Managed Motorways: Transporting Benefits from Melbourne to Denver

^{Image source: Colorado Department of Transportation}

^{The image above shows traffic on a portion of Interstate 25 (I-25) in Denver, Colorado (USA), where a pilot project applied the highly evolved coordinated and adaptive ramp metering (CARM) system based on  the managed motorways concept in Melbourne, Australia; CARM uses sensors to measure traffic volume on I-25 and along the on-ramps to the freeway and adjusts the entry of vehicles onto the freeway to minimize the formation of bottlenecks.}

Melbourne in Australia and Denver in the United States have been faced with a similar issue: these two state capitals have been challenged to address road congestion to accommodate continuing population growth. 

In the following Q&A, WSP transportation planning and intelligent transportation system (ITS) specialists discuss bringing the benefits associated with the managed motorways concept in Melbourne to the Denver metropolitan area through the Smart 25 Managed Motorways Pilot Demonstration¹; they address the collaborative work that supported implementation in Denver and the opportunity for future application and advancement of the managed motorways concept.

Backdrop

The Victorian Department of Transport and Planning introduced the managed motorways concept² in Melbourne, starting operations with the M1 Motorway in the early 2000's. Once in place, the pioneering managed motorways system demonstrated an increase in traffic flow by 5-8 percent, improved traffic speeds by 35-59 percent, and improved overall travel time reliability by 150-500 percent during peak periods. In addition, the five-year average crash rate on the M1 Motorway was shown to decline 31 percent in a comparison before and after project completion (9.15 to 6.31 crashes per 100 million Vehicle Kilometres Travelled (VKT).³ 

Fourteen thousand kilometres (or 8,700 miles) away, the Colorado Department of Transportation (CDOT), through the Smart 25 Managed Motorways Pilot Project in the Denver metropolitan area, seeks to address recurring peak-period congestion and severe unreliability on the I-25 corridor that connects Denver’s central business district and the Southeast Denver business corridor. I-25 handles a heavy bi-directional commute and significant freight traffic as it is the only north-south interstate for over 500 miles either east or west of Denver.

Can you discuss the managed motorways concept and how it is being applied in Melbourne? 

Lachlan Gray: Managed motorways incorporate intelligent system tools in and alongside urban freeways to manage traffic with the aim of reducing congestion for improved journey times and more reliable and safer journeys. The concept is deployed in jurisdictions in different ways. The Melbourne managed motorways concept—developed in the early 2000's by VicRoads [now the Victoria Department of Transport and Planning] and industry partners—came from the recognition that we can’t build our way out of congestion as Melbourne continues to grow.  There was a need to maximize the capacity of the motorway network at all times. The onset traffic flow breakdown and rapid decrease and instability in speed and throughput needed to be avoided.  

Whilst ramp metering and other motorway technologies have been deployed in many jurisdictions, they only offered a limited benefit to a motorway corridor; these techniques may delay the onset of a breakdown but not remove it, so they provide limited value over the long term.  By considering the corridor in a holistic way, as part of a whole system, it can be managed and controlled to mitigate disruptive events and increase system resilience. Understanding of the corridor begins with continuous real-time data about motorway performance across every lane along the whole length; managed motorways control—through coordinated ramp metering, variable speed limits and lane-use management systems—can stop flow breakdown.  This results in positive safety, efficiency and sustainability outcomes and importantly highly reliable journeys for travellers. 

The Melbourne Approach requires a range of physical infrastructure—particularly to create space for vehicles on ramps and possible lane allocation around ramps—ITS devices and control systems to support pre-emptive control beyond the motorway. The approach also requires a strong understanding of traffic flow and behavioral science and continual study and optimization, and finally a robust operational framework to ensure the results can be delivered reliably for road operators.

It’s also important to point out that the holistic approach, as outlined in the Victoria managed motorways framework document, includes adopting a Safe System approach [also known as Vision Zero in many parts of the world] to the design and management of motorways to reduce the incidence of severe crashes. 

Earlier, you noted variation relative to the application of the managed motorways concept. Can you provide an example?

