Corridor Optimisation – Canning Highway Route Reviews
Recent rapid population growth in Perth has contributed to increasing traffic congestion on arterial roads around the city.
In response, the Western Australia State Government established the Traffic Congestion Management Program in an effort to improve traffic flows through reduced travel times and increased reliability.
One initiative of the program involves reviewing traffic signal operational settings along strategic routes, the aim being to generate low cost but effective operational improvements.
The first route review under the program was carried out by GTA in 2013 on the Canning Highway between Riseley Street and Henley Street (refer to area circled in location map). It is three kilometre in length with eight signalised intersections along its length.
The route is an important east-west connection between Fremantle and Perth’s CBD, and includes the Kwinana Freeway interchange.
Scope and objectives
MRWA were particularly keen to see recommendations that optimised benefits to through traffic along Canning Highway, potentially at the expense of side road and turning traffic. Specifically, MRWA wanted to see:
- descriptions of possible traffic signal phasing modifications, modifications to SCATS data and recommendations for minor works (e.g. extend turn lane, ban right turn)
- detailed description of how the outcomes from each recommendation are to be achieved
- information as to which recommendation may be appropriate for different times of the day/days of the week
The operational review was conducted in two stages. The first stage involved detailed site inspections to understand existing traffic conditions, queues, delays and congestion locations.
The second stage involved a rigorous investigation of existing traffic volumes, composition, signal timing and signal operation setup via SCATS – a computer program that manages the real timing of signal phases at traffic signals.
Challenges and issues
The most challenging aspect of the review was gaining an understanding of the road network, local traffic generators, peak periods and other anomalies within a short period of time during the site inspections.
One of the biggest issues to the existing operation along this route was that a number of intersections had split phasing, which means that the side roads run in their own traffic signal phase. This arrangement is considered inefficient as a lot of green time is allocated to side road traffic, rather than the arterial road.
The review identified a range of interventions at each intersection covering strategic planning options and traffic signal optimisation options.
Strategic planning options looked at changes to the intersection or lane configuration, banning low demand turning movements, or prioritising Canning Highway over side roads.
Traffic signal optimisation recommendations included:
- improving the ability for SCATS to allocate green times on the basis of traffic volume demands
- minimising or removing “wasted green time” periods such as pedestrian early starts
- improving the linking between adjacent intersections
- recommending lower cycle times to improve lane utilisation, pedestrian behaviour and driver attention levels
MRWA implemented a significant number of the recommendations and subsequently undertook a before and after study to assess the effectiveness of the changes.
The outcomes of the review are discussed on the MRWA website at the link below, with quoted results being:
“…changes to the traffic signal timings have delivered a 6 minute reduction in the average journey time through the area, from 18 minutes to 12 minutes. The improved travel times have meant more traffic can travel on the Highway, with 8% more vehicles heading eastbound at the Canning Beach Road intersection. Other benefits include a reduction in queue lengths at traffic signals due to better traffic flow and minimised delays through decreased stopping times at signals. Anecdotal evidence also suggests that traffic using local streets to avoid Canning Highway has reduced, with more traffic returning to the Highway.”
Go to www.mainroads.wa.gov.au/OurRoads/KeepPerthMoving/whatsbeingdone/Signal-Improvements/Pages/default.aspx for more information.