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Control times are used to give a traffic stream that has red the option of cancelling conflicting traffic streams that have green and traffic before their maximum green time. They enable intervention in the:

• Transition,
• before the maximum green time is reached
• or the traffic stream goes to the higher level

The value of the control time is compared with the waiting time of the traffic stream. As soon as the waiting time is greater than the parameterised value, the corresponding intervention is triggered.

Explanation of the types of intervention:

• The control time for the stage transition is used to decide whether an intervention in the transition is permitted. If the intervention is permitted, a traffic stream can cancel a green command that has already been issued.
• Control times 1 to 3 can be used to limit the maximum green time of a traffic stream that has green and traffic. 
• Without a set control time, a traffic stream can only cancel its conflicting traffic stream after the maximum green time 2.
• The only safe area in which a traffic stream that is green cannot be cancelled is when the switched signal displays the transition image and the minimum green time 1 has not yet expired.

Control time in transition

• After the minimum red time, the traffic stream registers in the second line.
• Two seconds later, the traffic stream registers in the first line. The transition is started immediately.
• Another three seconds later, the phase transition control time of the second traffic stream is reached (traffic stream waiting time is greater than phase transition control time). The switching on of traffic stream 1 is cancelled (it does not yet have red/yellow or green) and traffic stream 2 is now switched. 

Figure 50: Intervention in transition

Control time 1

If the traffic stream waiting time in the red of a traffic stream exceeds the control time 1, only the maximum green time 1 (tg max1) is permitted for the conflicting traffic streams. A control time 1 of INAC means that the traffic stream in question can never cause a reduction in the green time of the conflicting traffic streams to tg max1. A lower value for control time 2 or 3 only has an effect if control time 1 is exceeded.

Figure 51: Intervention after maximum green time 1

Control time 2

If the traffic stream waiting time in the red of a traffic stream exceeds the control time 2, only the minimum green time 2 (tg min2) is allowed for the conflicting traffic streams. A control time 2 of INAC means that the traffic stream in question can never cause a reduction in the green time of the conflicting traffic streams to tg min2. A smaller value for control time 3 only has an effect if control times 1 and 2 are exceeded.

Figure 52: Intervention after minimum green time 2

Control time 3

If the traffic stream waiting time in the red of a traffic stream exceeds the control time 3, only the minimum green time 1 (tg min1) is allowed for the conflicting traffic streams. A control time 3 of INAC means that the traffic stream in question can never cause the green time of the conflicting traffic streams to be reduced to tg min1.

Figure 53: Intervention after minimum green time 1

Maximum waiting time: 

If the traffic stream waiting time has reached the maximum waiting time, the traffic stream is moved from priority level 1 to priority level 2.

Figure 54: Priority level 1 and 2