When the last leg of Route 100 was built, transportation planners knew it would be an attractive option for motorists to scoot between Howard and Anne Arundel counties in a hurry. What they didn't know was how soon drivers would catch on.

The stretch of road opened late last year, and traffic already averages about 57,000 cars a day on the section east of Route 29, a volume that is just 6,600 vehicles shy of what was expected in 2010.

"That happened a lot quicker than we thought it would," said Mike Haley, a regional planner with the State Highway Administration.

As a result, traffic is much heavier on Route 29, too, and as cars weave in and out of crowded lanes, accidents there are catching the attention of state officials.

Farther south on Route 29, cars stack up dangerously every morning at the exit for Route 32, where traffic has more than tripled in the last 15 years. Traffic there isn't near what planners say it will be in 2010, but it's bad enough that they want a fix, and soon.

That's why Howard County wants to add to the Baltimore Regional Transportation Plan two widening projects, on Route 29 near Route 100 and on Route 32 between Route 29 and Broken Land Parkway. The work, if approved, is expected to be finished within two years on Route 32, and within five years on Route 29.

On Route 29, commuters know the problem well. "This is primarily to relieve congestion in the a.m. and p.m. rush hour," said Jeff Smith, assistant division chief of regional planning for the State Highway Administration.

With the popularity of Route 100, traffic on Route 29 near Route 40, north of Route 100, has grown from 52,843 to nearly 120,000 in the last decade.

"That's why it's choked," said Ben Pickar, planning supervisor for Howard County's transportation planning division.

Although long-range plans call for Route 29 between Route 100 and Interstate 70 to be widened to eight lanes, officials say it needs a short-term solution.

Congestion on Route 29 is leading to accidents, most of them rear-end collisions, caused by dangerous merging and weaving.

Last year, 22 accidents occurred on that stretch of Route 29, Haley said.

The project would add a fourth lane to southbound Route 29 between Frederick Road and Route 100 and would restripe pavement to squeeze in a fourth lane north of Frederick Road.

It also would restripe the ramp from I-70 to southbound Route 29, so that I-70 traffic no longer would have to merge with Route 29 traffic.

On the northbound side of the highway, the project would involve restriping to add a lane from Frederick Road south to Route 100.

The entire project is three miles long, and early cost projections are about $2 million.

County and state officials haven't determined what Howard County's share of the cost would be, said county Public Works Director James M. Irvin. The improved road is expected to open in 2005.

The Route 32 project, which is more expensive, is a traditional widening to add a third lane to 1.5 miles of eastbound Route 32, between Route 29 and Broken Land Parkway.

The problem, planners say, is that through-traffic on eastbound Route 32 in the mornings is meeting up with traffic on Route 29 trying to merge onto Route 32. Many of the cars are headed to the major north-south routes to the east: Interstate 95, Route 1 and the Baltimore-Washington Parkway. On Route 29, where vehicles wait to get onto Route 32, Howard transportation planning chief Carl Balser said, "they're backing up on the southbound ramp, sometimes sticking out onto the southbound lane."

Heading east on Route 32, traffic gets heavier with each interchange. Every day, some 90,000 cars use Route 32 just east of Route 29. That's up dramatically from 28,975 in 1985.

Recent development in Clarksville is adding to the congestion. "I'm sure that that has had an impact," Balser said. But he said the road also carries heavy traffic from Carroll and Frederick counties to Anne Arundel County and beyond.

The widening project is expected to be completed in 2002 and cost about $6 million. The county would pick up about $4 million of that, Irvin said, covering the cost of the road work, while the state would pay to widen a bridge over Little Patuxent River.

The plans aren't certain, though. Commuters and residents interested in the projects may comment on them at a public hearing at 5:30 p.m. Oct. 18 at the Baltimore Metropolitan Council offices in Baltimore.

Later, the area's transportation steering committee will adopt or reject the proposed amendments, which, if adopted, would have to be approved by the Federal Highway Administration.