Capacity planning: how many hours you can actually give away

The distinction sounds academic and it is the reason most collection times slip. Between attendance on the rota and the time that actually reaches customer vehicles sits a row of deductions every shop knows and almost none quantifies: setting up, searching, internal jobs, rework, the phone.

The routine this article is about works with a whiteboard and a marker exactly as well as with a planning tool. It has three steps — work out the plannable time, book appointments against that time, leave the buffer alone — and the order is the whole trick.

Start with attendance and subtract everything that does not reach a customer vehicle. What remains is the plannable job time, and that is the only thing you give away.

The middle column is an aid to the arithmetic, not an industry figure. You only get your own deductions by writing them down for two or three weeks: a sheet at the lift, one line per interruption, added up on Friday. It is uncomfortable, and afterwards you know why the week never stretches.

Among the deductions, internal jobs are the line most reliably underestimated. Your own courtesy car, goods-in, sweeping the shop, the call to the supplier — none of it is optional and none of it appears on an invoice. What a plannable hour has to earn so that it carries this unproductive time as well is what the labour rate calculator works out.

The classic workshop calendar has one row per time of day and one slot per technician. A job gets a slot — regardless of whether it runs to 0.4 or 6.0 labour units. This is exactly where overbooking comes from, and it only shows up in the afternoon.

The whiteboard version

One column per technician, one row of boxes per hour. A job goes up as a strip as long as it takes. A strip hanging out of the bottom of the column is an appointment you cannot keep — and you can see that from five metres away. If magnetic strips are not your thing, run the same arithmetic on a weekly sheet: the planned duration next to every job entered, the running total under the column, the plannable time from section 1 beside it.

All that matters is that the planned duration is written down as you enter the job. It does not have to be right to the quarter hour; it has to exist at all. A rough estimate that gets added up beats an exact time nobody totals.

At this point a planning tool replaces exactly one manual step: the adding up. It totals the time handed out per technician and per day and says so when the sum runs past the plannable time. Which job you then move is still your call.

Every shop knows the three interruptions that tip a day's plan over: the regular customer's vehicle that would not start, the work that only shows itself once something is apart, and the customer who arrives an hour late. None of them is exceptional, and all three are treated as though they were.

The countermeasure is a fixed, empty column in the plan — not a good intention but reserved time you do not hand out. Two rules make it useful:

• The buffer sits at the end of the day, not at the start. A vehicle that finishes early fills it by itself; a buffer in the morning is used up by ten.
• Its size is measured, not guessed. For four weeks you note how much buffer time was actually needed. If it stays empty regularly, the buffer is too big; if it overruns several times a week, too small.

The emergency slot

If your customers are mostly private owners without a second car, a reserved slot in the morning is often worth more than an extra hour sold. It costs you capacity and saves you the refusal that sends the customer to the next workshop. Whether it pays depends solely on how often the slot is used — that too is a tally sheet, not a matter of opinion.

Anyone planning capacity counts lifts first. In most independent workshops the lift is not the scarcest resource, though. The queue forms at a qualification, at a piece of equipment, or at one person who is needed once more at the end of every job.

You find your own bottleneck with a week of notes: on every job you write down what it waited for. The answer is usually unambiguous and usually not the one you expected.

Work on high-voltage systems is a special case, because there the qualification is not merely scarce but required. Which level your shop needs for which work is a question for your trade association or the body that certifies that work where you are — it is a matter of authorisation, not of planning.

The second most common cause of standing time is not a planning error but an order of events: the vehicle is on the lift, the work begins, and only then does somebody order. From that moment on, a job blocks capacity nobody can sell any more.

The way out is a distinction that starts on the phone:

• Diagnostic appointment — short, no parts, outcome open. It can be handed out at any time.
• Repair appointment — only once the parts needed are ordered and confirmed. Without that confirmation the appointment is pencilled in rather than promised.

For the order to be possible in advance at all, you need the vehicle identification number, the mileage and a description of the symptom when the appointment is made. Three details, thirty seconds on the phone — and the difference between a vehicle that is finished the same day and one that stands for two.

If the diagnosis shows it will cost more than discussed, the customer's approval belongs before the order, not after it. Put the new figure to them in writing, however briefly, and wait for the answer — a message with a number in it is worth more later than a memory of a phone call.