Intersection accidents occur every day. Often the issue is a disputed traffic signal. The National Highway Traffic Safety Administration tracks fatal accidents through the Fatality Analysis Reporting System (FARS). FARS data shows that for the years 2000 to 2007, approximately 800 to 1,000 deaths per year happened in the United States as a because of "red-light running crashes". Man more people are injured in "red-light running crashes", with numbers ranging from 100,000 to 125,000 injuries per year from 2000 to 2007.
Accidents happen in a varieties of vehicular traffic situations, including automobiles, trucks, buses, motorcycles, bicycles and pedestrians. In most broadside collisions, both drivers claim to have entered the intersection with a green light. When there is a lawsuit, it is important to understand the operation of the intersection signal control system . Information should be used with accident reconstruction procedures to analyses who ran the light.
tt can take a lot of information to the anywise the crash
When an investigation starts, Depending on how the accident happened, there are several things an any lists most note. It can take a lot of information to the anywise the crash. Data gathering should begin as soon as possible.
Timing data and/or drawings that were in affect on the date of the accident
requests should identify timing data and/or drawings that were in place on the date of the crash . In a basic simple investigation, one should obtain the following items:
1. Signal timing chart.
2. As-built plans.
3. Lane striping drawing (may be the same as as-buiilts)
4. Signal maintenance history (obtain data before/after accident date)
When a government entity is a defendant
When a government entity is a defendant, then additional data is needed, such as:
1. Accident history
2. Prior design drawings and signal timing data of the intersection
3. City, County and/or State standards on intersection and signal design
4. Engineering studies, notes, etc. on the design of the intersection
Witness testimony is often the best tool to analyze a crash
Witness testimony is often the best tool to analyze a crash. Witness location most be established, as well as what was visible to the witness. Witnesses can help show traffic patterns patterns- light or heavy in a particular direction, backed up into the intersection, etc., as well as the presence of other vehicles or pedestrians, and the direction of travel of any other traffic.
The more detailed the information, the better
The more detailed the information, the better.
Things a witness can tell an investigator about a crash
1. How long the witness had been stopped there?
2. What was the condition of "ALL" of the traffic signals when the witness
arrived at the intersection (through, left turns, pedestrian phases)?
3. When did the left-turning vehicle arrive?
4. What was the condition of the traffic signals when the left-turning vehicle
5. What happened when the northbound lights changed?
6. Did the through (green ball) light and left turn lights change together?
Signal Timing in a red light crash
Signal Timing Definitions
The following terms are important to understanding signal timing issues:
Movement- a direction of the traffic pattern, such as the northbound through (straight) movement, the southbound left turn movement, etc. Phase- a number given to a particular movement on signal timing charts or phase diagrams. Interval- The amount of time assigned to a particular signal color, such as the northbound yellow interval. There may also be minimum times assigned, such as the minimum green interval, where the actual green time varies depending on traffic conditions.
Cycle- All of the phases served by the controller at an intersection (i.e. all of the movements) constitutes the cycle.
A few additional terms are listed here (see reference 1):
Average daily traffic (ADT)- The total volume of traffic passing a point or segment of a highway facility in both directions.
Types of traffic signal sensors
Most sensors are magnetic loop detectors. magnetic loop detector scan usually be seen in the road. They may be grouped with two or three detectors in a row to monitor traffic flow and gaps in traffic. Magnetic loop detectors will usually have a wire headed back towards the curb and eventually over to the controller cabinet.
Algorithms that detect changes in the pixel patterns to control traffic signals.
New designs have begun to use cameras for sensors. These detectors are often placed on a signal arm in the intersection. They cover approach areas to the intersection. Software within the control system analyzes the graphic image captured by the camera. A detector identifying the presence of a vehicle uses algorithms that detect changes in the pixel patterns to control traffic signals.
Traffic experts can do studies of the traffic patterns
Traffic experts can do studies of the traffic patterns in order to determine whether signals are needed at an intersection, and how the signals should be set. Such a study will often involve a "traffic count" to find out how many vehicles are turning left, going straight, or turning right at an intersection. Traffic patterns change over the course of the day, a traffic count will involve tracking a traffic over a pre-determined time period. The movements with the largest number of vehicles in their respective direction will receive more green time in the cycle in order to accommodate the traffic pattern. Timing data can be changed at different times of day in order to accommodate heavy traffic flow in particular movements.
Road and intersection design
The time length of yellow change interval will vary depending on the road and intersection design, local and state guidelines for signal timing also play a part. In general terms, the time for the yellow change interval will account for the speed limit of the approaches, angle on approach, visibility of the signal, and traffic volumes.
Pedestrian "WALK" and flashing "DON"T WALK" times
pedestrian "WALK" and flashing "DON"T WALK" times are also set using controller timing parameters. Seven seconds is often used for walk intervals, this allows time for the pedestrian to walk from the sidewalk and into the crosswalk. This time may be enlarged to accommodate heavy pedestrian traffic situations.
The flashing "DON'T WALK" period is calculated to allow the pedestrians to walking across the street . The standard walking speed used for the timing calculation is 4 feet per second. Therefore a crossing distance of 60 feet, requires15 seconds the time allocated to the flashing "DON'T WALK" phase would be approximately .
The solid "DON'T WALK" phase may come at the same time as the yellow phase
The solid "DON'T WALK" phase may come at the same time as the yellow phase for through traffic. In an actuated controller with heavy vehicular traffic on the through movement, the solid "DON'T WALK" could be shown during the green period.
Making a record of the crash as evidence
1. Make sure your insurance card and vehicle registration in the same place in your car. )
2. Remain calm. If hurt stay in the car (if it is safe to do so).
3. Call or have someone call the police and fire department using 911 immediately.
4. Don't' talk abut fault or or how the crash happened.
5. Make notes about the time, date and location of the accident.
6. Make a record of people in involved.
7. Take pictures of the crash scene and any damage to vehicles and injuries to people. (photograph any skid marks or tire gouges left on the roadway.
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