A freak parkway accident that wiped out three generations of a Bronx family is being touted by some transportation advocates as more evidence that New York City's aging highway system needs major upgrades.

Seven people died, including three children, when the family's SUV hit a concrete divider on the Bronx River Parkway, veered off a bridge and fell onto the grounds of the Bronx Zoo. Speed was a factor in the crash Sunday. Police said the vehicle was moving at 68 mph in a 50 mph zone. Still, the wreck seemed to validate the worst fears of motorists who navigate the city's pinball-machine expressways with white knuckles.

"The Bronx River Parkway is a glaring example of the deficiencies we see on area roadways," said Robert Sinclair, a spokesman for the American Automobile Association. "These roads were never envisioned as being the commuter arterial roadways that they are now. The roads are twisty. They are hilly. The lanes are narrow. There are no breakdown lanes. The on-ramps are too short."

Yet, federal, state and municipal transportation safety statistics show that the city's intimidating roadways are also far less deadly than their rural and suburban counterparts, and have probably never been safer.

New York City saw 243 people killed in traffic accidents in 2011, the lowest total in at least a century, according to the city's Department of Transportation.

A majority of those deaths involved pedestrians struck by vehicles on sidewalks and streets. Excluding pedestrians and bicyclists, the death count was 82, meaning you are many times more likely to die of accidental poisoning in New York than in a car wreck.

Most of the deaths were on surface roads, not highways, although last year's deadliest crash — a bus wreck that took 15 lives — happened on a wide-open stretch of I-95, right at the city limits.

By comparison, North Carolina, a state with a population not much larger than New York City, typically has more than 1,300 motor vehicle fatalities per year.

National statistics have long shown that the highest death rates, per mile driven, are on rural roads where people can go fast and maybe get lulled into complacency.

The national average for motor vehicle fatalities in 2010 was 1.11 deaths for every 100 million miles traveled by vehicles. That's nearly twice the fatality rate of 0.64 in urban areas in New York state.

Fatalities aside, groups like the American Automobile Association argue that New York City's arterial roadways are still undeniably outdated, in poor shape and lacking important features. For example, the lack of breakdown lanes on many highways means every time someone gets a flat, you block a lane of traffic and get a huge tie-up.

Replacing highways, however, isn't at the top of many urban planners' wish lists.

One factor is the enormous cost. The New York Metropolitan Transportation Council estimated in a recent report that merely operating and maintaining the present road and rail network would cost $951 billion between 2010 and 2035.

Also, in one of the world's largest and densest cities, there is simply no space for larger, straighter roads. Widening some highways even a little might involve seizing and razing thousands of houses and apartment buildings.

"The idea of replacing a parkway probably isn't realistic," said Gerry Bogacz, the Transportation Council's planning director. "It becomes a huge undertaking to even do something as simple as straightening a road, in a place where there might be a curve."

But there are things that can, and are, being done, he said.

The Bronx River Parkway bridge that was the scene of April 29 crash is scheduled to be rebuilt in the next few years. After the crash, state transportation officials said they would install new concrete barriers on the viaduct, and two others nearby, in an attempt to better guard against vehicles going off the edge of the road. There is a railing on the bridge, but the family's Honda Pilot hit a curb and vaulted over it onto the grounds of the Bronx Zoo. There were no open exhibits in the area where the SUV fell.

A funeral for the seven killed members of the family was held Friday.

Hundreds of other similar road projects are taking place on major roads and highways around the city. On surface roads, New York City officials have attacked the larger problem of pedestrian and cyclist deaths by adding bike lanes and creating more pedestrian-friendly plazas and sidewalks.

"This is the stuff that keeps New York going," said the Transportation Council's spokeswoman, Lisa Daglian. "Are they sexy? Not necessarily. But do you notice if they are not done? Absolutely."

Most of the biggest-ticket transportation projects happening in the city right now involve expanding the rail network, including two expensive expansions of Manhattan subway system, reconstructing a light rail station destroyed in the Sept. 11 attacks, and a new underground line connecting the city's two main train stations.