What a 15-minute drive really covers, and why circles mislead

A 15-minute drive covers whatever the road network lets a car reach in a quarter of an hour: an uneven shape that stretches out along fast roads and stops short at rivers, rail lines, parks and one-way grids. A circle drawn on a map ignores all of that, so it counts customers across water with no bridge and misses those along a motorway who can actually arrive sooner. For any decision about who can reach you, draw the travel area, not the ring.

This article is for anyone who sizes a catchment, a delivery zone or a sales patch: retail and restaurant expansion teams, logistics planners, clinic groups, property brokers. It explains how travel areas are shaped, how walking, cycling and driving differ, what to count inside an area, and the limits of the figures.

Why a circle gets it wrong

A radius treats every direction the same. Real places are not like that. A shop on the north bank of a river may serve the far bank only through one bridge two kilometres away. A store beside a motorway with a junction nearby reaches a long strip of suburbs quickly and the streets behind it slowly. A site at the foot of a hill or on a peninsula has half its circle in places nobody drives from.

• Water. Harbours, rivers and lakes cut circles in half. Cities such as Lisbon, Istanbul, Buenos Aires and Vancouver show this plainly.
• Barriers. Rail yards, airports, motorways without crossings and large parks add minutes that a circle never sees.
• Fast corridors. Ring roads and expressways stretch the area far along their length.
• Dense centres. Lights, one-way streets and pedestrian zones shrink a drive-time area in the middle of a city compared with the edge.

Drive, walk or cycle: three different maps

The way people arrive changes the shape completely. A 15-minute walk reaches about a kilometre in a town; a 15-minute drive reaches several. Cycling sits between the two and follows paths that cars cannot. Match the mode to how your customers actually come:

• Walking for convenience stores, cafes, pharmacies and anything in a dense centre or near a station.
• Cycling for city centres where couriers, field officers or students ride.
• Driving for supermarkets, car-based retail, warehouses, clinics in the suburbs and service areas for vans.

The Travel area block draws either a travel time (everything within so many minutes) or a distance by road (everything within so many kilometres along the roads, not as the crow flies). For now it goes up to 15 minutes and 10 km by road. Times are for usual traffic, not the traffic at the moment the flow runs, so an evening rush can shrink the real reach further.

When the area is an estimate

When the routing service cannot draw an area (it is not set up, the day's share of it is used, or a call failed), the block falls back to a circle at a typical straight-line speed: 25 km/h by car, 12 km/h by bike and 4 km/h on foot. That makes 15 minutes by car about 6.3 km, 15 minutes on foot 1 km, and 15 minutes by bike 3 km. The step and every email say the area is an estimate. Treat it as a first look, not a catchment.

What to count inside the area

A travel area is not an answer by itself. It is a boundary that the blocks after it search inside, as they would an Area of interest. Common pairings:

• Nearby places: the competitors, anchors or prospects a customer could reach instead. Each one found carries the name of the area it fell in, such as 10 minutes by car of a given store.
• Demographics: how many people live inside, by age group. Population figures exist in some countries only, among them France, Canada, India, Thailand, Egypt and Australia, and not yet the United Kingdom or the United States.
• Traffic incidents: closures and roadworks inside each depot's delivery area, so drivers hear only about their own patch.

A worked example

A made-up example: a bike repair shop in Melbourne wants to know which offices are within reach of a courier on a bike. A 3 km circle around the shop takes in a stretch of the river and a rail yard. A 15-minute cycling area instead follows the paths along the river and over the bridges, and leaves out the far side of the rail yard where the only crossing is a long detour. The shop then counts offices inside the cycling area with Nearby places and sends the list to its sales lead. The two shapes overlap, but the offices that differ are the ones that matter: reachable ones the circle missed, and unreachable ones it counted.

Mistakes to avoid

• One mode for every customer. A shopping centre draws drivers from far away and walkers from the flats next door. Draw both and look at each.
• Treating the edge as a wall. People just outside 15 minutes still come, less often. Use the area to compare sites, not to promise that nobody beyond it will visit.
• Forgetting rush hour. The area is drawn for usual traffic. If your trade peaks at rush hour, expect a smaller reach then.
• Mixing estimates and road areas when comparing sites. If one site's area is an estimate, compare it with care or run it again later.

Watching each store's area with an AI employee

1. Upload your stores to My data.
2. Add Travel area: 10 minutes by car of each store, Around set to each incoming place (up to 25 a run).
3. Add Nearby places for the rivals you care about, searching the area of interest the travel areas form.
4. Add Only new so each rival is reported once.
5. Email each Monday to the area managers.

Each Monday the managers get the new rivals inside their own store's real drive-time area, named by store, rather than a city-wide list. An area drawn once for a place, a range and a mode is kept for 30 days, so repeated runs reuse it.