"Dawn of the Dead," George Romero's dreadfully overextended elaboration of "Night of the Living Dead," his famous horror sleeper of a decade ago, could be defended-up to a point-as a comedy of social depravity. It certainly belongs to the modern tradition exemplified by Jean-Luc Godard's "Weekend" and Bertrand Bliter's "Going Places."

If Godard deserved congratulations for visualizing the collapse of bourgeois civilization as a massive traffic jam, Romero deserves a little credit for exploiting a suburban shopping center as the last resort of zombies and barbarians in the wake of a social breakdown.

The humorous allegory of "Weekend" was undermine by Godardhs deadly political lectures, but Romero doesn't bore you with prolonged indoctrination. He makes you whimper uncle by prolonging scenes of hideous violence until they start to look repetitive. There are only so many ways to show zombies feasting on human flesh or getting their brains blown out. The inflated running time of "Dawn," a much more lavish production than the gritty. "Night of the Living Dead," seems to force Romero to use all conceivable variations several times over.

The commercial success of "Dawn," which opens today at the Dupont Circle and Tenley Circle, probably depends far more on the appalling body count than Romero's droll sense of humor and pictorial dynamism. You can't blame those who, appalled beyond all endurance, walk out.

In the first film, a small group of people were besieged in a cabin by waves of living dead after some vague cosmic epidemic caused the newly deceased to rise from their graves and devour surviving friends, neighbors and loved ones. In the new film the epidemic has spread, causing a national social crisis and the proliferation of vigilante groups.

The principal characters are four self-serving deserters who escape from the decaying metropolis in a helicopter owned by a TV station and take refuge at a shopping center, located in the Pittsburgh suburb of Monroeville. It's one of Romero's shrewder touches to make this group of hold-outs difficult to root for. Like the marauding, armed bands they see scouring the countryside, our "heroes" are mercenaries looking out for themselves and even enjoying the opportunities created by the epidemic.

The quartet consists of National Guardsmen played by Ken Foree and Scott Reiniger and a pair of lovers played by David Emge and Gaylen Ross. They set up housekeeping at the shopping center,ripping off weapons,food clothes and furnishings from the abandoned stores. They seem to feel most at home in Penney's. The Guardsmen get a kick out of playing cat-and-mouse with all the poor gray-skinned zombies lurching around the parking lot and along the malls.

In fact, it's easier to sympathize with the zombies than the humans, who have no excuse for their perverse and barbarous behavior.This contrast between instinctive and willfull barbarism is, of course, intentional, and Romero plans an eventual concluding sequel in which the survivors have learned how to manipulate the zombies, who get socialized enough to do all the menial tasks and dirty work.

Witty as they sometimes are, Romero's ironies aren't subtle or devastating enough to justify lengthy comtemplation. "Dawn" seems like a good 80-minute horror premise stretched out at least half an hour too long. Moreover, the excess running time appears to be filled by repeated shootings, clubbings, stabbings and munchings, always vividly depicted, rather than further character exploration or mordant strokes of humor.

Foree, a taut-skinned black actor, and Reiniger, a cocky little blond who could pass as Nick Nolte's fiesty kid brother, make an amusing team of updated buccaneers. Between atrocities the movie has its funny moments and funny lines. It's just difficult to relish the humor when you're dripping in so much gore.