Choosing jersey barriers

Concrete or plastic

Working out how many you need

• Measure the run in metres and divide by the unit length. Order one extra unit for every corner or transition, and allow for the taper at each end of the run.
• For a temporary diversion, plastic barriers filled on site will normally be the cheaper answer once you count the crane hours concrete would need.
• For anything protecting people, plant or a live carriageway edge, the mass is the point. Plastic will not do that job.

Temporary works, or permanent

How long the barrier stays put changes the answer more than the price per unit does. A run that moves every few weeks costs money every time it moves, and that is where concrete stops being cheap.

• Short diversions and phased works: plastic. Placed and filled by hand, drained and moved in an afternoon, and the same units serve the next phase.
• Long-duration works, live carriageway edges and permanent boundaries: concrete. It is placed once, and the mass does the job plastic cannot.
• Ask about hire for a short run rather than buying it. Tell us the run length, the duration and the site access and we will price both so you can compare.

Which concrete profile — and why they are not interchangeable

A concrete barrier face is not a simple slope. It has a near-vertical toe about 75 mm high, then a lower slope, then a steeper upper face. On a shallow-angle impact the tyre climbs the lower slope, which lifts the vehicle slightly, compresses the suspension on the impact side and turns part of the sideways energy into vertical movement — so the car is steered back into its lane instead of stopping dead against a wall.

Everything that separates one profile from another is where that slope breaks. They look almost identical on a delivery note and get specified interchangeably all the time, which is how a job ends up with the wrong one.

• K-rail and Jersey are the same profile under two names. If a specification asks for K-rail and you are quoting a Jersey of matching height, you are quoting the same thing.
• The 330 mm break is measured from the finished road surface, not from the barrier. Every asphalt overlay buries part of the toe and shifts the geometry the profile depends on — which is the entire reason single slope exists.
• A single-side unit is heavier per metre than the double-sided equivalent of the same height and base width, not lighter. Removing the back face fills concrete in rather than cutting it away, and people size forklifts on the opposite assumption.
• A flat-back unit is not free-standing. Its stability assumes the back bears against something. Stood in open ground it is less stable than a double-sided unit, not more.

Questions worth asking any barrier supplier

Use these on us as well. A supplier who cannot answer them from a data sheet is quoting from a brochure, and they cost nothing to ask before an order rather than after a delivery.

• Is the stated weight calculated or weighed? Published barrier weights are very often calculated, and a calculated figure carries whatever error is in the assumed section. A weighbridge ticket for one unit settles it.
• What is the cross-sectional area, or the concrete volume per unit? With that and the length you can check any stated weight yourself in one line of arithmetic.
• Can I see a dimensioned section drawing — base width, top width, height and the break points? Without it, the profile name on a listing is just a word.
• What is the lifting arrangement and its working load limit? You need it for the lifting plan, and the anchor system carries its own certificate.
• How much clear space should I leave behind a free-standing run? If nobody can answer, nobody has tested it. A short, light, unconnected run deflects further than most buyers expect.
• Is there a crash or containment certificate? If yes: which standard, what rating, which laboratory, what date and what certificate number.
• Who holds the regulatory approvals — the supplier, or the manufacturer? A trading company and a manufacturer are not the same thing, and an approval belongs to whoever holds it.