The rickety buses careen down Lima's dusty avenues, steel hulks rattling. White-knuckled passengers hold fast. Tailpipes cough soot. Drivers grimace. Pedestrians scramble.

Too often, three or four buses at a time jockey for fares on haphazardly oversubscribed routes.

The drivers are in a perpetual race. If they don't meet a daily passenger quota, they don't get paid. So they put in nerve-racking 16-hour days and work seven-day weeks.

Peru's capital is afflicted by an anarchic, corrupt transit system the city's freshman mayor calls a shameful menace. She is promising, against tall odds, to fix it and the traffic chaos that might well lead the region in motorized hostility to pedestrians, cyclists and human lungs.

"I'd say the city is in serious collapse, given the quantity of vehicles, their age and the notorious absence of operating rules," says city councilman Rafael Garcia, a reform advocate.

Lima is far from alone among Latin American cities with exasperating traffic congestion and near-complete gridlock on major thoroughfares. But unlike in Bogota, Colombia, Sao Paolo, Brazil, or even Mexico City, it is not a surge in private passenger vehicles that is causing Lima's traffic nightmares. Vehicle ownership is low; four in five commuters use public transit.

The problem: chronic mismanagement and corruption dating back two decades. And it's not just the belching buses but also Lima's quarter-million taxis, half of them unregistered, all of them unregulated.

That's one taxi for every 18 Lima inhabitants. Mayor Susana Villaran blames the cabs for more than 70 percent of traffic jams.

Taxi drivers, like bus drivers, will stop anywhere. And forget meters. Cab fare is negotiated on entry.

More lethal, though, is Lima's sorry bus fleet, the chief culprit for air pollution that exceeds World Health Organization limits ninefold. A 2009 government report blamed vehicular contamination for 6,000 annual deaths in Lima from respiratory ailments.

The fleet coexists, and competes, with a shiny new rapid transit bus system with dedicated lanes that burns clean natural gas. Modeled on Bogota's Transmilenio system and launched last year, the Metropolitano is slated for expansion but so far only handles 3-4 percent of Lima's commuters.

The average age of Lima's buses exceeds 20 years, according to the citizen's group Lima Como Vamos. Thousands are mechanically unsound threats to life and limb. The average age of a Sao Paulo bus, by contrast, is 4.2 years, the group says.

The challenge for Villaran is to retool what emerged in the early 1990s after then-President Alberto Fujimori issued decrees aimed at cushioning the impact of layoffs from the privatization of state-run industries.

Anyone at all could get into the public transport business with whatever jalopy they had. Aggravating matters, all restrictions were lifted on the import of used vehicles.

A free-for-all ensued as more than three quarters of a million used vehicles flooded into Peru, said Edwin Derteano, president of the Peruvian Automobile Association.

Accidents surged by 30 percent; the public bus network devolved into anarchy.

Overnight, it became possible to "be assigned" a bus route, renewing it every six months, without owning a single bus or employing a single driver.

"All the incentives built into the (current) system make it a killing machine, I mean the entire system," says Gustavo Guerra, a former deputy transport minister and Villaran adviser.

"It's the same in Honduras, in Tegucigalpa and San Pedro Sula, the worst Latin American cities," said Guerra. He says they are the region's only big cities save Lima with such a system.

Ivo Dutra has a heart-wrenching reason for ending what he calls the "permanent battle" in Lima's streets: He lost his only child to it.

The August death of the 25-year-old photographer, also named Ivo, galvanized public outrage at the bus system, which officials blame for a big share of Lima's roughly 400 annual pedestrian deaths in traffic.

"My son was hit and thrown between 12 and 15 meters (40 and 50 feet)," says Dutra, by a bus whose driver ran a red light as he raced another bus.

The driver is on trial for criminal homicide in what lawyer Gustavo Ore, who is assisting the Dutra family, calls the first case of its kind in Peru. In past vehicular death cases, drivers always faced manslaughter charges. If convicted, the driver faces up to 20 years in prison.

Dutra calls him a victim, too.

"These drivers have a gun to their head every day as they go out and try to earn the quota they need to pay their employers nightly," he said.

Attempts to forcibly retire aged buses have so far failed, even though by law all buses and taxis older than 15 years were supposed to disappear by July 1, 2009, notes Luis Quispe, director of the citizen's group Luz Ambar.

The culprit is a system absent accountability: Drivers and bus owners are free agents hired by concessionaires, who obtain routes from the city transit office in an opaque process where bribes, not bids, have long determined who gets routes.

"What does it do? Congest, contaminate, create accidents. It's monstrous," said Mayor Villaran, who has been in office since Jan. 1, in an interview.

She has convened the parties involved for regular roundtables, bent on achieving what no predecessor had attempted: order and transparency.

A single route, with an average of 80 buses, can gross a concessionaire about $200,000 a year, according to Associated Press calculations. The administrative fees the concessionaires pay for a route, meanwhile, amount to just $1,600.

Several concessionaires were asked to disclose their revenues and declined.

"It's a helluva way to get rich," says 55-year-old bus driver Javier Diaz as he scarfs down a lunch of fried fish and rice during his half-hour midday break.

Diaz says he earns about $20 for a 16-hour day, roughly the norm for drivers. "I've got no pension for my old age. The day I quit, the vehicle's owner won't pay me severance, won't give me a thing."

Villaran says that's got to change.

The city is mandating that, beginning in July 2012, all route concessionaires own buses and employ salaried drivers and begin to scrap old, polluting buses. By then, says the municipal transit director Maria Jara the city will have reassigned routes with designated bus stops.

To achieve that, the city is pressuring transport companies to form consortia so they have enough buses and can meet cleaner-air standards. Currently, about 40 different concessionaires have routes on each of Lima's busiest thoroughfares. That number is supposed to be reduced to about four per thoroughfare.

One problem is that Lima doesn't have control over all the buses on its streets.

The adjacent port of Callao is 1/20th Lima's size yet runs more than 8,000 buses on its streets.

When Lima moved last week to reroute buses from a major boulevard to encourage more Metropolitano ridership, rioting broke out that authorites blamed on Callao concessionaires. At least 22 people were arrested.

Sociologist Claudia Bielich, who has studied Lima's transit system extensively, applauds Villaran's intent to end the chaos.

But she's skeptical. She's seen previous reform plans fail because they challenge the pocketbooks of "a big bunch of very powerful people."

And then, Bielich added, you need also persuade passengers.

"The Lima resident is accustomed to walking out to the corner, raising his arm and getting aboard the vehicle right there."

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Associated Press writer Martin Villena in Lima contributed to this report.

Frank Bajak on Twitter: http://twitter.com/fbajak

(This version CORRECTS mayor's first name to 'Susana.')