HISTORICALLY THE CANAL LENGTHSMAN was the vital frontline defence for Britain's inland navigations, writes Ralph Freeman.
Over recent decades, centralised management, remote offices, and reactive only, contractor based, maintenance have replaced this local presence, leading to record levels of stoppages.
This proposal outlines reintroducing the canal lengthsman—re-equipped with off-the-shelf technology to deliver proactive asset monitoring and early defect detection of potential breaches at a fraction of current operational costs.
Dual-pass bank inspections via drone
Inspecting miles of canal corridor—particularly high-risk embankments and inaccessible offside cuttings—is difficult on foot. Under this model, a lengthsman using an all-terrain e-bike and a compact autonomous drone can execute a detailed video survey over a five-mile section in a single morning.
The lengthsman carries a position-tracking beacon on the e-bike while the drone operates in an autonomous follow-me mode at a fixed offset. As the lengthsman rides along the towpath, the camera remains locked on one canal bank, recording continuous 4K video to detect wash damage, piling corrosion and bank erosion. On the return leg, the lengthsman reverses the camera offset so the drone targets the opposite (and normally obscured) waterline.
Embankment and cutting inspections
Many miles of canal, particularly along offside sections, remain hard to reach on foot. The drone proves particularly useful here, quickly sweeping offside embankments and cuttings to identify potential structural issues. In addition to saving significant time, it provides detailed video footage for high-resolution analysis back at base.
Reintroducing the lengthsman backed by lightweight technology offers a return to genuine local stewardship—combining boots-on-the-ground presence with low-cost high tech engineering.