We take a look behind the scenes to see how Suna gathers traffic info and broadcasts it to your GPS device.

Getting stuck in traffic is as much fun as watching Twilight at half the normal speed. Since mid-2008, Suna has been running a traffic messaging service that informs compatible GPS devices of traffic delays along a user's route.

As we've noted in many reviews and our traffic messaging FAQ, this system is far from perfect.

Suna is currently rolling out a series of upgrades to improve its service. Now that most of the "phase two" roll-out is complete, we paid a visit to Suna's headquarters to see how the company collates and sends out traffic information.

(Traffic Jam image by Bud Adams, royalty free)


Suna collects traffic information from a variety of sources. Road authorities, such as the RTA in New South Wales and VicRoads in Victoria, maintain thousands of in-road sensors, such as the one above that's responsible for controlling a set of traffic lights.

In addition to controlling traffic lights, these in-road sensors can also be used to determine traffic density and speed. With some road authorities installing sensors on freeways to monitor congestion.

Photo by: Derek Fung/CNET Australia

Scat cat

Many traffic light junctions have "intelligent" traffic lights that use road sensors to monitor traffic flows and adjust light timing accordingly. The most obvious example of this is when, late at night, you approach an intersection with a main road, come to a stop over the sensor plate and half-a-minute later you're given a green light.

Did you know, though, that this system was initially developed in Sydney in the early '70s by the local road authority, the then Department of Main Roads. The system dubbed SCATS (Sydney Coordinated Adaptive Traffic System) has now been exported to over 142 cities in 24 countries, including Hong Kong, Shanghai, Tehran, Atlanta and most other Australian cities.

Photo by: Derek Fung/CNET Australia

Probe vehicles

As part of Suna's "phase two" upgrade, it will also be using speed and tracking info from commercial fleets that have installed GPS tracking devices on their vehicles. These so-called probe vehicles come in all shapes and sizes, ranging from courier vans to semi-trailers and taxis. The value of this data ranges from vehicle type to vehicle type. For instance, taxis aren't a great indicator of traffic flow as they're able to use transit lanes.

According to Suna, this probe vehicle data is especially important in cities like Sydney where few road sensors are installed on freeways, motorways and highways.

Photo by: Toyota

Eye of the tiger

Road sensor, camera and other data is fed from the road authorities to Suna's headquarters in an unassuming building in an inner-Melbourne suburb. Other sources of information, such as tow truck operators, major events organisers and road work schedulers, are also monitored from here.

Additionally, a member of Suna's staff is located out at VicRoads' traffic management centre.

Photo by: Derek Fung/CNET Australia

What do we want?

A scheduled protest in front of NSW's Parliament House is entered into Suna's database, with the operator entering the start and end point of the road closure, time of the closure, as well as the incident description.

Photo by: Derek Fung/CNET Australia

Does the Love God know about this?

The upcoming protest, as well as other traffic events, are broadcast via a silent digital signal that's embedded into an FM radio station's transmission. On the screen above, Suna is monitoring the traffic codes (right) being broadcast to GPS devices in Sydney via partner station Mix 106.5.

Photo by: Derek Fung/CNET Australia

Go slow

The traffic speed information along a section of Sydney's Epping Road as recorded by the RTA's in-road sensors. Between about 6.50am and 8.15am average speeds dipped from around 40 to 50km/h to just 10km/h.

Photo by: Derek Fung/CNET Australia

In action

A report of congestion with an estimated average road speed.

Photo by: Derek Fung/CNET Australia

Internal network

At Suna headquarters, the company runs a low-powered antenna that broadcasts on a different frequency test traffic information, allowing nav makers to evaluate their devices.

Photo by: Derek Fung/CNET Australia

Map it out

Suna's traffic information is currently available on some Garmin, TomTom, Navman, Navigon and Uniden portable GPS units. It's also seen on equipped Eclipse, Pioneer, Continental and Alpine head units, as well as select cars from the Ford, Holden, Toyota and Nissan line-ups.

Photo by: Derek Fung/CNET Australia
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