Road warrior: Santiago bottles traffic and pollution with an interconnected system of toll roads.

Chile's capital city Santiago is looking a lot prettier to motorists, thanks to an extreme makeover. The Costanera Norte is a US$600 million east-west arterial highway that dips into a four-kilometer tunnel beneath a river and the city's center, an engineering achievement. It links four other electronic toll highways that traverse the city with the aim of reducing Santiago's notorious traffic.

Engineers say the final network of six, non-stop, integrated electronic-toll expressways, a $2.04 billion project when complete in the next couple of years, is the first of its kind not only in Latin America but in the world. Electronic toll highways are not new, yet none so far are as integrated as the Chilean project.

Before the Costanera Norte, Santiago was a city clogged with traffic as drivers tried to navigate narrow, Parisian-style city streets and underbuilt, overused bypasses. Stop-and-go traffic worsened the city's tough air-pollution problem. Drivers immediately took to the Costanera Norte. "Before the opening of the highway, I would take an hour and fifteen minutes to go to work and get back home. Now I just take 20 minutes to go to work and back," says Daniel Libedinsky, owner of a hair-products company.

Early praise for the superhighway is music to the ears of Diego Savino, president of the Italian construction company Impreglio, which won the concession to build and operate the Costanera Norte. "The highway cuts travel times dramatically," says Savino. "Santiago is now at a global level with the new, integrated electronic-toll highways coming on line."

The project was no mean feat. It went through a series of design changes before planners eventually decided that it needed to run beneath downtown Santiago and the Mapocho River, a shallow waterway that bisects the city and serves as a drainage ditch for winter storms and spring thaws from the Andes towering nearby. During construction, a variety of safety measures were put into place, including stronger floodgates to allow the Mapocho to flow without breaking its banks during the winter months, when rainfall is heaviest.

Building a four-kilometer tunnel under an unpredictable river posed a challenge. "In the summertime, as a historian said, it is just a miserly little creek, but in the wintertime, it carries a lot of water," says Fernando Orellana, business manager at Ingendesa, the engineering company hired to help build the Costanera Norte project. "So we channeled the river in order to manage the course and built an early-warning system in case the river rises."

Not only does the project strengthen the Mapocho's riverbanks but it has created more public parks in the capital. "We now have a friendlier, faster and safer traffic flow that reduces travel times at least by half," says Public Works Minister Jaime Estevez. "The river has been cleaned up and new, greener areas have been opened up to the city thanks to the Costanera Norte's design."

Now, drivers carrying an electronic transponder can enter and exit the new toll roads without the hassle of stopping to pay in cash at a manned booth. A toll is charged as the car passes under electronic sensors that run the length of the highway. At the end of the month, the motorist receives a single statement detailing the time spent on the tollways.

Fed up. "Our culture has adopted the transponder," says Ricardo Leon, operations manager at Kapsch Traffic-Com Chile, the Chilean subsidiary of the Swedish company that provides the transponders and sensory equipment. "Initially, there were some 900,000 transponders in the market and I believe we are at or over a million cars with transponders."

Fed up with traffic, motorists seem willing to dish out their hard-earned pesos on transponders and tolls--if it means getting to work on time. For some, that money comes right back. "Although our costs have risen due to the tolls we have to pay, our savings are in gas and less wear and tear of our vehicles" says Horacio Martino, traffic manager for TransVip, an airport passenger transportation service. "We have increased our turnaround times, carrying more passengers and making more trips."

JORGE GARRETON * SANTIAGO