Yard design

The Corwith yard is located in south Chicago near interstate 55 and S. Kedzie Ave. The entire yard covers 388 acres. It contains 13 loading tracks. The Corwith yard is broken down into 2 parts, inbound at the north end of the yard, and outbound at the south end. Inbound is then divided into two check-in locations, one at the main gate on Kedzie Avenue where tractors are brought in from haulers or other yards; and one in the yard where trains come in filled with containers. At both of these sites the containers are scanned or entered into the computer system by a hand-held device. Based on its final destination (such as another city, another rail yard, or to a nearby end-user) they are assigned to a location in the yard (such as a track, storage area, or to a chassis). Typically, a container comes in on a chassis and tractor from a trucking company such as JB Hunt, and goes to the gate check-in. After being assigned its destination, it goes to an area where it is off-loaded by a BOOM lift and taken off the private shipper’s chassis and tractor and put onto a yard chassis and tractor. It takes approximately 2:15 minutes to be unloaded. The yard tractor then takes this container to its track and unhooks the chassis and leaves it to be loaded onto a train it takes approximately 2:30-3:00 minutes for the container to be taken off the chassis, however, it then sits on the train until it is completely built and ready to leave. This can take up to 4 hours. The Corwith yard has 9 large straddle cranes which run 24 hours a day. This allows them to complete 24,000 – 26,000 lifts on a good day.

These large cranes are mounted on wheels and can drive the length of the track to access any container on the train. Each crane is controlled by an operator located near one of the wheels. The yard does an estimated 1905 lifts per day (2003). It is common for a truck to wait 1 hour at the entrance gate for truck check-in. In heavy traffic, a truck can wait much longer than that.

The GRAIL system is a fully automated container management system developed in the year 2000 to manage the heavy container flow through sea ports.

The structure is an overhead lattice with built-in linear induction tracks It is made out of steel I-beams and concrete footings. It is built only over the container storage area.

Hanging ‘shuttles’ run along tracks in the overhead structure and have access to everything underneath.

• Each shuttle is controlled by the central command and control computer system.
• Each shuttle contains a built-in lifting mechanism and locking system.
• Each shuttle is equipped with expert decision-making software to most effectively place containers in storage
• Each shuttle contains laser sensors that help it to avoid collision with other shuttles. These sensors also enable the shuttle to precisely locate a containers position along the track for pick-up.
• The shuttles transfer containers to other cranes by means of a ‘buffer’.

(The buffer is simply a flat surface that will move side-to-side and rotate in order to align the container directly under the GRAIL track for pick-up. The shuttle is laterally bound by the track in the overhead lattice so it cannot pick up a container unless it is perfectly aligned with the track.)

The rail system used within the yard is a shuttle-powered Linear Induction Rail system. This system is described in detail under the ‘Propulsion Team’ heading. The tracks in the GRAIL system use a method called ‘Passive Switching’ to switch the shuttles from one rail to another. Instead of using a moving piece of track to physically steer the train-car in another direction, Passive Switching uses a guide wheel on the shuttle to steer itself through the grid. Without moving parts, the track requires very low maintenance and provides quick access to all parts of the yard

The GRAIL system uses a form of artificial intelligence called the Expert Placing System to ‘decide’ where to place each container within the storage yard. This Expert system uses a point system to evaluate every possible storage position in the yard. Certain criteria are much more important than others and are therefore given more points. If a storage position is not accessible (i.e. it is occupied by another container or does not have adequate support underneath) the position can be assigned negative points. The system will determine which yard position has the highest point-value based on the programmed criteria and automatically place the container in that spot.