Optimizing TST of a 3740 km milkrun

Where: daily milkrun from San Luis Potosi (Mexico) to Rochester New York (USA). One supplier in SLP, 4 in Laredo Texas (USA);
What: Crossing the border in Laredo is sometime delayed;
Occurence: 3% of trips;
Severity: Traffic delayed up to 24h. Material is heavy and very expensive to fly: electrical motors and magnet cases.

Timing:

San Luis Potosi pic-up at 11am D+0 (for example Monday);
4 suppliers in Laredo. One shipped at 1pm, 2 shipped at 2:30 and the 4th shipped at 4pm D+1 (Tuesday);
Delivery in Rochester 7am D+4 (Friday)

Organization:

One driver for the entire route (slow truck);
A team of 2 drivers can be settle-up in Laredo when the material is delayed at the border to catch-up the schedule.

Results:

0 day of DST but one day of STT;
Over cost of the team for 3% of the trips (frequency of border delays in Laredo).

This solution allows a minimum transportation cost and in-house inventory.

Other solutions:

STT = 0, DST = 1: you run always with a team and you need to have space to store the extra truck;
STT = DST = 1: you save the cost of the team but you need to have space to store the extra truck and you increase your in-transit inventory by one day;
STT = DST = 0: you reduce your in-transit inventory by one day but you need to fly if the material is delayed at the border (too expensive).

TST calculation The best way to calculate a TST is to analyse the history of transportation arrival time.

Safety Transit Time (STT) Safety Transit Time impact the transportation route or/and its transit time.

Delivery Safety Time (DST) Delivery Safety Time has to cover the maximum delay of an order.

Transportation Safety Time Transportation Safety Time (TST) has to be known to insure a good sizing of the VRO loop.

TST : Think globaly You may not need to secure your transportation if you are the only one to do it!

Eliminating TST based on receiving hours An analysis of truck arrivals and receiving schedule may help to optimize your TST.

Using TST for weather events A classical example used by a lot of companies during winter.

Eliminating TST based on production hours An analysis of truck arrivals and consumption schedule may help to optimize your TST.

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Problem