Quasi-Experimental Field Assessment of Haul-Road Maintenance Effects on Fuel Consumption, Cycle Time and Mechanical Loading of Open-Pit Dump Trucks

Haul-road condition in open-pit mining affects fuel consumption, transport-cycle throughput and dump-truck mechanical loading. This study conducted a quasi-experimental field assessment of local maintenance effects on severely degraded road segments. The full cycle register contained 32,000 entries, of which 30,808 passed quality control and were used for background engineering characterization. The primary difference-in-differences (DiD) analysis used 2634 matched-control cycle–focal-segment observations, while 72,000 one-second telemetry records formed a separate 20 h dynamic validation subset. Relative to matched-control dynamics, maintenance increased RCI by 3.26 points and reduced IRI by 6.24 m/km, the apparent rolling-resistance descriptor by 2.71 percentage points and rut depth by 41.2 mm. Regression-adjusted effects were −10.6 L/cycle for fuel, −0.78 min for cycle time, +10.7 km/h for segment speed, −0.351 g for vibration RMS and −78.2 MPa-eq. for the suspension-stress proxy. A 14-day lead-placebo/event-time diagnostic found no detectable pre-intervention divergence, and non-negative cohort-weighted group-time ATT estimates closely matched the TWFE results. The coefficients are interpreted as site-specific local intervention-window effects rather than annual fleet-wide constants.