A major component of street car restoration and maintenance involves working on the "bottom," "under carriage" or under side of the car. Street car trucks (the wheel sets under each car) require frequent inspection and lubrication due to the high-intensity nature of their use. To accomplish this work, NCTM shop crews use a bit trench located between the rails on track 14 in the museum car shop. This area is known as an inspection pit and allows crews relatively comfortable access to the underside of the equipment. The space is fairly dark, cramped and usually filthy, however its considerably easier, and safer, then jacking a street car up into the air every time it needs work.
There are two types of inspection pits, and NCTM has both. A normal inspection pit and a bridge pit. The image shown above is of the normal inspection put. But notice that it is only as wide as the rails. Many times, crews need to access the part of the street car that "hangs" outside of the area between the rails. To accomplish this, crews use the bridge pit, as shown below. In a bridge pit, the rails are mounted atop concrete pillars - like a bridge - which allows access to the sides of the street car under carriage.
Volunteers working in the bridge pit. Notice the rails are suspended in the air atop pillars.
Inside the "normal" inspection pit. Notice the lack of space beyond the rails. The bridge pit is visible in the distance.