Speed Measurement: The Good, The Bad, and The Ugly
There are three common speed measurement methods employed by police officers in British Columbia. These methods are RADAR, Laser, and visual estimation. Each method has its advantages and its disadvantages. Although the significant problems and concerns with each method of speed measurement will be described in subsequent posts, this post will provide an overview of each.
The Good: Visual Estimation
Most police officers in British Columbia are trained in visual speed estimation. Often, they are required to make an estimation of another vehicle’s speed in situations where the other tools like Laser or RADAR are unavailable to them. In general, the speed estimations made by police officers are relatively accurate.
[pullquote]Road conditions and the presence of features on the road, such as other vehicles or tree-lined streets, can make it difficult to accurately judge speed. [/pullquote]
However, visual speed estimation is subject to virtually hundreds of variables. For example, road conditions and the presence of features on the road, such as other vehicles or tree-lined streets, can make it difficult to accurately judge speed. It is also difficult to judge speed when a vehicle is directly in front of the police car or directly behind it. For this reason, police often attempt to corroborate their visual estimation with information from other sources, such as a RADAR or Laser reading, pacing with a police vehicle, or information from a traffic helicopter overhead. From time to time a police officer may use road features to mathematically calculate speed. Of course, these calculations are complex and subject to mathematical error.
A future post will expand on many factors that contribute to inaccurate speed estimation.
An experienced BC Driving Lawyer is able to cross-examine a police officer in court on his or her visual estimation. Where these estimates are not corroborated by other sources, a driving lawyer can be essential. Even when speed estimations are corroborated, there are other defences.
The Bad: RADAR
RADAR is a system of speed measurement whereby a RADAR signal is broadcast at a moving object and reflected back. This method of speed measurement relies on the Doppler effect. The change in the frequency of the returned signal is transcribed by the device into a speed reading.
The benefits of using RADAR are clear. It is capable of being used in both stationary and moving mode, so police can use a RADAR gun to target a vehicle while they are in motion. However, RADAR is subject to a number of concerns. It has less range than other speed measurement devices. Primary concerns include the interference from nearby radio signals. Of course, nearly every vehicle now has a cell phone, GPS, and radio running at the same time. RADAR may also be less accurate when the speed is measured from directly in front of or directly behind a moving object. Police are trained, therefore, to measure speed at an angle to the oncoming traffic. At high degrees of angle to the target incorrect readings become common.
Police when using RADAR are required to corroborate the RADAR reading with a visual estimate. The two readings should be within a small margin of error with one another. Given the fallibilities of visual estimation, coupled with the problems experienced by a RADAR device, a BC Driving Lawyer is often able to undermine one or both readings.
RADAR is largely on the way out. With the exception of moving RADAR, it is being replaced with the Laser measurement systems discussed below.
The Ugly: Laser
The most common Laser devices used in British Columbia are the Marksman LTI 20-20 and the UltraLyte. At the BC Driving Lawyers offices, we have copies of the manual for these devices and others currently in service. These devices are primarily used by RCMP, though the West Vancouver Police Department, the Greater Vancouver Integrated Road Safety Unit, and the Vancouver Police Department.
Laser devices, while more accurate than visual estimation or RADAR, are not infallible. They require specific and precise calibration steps prior to each shift. If these steps are done out of order or are done improperly, the device may not produce an accurate reading. Police must therefore confirm the calibration of the unit at the beginning and end of each shift.
The Laser device has a longer range than RADAR. It is less susceptible to radio interference, though there are some frequencies which will still hinder its operation. The thing to watch out for with the Laser device is the fact that it requires a clean line of sight. Often this is impossible. The Laser can only be used only in stationary mode. Even a millimeter of movement while pulling the trigger to obtain a reading can result in an elevated speed reading.
These are the big three methods by which speed is measured in British Columbia. In the future we will deal specifically with each method and the shortcomings we have discovered through our work as BC Driving Lawyers. If you have received a Violation Ticket for speeding, you have 30 days to dispute your ticket. Our lawyers can assess your case and discuss your options. Call us today.