For years, transportation safety officials have worked to combat distracted driving -- the risky behavior that comes when people try to operate a car and a cell phone simultaneously.

But transit officials in Portland have launched a new effort to focus on an area that's getting increasing attention in traffic safety spheres as well: distracted walking.

This month, TriMet, the transit agency serving the Portland area, will outfit part of its bus fleet with extra devices thanks to a $400,000 Federal Transit Administration grant designed to study technology that can help prevent pedestrians -- often engrossed in their cell phones -- from walking into the path of a moving bus.

A study released by Ohio State University earlier this year estimated that more than 1,500 pedestrians nationwide were treated in the emergency room due to injuries sustained while using a cell phone while walking in 2010. That figure doubled since 2005, and it could double again by 2015, according to the report. Moreover, researchers say the real number of distracted walking accidents is probably much higher, since not every injured person goes to the hospital or admits to having been using a phone.

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Meanwhile, in a separate study from University of Washington, researchers set out to observe distracted pedestrians in the field by monitoring Seattle's 20 most dangerous intersections. They concluded that people who texted while walking were four times more likely than other pedestrians to do something risky while crossing the street, like jaywalking or not looking both ways.

In Portland, the focus on pedestrian safety comes in part because of a tragedy. On a late night in 2010, a TriMet bus made a sweeping left turn and smashed into five pedestrians, killing two of them. The pedestrians had the right of way, according to a 2011 court ruling, and the transit agency and bus manufacturer ultimately paid a $4 million settlement.

Portland is a place that encourages biking, walking and transit usage. Those three things don't always play well together.

So this month, TriMet will begin testing several types of devices that could help to reduce the likelihood of pedestrians getting struck by buses.

Two different devices will sound loud warnings when the bus driver's steering wheel is turned 45 degrees. An alert will loudly say, "Pedestrians: bus is turning." One version of the device also flashes strobe lights.

TriMet conducted a smaller-scale test in 2011 of those audible warning devices, but the alert often came too early or too late -- if it came at all. TriMet’s Executive Director of Safety, Security and Environmental Services Harry Saporta says the technology has dramatically improved since then.

Another device sounds a verbal warning when the driver uses his turn signal.

TriMet is also testing a headlight system that calculates the bus's speed and steering wheel angle to turn on additional LEDs inside the headlight that are pointed in the direction of travel. The idea is to make it easier for bus drivers to see people in intersections while turning and to also give pedestrians a signal.

A fifth safety device, developed by TriMet engineers working alongside a contractor, is a signal located at an intersection that illuminates to say "BUS" when one is turning. It's triggered by the same type of technology TriMet uses to make traffic traffic signals automatically switch to green when they sense an approaching bus.

All of the systems, except "BUS" sign, are commercially available. New Jersey Transit and the Greater Cleveland Regional Transit Authority use the audible warning systems triggered by the steering wheel. Meanwhile, the Richmond, Va. transit system uses the one set off by turn signals.

But Saporta says it's an exciting opportunity for TriMet, since many transit agencies lack the resources to evaluate multiple products at once. Saporta said each systems has advantages and disadvantages. "They each approach the problem a little differently," Saporta says.

The pilot will run through April, and transit officials will analyze data and hold focus groups to determine which of the technologies may warrant wider use.

For now, the focus is on alerting pedestrians to the buses -- not alerting buses to the presence of pedestrians. Saporta notes that there are some systems available in automobiles today that serve that function. But that technology has yet to be translated effectively to transit vehicles, he says.

The final report evaluating each of the systems is due next fall.