By: Maria Almenoar

You look at your speedometer and wonder: Why is my car going much faster than the official 'average' speed for this stretch of road?

After all, the Land Transport Authority (LTA) uses that number to determine where to put down new gantries and raise charges.

If that magic figure drops too low, you can expect to pay more.

When it comes to calculating averages, the LTA said that it looked at 'journey speed', not a single speedometer reading.

This means that it takes delays at traffic lights and road obstructions into account as well.

To capture all this data, about 6,000 taxis are fitted with LTA devices that measure the distance driven and the trip time.

Also, when checking if speeds have fallen, the LTA said that it measured speeds over a 'significant stretch of road' rather than just at the gantry point.