How to Do a Traffic Count: Vehicle Classes, 15-Minute Tally Sheets, and Heavy Vehicle Percentage

What is a traffic count? What you count and what it tells you

A traffic count records how many vehicles or people pass a chosen point during a set time, by type. The results are summarized in a time-slot table such as “from X to Y o’clock, N cars and M heavy vehicles,” from which you read the hourly volume, the busiest time (peak hour), and the share of trucks and buses (heavy vehicle percentage).

Many countries run large national programs. In Japan, for example, the Road Traffic Census surveys traffic volume and travel speed on roads across the country roughly every five years, and at most sites counts vehicles by class and by hour over 12 hours on a weekday, from 7:00 to 19:00. In the private sector, counts are scaled to their purpose: frontage traffic before opening a store, traffic impact studies for housing or commercial developments, and local surveys of school routes or shopping streets.

Preparation: choose the location, times, vehicle classes, and staffing

The accuracy of a traffic count is decided more by preparation than by the day itself. Settle these six things first, and on the day you can focus on counting.

1. 1

   1. Choose the count point and count line

   Pick a single reference line, such as “vehicles passing this utility pole.” A spot a little away from the intersection, where lanes are clear, is easier to count than the middle of the intersection. Where signal queues build up, choose a point beyond the end of the queue rather than at the stop line, so you don’t count the same vehicle twice.

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   2. Decide whether to split by direction

   Decide whether to count each direction separately. Many roads have directional patterns, such as inbound traffic in the morning and outbound in the evening, so if in doubt, split them. Adding directions together later is easy, but you can never split a combined count afterward.

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   3. Choose the times and the summary interval

   To see the morning and evening peaks, count 7:00–9:00 and 17:00–19:00; to see daily patterns, 12 hours from 7:00 to 19:00 is standard. Summaries are usually in 15-minute intervals, which also let you calculate the peak hour and peak hour factor. You can regroup into 10-minute or hourly intervals later, so keep records as fine-grained as possible.

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   4. Decide the vehicle classes

   The most basic split is two classes, “cars” and “heavy vehicles,” adding motorcycles, bicycles, and pedestrians if needed. The more classes you add, the less one person can count, so keep only the ones your purpose needs.

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   5. Plan staffing and shift changes

   On busy roads, divide the work, for example one person per direction. A 12-hour count needs relief staff for toilet and meal breaks. Hand over at slot boundaries (on the hour, quarter past, etc.) so records don’t get mixed up.

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   6. Gather your equipment

   Bring tally counters or a phone counter that records timestamps, recording sheets, a clock, pens, a power bank, rain gear, a folding chair, and drinks. Don’t forget notes on the survey date, weather, and anything unusual, such as roadworks or accidents.

Counting on the day: tips to avoid misses and double counts

The rule is simple: count one the moment a vehicle’s front wheels (or a person’s body) cross the count line. On real roads, though, congestion, signal queues, lane changes, and U-turns keep throwing up judgment calls. Keeping the following points in mind greatly reduces misses and double counts.

• Press the moment it crosses the line: if you press as a vehicle approaches, you will also count vehicles that turn off or turn back before the line.
• Don’t count stopped vehicles: count a vehicle waiting at a signal on the line only when it moves off and crosses.
• Don’t batch your presses: if you think “five just went by, so five presses,” you will easily miss vehicles that arrive meanwhile. Pressing once per vehicle is the most accurate in the end.
• Follow platoons to the back: motorcycles and cars hidden behind heavy vehicles are easy to miss, so track a platoon with your eyes to the last vehicle.
• Flag doubtful cases: for vehicles you weren’t sure about, note the time and situation, and classify them later according to the shared rules.
• Fix mistakes immediately: if you press the wrong button, undo it right away. If you try to fix it later, you won’t know which time slot the mistake belonged to.

On roads with continuous traffic, there is a limit to how many classes one person can handle. As a rough guide, two classes (cars and heavy vehicles) in one direction are manageable for one person, but adding motorcycles and bicycles becomes a heavy load at busy times. If you are new to counting, use the first 15 minutes as practice to check that you can keep up before starting the real count.

Building a 15-minute tally sheet and finding the peak hour

Summarize your counts in a table with time slots aligned to the clock. For 15 minutes, use 7:00–7:15, 7:15–7:30, and so on, and write the number of vehicles of each class in each slot. The table below is an example of one direction counted from 7:00 to 9:00.

Next, find the busiest hour. Comparing only 7:00–8:00 and 8:00–9:00, the larger is 8:00–9:00 with 506 vehicles. But the peak hour doesn’t necessarily start on the hour. The correct method is to add four consecutive 15-minute slots, shifting by 15 minutes each time, and compare.