Lachlan Gray: The Melbourne Approach does have some differences relative to the approach used in other Australian States and globally. For example, the key difference between the Melbourne approach and the UK [United Kingdom] approach, known as smart motorways, is the UK use of speed harmonization to prevent or slow down flow breakdown along with the use of dynamic lane management, including all-lane running where there is no permanent shoulder lane—as key parts of the deployments. All-lane running is rare in Australia. The other fundamental difference is that the UK does not use coordinated ramp metering or signalling—predominantly due to the relatively long distance between intersections and the lack of capacity for queueing vehicles on short, narrow ramps.

What is the aim of the Smart 25 Managed Motorways Pilot Project, and which features of the managed motorways system in Melbourne are being applied in the Denver metropolitan area?

Scott Pitera: The Colorado Department of Transportation [CDOT] was interested in the Melbourne managed motorways system to improve the performance of I-25 in Denver, without adding lanes. The I-25 corridor selected for the SMART 25 Pilot Project underwent a major reconstruction in the early 2000's that added lane capacity and an adjacent light-rail line. Fifteen years later, the freeway was more congested than it ever was before, and CDOT began to explore technology-based solutions to reduce travel times, improve travel time reliability and increase traffic flow without the major expense and community impacts of further freeway expansion. 

WSP, in partnership with VicRoads/VicDOT [now the Victoria Department of Transport and Planning] was responsible for introducing this concept to CDOT and conducting the initial regional screening and feasibility study. Through that process, CDOT chose to focus on the coordinated and adaptive ramp metering [CARM] aspects of Australian managed motorways for the SMART 25 pilot. CARM uses sophisticated algorithms and control systems and real-time data from advanced traffic detection systems to adjust the entry of vehicles onto the freeway to minimize the formation of bottlenecks. All the ramps are able to coordinate and work cooperatively to respond to real-time data, minimize flow breakdown and prevent impacts to adjacent arterials. 

How has the collaborative process between WSP teams helped deliver the SMART 25 Managed Motorways Pilot Project? 

Scott Pitera: WSP partnered with VicDOT and Transmax for delivery of the SMART 25 pilot. Transmax, [wholly owned by the Queensland Department of Transport and Main Roads], is the developer and operator of the STREAMS freeway management system that actually drives the CARM system. WSP staff visiting from the US were introduced to the concept and connected with Australian colleagues working on managed motorway projects. WSP staff worked together to connect WSP USA with VicDOT and Transmax, leading to a strategic partnership for the US market. WSP in Australia also provided guidance on the concept during early pilot planning and design stages of the CDOT project to move the project forward. WSP’s intelligent transport system teams meet on a regular basis globally to share knowledge, ensure teams are up to date on key developments and connect our partners to opportunities to develop solutions together. 

As the practices and tools available to road agencies for their network operations evolve regionally and around the world, what future advancements do you envision for enhancing the effectiveness of network services and supporting sustainability objectives? 

Scott Pitera: Through reducing travel time delay, improving travel reliability for the movement of people and goods and improving safety and reducing emissions through the reduction of stop-start traffic patterns, CARM can deliver significant benefits to a congested freeway corridor. As realized in Melbourne, these benefits continue to increase as CARM expands to a network scale. Additionally, other complementary tools, which are used in Melbourne and across Australia, such as variable speed limits and lane-use management systems, can further optimize operations for even greater safety and emission-reduction benefits. 

In the not-so-distant future, the real-time data needs of these systems may be sourced from the vehicles themselves through CAV [connected and autonomous/automated vehicles] vehicle applications, reducing reliance on roadside vehicle detectors. 

Explore WSP approaches relative to transport planning and intelligent transport systems.

 ^{1 also referred to as the Smart 25 Managed Motorways Pilot Project}

^{2 The definition of a managed motorway internationally and across Australia varies significantly and includes many different concepts. For example, any motorway having one or more ITS tools operating may use the term “managed motorway.” If basic ramp metering or lane control systems are used, it may also be considered to be a managed motorway. The “Melbourne Approach” is differentiated by the holistic approach focusing equally on 12 different elements that combine together to give the overall motorway productivity outcome. Source: Managed Motorways Framework, Network Optimisation & Operations Rationale and Technical Requirements, Victoria State Government, March 2017, p. 14.}

^{3 Vincent Vong and John Gaffney, Monash-Citylink-West Gate Upgrade Project: Implementing Traffic Management Tools to Mitigate Freeway Congestion, VicRoads, 2012.}