Miles of highways being shut down. Bag searches on the commuter trains. A halt to deliveries of liquefied natural gas to a terminal on the edge of Boston Harbor (search).

Tightened security during the Democratic National Convention (search) later this month, where Massachusetts Sen. John Kerry (search) will accept the party's nomination for president, will mean disruptions to everyday life for Bostonians and those who routinely travel through the city.

This is the first national political convention since the Sept. 11 attacks, and it comes just months after a terrorist bomb on a train in Madrid disrupted Spain's national elections.

The federal government has set aside at least $50 million for security. As part of the plan, security officials will deploy more than a half dozen mobile command vehicles — nicknamed "Winnebago Air Force Ones" — to ensure law enforcement and rescue agencies can continue to communicate in case of an attack.

"Our goal is to deter any potential attack with multiple layers of security," Homeland Security Secretary Tom Ridge said Wednesday during a visit to Boston.

In the months leading up to the convention, Bostonians were given a nearly weekly dose of bad news on how their lives would change amid tightened security during the convention, expected to draw more than 35,000 delegates, journalists and visitors to the city.

Some 40 miles of highway encircling the metro area will be shut down — starting in the afternoon and lasting through each night's convention festivities. Train service that normally feeds into the North Station commuter rail hub, located beneath the FleetCenter convention site, will be cut off outside the city and commuters shuttled in on buses.

Riders on the Massachusetts Bay Transportation Authority subway trains — known as the "T" — as well as buses and commuter rails, will be subject to baggage inspection.

It all translates into one big headache for Boston-area commuters, many of whom have made it clear that the hassles of the convention seem to far outweigh whatever benefit it brings the city.

The Federal Aviation Administration has banned all private and corporate flights in and out of Logan International Airport during the convention. The U.S. Coast Guard will deploy more than 600 men and women in air, land and sea patrols around Boston Harbor and the Charles River.

The massive liquid natural gas tankers that periodically travel through Boston Harbor to a terminal in Everett have postponed all trips during the convention.

The mayor has encouraged residents and commuters to take vacations or telecommute the week of the convention.