Weekly "cars held" data from the Surface Transportation Board's (STB) Rail Service Metrics. As part of their submission to the STB, railroads provide data on the average daily number of loaded and empty cars, operating in normal movement and billed to an origin or destination, which have not moved in more than 48 hours. The data is broken out by service type: intermodal, grain, coal, crude oil, automotive, ethanol, fertilizer, or all other. In order to derive the daily averages for the reporting week, carriers are requested to run a same-time snapshot each day of the reporting week, capturing cars within each category that have not moved in 48 hours or more. The number of cars captured on the daily snapshot for each category should be added, and then divided by the number of days in the reporting week (typically seven days). In deriving this data, carriers should include cars in normal service anywhere on their system, but should not include cars placed at a customer facility; in constructive placement; placed for interchange to another carrier; in bad order status; in storage; or operating in railroad service (e.g., ballast).

Fertilizer is defined by the following 14 Standard Transportation Commodity Codes (STCCs): 2871236, 2871235, 2871238, 2819454, 2812534, 2818426, 2819815, 2818170, 2871315, 2818142, 2818146, 2871244, 2819173, and 2871451. STCC 287 covers agricultural chemicals and STCC 281 covers industrial inorganic or organic chemicals (excluding pesticides).

Weekly "cars on line" data from the Surface Transportation Board's (STB) Rail Service Metrics. The STB began collecting service metrics from railroads in October 2014. As part of their submission to the STB, railroads provide data on the average (daily) number of cars on line, broken out by car type such as "box," "covered hopper," "gondola," "intermodal," "multilevel (automotive)," "open hopper," "tank," and "other." According to the STB, "each railroad shall average its daily on-line inventory of freight cars. Articulated cars should be counted as a single unit. Cars on private tracks (e.g., at a customer’s facility) should be counted on the last railroad on which they were located. Maintenance-of-way cars and other cars in railroad service should be excluded."