90% manned. A lot of money and time goes into getting track access.

And collecting unmanned data is still such a pain. At the moment, you stick calibration gear to a train and hope it gets as much noise free data as it can. All whilst going at least 40mph over the area you want - you’re fighting vibrations, vehicle grease, too much sunlight, not enough sunlight, rain, ballast covering things, equipment not calibrated before going out etc etc.