method and repair rules for damaged coating.
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Packing: list long rails, posts and small hardware separately. Mark bundles, cartons or pallets so site teams can count quickly.
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Shipping: state the destination port, delivery term, shipment window and any loading or marking needs.
8. Receiving Inspection: A Simple Site Checklist
Receiving inspection is the last chance to catch a mismatch before installation. Compare labels and quantities with the packing list and BOQ. Then sample-check parts against the drawing.
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Separate by BOQ line: keep rails, posts, spacers, terminal parts and fasteners apart while unloading.
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Check condition: note damaged bundles, bent parts, coating damage or missing hardware before acceptance.
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Compare samples with the drawing: check profile, holes, connection points and finish.
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Keep records: keep package marks, packing lists, inspection papers and photos.
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Fix problems first: never force a part that does not match the approved drawing.
9. Pre-Order Guardrail BOQ Checklist
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Approved drawing and BOQ pages attached
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Rail type, profile and connection details identified
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Post, spacer and foundation layout confirmed
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Fasteners listed by connection type, not as one general item
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Terminal and transition assemblies included where needed
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Coating, inspection, packing and delivery details stated
Example BOQ line:
Item 1: W-beam rail 4130 × 310 × 82 × 3.0 mm, Q235B, HDG 550 g/m², drawing GR-01, 263 pcs per 1,000 m.
Frequently Asked Questions
What are the main highway guardrail components?
Rail panels, posts, spacers, splice bolts, post bolts, terminal ends, transitions, base plates and post caps. Each needs its own BOQ line.
What is a guardrail BOQ?
A bill of quantities that lists every barrier part with its drawing reference, size, coating, unit and quantity. It lets suppliers quote the same scope.
Can I mix components from different suppliers?
Only if profile, holes, bolts and coating match the approved drawing. Parts that look alike may not fit or perform the same.
How is a guardrail BOQ different from an RFQ?
The BOQ defines the parts and quantities. The RFQ sends that list to suppliers with delivery terms. See our guardrail accessories RFQ checklist.
Related Pages
Need Help Checking a Guardrail BOQ?
Send the approved drawing, BOQ pages, destination country and any site photos. We will quote matching rails, posts, spacers, hardware, terminals and other guardrail components for your review.
