How Police Catch You Speeding in Pennsylvania


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Police can clock your speed using either a speedometer, a radio-microwave device (radar) or by an electronic device (VASCAR). Title 75 Section 3368 of the PA Motor Vehicle Code lists basic information about speed timing devices, including approved devices, restrictions on who can use these devices, distance restrictions on the use of timed speed devices, and calibration requirements.

The Pennsylvania Department of Transportation has adopted a list of approved speed timing devices as well as approved maintenance and calibration stations. 


Speeding tickets can be issued as a result of "pacing," which occurs when an officer follows a suspect, using his/her own speedometer to clock the suspect's speed. Under Section 3368 of the Motor Vehicle Code, an officer or trooper must pace your vehicle for a minimum distance of 3/10ths of a mile.

Speedometers must be tested for accuracy at least one year prior to the alleged violation date, and immediately upon a change of tire size.

Roadway configurations (i.e. hills vs. straight roadways), roadway conditions (day vs. night, clear vs. rainy, etc), and distances between your vehicle and the officer's vehicle can impact the accuracy of an officer's pacing. For example, if an officer is speeding up to catch your vehicle, a speedometer reading will be artificially high.

Radar Devices (referred to as radio-microwave devices or electronic speed meters)

Pennsylvania State Troopers are the only members of law enforcement who are permitted to clock your speed using a radar device. PA is the only state in the nation that prohibits local police officers from using radar devices.

Radar devices function by sending a radio signal in a narrow beam towards your vehicle and recapturing the signal after it bounces off the exterior of your vehicle. The device uses the "Doppler Effect," calculating your speed based upon changes in the frequency of the original signal after it makes contact with your vehicle.

If your speeding ticket is the result of a radar reading, it is important to have the trooper establish whether or not there was traffic in your lane or in any surrounding lanes. If you are traveling near other vehicles - particularly large vehicles - it is possible that the signal used to clock your speed was from another vehicle.

Radar devices must be tested for accuracy within a period of one-year prior to the citation date. These devices are usually calibrated using a tuning fork, which creates a known speed measurement using a specific radio signal. When using the tuning fork, the device should be pointed towards the sky to eliminate interference from passing vehicles. While not required, the National Highway Traffic Safety Administration (NHTSA) and US Department of Transportation recommend that calibration should occur at the beginning and end of shifts.

To establish proper calibration, the Commonwealth must offer the following into evidence: (1) Certificate showing that agency who tested the device was certified by Secretary of Transportation and (2) a Certification of Electronic Device (radar) Accuracy, signed by the person who tested the accuracy of the device, as well as the engineer in charge of the testing station.

If a trooper fails to use a tuning fork to calibrate the radar device, fails to calibrate the device as often as required, fails to present proper calibration documentation, or claims that calibration is unnecessary, these may be grounds to dismiss your citation.

Electronic Speed Timing Devices (Non-Radar)

Electronic speed-timing devices like VASCAR and VSPEC are non-radar devices which calculate speeds between two points. With VASCAR, a police officer measures the distance between two points by using measuring tape, or by connecting the device to the vehicle's odometer and driving the distance between the points. The officer then manually hits a trigger switch when you cross the first point and hits the switch a second time when you cross the second point. The device then calculates your speed by dividing the distance your vehicle traveled by the time it took to travel between the two points.

The VASCAR unit can be used when a police car is stationary, when following your vehicle, when driving ahead of your vehicle, or while driving in the opposite direction.

There are multiple ways to challenge a speeding ticket based upon a VASCAR reading:

First, with the exception of school zones and active work zones, under Section 3368(c) of the PA Motor Vehicle Code, electronic speed timing device readings cannot be used to convict you if:

  • The speed recorded is less than 6 miles per hour over the speed limit;

  • The legal speed limit is less than 55 miles per hour and the speed recorded is less than 10 miles per hour over the speed limit.

Second, if the two trigger points are located at a distance from the officer's vehicle, the officer may not be able to accurately observe when your vehicle passed the two points.

Third, since the officer is required to manually hit trigger switches as your vehicle crosses two points, errors in reaction time can create an incorrect result. If an officer is late to hit the trigger at the first point, and accurate as you cross the second point, you will be clocked at a faster speed than what you were traveling. An officer can be questioned about whether or not his or her reaction time had ever been tested for accuracy.

Fourth, if the officer connected the VASCAR device to the vehicle's odometer, and the odometer reading is off, then the VASCAR result will be off as well. The officer must be able to establish that both the VASCAR device and the odometer were calibrated.

Finally, PA Bulletin Doc. No. 11-2256 indicates that if a citation is contested, it is necessary for the police department to show the certificate of stopwatch accuracy, which was issued within 60 days of the citation, and an approved speed-timing device certificate issued by the Bureau of Motor Vehicles.


"Any person choosing to represent himself in a legal proceeding must, to a reasonable extent, assume that his lack of expertise and legal training will be his undoing."

If you are cited for speeding and attempt to contest the ticket yourself, you may be fighting an uphill battle. The officer who cited you may not appear in court, and if he/she does appear, may attempt to establish that the devices were properly functioning through inadmissible evidence. You may also find that the Court restricts your ability to cross-examine witnesses as a self-represented Defendant.

Don't fight your speeding ticket alone. Call the Zuckerman Law Firm today at 412-447-5580 for a free consultation.