New York City Transit's Wonder Train Car!

Ever wonder how New York City Transit inspects its 673 miles of track? Check out the track geometry car!

A track geometry car is an automated track inspection train used to test several geometric parameters of the track without obstructing normal subway operations. Some of the parameters generally measured include position, curvature, alignment of the track, smoothness, and the cross level of the two rails. The cars use a variety of sensors, measuring systems, and data management systems to create a profile of the track being inspected.

In the past, track inspection was originally done by track inspectors walking the tracks and visually inspecting every section of track. This was dangerous as it had to be done while trains were running. It was also manpower intensive, and inspectors were limited in the amount of track they could inspect on a given day. Manual instruments had to be used to measure various parameters of the track

New York City Transit's current track geometry cars cover large portions of the system in a single day. NYCT's two track geometry cars are self-propelled track measuring and inspection vehicles, each consisting of two units. One power car unit that houses the engines and an Ultrasonic Rail Flaw Measuring System, and one towed measuring car that holds all of the other testing and measuring tools. The cars are capable of detecting and recording track defects with incredibly high precision. So what does the track geometry car measure? Here's a partial list:

  • Longitudinal profile and horizontal alignment of both running rails
  • Track gauge
  • Tunnel and platform clearances
  • Corrugation of running rail surface
  • Third rail height and gauge
  • Vertical gap between the top of the third rail and the protective board
  • Internal rail flaws
  • Track grade

The measuring of track geometry involves a combination of video inspection of the right-of-way along with measurements taken with a variety of instruments including a high-speed rotating laser, thermal imaging, and an ultrasonic rail flaw measuring system. All measurements are continuously recorded by electro-mechanical, inertial or laser measuring equipment and an electronic data processing system consisting of an onboard computer network which allows the recoding and storage of the data as well as real-time evaluation and analysis at measuring speeds up to 50 mph.

The typical onboard crew for each car includes two or three analysts/engineers, two track equipment maintainers, and one maintenance supervisor. A "pilot" is assigned to each car during inspection runs and other support personnel analyze and compile the data collected and prepare reports. The cars operate under normal passenger train rules and regulations, and typically operate during the off-peak daytime weekday hours. Maybe you'll be able to spot one in the near future.