In this example the peak hour is 7:30–8:30 with 557 vehicles, about 10% more than the maximum of clock-aligned hours (506). This step matters so you don’t underestimate the peak when planning signal timing or estimating the effect of congestion measures.

If you counted for less than an hour, or started partway through, convert to an hourly rate for comparison: “vehicles counted ÷ minutes counted × 60.” For example, 143 vehicles in 20 minutes is 143 ÷ 20 × 60 = 429 vehicles per hour. Short-period conversions are strongly affected by chance, such as signal changes happening to coincide, so as a rule of thumb use records of 15 minutes or longer for comparisons.

Calculating heavy vehicle percentage and passenger car equivalents

The heavy vehicle percentage shows what share of motor vehicles are heavy vehicles (buses and goods vehicles). Heavy vehicles wear road surfaces faster and strongly affect noise, vibration, and pedestrian safety, so this figure is widely used in road design and roadside environmental assessments.

The heavy vehicle percentage changes greatly by time of day. Even in the example above, it is 14 ÷ 96 ≈ 14.6% for 7:00–7:15 and 22 ÷ 112 ≈ 19.6% for 8:45–9:00: the share of heavy vehicles rises as commuter cars thin out. In general, freight-heavy arterial roads have a higher share of heavy vehicles at night, and residential streets have a lower share. Looking at time-slot values, not just the daily figure, tells you a lot about the character of a road.

Passenger car equivalents (PCU) convert vehicles of different sizes and performance into “how many passenger cars’ worth.” Heavy vehicles are longer and accelerate more slowly, so they use more road capacity than one car. Japan’s Road Structure Ordinance treats one heavy vehicle as 2.0 passenger cars on flat terrain (a larger value is used in mountainous terrain). Other countries’ manuals use their own factors, so check the standard that applies to your study.

To estimate 24-hour traffic from a 12-hour count, multiply by the day-night ratio, defined as “24-hour volume ÷ daytime 12-hour volume.” Because the ratio differs by road type and region, it is common to use values published for nearby permanent or census count sites.

How to run a pedestrian count in a shopping street or near a station

Pedestrian counts in shopping streets and near stations are often run every year by local governments or chambers of commerce, on the same day at the same points, and serve as basic data for store openings and vacant-shop policies. The idea is the same as for vehicles: choose a line across the sidewalk and count the people who cross it, by direction and attributes.

• Survey days: one weekday and one weekend day is the basic set. Rain greatly reduces foot traffic, so always record the weather, and compare only days with similar weather.
• Times: choose times that match the area, such as 10:00–19:00 for a shopping street or 7:00–20:00 including commuting hours near a station. If you repeat the survey every year, keep the times the same.
• Categories: gender and age groups such as young, middle-aged, and older. These can only be judged by appearance, so agree on criteria in advance (for example, students in uniform count as young).
• Bicycles: decide how to treat them, for example people pushing a bicycle are pedestrians and people riding are cyclists.
• Groups: count people walking together one by one. Decide in advance whether to count children in strollers.

In busy locations it can be hard to count for a full hour. In that case, a common method is to count only a fixed 10 or 15 minutes each hour and convert to an hourly figure. For example, 74 people in 10 minutes is 74 ÷ 10 × 60 = 444 people per hour. It is convenient, but where train arrivals or bus departures make foot traffic come in waves, the result depends on where your 10 minutes fall in that wave. If possible, count for 15 minutes or more, or start at the same minute every hour.

Handheld tally counters vs. paper sheets vs. phone counters

A traffic count may bring to mind a board lined with palm-sized metal tally counters. They are still in use, but a counter on your phone or computer can greatly reduce the work of summarizing.

The biggest difference is time recording. With a handheld counter, you can’t make a time-slot table unless you copy down the numbers every 15 minutes. With a counter that records the time of each press, you just press while counting and build tables at any interval (5 minutes, 15 minutes, an hour) afterward. You also no longer need to look away at slot boundaries to write numbers down.

Recording and summarizing a traffic count with the tally counter tool

The multiple tally counter is a web tally counter that lines up to 12 counters in your browser and records the time of every press. Just choose a traffic survey template, and it automatically calculates everything covered in this guide: the time-slot table, peak hour, heavy vehicle percentage, and passenger car equivalents.

1. 1

   Choose a template

   The “Traffic survey (by vehicle type)” template lines up five counters (cars, heavy vehicles, motorcycles, bicycles, pedestrians), and the “Traffic survey (by direction)” template lines up four (cars and heavy vehicles in each direction). There are also templates for pedestrian counts by gender and age, visitors and customers, bird counts, and vote and survey tallies.

