Master Planning and Scheduling, 4th Edition

15Resource Requirements Planning and Rough Cut Capacity Planning

It is forgivable to be defeated, but never to be surprised.

Imagine that your job is hauling stacks of crates from Los Angeles, California (USA), to San Diego, California (USA), on a flatbed truck. You have decided to take Interstate 5 (I‐5), a highway that you know travels beneath several underpasses. Along the way you discover that your cargo is loaded 15 feet high, but the underpasses have only 14 feet of clearance. How can you continue your journey? Here are some possibilities:

• Crash on through, knowing that your top crates will wind up as two‐dimensional displays on the pavement.
• Unload enough crates to allow the truck to pass under each overpass, then reload the truck on the other side.
• Let some air out of the tires to lower the truck's height, then fill the tires with air on the other side and continue your journey.
• Take an exit and take a detour to bypass each underpass by going around them.
• Reconstruct the underpasses.

None of these options is either practical or acceptable. You should have planned ahead, loading the truck with respect to the height of the underpasses. This could mean stacking the boxes to a compatible height or picking a route that allows for safe passage of your cargo. Perhaps other constraints force you to stack the boxes to a certain height, making clearance under two of the underpasses impossible. In that case, you might still take I‐5 but seek other roads as you approach the ...