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7.1.8. Example 8 - Mixed Right Turn Opposed Movements and
Ahead Traffic in Multiple Lanes.
Whilst this situation can be modelled by LinSig V2, it may require a small amount of trial and
error before a final solution can be achieved. The difficulty is in deciding on how the Ahead
traffic will distribute between the Ahead lanes bearing in mind that once the offside lane
becomes blocked, ahead traffic will be reluctant to use it.
The Link on the offside can be set up as illustrated in Example 7. However, the default
automatic traffic assignment will allocate the right turn movement (300) to the link on the
offside, and then split the Ahead movement (800) in order to equalise traffic flows in each of
the two lanes. LinSig allocates 550 PCU of the Ahead traffic to the left lane and 250 PCU to
the right lane resulting in each lane containing 550 PCU. It may however be deemed that as
the right turning traffic causes disproportionately higher delay to the Ahead traffic the Ahead
traffic will be biased towards using the left lane. In this case the Route List in the Traffic Flow
View can be used to manually change the assignment of Ahead Traffic to Routes. This will
allow Ahead traffic to be transferred to the left lane in order to achieve equal delay or degree
of saturation on each Link as desired.
Mixed Ahead and Right Traffic in Multiple Lanes
Link Allocation – Auto assigned traffic
Link Allocation assuming only 150 Ahead PCU use offside lane
V2.4/A
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December 2007