Do It Yourself Gabion Retaining Walls for Rural Roads
2015 Edition

According to MORD 27 Clause 3.0, handmade and machine-made gabions differ significantly: Handmade baskets utilize rectangular (10x10) and hexagonal (10x12) meshes with larger wire diameters (3.25 to 4.06 mm), have non-uniform mesh sizes leading to bulging and material loss, and use commercial galvanizing that lasts only 3-4 months. They lack selvedging, which reduces structural strength and flexibility. In contrast, machine-made gabions feature uniform hexagonal 10x12 mesh with mechanically selvedged edges, smaller wire diameters (2.7 to 3.0 mm), higher mesh strength (32 to 40 kN/m), and heavy galvanizing compliant with IS standards for enhanced durability. Their double twist mesh design prevents unraveling, allows better stress distribution, and enables faster assembly with quality assurance. Overall, machine-made gabions provide superior durability, uniformity, strength, and ease of construction compared to handmade ones.

MORD 27 specifies the use of double-twisted hexagonal steel wire mesh for gabions to ensure durability. The mesh wire typically has an inner diameter of 2.7 mm and outer diameter of 3.7 mm, with edge wires thicker at 3.4 mm (ID) and 4.4 mm (OD), and lacing wires at 2.2 mm (ID) and 3.2 mm (OD). For corrosion resistance, a heavy zinc coating is applied, with zinc quantities ranging from 240 to 270 grams per square meter depending on wire diameter. Additionally, a PVC coating of approximately 0.5 mm thickness is applied over the zinc in aggressive environments for enhanced protection. The double-twist construction prevents mesh unraveling if wires break, while the zinc and PVC coatings extend service life significantly.

Installation of gabion retaining walls per MORD 27 involves first preparing a level, compacted foundation surface, often including placement of non-woven geotextile fabric behind or beneath the gabions for filtration and drainage. Gabion baskets are unfolded to their box shape with vertical front, back, and end panels. Inner diaphragms are lifted and secured by lacing wire to maintain cell integrity. All edges are tied using lacing wire with alternate double and single loops spaced no more than 150 mm apart. Empty gabions are positioned and tied edge-to-edge to form a monolithic structure, with front-to-front and back-to-back mating for stability. Stones sized 150 to 250 mm are placed in layers (300 mm lifts for 1 m high gabions, 250 mm for 0.5 m) and hand-compacted to minimize voids. Internal cross ties are installed at vertical thirds for 1 m high gabions and at exposed edges to ensure structural integrity.

Gabion retaining walls find extensive use in rural road projects, especially for stabilizing slopes and retaining earth on steep valley sides and hillsides where road cuts are needed. They support roadbeds on sharp inclines to maximize usable roadway space with minimal excavation. Gabions also serve as crash barriers on dangerous curves in hilly terrain. Suitable for walls up to 6 meters in height, these structures use locally sourced stones and provide an economical, labor-intensive solution. Furthermore, gabions are employed in mechanically stabilized earth (MSE) walls with double-twisted mesh facings, and green facia units combining gabions with coir mats promote vegetation growth for slope stability and improved aesthetics. The base width generally ranges from 0.5 to 0.7 times the wall height, with walls constructed in stepped or battered profiles for optimal performance.

Gabion walls offer superior flexibility compared to conventional PCC/RCC or Random Rubble masonry walls. Their permeable structure permits drainage, reducing hydrostatic pressure and enabling them to accommodate differential settlements and seismic forces without cracking. In contrast, traditional masonry walls are rigid, prone to cracking under settlement or seismic activity, and require substantial foundation preparation and drainage systems. Environmentally, gabions support vegetation growth, have a lower carbon footprint, and integrate naturally into the landscape, whereas masonry walls are less eco-friendly and may experience cracking from vegetation roots and contribute to noise pollution. Additionally, gabions require less skilled labor and simpler tools, making them economical and easier to construct.