Confirming with high technology what many Baltimore-area commuters know from experience, a study has found that traffic congestion worsened considerably on the Beltway and other key stretches of highway in the region since 1998.
The Baltimore Metropolitan Council used Global Positioning System and Geographic Information System technology to track driving speeds during the morning rush hour, from 7 a.m. to 9 a.m., in the fall of 1998 and again in the fall last year.
Researchers found that average speeds for all seven freeways surveyed stayed steady, at 59 mph, over the four years. But traffic slowed noticeably - by as much as 15 mph - on several key approaches into and around Baltimore.
Among the stretches with the greatest slowdowns were southbound Interstate 95 between the Beltway (Interstate 695) and the Fort McHenry Tunnel; the inner loop of the Beltway between Interstate 795 and the Jones Falls Expressway; and the outer loop of the Beltway between I-95 and Providence Road. Average morning commute speeds on those routes fell by 12 mph to 15 mph.
Also experiencing greater congestion were southbound Route 29 between Interstate 70 and Route 100, where the average speed plummeted 17 mph, and the outer loop of the Beltway between I-795 and I-95 in Arbutus, where average speeds fell 7 mph.
The researchers said yesterday that while the trouble spots were not surprising, the magnitude of the slowdowns underscores that congestion has become a serious problem for the Baltimore area.
"What we're seeing is that congestion continued in areas that experienced it previously, but may have gotten worse because of factors of where people live and where people want to go," said Harvey S. Bloom, director of the transportation division at the council, which advises the governments of Baltimore and the surrounding suburban counties.
Reports of worsening traffic in the area are not new. But never before, say the study's authors, has anyone been able to pinpoint the problem so precisely.
To determine speeds, researchers gave GPS units to commuters and instructed them to maintain the average speed of the general traffic by passing one car for every one that passed them.
Speeds were measured in the fall months to avoid flukes caused by summer and winter vacation or holiday traffic. Data was not collected on bad weather days.
In all, speeds were measured on 42 heavily traveled corridors of both highways and "arterial" roads, busy routes with stoplights.
