Signal Timing & Safety
Dilemma Zone Calculator
The dilemma zone is the critical area near an intersection where a driver is unable to stop safely or clear the intersection before the light turns red.
Stopping Boundary (Xc)
Xc = 1.47 × V × tstop + 1.075 × (V² / a2)
Perception time for safe stopping
Max deceleration rate to stop
Passing Boundary (X0)
X0 = 1.47 × V × Y - W + 0.5 × a1 × (Y - tpassing)²
Intersection + vehicle length
Constant acceleration rate
Perception time for safe passing
Result
Boundary Calculations
Stopping Boundary (Xc)
0.00
ft
Passing Boundary (X0)
0.00
ft
Interpretation
A dilemma zone exists because Xc > X0.
Dilemma Zone Range: 0.00 ft to 0.00 ft upstream of the stop line.
Dilemma Zone Length:
0.00 ft