Service territory design: draw it in drive minutes, not ZIP codes

Good service territory design groups work by how long it takes a truck to get between jobs, not by which ZIP code or county the jobs sit in. Draw boundaries in drive minutes at working hours, then size each territory by the hours of work and driving inside it, not by job count.

Most territory maps start the same way. Someone prints a map, colors in ZIP codes until each tech has roughly the same number, and tapes it to the wall. It works for a while. Then the company grows, a highway gets rebuilt, a big apartment complex opens on one side of town, and the map that was fair becomes the reason one tech drives 40 minutes between jobs while another finishes at 2:30.

Why ZIP codes are the wrong unit

ZIP codes were drawn for mail delivery. They say nothing about how long it takes a service truck to cross them. Three problems follow:

• Rivers, rail lines and highways split them. Two addresses in the same ZIP can be 4 minutes apart or 25, depending on where the bridge is.
• They vary wildly in size. A dense urban ZIP might hold a day of work in a few square miles. A rural one might hold two jobs a week across thirty.
• They ignore time of day. The same 12 miles takes one time at 7:00 a.m. and another at 4:30 p.m. A boundary that works in the morning may not work in the afternoon.

What you care about is the cost of one more job in that area, and most of that cost is the drive. So the unit has to be the drive.

Step 1: Map a quarter of real jobs

Pull every completed job address for the last 90 days, with the date, the tech and the time on site. A quarter catches enough variety without mixing in last year's seasonal pattern. If you are seasonal, do this for your peak quarter and your slow quarter separately; the right map may be different.

Plot them. You will usually see clusters with gaps between them, and a scatter of edge jobs. The clusters are your natural territories. The gaps are where boundaries belong.

Step 2: Measure in drive minutes from the start point

For each cluster, estimate the typical drive time between jobs inside it at working hours, and from where its trucks start the day. That start point matters. A tech who takes the truck home starts from home, not from the shop.

Territory reach = Typical drive minutes from the start point to the farthest common job, at 8:00 a.m. and at 3:00 p.m.

If the 3:00 p.m. number is much larger than the 8:00 a.m. number, that edge of the territory should get morning work, and afternoon bookings there should be treated with care. The service territory definition covers how crossing time and job density interact.

Step 3: Balance by hours, not job count

Equal job counts look fair and are not. A territory with 30 jobs a week and short drives is a lighter load than one with 30 jobs and long drives. Balance on the hours the work actually takes:

Weekly territory load = Jobs × (Average time on site + Average drive between jobs)

Trucks needed = Weekly territory load ÷ Productive hours per truck per week

Same 60 jobs a week, and South needs almost a full extra truck because of drive time alone. If both have three trucks, South runs late every day and North finishes early. That is not a people problem. It is the map.

The guide to planning a dispatch day around drive time shows how to size an individual day the same way.

Step 4: Decide what happens at the edges

Every territory has jobs near its border, and some outside it. Decide in advance:

• Soft borders. A job near the line goes to whichever truck can reach it, not whichever territory it sits in. Rigid borders send a truck past a closer one; soft borders stop that.
• Edge days. Far edge jobs get grouped onto certain days, which is zone scheduling. It trades customer choice for shorter drives.
• Edge pricing. Jobs far from any truck carry a trip charge or minimum. That is a pricing choice, but measure the drive cost first.
• Out of area. Some addresses are simply too far. Say so instead of offering a slot nobody can keep.

Soft borders only work if someone, or something, checks where the trucks will actually be at the time the customer wants. A tech who is the closest truck to the border at 9:00 may be the farthest at 2:00. CrewLink handles that check at booking: it offers a time only if a qualified tech can make it from their previous job, counting the drive at that hour, and an address outside every tech's area becomes an out-of-area request for the office instead of a fake slot. Branches, each with their own trucks, sit on one board. Where your boundaries go is still your decision.

Step 5: Redraw on a schedule

Territories drift. New customers cluster, recurring accounts move, techs move house. Put a review on the calendar every six months, or whenever you add or lose a truck. Rerun Steps 1 to 3 with fresh data and compare. If one territory's weekly load has grown by more than a few hours per truck, it is time to move a border.

The signal that you waited too long is backtracking: trucks crossing their own path, or two trucks from neighboring territories passing each other on the same road. Windshield time is where that shows up on payroll.

Common questions

How do you design a service territory?

Plot a quarter of real job addresses, group them by drive time from where trucks start, and size each group by the hours of work and driving inside it. Then decide how edge jobs are handled and review the map on a schedule.

Should service territories be based on ZIP codes?

ZIP codes are convenient labels but poor boundaries, because they ignore rivers, highways and traffic. Use them to describe a territory once you have drawn it in drive time, not to draw it.

How many jobs should each territory have?

Not a fixed number. Balance territories on weekly hours, meaning jobs multiplied by time on site plus average drive. A territory with long drives needs fewer jobs per truck.

What is the difference between territory design and route optimization?

Territory design decides which trucks cover which areas, usually for months at a time. Route optimization orders the jobs already on one truck's day. Good territories make every day's routing problem smaller.