Traffic control system

A method of controlling traffic along an approach lane of a street in the area of an intersection, which includes the steps of:

• (a) providing green, flashing green, yellow and red intervals wherein green, flashing green, yellow and red signal light units respectively are actuated;
• (b) determining a reaction point located a reaction point distance RPD from said intersection substantially according to the following formula:
• ##EQU2## Where:
• RPD=reaction point distance in feet
• P=perception--reaction time in seconds
• V=85th percentile speed of approach traffic in miles per hour
• f=co-efficient of friction for wet pavement
• g=percent of grade divided by 100 (added for upgrade and subtracted for downgrade)
• (c) locating a pre-intersection signal light assembly in proximity to said reaction point;
• and
• (d) actuating said pre-intersection signal light assembly.

A traffic control system for an intersection of first and second streets with respective approach lanes to the intersection, the control system including an intersection signal light assembly including red, yellow and green signal light units and a signal controller for sequentially actuating said signal light units, which comprises:

• (a) a flashing green signal light unit associated with said red, yellow and green signal light units;
• (b) control means associated with said signal controller for actuating said flashing green signal light unit for a predetermined flashing green interval immediately preceding a predetermined green interval wherein said green signal light unit is actuated;
• (c) a reaction point associated with each said approach lane to said intersection and positioned a reaction point distance therefrom derived substantially according to the following formula:
• ##EQU3## Where:
• RPD=reaction point distance in feet
• P=perception--reaction time in seconds
• V=85th percentile speed of approach traffic in miles per hour
• f=co-efficient of friction for wet pavement
• g=percent of grade divided by 100 (added for upgrade and subtracted for downgrade)
• (d) pre-intersection signal means located in proximity to said reaction point and including:
• (1) a pre-intersection signal light assembly with a vertical standard anchored adjacent a respective intersection approach lane and a pre-intersection signal light unit mounted on said vertical standard and facing oncoming traffic in said approach lane;
• (2) said pre-intersection signal light unit being operably connected to said signal controller for selective actuation when said flashing green signal light unit is operating;
• and
• (3) a rumble strip comprising a plurality of alternating lens and grooves extending transversely across said lane in proximity to said reaction point.