I then got a better picture at another crossing:
A little research found the following information.
From the "Salem Times-Commoner" (Don't sue me):
The vehicles are designed to perform a variety of electronic track inspections at speeds up to 70 miles per hour. A three-person crew operates the EC-4 and the EC-5. The particular vehicle in Salem was the EC-4. The cars perform inspections six days a week. The vehicles have full sized kitchens in them so meals can be prepared while on the go. In a year, the two geometry vehicles will test miles of tract equivalent to more than five times around the earth's equator.
Both geometry vehicles use complex computer systems that gather data from various types of lasers measuring track surface or level rail ear and tunnel measurements. The on-board computers also use Global Positioning Satellite systems to accurately record and report the location of variances for accurate repairs. Track maintenance crews follow the inspection vehicle and make repairs as needed when a track defect is found. The real-time data recorded by the vehicles also is used in scheduling track improvement projects.