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Photo Enforcement Program - Historical Perspective

SPEED ZONES

Fixed Speed Sites

The 2005 law authorized the use of automated camera systems for school zones.  Reduced-speed zones have been used to protect and improve the safety of children walking to and from school for years. Several criteria are taken into consideration when setting school zone enforcement standards.  Some of that criteria include the geographical environment of the arterial and school property, age of the students, speed of vehicles to include standard reactionary time and vehicle stopping distances are among a few.  

Why Is Going 20 MPH So Important?

The simple answer to this questions is that slower speeds provide more reaction time to unexpected student’s actions; reaction time for both the driver and the pedestrian. A standard reactionary time used in these calculations is 1.5 seconds.  During that reactionary time the vehicle is still traveling at a given rate of feet per second.  In addition to reaction time and stopping distance collisions at a lower speeds generally will cause less injury. The fatality rate for pedestrians or bicyclists struck by a vehicle at higher speeds is much greater than at lower speeds (see chart below). A pedestrian struck by a vehicle at 40 mph is almost always a fatality. If the vehicle is going 30 mph a pedestrian has 60 percent chance of surviving, but will likely not be walking away from the collision and may sustain life altering injuries. Even five miles per hour can make a big difference to the pedestrian.

One of the more shocking discoveries is that the risk of death greatly increases to 40 percent for a pedestrian who was struck at 30 mph, a speed that some drivers may consider "just 10 over" the school zone speed limit.  

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Children are generally carefree and are often oblivious to their surroundings; that is why it’s important that drivers go the extra length to protect them.  It only takes a moment for a child to run out in front of your vehicle and, if you are speeding, you may not have enough time to react.  

If an accident were to occur, the severity of the accident is reduced as a result of lower speeds. 

Studies suggest that a fatal pedestrian accident is 6 times less likely to happen if the vehicle speed is 23 mph (10 percent chance of fatality) as opposed to 28 mph (40 percent chance of fatality). 

A pedestrian hit at 20 mph has a 90 percent chance of survival. The transition from minor to major injuries occurs between 20 mph and 30 mph. 30 mph is a dangerous speed and potentially life changing for the injured pedestrian. With the reduced speed, more collisions are avoided by making it easier to brake, as well as reducing the severity of injuries should a collision occur.
(Source:  A Guide to School Area Safety August 2006 - Oregon Department of Transportation)

The information below has been provided by Traffic Investigator Ralph Hyett - stopping distances given human input of reactionary time.  When combining the speed impact/injury ratio with the vehicle’s travel distance (speed + reaction time + breaking distance) in school zones it is apparent that even minor incremental enforcement adjustments can have dangerous results for student/pedestrians.  

  • 20 mph = 29.32 fps, a reactionary distance of 43.98 feet, a stopping distance of 19.04 feet taking 1.30 seconds to stop.
  • 26 mph = 38.11 fps, a reactionary distance of 57 feet, a stopping distance of 32.19 feet taking 1.69 seconds to stop.
  • 28 mph = 41.048 fps, a reactionary distance of 61.57 feet, a stopping distance of 37.33 feet with a time of 1.82 seconds
    * Based on 1.5 seconds reaction time on a surface with a .70 coefficient of friction

Here is a different way of explaining the above bullet points:

A vehicle traveling 20 miles per hour travels at 29.32 feet per second.  Given the standard reaction time of 1.5 seconds the vehicle will travel 43.98 feet before the driver’s input on the vehicle is initiated.  If the driver's input is braking, the vehicle will continue to travel 19.04 feet before coming to a complete stop. 

ATS also designed an automated camera system that could detect speed and be used to enforce violators in school zones.  These systems were already in use in other parts of the United States.  The City looked at using these systems to increase the safety of its citizens in school zones. 

Members of the Renton Police Department conducted speed studies at school sites in the City.  These school sites were selected due to the recurring speeding problems noted at the schools.  Studies showed that three schools presented some startling data.  Each of these schools are located next to a main arterial that is used by traffic commuting through Renton. Often these arterials are used as a by-pass resulting from congestion on both I-405 and SR-167. Traffic flow at these locations ranged from 6,300 vehicles bidirectional per day at Talbot Hill Elementary on Talbot Road S to 11,100 vehicles per day on S 2nd Street in front of Renton High School.  The traffic flow for McKnight Middle School is 7,400 vehicles per day.  These traffic flows were recorded in 2006.  

The speed studies showed the following results:

Renton High School:  During a 30-minute time frame in the morning while monitoring only two of the four lanes 41 percent of the vehicles exceeded 5+ miles per hour with the fastest at 15 mph over the 20 mph school zone speed.  The average speed through the zone during that 30 minute period was 28 mph. 

McKnight Middle School: During a 20-minute period in the morning 200 vehicles passed through the school zone and 67 percent were 5+ mph over the school zone limit with the fastest at 51 mph. 

Talbot Hill Elementary School: Again a 20-minute glimpse showed 258 vehicles traveling through the school zone with 22 percent exceeding the limit by 5+ mph even with crossing guards at the crosswalk. Here again the average speed was 27-28 mph with the top speed measured at 36 mph. 

The above three schools were selected for installation of the automated camera fixed speed system. Construction of these sites began in May of 2008.  Both Renton High School and McKnight Middle Schools became operational in July 2008.  These schools operated summer school programs during the month of July allowing the City to operate these sites fixed speed sites in concert with the school’s summer programs.  

Warning notices were issued to violators during the summer school period.  All three school zone sites were operational for the beginning of the 2008 – 2009 school year.  The Police Department ensured that each site met the 30-day warning period prior to sending out infractions notices.  During the warning period a total of 4,786 warnings were issued for school zone violations.   

The following graph shows the number of school zone speeding citations issued in 2008 and 2009.  

Graph 6

The City took extra steps to communicate to the public that these fixed systems were operational prior to the start of the school year. The Transportation Department designed and installed several warning signs.  Variable reader board signs were ordered and placed in two of the school zones notifying drivers of the school zones and the photo enforcement capabilities. 

Speed infraction notices were authorized for approximately the last eight school days in September for violations at Renton High School and McKnight Middle School after satisfying the warning period.  In October of 2008 the warning period for Talbot Hill Elementary School had been satisfied and infraction notices were beginning to be issued for violations. 

The graph illustrates that fewer citations were issued during the months of November, December and February.  These three months had scheduled school breaks: Thanksgiving, Winter Break, and Mid-Winter Break.  Additionally the fixed speed sites were taken off line for approximately eight days to allow time to collect necessary certified documentation for the courts. Due to the inclement weather in December, January and February, school in Renton was either cancelled or delayed on a few days.  The culmination of school cancelations, late starts and school breaks accounts for some of the notable reduction of issued fines during these months.  

The graph below depicts the number of violations issued for each fixed speed site. It is probably important to remember that the number of vehicles traveling through the Renton High School site is roughly 30 to 40 percent higher than the number traveling through the other two sites.

Graph 9

As noted below, the majority of the speed zone violations fall into the category of 6 – 10 miles per hour over the posted school limit.  There have been several instances where vehicles were traveling in excess of 35 miles per hour and even some traveling faster than 41 miles per hour.

Graph 8

The City’s Photo Enforcement program has been operational for less than one year. There are some facets of this program that have yet to be implemented.  Some of the initial data indicates that the City is gaining voluntary compliance by drivers at the intersections and school sites.