FAQs: Dublin Road and Knaith Road proposed traffic signal implementati

The State Government’s Towards Zero 2016-2020 Road Safety Strategy and Plan is underpinned by the philosophy that there should be no casualty crashes on the road network.

The intersection was nominated for consideration within the Blackspot funding program on the basis there were several reported casualty crashes within the last five years of available data including two right-turn crashes (driver side T-bone) with serious injuries. It is considered there is an obvious crash trend that would be effectively addressed by traffic signals.

Historically, sites with at least three casualty crashes over a five-year period are eligible for funding through the Blackspot Program and the Knaith Road and Dublin Road intersection meets historical guidelines. Recently, VicRoads has relaxed this requirement to some degree, with locations that have fewer than three casualty crashes or any location that has been subject to a road safety audit also potentially eligible for consideration through the Program

To understand the impact of the proposed signals on the function of the road at this location in terms of delay and queuing, an independent traffic engineering expert was engaged to conduct traffic modelling on the proposal.

Morning and afternoon peak models were prepared for three different phasing sequences:

• Option 1 - A separate stand-alone phase for the East to West crossing on Dublin Road.
• Option 2 - A shared phase for the East to West crossing on Dublin Road and the right turn from Dublin Road into Knaith Road.
• Option 3 - A shared phase for the East to West crossing on Dublin Road and the Knaith Road traffic (both left turns and right turns).

Each of these phasing options were also modelled for three different time periods:

• Scenario 1 - Operation of the intersection under existing conditions (i.e. based on volumes and pedestrian data collected in 2018).
• Scenario 2 - Operation of the intersection based on 10 years’ growth.
• Scenario 3 - Operation of the intersection based on 10 years’ growth with double the amount of pedestrian/cyclist crossings.

Option 1 is a conservative phasing sequence that offers the East to West pedestrian crossing the ultimate level of protection as all other movements will be stopped. This is not considered necessary at this point in time and the strong likelihood is that either Option 2 or Option 3 will be adopted in practice.

The average delay for any vehicle travelling in the northbound or southbound approach was modelled to be no higher than 15.4 seconds and to be no longer than 91m. The subsequent level of service provided by the proposed signals is considered appropriate.

Delays on the Knaith Road approach were modelled to be no higher than 45.1 seconds and no longer than 47.5m. Based on the modelling, most queues are expected to clear within two cycles during the AM and PM peaks 

Comprehensive summary of options

See a more comprehensive summary of the results below:

Option 1

Table 1: Delay and queue lengths for a separate stand-alone phase for the East to West crossing on Dublin Road.

Option 2

Table 2: Delay and queue lengths for a shared phase for the East to West crossing on Dublin Road and the right turn from Dublin Road into Knaith Road.

Option 3

Table 3: Delay and queue lengths for a shared phase for the East to West crossing on Dublin Road and the Knaith Road traffic (both left turns and right turns).

Speed limits and their implementation or alteration requires the approval of VicRoads.

Based on VicRoads’ Traffic Engineering Manual on Speed Zoning Guidelines, a lower speed limit such as a 40km/h is to be used in high pedestrian activity areas such as shopping precincts, town centres and school zones. The intersection of Knaith Road and Dublin Road is not within a pedestrian activity area (as defined in the guidelines) and would not meet the guidelines for a 40km/h speed limit.

Based on traffic modelling undertaken for the proposed signals, most queues in AM and PM peak periods are anticipated to clear within two cycles including the ultimate scenario which factors in 10 years’ growth and a doubling of pedestrian crossing volumes.

The traffic modelling also indicates the Knaith Road approach will not reach capacity even under the ultimate scenario. The modelling indicates queues will generally clear within two cycles, and as such it is anticipated that any traffic diversion as a result of the signals would be minimal.

To facilitate the construction of the intersection, it is anticipated there will be a loss of approximately 15 on-street parking spaces.

During the development of the submission plans, significant consideration was given to minimising the loss of parking as well as investigating opportunities for indented parking, however, opportunities were limited due to the proximity of nearby services and nature strip space, as well as the difficulty of making any such parking function safely within the proposed intersection arrangements.

In some instances Council is obligated to remove parking to implement road safety improvements. This practice is consistent with the key direction of the Maroondah Parking Framework

Raised pavements (or speed humps) are generally not appropriate for roads that carry higher levels of general traffic and heavy vehicle traffic.

Heavy vehicles generally have significantly lower ground clearance tolerances, requiring a significant reduction in speed to navigate the speed hump, or are unable to navigate over the speed humps altogether. As it is within the function of a major road like Dublin Road to carry trucks, some of which may be serving the local area, the implementation of speed humps is not considered appropriate.

This location on Dublin Road also forms part of the route used by the 380 bus service. Raised pavements are not a Public Transport Victoria approved traffic management device and as such, are not appropriate at this location.

A review of historical traffic related complaints received by Council on Dublin Road indicate community concerns are generally not related to speeding. As such, Council does not consider there to be a speeding issue on Dublin Road.

Traffic signals eliminate the need for motorists exiting Knaith Road to select a gap in the Dublin Road traffic stream, addressing the identified crash trends with the right-turn movement from Knaith Road.

There may be circumstances where traffic signals are unable to deter inappropriate driver behaviour such as intentional speeding to pass a set of green lights or the intentional undertaking of an illegal movement. 

While traffic signals are not infallible, signals create an overall safer road environment where:

• problematic vehicle movements are controlled
• pedestrian crossings are controlled
• the overall speed at which the vast majority of traffic is travelling is reduced.

Other benefits provided by the proposed traffic signals include:

• Controlled access to the bus stops on both sides of Dublin Road
  Transport authorities have to supply the best ‘whole of journey’ experience for customers of all abilities by delivering bus stops that provide the best possible customer comfort and the safest waiting experience. Controlled crossings facilitate safer and more convenient access to the bus stops especially for more vulnerable users.
• A controlled crossing to a shared path on the western side of Dublin Road
  The only other viable alternate crossing configuration would be a pedestrian refuge/pedestrian operated signal implemented north of Knaith Road. A crossing at this location would require an even greater loss of on-street car parking noting the requirement to maintain turning movement access for larger vehicles. Also, pedestrians crossing at this location are more vulnerable to the uncontrolled right-turn movement from Knaith Road.