Introduction

Many communities use red light cameras as a revenue source, then claim it is for safety. Some places go so far as to shorten the yellow duration forcing more drivers to run the light (more revenue, less safety and harder braking). To make matters worse many states use an unrealistic (fast) driver reaction time to determine yellow light duration.

A way to safety rate a traffic stoplight (including red light cameras) is to determine potential maximum driver braking (worse case). Worse case is the distance a vehicle can legally continue (at speed), greater distances and the vehicle would run the light. Using a realistic driver reaction time, a realistic (objective and predictable) braking number can be determined. Using a braking "g's" scale (deceleration compared to acceleration due to gravity), braking g's can be used to determine (braking) safety and comparing other stoplights.

This document explains how to determine braking g's using speed limit, yellow light duration, road grade (incline), and stop bar to clear point (usually intersection) distance. Includes a discussion of factors involved, mathematical model and proof, equations and calculators, and braking scale levels.

Calculate Driver Braking (g's)

RED LIGHT CAMERA CONCERNS

Cameras do not improve safety or fix problematic intersections -- intersections can usually be fixed by increasing yellow light duration, -- longer yellow light duration lowers braking action (safer stops). Cameras have been known to cause collisions -- some drivers aware of a camera brake too soon and get rear-ended. The person the vehicle is registered to gets ticketed -- person vehicle registered to may not have been driving. -- presumption the owner is guilty (until proven innocence) -- evidence against vehicle, not driver (no direct evidence against owner). The process is automatic -- a police officer does not have to see alleged violation, -- cannot cross examine electronic circuits (loss of right to confront witness). Camera's real purpose is to collect lots of $money$ -- sometimes the yellow duration is decreased (more tickets and more dangerous). -- up to half of fine can go to a 3rd party (private company that maintains system). -- some contacts forbid increasing (making safer) yellow duration.

Any measuring device, especially automatic devices (speed and red light cameras), should have established tests (calibrations and/or laboratory test) scheduled on a regular basis. Test records should be maintained and available. Any device not tested and maintained properly has questionable accuracy. Also the chain of control of evidence (photos and data) should have checks and balances with accountability and be well established and followed.

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How To Safety Rate Red Light Cameras

© Copyright 2005, 2010, 2011 Donald S. Sawicki, All Rights Reserved.