Drain measuring wheel

A drain measuring wheel is a wheeled device with a counter that records linear distance as it is rolled along a paved or unpaved surface. It is used to record the distance between gullies, inspection chambers, downpipe connections and property boundaries as part of a drainage survey or quotation visit. Typical wheels measure to within 1% accuracy and are calibrated periodically against a known distance. Engineers use the recorded distances to plan jetter and crawler reach, to estimate liner lengths, and to support drainage as-built drawings. The traditional measuring wheel is being supplemented by GPS-based survey apps and laser distance meters on London sites where accuracy is critical, although mechanical wheels remain the most rugged and reliable option for routine works.