Attachment 6 - Traffic Impact Assessment

For the second stage of the right turn analysis, entering the southbound David Low Way traffic stream,
the following steps were undertaken in Sidra:

(i)         A basic j-junction layout was established, without turn lanes, and with the left turn from
            Woodland Drive prohibited.

(ii)        The northbound David Low Way traffic flow was set to zero, as was the right turn from David
            Low Way into Woodland Drive.

(iii)       The gap parameters for the second stage right turn were altered to take account of the different
            configuration, being that the right turn from the central median into the southbound traffic
            stream is essentially the same as a left turn into the northbound traffic stream, and when that
            vehicle enters the southbound traffic stream, there is not a vehicle waiting immediately behind it
            in the median to follow it if there is a large gap in the southbound traffic. To account for these
            factors, the “critical gap” for the second stage of the right turn was reduced from 7.0s to 5.0s
            (so that is the same as the Sidra default for left turn movements) and the “follow-up headway”
            was increased to 10s.


The Sidra analysis under predicted 2036 peak hour conditions with the redevelopment fully operational,
during the critical PM peak (when the right turn movement from Woodland Drive is significantly higher
than in the AM peak) using the procedure for the existing intersection as described above, indicates
satisfactory operation of the intersection with the following summary output:

2036 AM with redevelopment                DOS          Right turn queue (95th percentile)
existing intersection config
Stage 1 right turn                        0.65         1.4 vehicles
Stage 2 right turn                        0.57         1.1 vehicles

2036 AM with redevelopment                DOS          Right turn queue (95th percentile)
existing intersection config
Stage 1 right turn                        0.50         1.4 vehicles
Stage 2 right turn                        0.57         1.1 vehicles




15.s.24.2                                            Page - 8