vs | plus

The basic behaviour of the detector is defined with the detector function. This also has an effect on how the traffic stream functions. 

The call mode defines the behaviour from when a new request is recognised. For the occupancy type, the duration from which a request is recognised must also be specified. After a new request, you can specify how long it is valid. This can be set via the debounce time, delay time, reset time and hold time. In earlier vs | plus versions, the hold time had a limited function for PT traffic streams. The hold time only had an effect for traffic streams that allowed a forced cancellation in red. This behaviour has been revised in vs | plus version 8.0.0. 

The reporting points of PT traffic streams are used to track individual vehicles. This requires a theoretical journey time and a calibration value for each reporting point. The theoretical journey time (target value) corresponds to the time of the requesting vehicle from the reporting point to sign-off. vs | plus uses this time to calculate the expected arrival time (TX as time within the round trip) of the public transport vehicle. The arrival time in turn forms the basis for influencing the control system depending on the framework plan and reporting point function.

Figure 41: Theoretical travelling time of a PT vehicle

Vehicles making requests at the individual call points are normally travelling faster or slower. 

Figure 42: Driving a PT vehicle that is travelling slower

With the calibration value, the traffic stream waiting time at each call point is recalibrated to the reference value. 

Figure 43: Calibrating the journey to the theoretical travel time

The following can be assumed as a rule of thumb: The sum of the theoretical travelling time and the calibration value for each call point is equal to the travelling time of the first call point. 

In connection with the detector functions for the preparation of a stage (ASCPTxx, ASBPTxx), the duration of action for a preparation must be defined. The effect of the preparation remains active for the duration of the set time. Both functions ASCPTxx and ASBPTxx receive the functionality of a signalling point with the function ANxx after the comparison value "Preparation time" has elapsed. This means that a main request can also be triggered with the ASCPTxx or ASBPTxx functions if parameterised accordingly. It is essential that the hold time is longer than the preparation time. A main request is only triggered if the hold time is longer than the delay time and the preparation time.

The function performed by vs | plus during preparation depends on the set value. The effect of the change (ASCPTxx) or block (ASBPTxx) detector functions is different: 

• Only preparatory effect (bringing forward WITH consideration of tg min2). 
  Depending on the remaining travel time, vs | plus changes the functionality of the signalling point. If "Change stage" is parameterised, a ASCPTxx is performed, optimised according to the remaining travel time. If this is no longer possible, or if "Block stage" is defined, the ASBPTxx function is executed. If the remaining travelling time reaches a value that requires switching on, the PCIPTxx function is executed.
• Duration of the preparatory effect of a request. 
  If the remaining travelling time is not taken into account, ASCPTxx or ASBPTxx is automatically executed. This means that a ASCPTxx or ASBPTxx is executed during Tprep, even if the remaining travelling time would no longer allow it. If the detector waiting time [twdet] is greater than Tprep, the SCIPTxx function is executed.
• Only a preparatory effect (pull forward WITHOUT consideration of tg min2). 
  ASCPTxx or APBPTxx are optimised according to the remaining travel time. If the remaining travelling time reaches a value that requires switching on, the SCOPTxx function is not executed. The traffic stream must first receive a main request via another call point.

In addition to the function of correcting the traffic stream waiting time in the event of irregularities in the route, vs | plus provides the option of a forced request. This can be controlled depending on the traffic stream or detector. The forced request time of the call point controls the differentiation between traffic stream and detector-dependent forced request.

• Forced request time = 0: call point-dependent forced request. 
  If the traffic stream waiting time of a traffic stream reaches the forced request time of a call point, a forced request is started for this point. This means that the waiting time of this call point is started even though no request has been made.
• Forced request time = [1 ... 3276]: Traffic stream-dependent forced request. 
  If the traffic stream waiting time reaches the forced request time of the call point, a main request is triggered.
• Forced request time = INAK: no forced request. 
  The prerequisite for deactivating the forced request is that the traffic stream in question must be given green in another way. This can be done by an auxiliary call point, a second traffic stream (e.g. bus to vehicle traffic stream) or a base green.

If no check out call point is assigned to a traffic stream, the forced request time is controlled depending on the call point. If several check out devices are assigned to a traffic stream, the values of the last-mentioned check out device apply according to the assignment table.

A special feature is also "no forced request" with regard to forced deletion. In this case, vs | plus triggers a forced cancellation independently of the green to prevent further requests from being blocked. Forced cancellation takes place when all detector wait times have reached the hold time.

Especially with trams travelling at high line speeds towards an intersection, it is necessary for the train driver to see in good time whether his signal will open. As a rule, green should already be displayed in the braking distance. For this problem, vs | plus provides the parameter advanced display time. vs | plus switches the PT traffic stream to green by the set time before the "expected arrival second" calculated with the theoretical journey time (target time).