MnDOT assessment of drone-use as part of a risk- based approach to bridge inspection realizes safety, cost and quality improvements.
Minnesota, United States
The Minnesota Department of Transportation (MnDOT) is utilizing drones to collect and process large amounts of data during bridge inspections with the goal of improving the quality of bridge inspections and improving safety for both inspectors and the traveling public.
In the summer of 2015 and 2016, a research team implemented Unmanned Aerial Systems (UAS) technology on 39 bridges including a wide range of bridge sizes, types, and locations to demonstrate the benefits and challenges of employing UAS on a large scale. Applications included using the drones to survey confined space inspections in steel and concrete box beams and pier towers, as well as inspections between beams for multi-girder bridges and bearing inspection for beam bridges.
Data was collected primarily from an imaging payload intergraded into the UAS body. Case study inspection reports that included a cost analysis were compiled for 12 bridges representative of various use cases.
The following tables compare the costs between traditional inspection and access methods with UAS assisted inspection.
Capital Costs:
| Traditional Under Bridge Inspection Vehicle: Purchased: $500,000 to $1,000,000 Rental: $3,000/day |
UAS-Assisted Inspection-specific drones equipped with state of the art imaging devices: $15,000 to $40,000 Rental: $300/day |
Inspection Costs:
| Cost Assumptions | Cost |
|---|---|
| Bridge Inspection Team Leader | $150/hour |
| Assistant Bridge Inspector | $120/hour |
| Under Bridge Inspection Vehicle with Operator | $3,000/day |
| Drone Equipment | $300/day |
| Post Processing Engineer | $120/hour |
| Low Speed Lane/Shoulder Closure | $2,000/each |
| Mobile Lane/Shoulder Closure | $1,500/each |
| High Speed Lane/Shoulder Closure | $2,500/each |
| Bridge Structure ID | Traditional Inspection Cost | UAS Assisted Inspection Cost |
|---|---|---|
| 19538 | $1,080 | $1,860 |
| 4175 | $15,980 | $13,160 |
| 27004 | $6,080 | $4,340 |
| 27201 | $2,160 | $1,620 |
| MDTA Bridges | $40,800 | $19,800 |
| 2440 | $2,160 | $1,320 |
| 27831 | $2,580 | $540 |
| 82045 | $2,660 | $1,920 |
| 62080 | $2,580 | $1,350 |
| 62090 | $2,410 | $1,570 |
| 62504 | $3,660 | $1,020 |
| 82502 | $3,240 | $2,400 |
Improving the Quality of Bridge Inspections Using Unmanned Aircraft Systems (UAS)
Inspection-specific drone equipped with state of the art imaging devices: $15,000 to $40,000 Rental: $300/day
