The southern German city of Stuttgart, home to both Mercedes-Benz and Porsche, has gotten approval for a railroad project worth 4.8 billion euros ($6.6 billion).

The plan will replace Stuttgart's main train station, built in the 1920s, with an underground station, and will drive a new main rail line -- including a nine-kilometer (six-mile) tunnel -- through the urban area. Smart new mixed-use commercial and housing developments will replace the old station.

Perhaps surprisingly, Germany's "motor city" sees no contradiction in using public funds to lure motorists away from busy roads onto fast inter-city trains. But after the plan was approved, some taxpayers began complaining that the project would be a gigantic waste. And conservationists and developers immediately faced off on the issue.

No more 'dead end' station

The scheme, which will replace a "dead-end" train station with a time-saving drive-through station, will be funded mainly by the state and federal governments and land sales. It will do away with a 19th-century rail line that runs through a valley between the steep, green hills that surround the city center. The new plan calls for drilling tunnels through the forest-clad hills that give the city so much charm -- but also hamper road and rail connections.

Stuttgart, in the state of Baden-Württemburg, is one of Germany's most prosperous cities and a main stop on the rail line between Paris and Vienna. It has always been an oddity because of its dead-end train station. As locomotives enter the station, they have to stop at buffers and be uncoupled. Another engine must be hitched at the other end to haul a passenger train on the next leg of the journey, or a special two-headed train must be used.

The plan is to avoid this by letting trains drive straight through the city, using a new train station that will be built underground. Planners say this will greatly improve travel times, shaving nearly an hour from the trip between Munich and the French city of Strasbourg, for instance. It would allow France's high-speed TGV train, which began services to Stuttgart in May, to sweep through and keep going as far as Hungary.

New housing is planned

A key aspect of the product is the plan to replace an enormous eyesore -- land currently covered with train platforms, sheds and sidings -- with upscale housing and offices, effectively creating a new neighborhood in pricey downtown Stuttgart.

If the plan is carried out, it would make Stuttgart the first German city to try building a rail line from scratch, as opposed to using the already existing lines.

Stuttgart Mayor Wolfgang Schuster stands behind the railway plan despite its high costs, citing an overall need in Europe for high-speed rail lines.

"What would be the alternative in central Europe?" asked Schuster rhetorically. "Either we expand the autobahn, which faces political opposition, or increase flights -- which is hardly possible considering how busy the airways around Paris and Frankfurt are. For me, the right answer is: high-speed rail."

Meanwhile, state environmentalists oppose the project, fearing it will suck up federal funds that could have been used to reduce car use by improving tram and train lines in other cities in the state.

Heribert Rech, the state's minister for transport, denies other communities will receive less, but the state's finance minister, Gerhard Stratthaus, says that is the logical consequence of locking a federal government grant into the station project.

The European Union will support the project with 250 million euros. The state of Baden-Württemburg will pay about a billion, and the federal government will chip in some 1.5 billion euros.

Even so, that leaves a shortfall, which planners have covered by agreeing to sell to a mixed palette of developers the land that will be freed up by the new underground routes.

Citizens' opposition

The city and state stand squarely behind the project, which aims for completion in 2019 and which goes by the name of Stuttgart 21.

But local opposition has arisen, mainly from a citizens' initiative called Stuttgart Living.

Gangolf Stocker, the spokesman for Stuttgart Living, considers the underground train station technically ill conceived. He also worries about the effects of so much construction -- the inevitable dust, noise and trucks -- on daily life over a long period.

Moreover, Stocker argues, the plan itself is faulty.

"Investors who buy this land want guaranteed return on their investment. The building will reflect that. There will be no urbane construction, or anything like it," he said.

And, he argues, a cold windstream runs through the east section of the train station area, mainly at night; that means high buildings should not be allowed, he said. "Even though the east section shouldn’t be built on, it will be. It's in the plans," Stocker said.

Opponents plan to start a petition drive to put a stop to the plans.

Critics also question why state premier Günther Oettinger promised 950 million euros in grants to the federally-owned rail company.

Even scarier for state taxpayers is a guarantee by Baden-Württemberg to pay up to 940 million euros if those digging tunnel discover unstable rock under the city and have to start again or use a more expensive building method.

The scheme requires 57 kilometers of new rail-bed through the city, including 33 kilometers of new tunnels. Another 60 kilometers of track for 250-kilometer-per-hour ICE bullet trains will be laid to the nearby city of Ulm, including a bridge across the Danube River.