The Evening Queue at a Guwahati Kirana
Umesh runs a 600 sq ft neighbourhood grocery in a Guwahati locality. The single billing counter sits near the entrance, and the cold-drink fridge is directly beside it. Between 6 pm and 8 pm about 90 customers pay, each taking roughly 2.5 minutes at the counter; the queue spills onto the pavement, and about two customers a week abandon full baskets. Staple rice and dal are kept on the back shelf, so customers walk the full length of the store twice. A 4 ft impulse rack of chips and chocolates stands inside the queue lane, but it blocks the aisle when two people try to pass. Shrinkage of small items such as razor blades and chocolates is running at about 1.8% of sales against the owner's target of 0.8%. Umesh has ₹35,000 for fixtures and can add one staff member to the evening shift. He wants the crowding fixed without losing impulse sales.
1. Identify the three highest-impact layout or operations problems in this store and explain the change you would make for each, staying within the ₹35,000 fixture budget and the one extra evening staff member.
Read the worked answer
1. Billing capacity is structurally short. One counter can process only 120 ÷ 2.5 = 48 bills in the two-hour peak against 90 customers. Add a second billing point and staff it with the extra evening person; split the existing counter rather than building a new one, so the fixture cost stays low. Give customers with 1–3 items (about 60% of the traffic) an express lane averaging 1.5 minutes.
2. Entrance congestion. The cold-drink fridge beside the entrance narrows the entry and competes with the queue. Drinks are usually a destination purchase, so move the fridge to the rear wall and keep the entry clear.
3. Staples position. Rice and dal at the back is right for a kirana, but the double walk is caused by missing adjacencies. Add a small 'tonight's dinner' rack near the staples with the top two staple SKUs and complementary items.
4. Shrinkage. Move the impulse rack out of the walking lane but keep it within the cashier's sightline; put razor blades and chocolates within 2 m of the counter and add a convex mirror. The 1% shrinkage reduction on monthly sales is the payback test.
2. Calculate the billing capacity of one counter during the 6–8 pm peak. How many counters does the store need, and what caveat would you add before treating that number as sufficient?
Read the worked answer
Peak window = 120 minutes. Service time = 2.5 minutes per bill.
One counter capacity = 120 ÷ 2.5 = 48 bills.
Demand = 90 customers, so utilisation of one counter = 90 ÷ 48 = 188%. One counter is not merely busy, it is impossible.
Two counters give 96 slots, utilisation = 90 ÷ 96 = 94%. On paper this covers demand, but 94% utilisation is fragile: arrivals are not evenly spaced, one slow bill (price check, card failure, large basket) blocks the lane, and waiting time rises steeply as utilisation approaches 100%.
The practical answer is two full counters plus one express lane for small baskets, or two counters with the extra staff member able to open a third till when the queue exceeds about six people. If the express lane handles 54 small baskets at 1.5 minutes (81 minutes of load) and the main lane handles 36 larger baskets at 2.5 minutes (90 minutes), the load is balanced with a small buffer rather than relying on average capacity alone.
3. Which two measurable KPIs would you track for four weeks to judge whether the changes worked, and what result would make you reverse a specific change?
Read the worked answer
Track queue abandonment (customers who leave or drop a basket, counted daily at the counter) and impulse attach rate (units sold from the queue rack per 100 bills, or average basket value). Add shrinkage % as a secondary check.
Set a two-week baseline before moving anything. Then judge the change against both KPIs together, not one at a time. For example, if abandonment falls from 2 baskets a week to 0.5 (recovering roughly ₹1,000–1,500 of sales) but impulse sales fall by ₹3,000 because the rack moved out of the lane, the rack move has failed on net contribution. In that case keep the extra counter and the fridge move, but restore the impulse rack to a position within the cashier's sightline and within arm's reach of the queue, even if it slightly narrows the lane.
If shrinkage does not fall below about 1.2% within four weeks of moving the small-value items, the problem is likely process (cashier vigilance, receiving checks) rather than fixture placement, and the mirror and rack position should be reviewed with staff.