Highway authorities and infrastructure asset managers operate within increasingly constrained inspection budgets while facing expanding asset portfolios as infrastructure networks age. A single under-bridge inspection unit (UBIU) mobilization for a routine principal inspection costs between £2,500 and £5,000 per day, requires two lanes of traffic management at approximately £800 per day, and typically achieves 4-6 hours of productive inspection time within an 8-hour traffic management window due to setup and demobilization overhead. For bridges where the critical inspection areas are within 8 meters of deck level—bearing shelves, expansion joints, deck soffit edges, and parapet beam connections—the Bridge Inspection Cantilever Tower provides an alternative access methodology that eliminates the UBIU mobilization cost, reduces traffic management requirements from lane closures to shoulder narrowing, and extends productive inspection time to a full 8-hour working day.
Whole-Life Cost Comparison: UBIU vs. Cantilever TowerA comparative whole-life cost analysis for a hypothetical highway authority managing 120 bridges requiring biennial principal inspections demonstrates the economic case. Of these 120 structures, approximately 45 (37.5%) have critical inspection areas within 8 meters of deck level where cantilever tower access is applicable. Current practice using UBIU access for these 45 bridges costs approximately £148,500 per inspection cycle (£3,300 average UBIU day rate including traffic management × 45 bridges), or £297,000 per biennial cycle. The capital cost of three cantilever tower units with training and certification is approximately £28,500, with annual maintenance and recertification costs of £3,200. Amortized over a 10-year service life with five biennial inspection cycles, the cantilever tower approach delivers a total cost of £60,500 versus £1,485,000 for UBIU access—a 96% cost reduction. Beyond the direct cost comparison, the cantilever tower approach eliminates the 6-8 week UBIU scheduling lead time, enabling reactive inspections following extreme weather events or vehicle impact incidents that would otherwise wait for UBIU availability.
Key Features| Parameter | Specification |
|---|---|
| Cantilever Extension | Up to 1.2m Beyond Parapet |
| Platform Dimensions | 2.0m x 0.6m + Cantilever |
| Working Height Range | 2m - 8m Above Deck |
| Tie-Back System | 4-Point Steel Wire Rope Turnbuckle |
| Tie-Back Tension Control | Calibrated Torque-Limiting |
| Laser Mount | 3-Axis (Standard Survey Thread) |
| Camera Rail | Full Cantilever Edge T-Slot |
| Mounting System | T-Slot Compatible (M8) |
| Material Grade (Tubes) | Aluminum Alloy 6082-T6 |
| Tube Diameter | 50.8mm |
| Tube Wall | 3.2mm |
| Cantilever Load | 150 kg Including Personnel |
| Surface Treatment | Anodized Silver |
| Wheel | 200mm Lockable with Chocks |
| Standards | EN1004:2004, BA 62/18 |
Cantilever platform, triangulated brace, and tie-back anchor system in dedicated road-case package. Steel wire rope assemblies individually proof-loaded with LOLER test certificates. Tie-back anchor installation kit with four epoxy-anchor bolt sets for permanent deck anchor point installation included. 24-month structural warranty, 12-month tie-back warranty, annual re-certification service available.