Nelson region - The application of dual crossings at an existing roundabout

Overview

Location: Champion Road / Salisbury Road, Richmond

Project type: Roundabout with dual cycle/zebra crossings on raised platforms

Project elements: CNG: Dual cycle / zebra crossings, CNG: Roundabouts, PNG: Raised zebra crossings

Project Owner: Tasman District Council

Project completion: May 2021

Project summary 

Purpose of the case study

To illustrate how a retail development next to an existing roundabout was the catalyst for road safety improvements, particularly for pedestrians and cyclists. Additionally, quality connections were made to existing walking and cycling routes, schools, and the retail development. This was achieved by retrofitting and reconfiguring an existing roundabout intersection.

Further details can be found in the Road to Zero video: Championing the Safe System in Tasman(external link)

Benefits

Project background and desired outcomes 

Problem and opportunity

The location has local land uses of retail, parks, and school but the former intersection was oversized for these uses and limited movement of people.

A new development of a supermarket initiated an opportunity to create a quieter place more conducive to cycling with better connections to surrounding paths and schools.

The alternative arterial road, SH6 Whakatu Drive, is available nearby to better cater for through traffic.

Location map, case study intersection in the blue circle.

The previous intersection lacked quality cycling and walking provision despite the nearby proximity of schools and walking / cycling paths. This is obvious in the images below.

Before photograph, looking towards Saxton Fields from Salisbury Road.

Before photograph, looking from the roundabout towards Champion Road (S), the yet to be developed Countdown site and Salisbury Road (W).

Options stage

An underpass was considered safe and kept cars flowing but was too expensive. A safer roundabout that also helped bikes could serve the multilane approaches and better fit with the land use and movement of people, and while it slowed cars a little it also met driver safety needs.

Extensive consultation included adjacent landowners, the local schools (7 in total), groups representing different aspects of transport (biking, AA, local businesses) and traffic modelling identified a reduction to a single lane on one of the approaches was feasible.

Design stage

Two of the roundabout arms with walking and cycling desire lines were treated with raised dual crossings on single lanes approaches for safety, a minor side road was aided with a table because crossing movements were already easy, and the remaining arm was unchanged due to lack of pedestrian desire lines. Crossing positions were located as close to natural desire lines as possible, crossing locations were modelled (in a Paramics Model) to refine the location and enabled an informed evidence-based decision.

Constructed form

Challenges and solutions 

• The original proposal involved an underpass that minimised the impact on traffic. This option was in the public arena, as a result changing the design to an at grade solution was a challenge. This was addressed through targeted consultation, budget analysis and creating a design at grade that did not rule out later grade separation.
• The desire to connect up a number of routes and address gaps in route continuity while making the facilities usable to the child cyclist. This in part drove the at grade proposal but was further supported by a change to the speed environment, raised crossings, speed cushions, and warning signs in order to support travel choice and safety in relation to seven nearby schools.
• Wishing not only to provide a walking and cycling facility but to positively influence traffic speed and driver behaviour on Salisbury Rd. As part of wider work council was seeking to change the way this part of the transport network functioned. Having this network aspiration helped support local changes.
• Provide a facility that allowed for future adaptation and alteration where and if necessary (eg adding a crossing on the untreated approach). The design allowed for later adaptation, for example a crossing and central island on the untreated approach.

Successes and learnings 

• It is important to engage with a wide range of groups very early and continue this relationship throughout the project.
• Ensure the project addresses existing problems for people riding a bicycle or travelling around on foot. Also be aware of wider outcomes and goals and how the solution supports these.
• Understand how local businesses operate (existing and future) and keep local decision makers in the loop.
• Create a solution that allows future development, tweaks, and changes.
• Don’t be scared to tailor the facility type to certain approaches to a complex intersection. All the approaches do not need to be treated in the same manner.
• When raising crossings allow the design to reflect the need to slow approaching traffic but let departing traffic depart smoothly. The ramp profiles do not need to be the same. 
• Link in the new facility to existing networks of guide signs.
• Recognise that markings should contrast with the surface on which they are installed. Also note concrete can be coloured using pigments.