Bridging the highway travel information gap

A new traffic management solution is attempting to bridge the gap in information available on freeways and arterial roadways. Andrew Bardin Williams reports

Agencies responsible for national networks of roads around the world have the ability to measure, analyse and disseminate accurate travel information to drivers. Millions of dollars go into data collection infrastructure to collect traffic congestion and travel time information on major freeways or highways. For example, a driver on the I-210 in the Los Angeles area can get a reasonably accurate estimate of how long it would take to travel from San Fernando to Pasadena.

But what happens when the driver exits the freeway and continues on secondary arterial roadways? Unfortunately, reliable travel information on surface roads is far less readily available than data culled from highways and freeways.

A new traffic information solution from Smart Signal Technologies and the 584 University of Minnesota hopes to bridge this information gap, providing transportation agencies with a cost efficient method of collecting congestion and travel time information on any signalised road.

Congestion on arterial roadways is becoming a major concern, particularly in areas of suburban sprawl, where secondary roads are vital for drivers navigating between freeways and their home, workplace or commercial districts. Often, because of vehicle volume and density at major intersections, congestion is far worse on these connecting roads than on surrounding freeways. At the same time, traffic signal control systems interrupt traffic flow cyclically; making it more prone to ‘back-ups’ and other congestion causing events.

While travel information on freeways is collected from a variety of robust data collection tools such as road sensors and surveillance cameras, data collection rarely exists on arterial roadways, making it tough to provide the public with reliable journey and congestion information. Costs to fit the technology to every intersection is well outside the means of most transportation agencies. Yet, the need to collect and analyse traffic information on these secondary roads is just as great. The National Transportation Operations Coalition consistently gives the nation’s traffic signal monitoring infrastructure failing grades when it comes to reducing congestion.

“Congestion can be a major disruption on surface roads throughout our region,” says director of transportation for the City of Pasadena in California, Fred Dock. “Unfortunately, our roads are pretty much saturated and we are unable to expand intersection capacity. It became obvious that we had to look to other ways to reduce congestion, including the use of technological ITS solutions to give us better visibility and control over traffic.”

Over the last 10 years, the City of Pasadena has adopted a mobility corridor strategy with the aim of reducing congestion and travel times on its arterial roadways. According to Dock, the city’s strategy is concerned with enhancing automobile movement on major roads and reducing the use of smaller neighborhood streets as throughways. A big part of the strategy under Dock’s leadership is to encourage reasonable speeds and more uniform travel times while communicating better traffic information with drivers in real-time.

In the past, a lack of data collection capability on arterial roadways would have meant lengthy and expensive studies powered by information collected by multiple probe vehicles and manual traffic counts. Now, however, with the help of Smart Signal Technologies’ iQueue system, the process of determining travel times and queue length has been reduced by months and thousands of dollars – and according to Dock, the system has produced more accurate and useful travel information.
Smart Signal Technologies president Ken Shain says iQueue is ideally suited for agencies like the Pasadena Department of Transportation that want to improve congestion management on arterial roadways without spending thousands of dollars and hundreds of man hours on each intersection. According to the company, iQueue saves transportation agencies up to $3,500 per intersection every 18 months and gives traffic engineers valuable information they are able to use to keep traffic moving.

Streamlined forecasting

Based on technology developed by Dr Henry Liu, an associate professor of civil engineering at the University of Minnesota, iQueue collects traffic data from existing infrastructure to help traffic engineers monitor, evaluate, forecast and optimise traffic flow to reduce congestion. The system simultaneously collects event based high resolution traffic data from multiple intersections and generates real-time arterial performance measures, including queue length and travel time. Dr Liu’s research was supported by the Minnesota Department of Transportation – another current user of iQueue. Smart Signal Technologies licenses the technology from the university for commercialisation.
While competing solutions require extensive hardware investment and installation, iQueue can work with existing data collection infrastructure and communication networks. The system’s equipment has a small footprint that can be easily installed in existing signal controller cabinets.
“There are wonderful products out there but many solutions require a lot of ripping out and replacing of existing traffic management infrastructure – both in traffic management centres (TMC) and out in the field,” Shain says. “Our solution is non-intrusive in that we can plug in to existing networks without major disruptions. Installation for a traffic corridor with multiple intersections takes just a few days.”
The results are impressive. Tests conducted by an independent third party have found that iQueue’s travel time estimates are within 89% of the actual time calculated by probe vehicles. Simulations can be run as many times as necessary in a matter of minutes with a variety of traffic conditions and times of day. While it would normally take months to compile traffic information data that covered the appropriate conditions and times, iQueue can complete hundreds of simulations in little more than a day at a fraction of the cost. Some transportation agencies are using both: iQueue simulations provide a reliable baseline which is then verified using probe vehicles – cutting months from the process of collecting good data
“Our previous method of collecting traffic data was extremely labour intensive,” Dock says. “We had to have people standing outside in all weathers and hours of the day, physically counting cars. Now, the simulations are done with iQueue in the TMC in real time. It allows us to tackle serious traffic issues immediately.”
The City of Pasadena worked with technology supplier 73 Iteris in deployment of the system in May 2011. Iteris held a limited license for the technology during the Pasadena project before the rights were picked up by Smart Signal Technologies. Shain is keen to work with Iteris on this and future projects. “It’s a fine company and fits the profile of the types of firms we’re seeking to assist client agencies in deployment of this technology,” he says.

Adding automation and intelligence

Dr Liu and the University of Minnesota are already looking at the next evolutionary step by working on a system that would automate signalling based on real-time traffic information collected by iQueue. According to Shain, traffic engineers will be able to adjust signalling to clear lanes and intersections based on real time information on conditions on the road. It’s a capability that the City of Pasadena is ready for. The city is developing a system with Smart Signal Technologies that could send this information automatically to drivers through mobile devices and over the Internet.
“We need a lot of data to fulfill our transportation goals for Pasadena,” Dock says. “iQueue gives us the information foundation to better understand traffic patterns and be able to rapidly respond to changing conditions.”