Redesigning a Process to Improve the Customer Experience and Increase the Capacity of a System
By: Conor Byrne
Tags: Lean, Optimization, Efficiency, Process Improvement, Simulation

Redesigning a Process to Improve the Customer Experience and Increase the Capacity of a System Conor Byrne Sep 3, 2020·4 min read

This piece will give a brief overview of a project I worked on for the Process Modelling, Simulation and Optimisation class I took in Technological University Dublin.

I’ll show how the capacity [0] and the throughout [1] of a system can be improved by making simple adjustments to the process layout [2], leading to improvements in the customer experience.

Consider the process sketched out below. This is the checkout queue at a real retail store in Dublin City.

Existing Process Design

The Process

Customers enter the process at the right foreground of the image. When they reach the top of the queue, seen at the left foreground, they proceed to the closest available checkout to pay for their items. When they have paid, they leave the process through the exit seen in the right middle ground.

There is quite a bit of waste in this process. Can you see it? If not, read on!

When a cashier at a checkout has processed a customer, and their station becomes available, there is an idle-period [3] as they wait for the next customer to travel [4] from the top of the queue and arrive at their checkout station. For cashiers operating Checkout Station 1, this idle-period is negligible, as customers travel a short distance from the top of the queue to their checkout. However, this cashier idle-period increases incrementally for each checkout station along the line, as customers have to travel further distances to reach their checkout. The highest cashier idle times, and the highest customer travelling distances, are at Checkout Station 15, with the second highest being at Checkout Station 14, and so on.

In practice, this inefficiency means the cashier at Checkout Station 1 is working considerably harder than the cashier at Checkout Station 15 over the course of a busy shift.

If the average distance from the top of the queue to a checkout could be reduced, the average idle-period for cashiers would be reduced. This would improve the utilisation of the resources available, and the capacity and throughput of the system would increase. In turn, this would create a better customer experience, as queuing times would be reduced if customers moved through the checkout process more quickly.

Process Redesign

My idea for achieving this is sketched out below.

Proposed Process Redesign

By moving the top of queue point to the middle of the checkout line, the average customer travel distance to the checkout will be significantly reduced. For example, the travel distance from the top of the queue to the furthest Checkout Stations (now 1 & 15) will be roughly halved, removing a substantial amount of the travelling waste present in the previous design.

This means the idle-period for staff members between the serving of customers will be decreased, increasing their utilisation, and improving the efficiency of the system. Ultimately, this translates to an improved customer experience, as customers will spend less time queuing in the new system. Crucially, this improvement comes at no expense or investment from the business — it is 100% efficiency gains.

Results

I modelled this process change using a simulation tool called ExtendSim. My model was based on real data collected from the store, such as time customers spent moving through the process, processing times at the checkouts, the rate at which customers enter the process, and distances from the top of the queue to each checkout.

After running simulations of the existing and proposed designs, I found that the redesign could reduce the average customer queuing time from 2 minutes down to 1 minute and 9 seconds, a ~43% improvement. This was driven by two factors 1) Reduced average customer travel distance, from 7.5 metres to 5.3 metres, a ~30% improvement. 2) An increased utilisation of cashiers at the Checkout Stations furthest from the top of the queue — rising from 62% to 74%.

Notes

[0] Capacity refers to how many people / items a system can serve, or how much output it can produce, in a given time. For example, a checkout system that can serve 1,000 people between 9AM and 6PM has a capacity of 1,000.

[1] Throughput refers to the rate at which a system can process people / items. For example, Checkout Station 1 can serve two people per minute. Crucially, in this example, each checkout has a different throughout rate, as the time it takes to get from the top of the queue (beginning of the process) to each checkout is different.

[2] Process flow refers to how the queue and equipment are arranged on the shop floor, and how people pass through each step.

[3] In this example, the idle-period refers to the cashier time that elapses between the serving of customers.

[4] In Lean operations management, travel is one of the eight process wastes. It refers to the inefficient or unnecessary transportation of people, materials, information or products. The other seven wastes are inventory, motion, waiting, overproduction, over-processing, defects, and underutilisation of skills.