Directional drilling in UK utility work is priced as a complete crossing, not as a rate per metre. Mobilisation, ground investigation, launch and reception pits, drilling fluid management and reinstatement of the pits make up a large share of the total, so a 20 m bore and a 200 m bore rarely share a sensible unit rate. On short crossings the fixed costs dominate. On long ones the drilled metres finally start to matter.
That makes the question harder to answer than most cost guides admit, but not impossible. There is published UK evidence that puts a number on the difference between trenchless and open-cut installation, and there are statutory street works charges that swing the comparison further than the drilling itself does. Both are set out below.
McFadden’s directional drilling capability covers water mains, service pipes and ducting across Hertfordshire, London and Surrey, and the way these jobs get priced follows the same logic whoever is holding the rig.
What published UK rates actually show
United Utilities publishes one of the few UK schedules that prices trenchless and open-cut installation side by side for the same work. Its New Connection and Developer Services Charges Scheme 2026/27 lists a “not in trench, surfaced” rate alongside the standard surfaced rate for polyethylene mains, and an explicitly labelled trenchless rate for additional service pipe metres.
United Utilities published rates, 2026/27 charges scheme (excluding VAT)
| Work item | Open-cut, surfaced | Not in trench / trenchless | Difference |
|---|---|---|---|
| PE water main, 50 to 99 mm | £480.40/m | £414.22/m | 13.8% lower |
| PE water main, 100 to 150 mm | £628.09/m | £500.45/m | 20.3% lower |
| PE water main, 151 to 300 mm | £930.90/m | £697.02/m | 25.1% lower |
| PE service pipe, 25 or 32 mm, each metre after the first two | £349.78/m | £113.70/m | 67.5% lower |
Read those figures for their shape rather than as a market price. They are one water company’s charging rates, they include testing, fittings and reinstatement where required, traffic management is charged separately, and the “not in trench” category is not expressly limited to horizontal directional drilling.
What the shape tells you is useful all the same. The saving from working trenchless widens as diameter increases on mains, and it is dramatic on small-diameter service pipe, where the trench would otherwise be almost the entire job. A 25 mm service run that costs £349.78 a metre surfaced drops to £113.70 a metre trenchless in the same schedule. The pipe has not got cheaper. The highway has.
Why a single per-metre rate does not survive a real crossing
Six variables move a directional drilling price more than bore length does.
- Rig class and mobilisation. A compact rig for a 90 mm duct under a residential street and a mid-range rig pulling 315 mm PE under a dual carriageway are different mobilisations, different crews and different transport. That cost lands whether the bore is 15 m or 150 m.
- Ground conditions. London clay steers predictably. Made ground, running sands, flint gravels and cobbles do not. A bore that needs a rock head or repeated reaming passes costs more per metre and carries more risk of a re-drill.
- Bore length and pit count. Longer bores spread the fixed cost across more metres, which is why per-metre rates fall as length rises. Intermediate pits push it back the other way.
- Product pipe and diameter. Larger diameters need pre-reaming, higher pull-back forces and more drilling fluid. Barrier pipe, where a soil risk assessment calls for it, costs more again.
- Survey and utility detection. A crossing under a street with unrecorded apparatus needs proper detection, trial holes and sometimes a revised bore path. Skipping this is where strikes happen.
- Drilling fluid management. Bentonite mixing, containment and licensed disposal are real line items, and on sensitive sites they are significant ones.
The street works charges that decide the comparison
On an urban crossing, the drilling is often not the largest variable. The highway is.
Permit fees are set by DfT statutory guidance for permit schemes and charged per permit, per street. A standard activity on a category 0, 1 or 2 road or a traffic-sensitive street attracts up to £130. A major activity running over 10 days, or one needing a traffic regulation order, attracts up to £240. A route crossing several streets needs several permits.
Lane rental is the bigger number. Under DfT lane rental guidance for English highway authorities, charges are capped at £2,500 per street per day on designated streets during designated hours. The Transport for London lane rental scheme bands its charges at £350 for footway occupation and £1,000, £1,500 or £2,500 for carriageway occupation depending on the road. Kent, Surrey, West Sussex, East Sussex, Oxfordshire and a growing list of London boroughs run their own schemes on similar bands.
Overrun exposure has just widened. The Street Works (Charges for Unreasonably Prolonged Occupation) amendment brings weekends and bank holidays into section 74 overrun calculations in England from 5 January 2026, and lane rental can still be charged on top.
Then there is what you are left holding. A trench needs continuous reinstatement to the Specification for the Reinstatement of Openings in Highways, guaranteed for two years, or three for deep openings. A bore needs reinstatement at the launch and reception pits only. The guaranteed surface area, and the defect liability that comes with it, shrinks to a fraction. Anyone pricing a scheme over its whole life should be putting a number on that, and most quotes do not. Our guide to the street works licence and permit process sets out what has to be in place before either method starts.
