Product and assembly brief
This selector concerns round or button-head bolts with a specified oval underhead neck for a receiving rail slot. Rail splices and rail-to-post connections have different component stacks. Select the exact bolt and assembly from the controlled barrier-system drawing, not the application name alone.
Product forms and reference names
| Choice or field | What to identify |
|---|---|
| Oval-neck splice form | An original maker describes the oval neck engaging the rail slot and splice bolts joining overlapping rail sections. Confirm head, neck and slot geometry; no universal size or anti-rotation rating is supplied. |
| Post-attachment form | Identify the rail, post and any intervening blockout or plate stack from the selected system drawing. The post duty is distinct from a panel splice, even when catalogue head/neck descriptions are similar. |
| Standard or trimmed head | A maker lists separately identified splice-head variants. Any head-envelope alternative needs its own controlled drawing; this is not permission to trim or modify a bolt on site. |
| Other barrier hardware | Hook, hex-head and anchorage components are separate choices. Neither an oval-neck label nor this illustration establishes suitability for every terminal or proprietary system. |
Oval neck is not a square carriage neck
The existing carriage-bolt detail describes a square neck; timber bolts use underhead fins. Compare the whole receiving geometry and head-bearing arrangement rather than substituting because the heads look rounded.
Splice versus post connection
State the connection location and drawing reference before selecting length and components. Identify the specified head-facing arrangement, hole or slot, stack thickness and nut-side access. No universal bolt count, field-slot alteration, torque or installation sequence is provided.
Nut, recess and washer stack
Maker catalogues list recessed nuts and several washer forms as separate components. Define each selected nut, recess and washer or plate on the assembly drawing, including thread/finish fit. Do not assume a generic bolt-and-nut kit matches the barrier specification.
Material and coating are independent requirements
Appearance does not prove material, mechanical properties, coating or traceability. Supply the requested designations and inspection documents. Maker-specific grades, dimensions, stock, domestic origin or project qualifications are not FastenerBridge supply evidence.
Standard identity is not system qualification
AASHTO M 180 and ASTM A307 appear in the original maker's reference context. State the exact contract document and edition or controlled drawing revision. This page does not assert a latest M 180 edition, standard conformity, road-authority approval or crash performance for a bolt or complete barrier.
Specification fields
| Choice or field | What to identify |
|---|---|
| System and connection | Barrier/system drawing number and revision, splice/post/other duty, component identifier and exact specified standard edition. |
| Head and neck | Head profile/envelope and oval-neck major/minor dimensions, axial height and transition details, with drawing-defined tolerances. |
| Receiving geometry | Rail hole or slot geometry/orientation, head-bearing surface, selected stack components and access constraints. |
| Thread and length | Metric or inch thread system, diameter/pitch/fit, length measurement datum, thread length and required plain-shank region. |
| Material, coating and inspection | Required material/property designation, coating and mating-thread allowance where specified; requested traceability and inspection documentation. |
| Assembly and order | Separate nut/recess/washer/plate identities, controlled installation and acceptance requirements, quantity with units, packaging and destination. |
Common product questions
Is an oval-neck guardrail bolt interchangeable with a carriage bolt?
Do not assume so. A square neck and an oval neck require different receiving geometry; compare the controlled head, neck, slot and assembly drawing.
Can a splice bolt be selected for a post attachment by diameter alone?
No. Duty, stack thickness, length, thread engagement and selected components must be defined for that connection.
Does a named standard or this image prove barrier approval?
No. The exact component documents and system-level acceptance evidence must be supplied and reviewed separately; this page makes no crash-performance or approval claim.
Related product choices
Product references
References checked 10 October 2026 identify structures, not FastenerBridge stock, compliance or brand affiliation. Final requirements follow the selected specification. No normative dimension, load rating or tightening torque is stated.