COLLEGE PARK — - Baltimore was still digging out from the first blizzard last month when the second one struck. A foot and a half of new snow clogged highways across the state. Scores of motorists were trapped by conditions that forced plow crews off the roads.
For a time, not even wreckers or the State Highway Administration's rescue trucks could reach them.
But while the travelers sat stranded, 53 disabled vehicles remained in view on dozens of highway traffic cameras, or as flashing icons on computer screens. The terminals were powered by RITIS, a computer network developed by the University of Maryland to give traffic managers and police in Maryland, Virginia and the District of Columbia a real-time view of road conditions across state and district lines.
"The powerful thing is [the network's users] don't have to be sitting here," said Jason Ellison, senior engineer at the UM engineering laboratory where the system was born. "We bring together a lot of different data sources they don't necessarily have ... and we push it into our Web site."
Much of the information might soon be made available online to the public, he said.
As solitary as they might feel in their cars, motorists on the region's arterials are never truly on their own.
In Maryland alone, data from 300 traffic cameras, 187 speed and volume sensors, and 64 weather stations flow into RITIS (for Regional Integrated Transportation Information System).
It arrives in a locked, computer-filled laboratory at UM's Center for Advanced Transportation Technology (CATT). Updates on accidents, construction and highway incidents are fed into the system by police and highway crews through a mobile communications system called CapWIN, also developed by the College Park lab.
With a few mouse clicks, state and district traffic managers can identify problems anywhere across jurisdictional boundaries, see which lanes are blocked, contact and coordinate first responders and select detours.
RITIS provides better "situational awareness" and "enhanced coordination on a regional basis," said Alvin Marquess, deputy director of operations at CHART, the State Highway Administration's highway incident response team. "If something were to happen in anyone's region, we'd try to support each other with information devices - overhead signs, travel advisory radio, media broadcasts."
When Gov. Martin O'Malley asked about conditions in Virginia during last month's snowstorms, Marquess simply called up the information on RITIS. "If the same question were asked about Pennsylvania and West Virginia roads, I'd have to make a series of phone calls to answer," he said.
Operational since 2006, RITIS had its biggest test early last year as hundreds of thousands of people descended on Washington for the inauguration of Barack Obama.
"There's a huge number of people involved with the inauguration who were looking at our Web site," Ellison said.
February's snowstorms provided another kind of test. In all, the RITIS system logged more than 1.2 million hits from 600 users in federal, state and local emergency operations, transit and transportation centers during the storms.
Maryland, Washington and Virginia operate their own traffic management systems. But before RITIS, no one had "the big picture," Ellison said.
Motorists "don't care that ... when they drive between their home and their business, that Maryland's jurisdiction ends at the border and Virginia's jurisdiction begins," he said. "They just want to know: 'Is there an accident in the way?' This gives them a total view of that."
The CATT Lab can serve as a backup traffic management center, but its primary job, funded by federal, state and private dollars, is maintaining and improving the system for all three jurisdictions.
In the works now are new data feeds to track area transit systems, and new 3-D visualizations - detailed virtual images of the region, complete with roads, buildings and traffic - animated by real data. The working version of RITIS is two-dimensional. On its maps and graphics, traffic tie-ups turn green highways yellow. When speeds drop below 30 mph, the roads turn red.
In Maryland, the speed and volume data come from solar-powered microwave sensors - some private, some state-owned - mounted on aluminum poles along many of the state's highways.
RITIS integrates traffic data from INRIX, a company that extracts highway speed data from satellite navigation systems on commercial fleet vehicles.
Reports of accidents, breakdowns and work zones are fed into the system by police and highway crews through the region's five-year-old CapWIN network (for Capital Wireless Information Net).
Developed at the University of Maryland's Clark School of Engineering, CapWIN currently has 5,000 users in 150 public safety agencies across the region, from the Pentagon to the Red Cross to the Hurlock Police Department in Dorchester County, program director John Binks said.