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Question on Applying Lean Six Sigma in Field Service Scheduling

Six Sigma – iSixSigma Forums General Forums Methodology Question on Applying Lean Six Sigma in Field Service Scheduling

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  • #53876

    Mitchell Steffen
    Participant

    While our primary metric is achievement of contracted response time, in order to maximize customer satisfaction, there are certain conditions in which travel time is just as or even more important than response time, in order to minimize cost. Customer and/or Call priority often needs to be considered when making this trade-off between response time and travle time.

    Does anyone have experience in identifying and characterizing the conditions in which travel should take precedence over response time in particular, and balancing response time and travel in general?

    Thanks, Mitch

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    #191732

    Andell
    Participant

    I apologize for my ignorance, but can you give a tangible example of how you differentiate travel time vs response time? I don’t yet understand what the starting and ending events are for the two, or how the customer might be affected.

    If we’re all lucky, maybe answering those questions will lead to the answer you seek. Usually I’m not quite that lucky.

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    #191733

    Mitchell Steffen
    Participant

    Sorry for not explaining the context of the problem. The basic Field Service Scheduling problem involves assigning N service calls to M service engineers, ordering the sequence of the calls so that total travel is minimized while fulfilling time constraints on the arrival times. Normally each engineer starts and ends the scheduled shift at his/her “home base”, so the structure of the problem becomes M Traveling Saleman problems that must be solved in parallel. What makes the problem really interesting is that new calls arrive in real time, and the status and duration of existing calls can change at any point in time, invalidating the current schedule. So real time schedule updates are esssential and determine the final quality of key metrics.

    Key Metrics:
    Actual Response Time = Engineer Arrival Time – Call Creation Time
    %Achievement Target Response Time = Actual Response Time / Contracted Response Time
    Travel Time = Sum of Travel from Home Base to each service call and back to Home Base

    General principle: poor choices of call sequences result in long travel times, which in turn increase respone times. So schedules that minimize travel also minimize the *average* respone time, and therefore under conditions of 1) all customers have the same priority, and 2) call backlog is low so engineer capacity is much greater than call demand, then minimum travel schedule is also the best schedule for response time. However, not all calls and customers have the same priority, and in the current economy, call backlogs tend to exceed engineer capacity, creating large backlogs and hard choices on which calls to schedule first. So the minimize travel schedule does not meet response time constraints, especially when weighted by customer/call priority.

    So the challenge is designing experiments which will provide insight on what factors drive the best trade-off between response time, travel, and customer/call priority. Some of the factors the Business users currently focus on include 1) light vs moderate vs heavy call backlog (capacity/demand balance or imbalance), 2) geography type (dense urban vs suburban vs rural), 3) product types and mix (single specialized teams vs jack-of-all-trades teams).

    Thanks, Mitch

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    #191829

    Mike Carnell
    Participant

    I don’t get the question. The first question had some cost/customer benefit trade off and in you expanded explaination it doesn’t seem to concern cost.

    Are the field service issues also warranty issues?

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