Field Evaluation of Chemical Methods for Vegetation Removal and Control in Reinforced Earth Wall Maintenance for Highway Infrastructure

Abstract

Reinforced soil and Reinforced Earth (RE) walls are increasingly used in highway embankments, bridge approaches, flyovers, grade separators and constrained corridors because they can be constructed rapidly, tolerate controlled differential settlement and reduce the footprint and cost of retaining systems. However, the long-term serviceability of these structures depends not only on geotechnical and structural design but also on systematic maintenance of facing elements, joints and drainage provisions. Uncontrolled vegetation is a recurring maintenance problem because soil fines, organic debris and retained moisture can accumulate around panel joints, drainage outlets and local surface irregularities, creating favourable conditions for weed establishment. This paper presents a field-based assessment of vegetation growth on RE walls and evaluates chemical vegetation control as one component of an integrated maintenance strategy. The study documents the observed mechanisms of vegetation establishment, the implications for inspection, drainage and wall appearance, and the sequence of chemical treatment and post-treatment observations reported in the original field work. The observations indicate that vegetation removal improves access to wall faces, joints and drainage features and reduces the immediate presence of above-ground weed biomass. The paper also emphasizes that vegetation should not be treated as an independent cause of structural failure; rather, root growth, moisture retention, blocked drainage and accumulated debris can act as interacting serviceability and deterioration factors. Chemical treatment should therefore be undertaken only with approved products, label-compliant application, environmental safeguards and qualified personnel. A preventive maintenance framework combining inspection, debris removal, drainage management, mechanical removal and selective chemical control is proposed. The study provides practical guidance for highway agencies and asset managers while identifying the need for future quantitative studies involving vegetation coverage, recurrence rate, drainage performance and lifecycle maintenance cost.