Under-Bridge Access Unit Safety

Under-bridge inspection units (UBIUs) are truck-mounted platforms that extend beneath bridge decks for access.
They allow inspectors and workers to access the underside of bridges without scaffolding or rope access.
UBIUs are heavy specialist vehicles that must be positioned on ground capable of supporting the imposed loads.
The platform extends over the bridge edge or parapet, placing workers in exposed elevated positions.
Outrigger pads must be fully deployed on stable ground before the platform arm is extended.
Traffic management is required on the bridge deck and the road beneath when the unit is deployed.
Wind speed limits for UBIU operation are typically 30–40 mph depending on the manufacturer.
Workers on the platform must wear harnesses clipped to anchor points within the platform basket.
The operator controlling the arm must maintain communication with the platform occupants at all times.
Pre-use inspection includes checking hydraulics, outriggers, platform condition, and safety interlocks.

Fall from height	Workers on the UBIU platform are suspended at height beneath the bridge — a platform failure or fall is likely fatal.
Overturning	Incorrect outrigger setup or overloading the platform can cause the vehicle to overturn off the bridge.
Traffic hazard	The UBIU occupies bridge deck space and extends beneath, requiring traffic management above and below.

Do

Don't

Verify the ground can support the UBIU weight and outrigger pad loads before setup
Deploy all outriggers fully and check pad contact before extending the platform arm
Wear a harness clipped to the platform anchor points at all times in the basket
Install traffic management on the bridge deck and beneath before deploying the unit
Check wind speed before and during operation — cease work if limits are exceeded
Maintain continuous communication between the platform occupants and the arm operator
Complete the pre-use inspection of hydraulics, interlocks, and basket condition
Ensure only trained and authorised operators control the UBIU arm and platform
Brief the inspection or work team on the platform capacity and emergency procedures
Keep tools and equipment secured within the platform basket to prevent drops below

DON'T extend the platform arm until all outriggers are fully deployed and stable
DON'T exceed the maximum number of persons or weight capacity of the platform basket
DON'T operate in wind speeds above the manufacturer's stated maximum for the unit
DON'T stand on the platform without a harness clipped to the designated anchor points
DON'T deploy the UBIU without traffic management on and beneath the bridge
DON'T position outrigger pads on soft ground, manhole covers, or hollow structures
DON'T allow untrained personnel to operate the UBIU arm or position the vehicle
DON'T lean over the platform basket edge or climb outside the basket at any time
DON'T leave tools or equipment unsecured on the platform where they could fall below
DON'T continue working if the hydraulic system shows warning lights or unusual behaviour

See also: Bridge Inspection Safety | MEWP Pre-Use Checks

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