How to recalculate shipment stop times after updating distance manually on the shipments

Summary: I have requirement to recalculate service time after updating distance on the shipments manually.

for example. distance was 120 KM(in the rate service 30KM Per hour) = service time is 4 hours

but due to some route issue truck has to go via different route and distance would be 150 KM which I have manually updated on the shipment so expected service time is 5 hours. how to calculate duration and stop time on the shipment.

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