The nine cost drivers
| Driver | What moves the price | What to check in a bid |
|---|---|---|
| Energy class and height | Higher MEL means heavier ropes, posts, brake elements and anchors; height adds post length and net area. Within one class, height often moves the price more than the class step itself | MEL in kJ (not SEL) and nominal height, both from the ETA of the offered system — see Reading a rockfall barrier specification: ETAG 027 to EAD 340059 |
| Line length and geometry | Priced per running metre; bends, steps and end anchors add cost per metre on short or broken lines | Metres of net, number of posts and end/side anchors, not a lump sum |
| Anchoring and ground | Drilling depth, grout volume and anchor count follow the rock: fractured or weathered rock needs longer or more anchors, and a pull-out test plan | Anchor type, length, number per post, and how many are tested (Anchor and rock bolt pull-out testing on site) |
| Access | Crane or truck at the toe is cheapest; rope access costs time; helicopter lifts are usually the largest single logistics item on a face without a road | Access method stated and priced separately, with the lift plan |
| Corrosion class | Marine and humid sites need zinc-aluminium coated wire and protected fittings; the class is a material decision made once and paid for once | Coating class of wire, ropes, posts and fittings, matched to the site |
| Scaling and preparation | Loose rock must come off before the line goes in; the amount is only known from a survey | Scaling included or excluded, and on what basis (Slope and rock scaling: methods, measurement first, acceptance) |
| Traffic and working windows | A road that stays open needs traffic management, night or short-window work and lane closures for lifts | Who provides traffic management, and the working hours assumed |
| Design, survey and testing | Trajectory analysis on a surveyed profile, anchor design and pull-out tests are engineering hours, not steel | Included, or assumed to be provided by the client's consultant |
| Logistics and lead time | Certified systems are manufactured to order and shipped; customs clearance and site storage are real costs and real weeks | Delivery period from order, and who carries clearance |
Why a cheap bid is sometimes not
- The energy figure quoted is the SEL, or a manufacturer's marketing number, while the specification asked for MEL.
- The height is lower than the trajectory analysis needs, so blocks pass over the line — see How to choose the energy class of a rockfall barrier.
- Plain galvanised wire on a coastal site: cheaper on the day, replaced within the design life.
- Fewer or shorter anchors than the ground needs, with no test plan.
- Scaling, traffic management or the design report left out of the scope and added later as variations.
- No maintenance manual or inspection schedule, so the first storm becomes a dispute (Rockfall barrier inspection and maintenance: checklist).
How to make two bids comparable
- Fix the system by its ETA: MEL, height, residual height category and corrosion class.
- Fix the line: metres, posts, end anchors, on the same surveyed profile.
- Fix the ground: anchor type, length and count per post, and the number of pull-out tests.
- Fix the scope: scaling, access method, traffic management, design, testing, handover documents.
- Only then compare the price per metre — and ask each bidder to confirm the assumptions in writing.
We do not publish unit prices, because a price without the nine items above would mislead. We do quote per line, after a site survey, with every driver priced on its own row — so the number can be checked.
Questions on this topic
Can you give a price per metre of barrier?
Not before a survey. The same class of barrier can cost several times more per metre on a helicopter-only marine face than on a cut slope with truck access. We quote per line after seeing the profile, with access, anchoring and scaling as separate rows.
Is a higher energy class always more expensive?
Per metre, yes — heavier components and more anchoring. Over the whole scheme, not always: a correctly placed lower line, chosen from the trajectory analysis, can protect the road at less cost than a high-class line placed by assumption.
What is the biggest hidden cost?
Access. A face without a road at its base turns every post and rope into a helicopter or rope-access lift, and the working hours of a road that must stay open set the pace.
Sources
- EAD 340059-00-0106 (falling rock protection kits) — the assessment document that defines MEL, SEL, residual height and the numbers a bid must quote.
- Artusa project record, Khasab–Tibat coastal road (Musandam): barriers of 5,000 and 2,000 kJ class along about 1.5 km, installed by helicopter and rope access — https://artusaoman.com/projects/khasab-tibat-coastal-road/