Stantec // Oceana Gold NZ Ltd // Waihi North Project Transportation Assessment 29 The intersection has been modelled also for the morning peak hour (ending 8am) and the resultant intersection modelled flows and movement performance is summarised in Appendix C. As for the evening peak period, no expected operational issues at the intersection with the maximum delay to vehicles exiting from Willows Road around 7 seconds which is considered a high level of service (LOS A). 7.2.2 SH25 Intersection Layout/ Safety The existing intersection layout has limited shoulder widening for right or left turning traffic. As reference only, the minimum Waka Kotahi layouts for an access with low to moderate use by heavy vehicles and up to 100 veh/d requires a Diagram E layout8 of the Planning Policy Manual (PPM) which would require a widened shoulder on the east side of SH25 over 180 m and over 90 m for left turn in traffic. A similar scale of widening, but of reduced length, would result from the use of Austroads minimum right turn provisions at an intersection (Basic right turn (BAR) at Figure A28 of Austroads Guide to Road Design (GRD) Part 4 Intersections and Crossings (Austroads). The majority of traffic associated with the project is expected to travel to and from the south and therefore the volume of right turn movements into Willows Road is expected to be minimal. In the morning arrivals period (around 7 am) the expected traffic volume on SH25, together with the likely volume of right turning traffic into Willow Road, does not meet the Austroads warrant for a right turn bay (Figure A10). However, at other times of the day SH25 traffic volumes are around 400 veh/h which would meet the threshold for a right turn bay with as few as 5 veh/h right turn in vehicles. Unless right turn in movements are able to be managed within acceptable thresholds (which vary by time of day) then it is recommended that a right turn bay is provided on SH25 with a layout meeting the minimum requirements of the Waka Kotahi Manual of Traffic Signs and Markings Figure 3.25. While the right turn bay is expected to have low demands, OGNZL have adopted the prudent approach of upgrading the intersection at the outset rather than waiting for issues to develop which would then require additional work. The existing intersection of SH25 and Willows Road currently has appropriate intersection sight lines in each direction of travel for the expected operating speed of vehicles on each approach (see discussion in Section 2). It is acknowledged that the forward sight distance (for which Austroads standard requires 165 m to 193 m for 100 to 110 km/h design speeds respectively) is marginal around the inside of the curve adjacent to the intersection as a result of vegetation / embankment directly opposite the intersection (for southbound traffic). While this is an existing issue with the highway, it is acknowledged that southbound drivers have similarly restricted visibility to right turning vehicles from Willows Road as they accelerate to the south of the intersection. This is more of a concern f or slow moving and hence slow to accelerate vehicles such as laden trucks. It is recommended that the forward sight distance requirements are considered in combination with the recommended other improvements below. The tracking path of a truck and trailer (19.2 m long) has been plotted on available aerial photography as shown in Figure 36, which demonstrates that a truck and trailer is able to make the right turn out and left turn in based on the current layout whilst remaining within the correct lane. The safety benefits of widening an intersection shoulder to provide a left turn lane, as opposed to a through vehicle being forced to slow for a turning vehicle, are widely debated and any solution needs to be site specific. These options were discussed with the Waka Kotahi as part of preliminary consultation, and it has been agreed that as the operation was for a finite period a full left turn lane is not required9. In summary for this development, with consideration to the expected demand for the right turn in traffic movement, good sightlines in each direction from the side road but limited forward sight distance around the curve, the following measures are recommended, subject to final consultation with Waka Kotahi: • Provide a right turn bay on SH25 meeting the minimum requirements of the Waka Kotahi Manual of Traffic Signs and Markings Figure 3.25 and meeting Waka Kotahi requirements for forward visibility. • Include a left turn 2.5m wide shoulder in accordance with Diagram E in the Waka Kotahi Planning Policy Manual. • Street lighting to meet the requirements of Waka Kotahi M30. The upgrade should be completed prior to commencement of the substantive construction phase. 8 Diagram E of PPM for more than one truck per week and 100 equivalent car movements (ecm) for a private access 9 Waka Kotahi preliminary feedback suggests a left turn 2.5m wide shoulder in accordance with Diagram E in the Waka Kotahi Planning Policy Manual is supported. Additionally, streetlighting to be considered in the design.
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