The summer -- sadly for most folks -- is over. School has begun. It's time for everyone to get back to work. And if you plan to set out to tackle this day -- Tuesday, Sept. 4 -- with a new and steady resolve, a shoulder-to-the-wheel mentality, with all the grit and gusto you can muster, it's critical that you prepare to be utterly frustrated by traffic.

Historically, the Tuesday after Labor Day will seek to thwart your best resolution for success with traffic backups of the likes rarely seen on other days this year. Ironically, bad though it seems, it will get even worse in another month.

“How terrible is it?" asks AAA spokesman John B. Townsend II. "The breathing space we enjoyed on area freeways during the first two weeks of August will be in short supply. It all returns now that summer is in the rearview mirror.”

Townsend says that -- no surprise here -- the worst of it may be on seven major freeways. He cites data from the Center for Advanced Transportation Technology Laboratory at the University of Maryland and the Metropolitan Area Transportation Operations Coordination.

· Interstate 270 in Maryland from the Interstate 495 (the Capital Beltway) to Interstate 70.

· Interstate 66 from the Potomac River (D.C.) to US-17.

· Interstate 395 from the Springfield Interchange (the “Mixing Bowl”, I-495) to the Third Street Tunnel.

· State Route 267 (the Dulles Toll Road) from I-66 to the Leesburg Bypass.

· The Capital Beltway counterclockwise (Outer Loop).

· The Capital Beltway clockwise (Inner Loop).

· Interstate 295 (including Interstate 695) from the Beltway to the Third Street Tunnel.

The Tuesday after Labor Day is not the worst of the worst, it simply marks the beginning of the beginning, serving up a harbinger of the autumnal surge in traffic on area freeways and arteries. Travel times and congestion delays are consistently longer in October than even in September.

“After a summertime respite, it is a shock to the system," said Michael Pack, who heads the center at the University of Maryland. "Each year, morning travel delay consistently jumps by 15 to 45 percent between August and September."

In September, “up to 20 or 30 percent of morning traffic can be generated by parents driving their children to school,” according to the Safe Routes to School National Partnership, which adds that “In 2009, American families drove 30 billion miles and made 6.5 billion vehicle trips to take their children to and from schools, representing 10-14 percent of traffic on the road during the morning commute.”

Taran (Hutch) Hutchinson, who heads the Metropolitan Area Transportation Operations Coordination (MATOC) Program, says that beginning after Labor Day, "it only takes little things such as road work and lane closures to increase travel delays, and so can ‘one-off events,’ such as bad weather, a stalled vehicle, or a crash on a freeway segment during the height of rush hour. That’s when things go from bad to worse. "

Hutchinson said, "The ripple effects of a temporary 50 percent reduction of roadway capacity during rush hour can have long-lasting impacts on the area’s roadway network, not to mention other transportation modes.”

He said that about half of all delays can be attributed to nonrecurring congestion, like collisions, disabled vehicles, work zones, weather or special events.