Low - Less than 50 riders per car. Riders can expect to find a seat at least one row from other riders.
Some - 50-70 riders per car. Riders can expect to find a seat and not have another rider sitting next to them.
Moderate - 70-100 riders per car. Riders may have to stand to avoid sitting next to another rider.
High - 100+ riders per car. Limited space available. Riders may need to stand near other riders, and the train may skip stations in order to avoid further crowding.