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PhotoSafe Intersections - Signal Timing Information
A chart to show the traffic light timing at the intersections at which PhotoSafe cameras will be installed.
The charts below show the VDOT approved signal timing for Newport News' 3 PhotoSafe interesections.
Please Note: Measurements are in feet, and timing is calculated in seconds.
Mercury Boulevard and Jefferson Avenue
| Approach Direction | Posted Speed Limit | Intersection Width | Yellow Interval Existing | Yellow Interval Calculated | Red* Interval Existing | Red* Interval Calculated |
| North | 45 | 130 | 4.3 | 4.3 | 2.3 | 2.3 |
| South | 45 | 130 | 4.3 | 4.3 | 2.3 | 2.3 |
| East | 35 | 122 | 3.6 | 3.6 | 2.8 | 2.8 |
| West | 35 | 122 | 3.6 | 3.6 | 2.8 | 2.8 |
Oyster Point Road and Jefferson Avenue
| Approach Direction | Posted Speed Limit | Intersection Width | Yellow Interval Existing | Yellow Interval Calculated | Red* Interval Existing | Red* Interval Calculated |
| North | 45 | 181 | 4.3 | 4.3 | 3.0 | 3.0 |
| South | 45 | 151 | 4.3 | 4.3 | 2.6 | 2.6 |
| East | 35 | 163 | 3.6 | 3.6 | 3.0 | 3.0 |
| West | 45 | 176 | 4.3 | 4.3 | 3.0 | 3.8 |
Denbigh Boulevard and Jefferson Avenue
| Approach Direction | Posted Speed Limit | Intersection Width | Yellow Interval Existing | Yellow Interval Calculated | Red* Interval Existing | Red* Interval Calculated |
| North | 45 | 112 | 4.3 | 4.3 | 2.0 | 2.0 |
| South | 45 | 115 | 4.3 | 4.3 | 2.0 | 2.0 |
| East | 35 | 126 | 3.6 | 3.6 | 2.8 | 2.8 |
| West | 35 | 120 | 3.6 | 3.6 | 2.7 | 2.7 |
*Red refers to the phase of time referenced by VDOT as "All Red", which is a phase of timing in which all approaches are red at the same time. This provides for the safe exit of vehicles that enter the intersection as (or shortly after) the signal turns red. Virginia red light camera enforcement timing is based on the posted speed limit.
VDOT Computation Formula Used for the Above Numbers:
1. Yellow Change Interval = t +v/(2a ± 64.4g)
t=perception time; use 1 or 1.4 seconds
v=posted speed in ft./sec.
a=deceleration rate; use 10 ft./sec.2
g=grade of approach
2. *All Red Interval = (w+1)/v
w=width of intersection in ft.
l=vehicle length; use 20 ft.
v=posted speed in ft./sec.
