Accumulation areas are incorporated into a system design when it meets any of the following criteria :

1: no manual work performed in this area

2: Critical time sensitive flash, cool or drying rate

3: limited area.

4: Queue zones required for staging.

RSI accomplishes this by rotating the cart top 90 degrees. This allows the carts to accumulate end to end with only 1 stop unit , at the front of the area. This allows for a smaller footprint . By having a smaller footprint, work that previously would not have been on the conveyor, can be incorporated  or the extra area can be used for any number of things.