Simulation for STREAMS

When Main Roads Western Australia installed the STREAMS traffic management system, the staff needed to learn how to use it in a risk-free environment: Aimsun’s simulation software provided a safe and efficient digital training ground.

? Alexandre Torday and Mohammad (Saif) Saifuzzaman of Aimsun explain: ?

Everybody loves getting a technology upgrade, but there’s usually an initial challenge in learning how to use new tools. Main Roads Western Australia aced exactly this problem when they installed the STREAMS? traffic management solution in the Perth Road Network Operations Centre.?

STREAMS allows operators to manage the motorway and incident response, ramp metering and other traffic services from a single system. Developed by Transmax Pty Ltd , STREAMS has a great track record, with documented improvements in peak flows and substantial reductions in travel time and motorway accidents. These enhancements have a knock-on effect of lowering emissions.

With results like this, naturally traffic managers are keen to maximise benefits as soon as possible and train operators in how to get the most out of the system in every possible scenario. It is clearly inefficient to wait for incidents to happen on the road before learning how to manage them – operators need to test STREAMS ahead of time across a range of scenarios while exploring all possible options offered by the new traffic management tool.

?By learning in a highly realistic simulated environment, operators can gain expertise with new systems and software while the real world outside flows as normal.

Simulation

This is where Aimsun came in, building a tool to simulate the live traffic environment based on a pre-calibrated Aimsun next traffic model; this model links to STREAMS to offer a realistic test environment for the operators. Any scenario and any incident can be created in the Aimsun Next model, where operators can then learn to use STREAMS to find the best possible strategies to mitigate those incidents.

Aimsun Next replaces the physical vehicle detection system that is required for STREAMS’ operation by simulating the traffic detection data instead. It also receives any traffic management actions shown in the overhead gantries (known as Lane Use Message Signs or LUMS) and ramp metering values in real time from STREAMS. Driver behaviour is updated accordingly, based on the LUMS display.

A key feature of this interface is the ability to repeat scenarios many times, as operators can re-run any traffic incident over and over again and try out different strategies. The real-time traffic animation mimics the traffic monitoring cameras with some added benefits such as zooming and following the traffic. By trying different solutions within the simulation, the operator will already have a good idea of what to do when faced with a similar situation in real life.

The training allows operators to have hands-on, experience-based training, bypassing the process of learning by trial and error on real roads.

The Toolkit

In one example, the operators were given a simulated accident and lane closure on State Route 2, south of Perth’s Central Business District.?The operator had the tools within the STREAMS software to adjust the speed limits, which would then show up in the overhead LUMS gantries. The operators could also inform the upstream traffic about the incident and ask them to avoid any affected lane.

?The Aimsun Next model received the LUMS changes and updated driver behaviour to reflect those changes. The operator was able to watch how the traffic responded, even down to a simulation of an individual vehicle.?They could see whether jams built up, the effect on other roads and intersections, and how the traffic cleared once it had passed the road closure.?Once they had learned from this, they could go back to the beginning and rerun the scenario, trying out different ways of managing it until they became confident to manage a similar incident in the real world in the most efficient and effective way.

Real time

The integration between Aimsun Next and STREAMS is set up in the Amazon Web Services (AWS) environment, which provides easy access to both systems remotely. All the communications between Aimsun Next and STREAMS happens in real time, meaning the operators can practice as though this were a real event happening right now.

The training allows operators to have hands-on, experience-based training, bypassing the process of learning by trial and error on real roads.

?This tool also provides an excellent opportunity for the road safety team to test and improve their recovery plan in the event of any accident where emergency vehicles might require access. They can test how fast first responders can access the accident location and how STREAMS can help to minimise the delay. The simulation can test the limit of the current facility by changing the location/severity/response time of incident. The interface can also be deployed to plan roadworks and other events where lane restrictions would be needed.?

No longer do operators have to wait for weeks or months on shift before being faced with a new or unusual edge scenario, and their expertise in turn improves the user experience on the roads.

This system has been set up with a specific piece of software in a specific place, STREAMS at Main Roads WA, but the concept could be used anywhere, with any piece of traffic management software.?By learning in a highly realistic simulated environment, operators can gain expertise with new systems and software while the real world outside flows as normal.

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