An average speed check, also called section control, does not measure your speed at one spot. It measures the time you take to drive from one point to another and works out your average speed over that stretch. The Netherlands and Belgium call it a trajectcontrole. In Türkiye the official name is Ortalama Hız İhlal Tespit Sistemi, and route maps show the stretch as a hız koridoru. This guide explains how average speed checks work in these three countries, based only on what the authorities themselves publish, and what BlitzBuddy shows while you drive through one.
How an average speed check works
Cameras stand at two or more measuring points along the road. Each camera reads the number plate of every vehicle that passes and records the time. The system knows the distance between the points, so the time you took gives your average speed.
A simple example: a 10 kilometre section driven in exactly 6 minutes is an average of 100 km/h. Drive it in 5 minutes and your average is 120 km/h, even if you were never caught at one precise moment.
If the average is above the limit, it is a speeding offence. In the Netherlands the fine is sent to the registered keeper of the vehicle. In Flanders the system passes the details to the federal police.
How the average is measured
The Dutch public prosecution service, the Openbaar Ministerie (OM), publishes the most detailed explanation of how the systems measure. The main points from its page:
- Sections. Some average speed checks are split into several sections, usually because there are junctions with slip roads along the way. The shortest distance over which an average is calculated is at least 200 metres.
- One fine, for the worst section. On a check with several sections you never get more than one fine. It is for the highest offence. Slowing down in a later section does not cancel speeding in an earlier one.
- Every lane. The check works on all lanes, recognises vehicles that change lanes, and also covers the hard shoulder.
- Every vehicle. Motorcycles are measured the same way as cars. For lorries, buses and cars with a trailer, the system uses the size and the number plate to apply the lower limit that holds for them.
- Always on. The checks run 24 hours a day, seven days a week. You cannot see from the outside whether a system is on. Roadworks can sometimes stop a system from enforcing for a while.
Measurement correction in the Netherlands
The OM also publishes the measurement correction it applies: 3 km/h on limits up to 100 km/h, and 3 percent of the measured speed above that. On limits up to and including 120 km/h, a fine follows from 4 km/h over the limit after that correction. On 130 km/h roads there is no such margin, and a fine follows from 1 km/h over after correction. These are enforcement rules, not a target. The limit on the sign is the limit.
Average speed checks in the Netherlands
In the Netherlands the OM keeps the official list of current average speed checks, on motorways and on provincial N roads, in both directions unless it says otherwise. One example from that list is the A2 between the Holendrecht junction and Maarssen. The OM describes section control as an addition to other checks such as fixed speed cameras, not a replacement for them, and says it gives calmer traffic because speed differences between vehicles get smaller.
Average speed checks in Belgium
In Flanders, the Agentschap Wegen en Verkeer (AWV), the Flemish roads agency, places the installations. It describes a trajectcontrole as a measurement of your average speed over a longer distance using automatic number plate recognition. Once installed, a system works non-stop.
Two points from the AWV page are worth knowing. First, its map only shows the average speed checks that AWV places itself. Local police zones can install their own, and those are not on the map. Second, besides fixed checks there are mobile average speed checks that can be moved, for example to a stretch with temporary roadworks. AWV also notes that section control is not possible in bends at interchanges or on ring roads where slip roads follow each other closely.
Average speed checks in Türkiye
In Türkiye the Emniyet Genel Müdürlüğü (EGM), the General Directorate of Security under the Ministry of Interior, installs average speed systems on intercity roads, on routes where accidents are frequent. They use the existing number plate recognition system, known as PTS. According to EGM, traffic signs and warning signs are placed ahead of the systems to inform drivers. In its announcement of 20 August 2025, EGM said a new group of systems would be used for enforcement from 22 August 2025.
The EGM Traffic Presidency also runs a route page on trafik.gov.tr. For a chosen route it shows the hız koridoru stretches on a map, and it says its data is refreshed every 30 minutes.
What BlitzBuddy shows on an average speed check
BlitzBuddy warns for average speed checks in the Netherlands, Belgium and Türkiye, and for most average speed checks in France. The sections come from official lists where they exist, such as the OM list in the Netherlands and the Ministry of Interior route data in Türkiye, and from OpenStreetMap. Each section is stored as a line with a start, an end, a length and a limit, separately for each direction of travel.
- Before the start. The start and the end of the section appear in the list of upcoming events, each with its distance.
- At the start. One short spoken alert with the length of the section. The limit is on the screen. When the app is on screen, the section screen usually opens by itself.
- On the section. A full screen shows the road and the start and end names, your average in large numbers, how far you are under or over the limit, a progress bar, your current speed, the distance remaining and the minutes to the end. Your average appears after the first 200 metres.
- If your average is too high. The screen, and a short spoken alert, give you the highest speed you can keep until the end to finish under the limit.
- At the end. One alert with the average you drove.
Between the start and the end the app stays quiet unless your average goes over the limit, and the screen needs no taps. If you close it, the section stays in the drive card with your average. You can turn these warnings off under Settings, Average speed checks.
Germany and France
In both countries BlitzBuddy shows fixed speed cameras, with their exact positions, and speed limits. In France it also warns for most average speed checks; in Germany it does not warn for average speed checks. In Germany, using a speed camera warner while driving is not permitted (§ 23 (1c) StVO). In France, article R413-15 of the Code de la route has, since 5 January 2012, also banned devices that warn of or inform about the location of the equipment used to record traffic offences (paragraph V). In both countries, using these warnings is the driver's own responsibility. Read where speed camera warnings are allowed before you drive abroad.
Sources
- Openbaar Ministerie, Trajectcontroles: om.nl
- Agentschap Wegen en Verkeer, Trajectcontroles: wegenenverkeer.be
- Emniyet Genel Müdürlüğü, PTS-EDS Ortalama Hız İhlal Tespiti, 20 August 2025: egm.gov.tr
- EGM Trafik Başkanlığı, route map with radar and control points: trafik.gov.tr
- Section and speed limit data: © OpenStreetMap contributors
Pages read on 24 September 2026. Back to the BlitzBuddy home page.
Frequently asked questions
Is section control the same as a trajectcontrole?
Yes. Section control, average speed check and trajectcontrole (Dutch) all mean the same thing. In Türkiye the official name is Ortalama Hız İhlal Tespit Sistemi, and route maps call the stretch a hız koridoru.
How is the average speed calculated?
Cameras at the measuring points record your number plate and the time. The system divides the distance between the points by the time you took. If the result is above the limit, it counts as a speeding offence.
Can I slow down at the end to make up for driving too fast earlier?
Not reliably. In the Netherlands the Openbaar Ministerie explains that systems with several sections calculate an average per section, over at least 200 metres, and fine the highest offence. Keep to the limit for the whole stretch.
Does BlitzBuddy warn for average speed checks in Germany and France?
In France, yes: BlitzBuddy shows most French average speed checks at their exact location, next to the fixed speed cameras. In Germany it shows fixed speed cameras and speed limits, but no average speed checks. In both countries the law limits speed camera warnings, and the driver is responsible.
Is the average in the app the official measurement?
No. The app calculates your average from GPS, from the moment you entered the section. The official system uses its own measuring points. Use the app as a guide and the sign as the rule.
