QTS-041 · Business case chapter or appendix · 2020
Appendix B27 Technical Note 42: SH6A Bus Signal and Virtual Priority (with Appendix B28 Queenstown Arterial Stages 1 and 2 – Intersection Optioneering)
Two technical notes appended to the 2020 NZUP Queenstown Detailed Business Case. TN42 (Final, 6 October 2020) uses SIDRA to test signalising the SH6A Frankton Road/Marina Drive/Sugar Lane intersection. Option 1 is a short-term layout with fully protected crossings on all arms. Option 2 is a longer-term layout with a new Frankton Marina access to the west, the eastbound right turn banned, and a staggered crossing. Signalisation gives near-capacity operation even at 2018 volumes. Option 1 becomes over capacity once SH6A crossing call rates exceed about 25%. TN42 recommends Option 1 only short term, with pedestrian volumes monitored, and Option 2 with the new Marina access towards 2028. It notes the F2Q SSBC strategy of capping SH6A traffic at about 2018 levels through signalised intersections and gating at Frankton. TN44 (Final, 27 October 2020) reviews November 2019 optioneering for the Shotover Street/Gorge Road/Henry Street intersection on Arterial Stages 1 and 2, updated with August 2020 modelling. It recommends a 'double-T' arrangement of two 3-arm intersections over a 4-arm intersection.
What the document says
Context and purpose: Appendices B27 and B28 of the Queenstown Transport Business Case (NZTA Contract 2018235). Author names are redacted (s 9(2)(a)). Sign-off roles are Principal Transportation Engineer, Project Design/Integration Manager and Project Team Leader (pp.11, 22).
TN42 (pp.2-11): Existing priority-controlled operation of SH6A/Marina Drive/Sugar Lane is poor, with side-road LOS F and drivers accepting very short gaps. This 'suggests a road safety issue' (p.4). Protected right turns and fully protected crossings were assumed in discussion with the Transport Agency (p.4). At 2028 PM peak, SH6A westbound v/c ranges from 0.99 (0% calls) to 1.46 (100%) under Option 1, and from 0.95 to 1.17 under Option 2 (p.9). Holding westbound v/c at 85% at a 50% call rate would need demand cut by 419 v/h (Option 1) or 256 v/h (Option 2) (p.10). The F2Q SSBC 'is likely to recommend the installation of a number of signalised intersections along Frankton Road', capping SH6A traffic near 2018 demand so that PT mode share must rise (pp.10-11). Bus lanes shown in Option 2 are 'still under investigation' (p.4).
TN44 (pp.13-22): The Town Centre Masterplan identified Options 4, 4.1 and 5 for the Gorge Road/Shotover/Henry Street intersection (p.13). With fully protected, single-phase pedestrian crossings, the 4-arm layout operates at LOS F at 2028 interpeak (p.16). An expanded 4-arm layout reaches LOS E but needs extra land, and the Masterplan Advisory Group was concerned about intersection size (p.17). The double-T operates at LOS C-D (p.20). August 2020 volumes (Arterial Stage 1 only; total +7.5%) worsen all options, with the 4-arm worst movement at 142% (p.21). The note recommends the double-T as preferred (p.22). It also records that the 'shovel ready' funding announced 26 June 2020 was for Stage 1 only (p.13).
Mass rapid transit: Neither note mentions mass rapid transit or offline public transport. TN42 does set out the corridor strategy of capping SH6A traffic volumes near existing levels, which requires future growth to be carried by public transport (pp.10-11).
Key figures
- 2028 PM SH6A westbound v/c at Marina/Sugar Lane: Option 1 0.99-1.46; Option 2 0.95-1.17 across 0-100% pedestrian call rates (p.9)
- Demand reduction to hold 85% v/c at 50% call rate: 419 v/h (Option 1) vs 256 v/h (Option 2) (p.10)
- Gorge Rd/Shotover/Henry 4-arm: LOS F 2028 interpeak; double-T LOS C-D (pp.16, 20)
- August 2020 update: total intersection volume +7.5% (2,025 to 2,175 veh/h); 4-arm worst movement 142% (p.21)
Files
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Actions recorded
Implement Option 1 signalised layout at SH6A/Marina Drive/Sugar Lane on a short-term basis only, monitoring pedestrian crossing volumes.
Not assessed · Short term
Option 1 can be implemented at the location, but only on a relatively short-term basis
Move to Option 2 layout with an additional Frankton Marina access intersection to the west as demand grows towards 2028.
Not assessed · Towards 2028
Option 2 provides a more suitable layout at this location, together with the installation of an additional Frankton Marina access
Take forward the double-T arrangement as the preferred Shotover Street/Gorge Road/Henry Street intersection for Arterial Stages 1 and 2.
Not assessed
it is recommended that the double-T arrangement is taken forward as the preferred option
Carefully consider phase arrangement changes at Stanley/Shotover Street to coordinate with the double-T and limit internal queuing.
Not assessed
there will need to be careful consideration of any alterations to phase arrangement
Study cost
A study cost has been requested under the Official Information Act or LGOIMA. No figure has been received.
Citation
NZTA (Waka Kotahi). Appendix B27 Technical Note 42: SH6A Bus Signal and Virtual Priority (with Appendix B28 Queenstown Arterial Stages 1 and 2 – Intersection Optioneering) (2020). NZTA Contract 2018235 - F2Q SSBC & QTC DBC; Technical Notes #42 and #44.