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   Adjust names, number, and order

   Delete counters to reduce categories or add them to increase. Names are editable, so change them to suit your survey, such as “Northbound motorcycles” or “Southbound bicycles.” Entering a survey name and unit (vehicles, people, etc.) also makes saved records easier to understand.

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   Turn on “Keep screen on” and count

   If the screen dims while you count, you will miss presses, so turn on “Keep screen on.” On a phone you can also have it vibrate when you press. On a computer, the number keys 1–9, 0, -, and ^ (from left to right) press the counters, so you can count with the keyboard without looking at the screen.

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   Fix mistakes with “Undo”

   “Undo” deletes the last press, and “−1” subtracts one from that counter. When you press the wrong button, undoing it right away is the most reliable fix.

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   Choose an interval and view the table

   Choose 5, 10, 15, 30, or 60 minutes to see a clock-aligned time-slot table. The peak hour (busiest hour) is highlighted in the table, and the heavy vehicle percentage and passenger car equivalents (heavy vehicles × 2.0) are shown automatically. Time slots with no presses appear as 0.

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   Save as CSV or paste into a report

   “Save the 15-minute table as CSV” saves the time-slot table in a format that doesn’t garble in Excel. You can also save every press record. For reports and emails, use “Copy summary as text” and paste. How CSV garbling happens is explained in why CSV files garble in Excel.

Things to watch out for when counting outdoors

• Stand somewhere safe: avoid the roadway, intersection corners, and blind bends, and count from a position that doesn’t block the sidewalk. After dusk, a reflective vest is reassuring.
• Get permission on private property or in front of shops: if you will stand in a shopfront or a parking lot, speak to the manager beforehand.
• Prepare for the weather: heat in summer and numb fingers in winter both increase mistakes. Choose a spot with shade or shelter from the wind, and plan drinks and breaks.
• Secure power: if you will count on a phone for 12 hours, bring a power bank large enough to keep the screen on throughout.
• Record anything unusual: note time slots with accidents, roadworks, events, or road closures so you can treat them separately when reading the results.
• Don’t photograph faces or license plates: counting traffic doesn’t require photos. If you do take any, make sure faces and plates aren’t visible.

FAQ

What interval is standard for summarizing a traffic count?

15 minutes is the most common. With 15-minute records you can regroup into hourly tables and calculate the peak hour and peak hour factor (PHF). With a counter that records the time of each press, you can switch to any interval (5, 10, 30, or 60 minutes) after counting.

How do I tell cars from heavy vehicles?

In Japan’s Road Traffic Census classes, passenger cars and light goods vehicles (kei trucks, small vans, etc.) are cars, and buses and goods vehicles (trucks of 2 tons or more, etc.) are heavy vehicles. Other countries use their own classification schemes, so follow the one your study requires. For borderline vehicles, agree on a rule with everyone before the count.

How do I calculate heavy vehicle percentage?

Heavy vehicles ÷ (cars + heavy vehicles) × 100. Motorcycles, bicycles, and pedestrians aren’t included in the denominator. For example, with 852 cars and 142 heavy vehicles, 142 ÷ 994 × 100 ≈ 14.3%.

How do I find the peak hour?

In a 15-minute table, add four consecutive slots to make one-hour windows, shift by 15 minutes each time, and pick the busiest window as the peak hour. If you only use clock hours like 7:00–8:00 and 8:00–9:00, you can miss a peak like 7:30–8:30 and underestimate peak volume.

What are passenger car equivalents?

They convert heavy vehicles and other types into “how many passenger cars’ worth.” Japan’s Road Structure Ordinance counts one heavy vehicle as 2.0 passenger cars on flat terrain, so 852 cars and 142 heavy vehicles equal 852 + 142 × 2.0 = 1,136. They are used when thinking about road capacity and congestion.

How many vehicles can one person count?

It varies a lot with traffic volume, number of classes, and experience. Two classes (cars and heavy vehicles) in one direction are manageable for one person, but adding motorcycles and bicycles becomes a heavy load when traffic is continuous. Use the first 15 minutes as practice to check that you can keep up before deciding classes and staffing.

Can I count pedestrians for just 10 minutes and convert?

In busy locations, counting a fixed 10 or 15 minutes each hour and converting to a per-hour figure is a common method (74 people in 10 minutes = 444 people per hour). Where train or bus arrivals make foot traffic come in waves, results vary, so count for 15 minutes or more, or start at the same minute every hour, to make comparisons easier.

Can I use data recorded on a phone counter in Excel?

With the multiple tally counter, you can save the time-slot table and the list of press records as CSV. It is saved in a format that doesn’t garble in Excel (UTF-8 with BOM), so you can use it directly for charts and report tables. Records are saved only in your device’s browser and are not sent to a server.