2020.11.30 - Response to further RFI - OPW200145

Item 9 – Grading of Hofmann Drive and Road B

The Barlow Shelley letter of 16 October 2020 indicates that this item has been addressed by flattening
the grades to 6% in accordance with Austroads. This has been done for Road B, but the longitudinal
section for Hofmann Drive still shows a grade of 9% down from the roundabout. This needs to be
rectified.

Stockwell Response

The longitudinal section for Hofmann Drive has been regraded to 6%. Please refer to Barlow Shelley
drawing 1856 R48-E.

Item 11 – Diameter of Roundabout Central Islands

The proposed roundabout dimensions are for a 12m central island radius, with a 12m circulating
carriageway, thus having an outside radius of 24m. The proposed 12m circulating carriageway is too
large for a single lane roundabout, and is the carriageway width that would be provided for 2-lane
roundabout. For reference, Austroads 4B, Table 4.3 indicates that for a roundabout having an outside
diameter 48m (24m radius) as proposed, the circulating carriageway width should be approximately
7m. It is thus requested that the central island radii of the two roundabouts be enlarged as much a
possible within the currently proposed roundabout footprints (as close to the 7m circulating
carriageway width suggested in Austroads 4B, Table 4.3), so as to satisfactorily accommodate the
design vehicle (articulated vehicle) while also constraining and deflecting paths through the
roundabout as much as possible for all vehicles.

Stockwell Response

The new Northern and Southern roundabouts have been widened from a 12m central island radius to a 15m
central island radius. This results in a 9m circulating width and allows for a 19m Articulate Design Vehicle to
satisfactorily manoeuvre both roundabouts. Please refer to Barlow Shelley drawings 1856-T12B – T14B for
swept path analysis confirmation.




    Figure 3: Barlow Shelley Drawing 1856-T12 B              Figure 4: Barlow Shelley Drawing 1856-T14 B
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