# Short explanation on layout

This page gives a short explanation on the questions, which are asked at the left side of the screen. To visualize the explanation, a clickable plan of a warehouse in which several terms are displayed, is used:

## Aisle length

The aisle length is the distance between the front end and the rear end of one aisle in the warehouse, this does not include the width of the (potential) cross aisle(s).

## Centre distance between aisles

This is the distance between the centre of one aisle and the centre of the next aisle.

The total width of the warehouse is the number of aisles multiplied by the centre distance between aisles.

## Number of aisles

The number of aisles is the number of aisles, in which one picker collects items. This means that this picker is allowed to pick anywhere in these aisles.

## Cross aisle

A cross aisle is an aisle which is perpendicular to the storage aisles in which the items can be picked (the pick aisle). Its main function is to enable aisle changing. A cross aisle crosses the pick aisles.

## Cross aisle width

The width of a cross aisle is the distance of the interruption of the pick aisles, thus the distance between the left side and the right side of the cross aisle.

## Depot location

The depot location is the point in the warehouse where the pickers start and end their routes (a path in which all items are retrieved) through the warehouse. The depot is visited to receive the pick list, pick up an empty pick device, to drop off the collected orders and/or to continue the pick. The depot can be situated at the left side, the right side or in the middle of the front end of the warehouse.

## Average speed

The average speed inside and/or outside the aisles is the velocity at which the orderpicking vehicle travels on average, this includes accelerating, decelerating and stopping. Of course, this speed depends on the material handling equipment you are using in your warehouse. There will not be very large differences between the speed inside or outside the aisles, but if the trucks in a narrow aisle warehouse are guided by rails, the speed inside the aisles will be higher than the speed outside the aisles.

## Additional time to switch aisles

The additional time to change aisles is the time needed to go from one aisle to another on top of the normal travel time it takes to cover the distance. If the distance between two aisles is 10 metre and the speed outside the aisles is 1 m/s, then it would take about 10 seconds to leave the first aisle and enter the next. If it takes 20 seconds to change aisles actually, then the additional time to change aisles is 10 seconds. Especially in narrow aisle warehouses this additional time may occur due to the truck backing in and out the aisle. It may be as much as half a minute. In the other types of warehouses, the aisles are rather wide and the trucks are easier to manoeuvre, so that the time needed to change aisles will be roughly equal to the normal time (outside the aisles) to cover such a distance. In a narrow aisle pallet warehouse the default additional time is 10 seconds per aisle change.