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## Solution for Supply Chain Network Design: Applying Optimization and Analytics to the Global Supply Chain 1st Edition Chapter 4, Problem 2

by Michael Watson Sara Lewis Peter Cacioppi Jay Jayaraman
106 Solutions 14 Chapters 19694 Studied ISBN: 9780133017373 5 (1)

# Chapter 4, Problem 2 : 2. A major chemical company operates a private...

2. A major chemical company operates a private fleet of tank trucks that deliver full loads of liquid chemicals from warehouses to all associated customers. The “customers” in this case are plants using these chemicals within production processes that run 24 hours a day. If these plants run out of any of the necessary raw chemicals, they must shut down the ongoing production, which wastes precious time and costs them a lot of money. For this chemical company to fulfill the needs of these demanding customers, they need to offer no less than two-day service for all demand. The modeling team understands this policy but is puzzled about how they convert the service promise into a constraint within their network design model.

a. Based on the following facts, show these modelers how to properly calculate the maximum distance (in miles) they should apply to constrain the outbound lanes in their model. (Your answer should be in the form of a formula including the solution.)

Drivers can work for only 10 hours per day (this includes the prep time).

Trucks travel at an average speed of 50 mph (miles per hour) when making customer deliveries.

Tank trucks must be hooked up with hoses that load and unload the liquids. It takes approximately 112 hours to fully load and unload one tank truck.

b. What if the company decided to start using team drivers as opposed to the single drivers we assumed within our initial calculation? In this case, two drivers are assigned to each truck, allowing the team to work twice as long (20 hours as opposed to the original 10 hours) before having to stop for the day. Based on this change, what is the new mileage constraint that should be applied within their model?

## Step-By-Step Solution

2. For Part a, there are 10 hours per day, so 20 hours in two days. We need to subtract the 1.5 hours and are left with 18.5 hours at 50 mph, giving us a distance of 925 miles.

For Part b, the total hours goes up to 38.5 (20 x 2 less the 1.5). So, the total distance would be 1925 miles.