Heres another example how life goes on in the Philippines. There are laws but not enforced and there is also logic in enforcing those laws even if its incorrect. You see the piece below about how drivers are being fined for speeding? In the west that method to capture and fine drivers would not wash. It would be laughed out of court yet is the way its done in the Philippines and like all the other articles on this blog noted eg. here locals who received a fine would not even dare to complain and most likely pay it.
Because traffic enforcers dont have speed guns they then jump in a vehicle and run at a constant 40 kilomters an hour. Sounds reasonable… cars overtaking must be doing more than 40 kilomters an hour so lets book them for speeding. But at what speed? Were the cars doing 45? 50? 70? The enforcers would have to speed up to pull over the driver and then its their word against the drivers.
But are they aware of the term “calibration”?
Several factors can affect the accuracy of speedometers:
Worn tires: As the rubber on the tire wears, the tire diameter becomes smaller. This will make the wheel travel a shorter distance per revolution. Your speedometre might think one revolution is 170cm, but due to tyre wear it is in fact 167cm. So a car running at the same RPM will actually travel less distance. Instead of covering 100km in one hour, it goes only 99km. As the rubber wears, the vehicle’s actual speed drops relative to the displayed speed. Because speedos should always be calibrated when tyres are new, not when they are worn, driving on worn tyres will mean your speedo over-reads. Actual speeds will always decrease relative to a fixed displayed speed as the tyres wear. Having worn tyres can not cause you to speed inadvertently.
Tire Pressure: If you decrease the tire pressure, the diameter of your wheel decreases and the wheel will travel a shorter distance per revolution. This will decrease the actual speed of your vehicle in comparison with the displayed speed. If you drive with low pressure in your tires you reduce the risk of unknowingly driving over the speed limit. Because speedos should always be calibrated when tires are fully inflated, driving on low pressure tires cannot cause your speedo to under-read. However, heat build-up or over inflation could possibly cause the tires to balloon slightly which can increase their diameter and could theoretically cause under-readings if there were no other factors offsetting this error.
Rim size: If you change the diameter of your wheels you will affect the accuracy of the speedo. Changing from 16 inch wheels to 17inch wheels does not necessarily change the total diameter of the wheel. It depends a lot on the type of tire that is used. Changing to a wider diameter rim will usually result in a larger diameter wheel. A larger wheel causes your car to travel further with each revolution. If the speedo is not recalibrated it may under-read, which will mean your actual speed might be greater than that displayed on your speedo. If you are increasing the rim size of your tires, you should recalibrate your speedo to make sure you do not inadvertently exceed the speed limit.
Differential ratios: Changing the gear sizes in your vehicle’s differential or gear box can affect the accuracy of the speedometer, resulting in either over-reading or under-reading depending on what the change was.
Vehicle load: When you load your car the tires carry more weight, which can cause them to depress slightly and have a smaller diameter. This can cause an over-reading. It can never cause under-reading. It can not cause you to exceed the speed limit unknowingly. Just as you calibrate your bathroom scales when there is no weight onboard, so too are car speedos calibrated when there is no extra load on the tires.
Speedo Displays: Many modern speedos display in increments of 5 kmh and do not easily display speeds down to 1kmh accuracy. The needle mechanism has its own accuracy limitations. Some old vehicles will have faulty speedos or they have fallen out of calibration, or the needle may wag up and down slightly making it difficult to determine exactly what speed is being displayed.
Speedo Needles: The size and shape of needles can make it difficult to tell exactly what speed is displayed. Given the variables mentioned above, the observable displayed speed is a reasonably accurate, and usually conservative, estimate of actual speed.
These potential errors have been widely known for decades.
The list goes on as to why this so called speed enforcement process is completely … and uterly … INACCURATE!
The drivers that were issued fines using that process should DEMAND A REFUND or the CITOM do the right thing and contact those drivers who were fined on SRP and issue a refund. Sorry, but you just applied “dumb logic” to enforce the law and penalise drivers.