"Transit can make a difference, there's no doubt about it," Cahalan said. "Our priority under Governor [Martin] O'Malley's administration is to continue that trend where possible."
But Cahalan said the state is also working to speed traffic through the I-95 corridor. He noted that the state's biggest investment is the $994 million Express Toll Lanes project on I-95 between Baltimore and White Marsh, which will add two lanes of capacity in each direction in 2014.
AAA Mid-Atlantic and a daily commuter on I-95 from Harford County, said that project should help alleviate congestion that is frequently aggravated by crashes or bad weather.
"While at first glance these toll lanes may appear to only benefit wealthier commuters who can afford to pay to drive in congestion-free lanes, all commuters will benefit as it will help to alleviate congestion in all lanes," Averella said.
Cahalan said Maryland is also undertaking smaller projects that will make a difference in alleviating backups on I-95. He pointed to the reconfiguration of the Route 24 intersection in Harford County, slated for completion in the fall, and the recently finished addition of a second lane to the ramp leading from I-95 to the westbound Beltway south of Baltimore.
Maryland is also moving to address the potential for increased I-95 corridor traffic related to base relocation, Cahalan said. He said road projects on Route 715 near Aberdeen and Route 175 at Fort Meade are intended to improve traffic flow onto the bases and to prevent backups onto I-95.
"BRAC has always posed a challenge and it's a challenge we're moving to address in a variety of different ways," he said.
But Cahalan said Maryland and other cash-strapped states will have trouble heeding the report's call for stepped-up construction of new facilities.
"It doesn't change the reality that investment is extremely difficult given today's economic climate," he said.
This year's mobility report incorporates some sweeping changes to the institute's methodology that in some cases restate the outcomes of past studies. The new report makes much greater use of GPS technology to track driving speeds, Turner said.
The changes have brought some dramatic results. For instance, in the report based on 2007 figures, Baltimore was ranked 16th in the nation in the cost of congestion per peak auto commuter. The new report, which more fully reflects the impact of I-95, shows Baltimore in fifth place for the past three years.
Last year, a group called CEOs for Change issued its own report criticizing the institute's methods for calculating congestion, saying they are biased in favor of justifying highway construction and urban sprawl. Some of the changes, Turner said, address the criticisms leveled at the institute's methodology, but he said the refinements were in the works before the critical report was released.
Turner said the institute views itself as a "messenger" providing facts rather than as an advocate. But he said the group's statistics are routinely used by advocates of road-building, transit services and other interests to make their case.