The Cheapest Trench Is the One You Never Dig
Open-cut looks cheaper in the bill of quantities. Then come the road closure approvals, the traffic management, the reinstatement, the service strikes and the residents. Trenchless removes most of that line by line.
Open-cut against pipe jacking, item by item
Both methods put the same pipe in the same place. What differs is everything that happens above it. This is the comparison we walk clients through before a method is fixed.
| Item | Open-cut | Pipe jacking |
|---|---|---|
| Ground opened | The full length of the alignment | Two shafts only, launch and reception |
| Road closure | Needed along the route, with authority approval and lead time | Usually none. Shafts sit off the carriageway where alignment allows |
| Traffic management | Signage, barriers, flagmen for the duration | Limited to the two shaft locations |
| Reinstatement | Full road or surface reinstatement, and a defects period on it | Shaft locations only |
| Existing services | Every metre is exposure to unrecorded cables and pipes | The drive passes below them at a controlled level |
| Depth | Cost and risk rise sharply past about 3m | Depth is largely neutral to cost |
| Crossing a road, rail or river | Often not permitted at all | The normal method |
| Spoil | Full trench volume out, imported backfill in | Bore volume only |
| Weather | Open trench floods and collapses in monsoon | Work continues, the drive is sealed |
| Public | Noise, dust and access loss along the whole route | Confined to two points |
Specifications, drive lengths and diameters are on the pipe jacking service page.
When trenchless pays, and when it does not
Trenchless is not the answer to everything. Quoting it where open-cut is obviously better wastes your money and our time, so here is the line we draw.
Jack it
- Crossing a road, highway, rail corridor, river or drain
- Passing under an existing structure, bridge piles or building foundations
- Invert deeper than about 3 metres
- Live traffic or an occupied development along the route
- Road closure approval would sit on the critical path
- Reinstatement of a finished road surface would be expensive or refused
- Long continuous runs where one drive replaces hundreds of metres of trench
Open-cut is the sensible choice
- Shallow runs in open ground with no traffic over them
- Short lengths where two shafts would cost more than the trench
- Greenfield sites before the roads are built
- Alignments with many bends, tees and chambers close together
- Ground that cannot support a shaft without disproportionate temporary works
We hold SPAN permits and CIDB registration for both methods, so the recommendation is not driven by what we are licensed to do. See our licences.
Ground conditions decide the machine, and they change mid-drive
Granite with a weathered profile above it runs through much of Peninsular Malaysia. A drive can start in soft residual soil and meet rock partway. A machine set up for soft ground does not simply slow down when it reaches rock. It stops, and recovering a stuck shield from under a live road is a different kind of problem from a slow programme.
That is why our micro-tunnelling setup is a slurry machine with two cutter heads: a soft ground head, and a rock head for weathered and fresh granite. The machine and both heads were specified and imported together, not adapted afterwards.
- Slurry balance micro-tunnelling to keep the face supported in mixed and water bearing ground
- Two cutter heads, soft ground and rock, so the drive is not committed to one assumption about what is down there
- Drives beyond 300 metres in a single push, and diameters to 2400mm
- Curved drives and long jacks where a straight alignment is not available
Ask for the ground investigation to be read against the method before a price is fixed. A drive priced on soil and delivered in rock is a variation waiting to happen, for whoever carries the risk.
Two holes instead of a road
Minimal disruption is a phrase every contractor uses. In practice it means this: the working area is a launch shaft and a reception shaft, each roughly the footprint of a parking bay or two, with the pipe string, slurry plant and control container beside the launch shaft.
Between those two points, nothing at surface level changes. The road stays open. Shop access stays open. The bus route does not move. Residents along the alignment often do not know the work happened until the pipe is being tested.
For the client that turns into fewer authority submissions, no reinstatement liability along the route, no traffic management bill running for months, and no complaint file for the project team to manage.
For the ESG section of your report
Developers and data centre operators increasingly have to report the environmental impact of their construction supply chain. Trenchless gives you something real to put in that section, because the reductions are physical rather than accounting.
- Less excavation and less spoil to landfill. Only the bore volume is removed, instead of a full trench section over the whole length.
- Less imported material. No granular backfill and no road reinstatement along the route.
- Fewer lorry movements. Spoil out and material in both fall, which takes vehicles and their emissions off local roads.
- Less habitat and vegetation disturbance. A drive can pass under a river reserve, a mature tree line or a protected area that a trench would have to cut through.
- Lower community impact. Noise, dust and access disruption stay at two points rather than following the alignment.
We do not publish a carbon figure, because an honest one depends on the drive length, diameter, ground and haul distance of your specific job. If your reporting needs a number, give us the alignment and we will work it with you rather than quote an industry average.
Frequently asked
Is pipe jacking more expensive than open-cut?
On the pipe rate alone, usually yes. On the total cost of getting the pipe in the ground, often no. Open-cut carries road closure approvals, traffic management for the duration, full reinstatement with a defects period, service strike risk along every metre, and programme exposure to weather. Where the route crosses a road or sits deeper than about 3 metres, trenchless is frequently the cheaper method overall.
When should I not use trenchless?
Shallow runs in open ground with no traffic over them, short lengths where two shafts cost more than the trench, greenfield sites before roads are built, and alignments with many bends and chambers close together. In those cases open-cut is the sensible choice and we will say so.
Can you jack through rock?
Yes. Our slurry micro-tunnelling machine carries two cutter heads, one for soft ground and one for rock, and that matters anywhere weathered granite is present, because a drive can start in soil and meet rock partway.
How long can a single drive be?
Beyond 300 metres in one push, at diameters up to 2400mm, including curved drives and crossings under roads, rail and rivers.
Do you still do open-cut work?
Yes. Water reticulation, sewerage reticulation and drainage are largely open-cut, and we hold the CIDB registration and SPAN permits for both methods. The method recommendation is driven by the alignment and the ground, not by what we are licensed to do.
What is the working area for a drive?
A launch shaft and a reception shaft, each roughly the footprint of one or two parking bays, with the pipe string, slurry plant and control container beside the launch shaft. Between the two shafts nothing at surface level is disturbed.
Send us the alignment before the method is fixed
Give us the route, the invert level and the ground investigation. We will tell you which sections are worth jacking and which are not, before anyone prices it.