When directional drilling costs more than open-cut trenching
Trenchless is not automatically the cheaper method, and the government’s own modelling says so plainly.
The DESNZ report on undergrounding transmission cables models a hypothetical whole-route HDD installation at 1.1 to 1.9 times the cost of conventional cut-and-cover for large transmission work. The same study found that reduced-excavation techniques cut the civil works cost to 28 to 34% of cut-and-cover, yet only brought total build cost down to 60 to 80%, because cable materials dominate the bill regardless of how the trench is formed.
Three situations where open-cut or a cheaper trenchless method usually wins on price:
- Very short crossings. Under about 10 m, mobilising a drill rig rarely beats a mole or a short trench. Our breakdown of moling costs per metre in the UK covers the alternative, and the moling versus directional drilling comparison sets out where the crossover sits.
- Open ground with no highway involved. A field, a verge or a construction site with no permit, no lane rental and no surfaced reinstatement removes most of the advantage.
- Deep or large-diameter bores in difficult geology. Pre-reaming passes, heavier rigs and fluid management can overtake the trench cost outright.
What a defensible directional drilling quote contains
A quote that arrives as a single lump sum with no breakdown is not something you can compare, defend to a client or programme against.
Ask for the price split into mobilisation, bore, product pipe, pits and reinstatement, drilling fluid management, and street works fees. Ask which ground investigation the bore path is based on. Ask what happens commercially if the bore has to be abandoned and re-drilled, because that is the risk that turns a fixed price into a variation.
Where the crossing forms part of a new supply, the water company’s own charges sit alongside the civils cost, and our guide to new water connection costs explains how those two bills fit together.
The honest answer on cost
Directional drilling cost in the UK is decided by four things: how much rig and crew you have to mobilise, how the ground behaves, how many metres you spread that fixed cost across, and what the highway would have charged you for the trench you did not dig. Published water company schedules put the trenchless saving somewhere between 13% and 25% on mains and around 67% on small-diameter service pipe, while government modelling shows the same method costing more than cut-and-cover on large deep installations. Both are true, because they are describing different jobs.
The practical move is to stop looking for a rate and start comparing two priced methods for your specific crossing, with permits, lane rental and reinstatement liability in both columns. That comparison usually answers itself.
If you have a crossing to price, McFadden’s directional drilling capability covers survey, bore path, installation and pit reinstatement as one scope, so the numbers arrive in one place rather than three.
Sources and further reading
- United Utilities, New Connection and Developer Services Charges Scheme 2026/27
- DESNZ, Undergrounding transmission cables: study of costs of innovative methods
- DfT, Lane rental schemes guidance for English highway authorities
- DfT, Permit schemes statutory guidance for highway authorities
- The Street Works (Charges for Unreasonably Prolonged Occupation of the Highway) (England) (Amendment) Regulations 2025
Questions on this topic
There is no reliable single per-metre rate, because mobilisation, pits, survey and drilling fluid management are largely fixed costs that get spread across the bore length. A 20 m crossing and a 200 m crossing with the same rig will show very different per-metre figures for identical work. The most useful published comparison is United Utilities’ 2026/27 charges scheme, which prices PE mains at £414.22 to £697.02 per metre “not in trench” against £480.40 to £930.90 per metre open-cut and surfaced, depending on diameter. Those are one water company’s charging rates rather than contractor prices, but they show the size of the gap.
Usually on surfaced highway, and often not elsewhere. Published water company rates put trenchless installation 13 to 25% below open-cut for mains and around 67% below for additional service pipe metres. The saving comes mainly from avoided reinstatement, shorter road occupation and lower lane rental exposure. On open ground with no permit or reinstatement involved, or on deep large-diameter bores in difficult geology, open-cut frequently wins. DESNZ modelling puts whole-route HDD at 1.1 to 1.9 times cut-and-cover cost for large transmission installations.
Every crossing carries a mobilisation floor covering rig transport, crew, setting up the launch and reception pits and drilling fluid handling. That floor applies whether the bore is 10 m or 100 m, which is why very short crossings look expensive per metre and why contractors quote a job price rather than a rate. Below roughly 10 m, moling or a short open-cut trench is often the cheaper route.
They should be shown as separate line items, and a quote for a highway crossing that omits them is incomplete. Permit fees run up to £130 for a standard activity on a traffic-sensitive street and up to £240 for a major activity over 10 days, charged per permit and per street. Lane rental is capped at £2,500 per street per day on designated streets, with Transport for London banding at £350 for footway and £1,000 to £2,500 for carriageway. Shorter road occupation is where directional drilling earns most of its money back.
Ground conditions that were not investigated, unrecorded apparatus forcing a revised bore path, an abandoned bore needing a re-drill, and street works overrun charges. The first three are managed by proper survey and trial holes before pricing. The fourth is now sharper in England, since weekends and bank holidays count towards section 74 overrun calculations from 5 January 2026. Agree in writing who carries the re-drill risk before work starts.
