Excavation depth
Increasing depth beyond 1.2 m typically adds £250–£700 each through extra excavation, support, lifting and backfill.
Surface reinstatement
Saw-cutting and reinstating an existing asphalt carriageway generally adds £400–£900 each.
Ground conditions
Rock, running sand or contaminated arisings can increase the installed rate by 20–50%.
Service congestion
Trial holes, hand excavation and service protection commonly add £250–£750 each.
Grating specification
Moving from a standard highway grating to a higher-specification hinged, locking or cycle-safe unit can add £100–£350 each.
Drain connection
A long, deep or difficult lateral connection can add £150–£600 each compared with a short connection into an accessible drainage run.