Back in 2010, Gov. Christie shocked transportation experts when he canceled construction of a new rail tunnel to Manhattan, one of the nation's busiest routes. The project would have doubled capacity, relieving the terrible rush-hour delays that force NJ Transit and Amtrak trains to queue up to snake through two century-old, single-track tunnels. But Christie argued that the state couldn't afford its part of the tab, $3 billion to $5 billion, for relieving the rail congestion.

Price wasn't an issue earlier this month when South Jersey officials boisterously celebrated the start of another project aimed at reducing congestion. This one will reconstruct the chaotic Camden County interchange where Interstates 295 and 76 converge with Route 42. Fixing this one trouble spot - or, rather, making it more tolerable - will cost U.S. taxpayers just shy of $1 billion.

The different responses to these projects speak volumes about how our policymakers think about congestion. Highway traffic jams are still considered unacceptable. But rail commuters routinely make do with antiquated systems that cause regular delays and breakdowns, like the one that left PATCO riders stranded on the Ben Franklin Bridge for 90 minutes during St. Patrick's Day weekend.

What makes the I-295 project stand out is its staggering price tag. Officials say it will take at least $900 million to untangle the South Jersey interchange - a sum equal to 75 percent of SEPTA's entire annual operating budget. Yet it doesn't appear that New Jersey or federal officials ever stopped to ask, "Is this problem just too expensive to fix?"

Sure, the interchange is a hot mess. The road peels off like a banana skin, offering different paths. If you don't pay attention, you'll be careening across half-a-dozen lanes at the last minute.

Because of the overlapping exits, the accident rate on that stretch is seven times higher than New Jersey's average, the state's environmental impact report found. Commuters frequently stew in traffic during rush hour, emitting exhaust that poisons the air. No one would claim this is "a bridge to nowhere" sort of project. The situation is bad.

But is it a billion dollars bad?

Until recently, we haven't needed to ask that question because the federal government was always willing to foot the bill for road repairs, as it is doing for the I-295 project. But highway funding is becoming increasingly tight, partly because Congress is unwilling to raise the gasoline tax. We're so far behind on infrastructure repairs that the American Society of Civil Engineers recently gave a D+ to the nation's bridges and roads. Many experts predict that states will soon turn to privatization and tolls to pay for road repairs.

So, where do we start drawing the line on road costs? Are there times when we should learn to live with jams and delays? Especially since drivers eventually find alternative ways to get around?

Transportation advocates hate to compare transit and road projects, since they're financed from different pots of money. But this schizoid approach has cost us dearly. No highway project has ever made a city a better place to live, while transit projects improve our quality of life in a variety of ways, and are better for the environment.

Marilyn Jordan Taylor, the dean of PennDesign and a renowned transportation planner who has worked around the world, argues that no other developed nation spends its transportation funds so haphazardly. States dedicate money to low-priority road projects simply because they have the political mojo to claim federal funds. North Dakota, for instance, has cashed in big, despite having virtually no congestion. Yet we continue to treat mass transit like an unloved stepchild, even though Taylor argues that rail and bus projects "are far more cost effective."

Since the $900 million for the I-295 project is such a huge sum, I asked several transit experts how the money might be better spent to benefit the entire region. This is purely a fantasy exercise, since the funds aren't transferable to another project, never mind to another state.

But let's consider:

For about the same price as that interchange, PATCO could pay for a good portion of its proposed light-rail spur from Camden to Glassboro. This project, now undergoing environmental review, promises to revive the downtown cores of a dozen older South Jersey towns. By making commuting easier, they will be more attractive places to live and will help prevent sprawl from gobbling up more farmland. It will reduce South Jersey's highway congestion, too, taking an estimated 20,000 people off the road.

The benefits to Pennsylvania could be even more dramatic. The $900 million would just about pay for SEPTA to extend its Norristown High Speed Line to the King of Prussia Mall. The project would take thousands of cars off the Schuylkill Expressway and help Philadelphians commute to the mall for work and shopping.

In Philadelphia, you could practically do two transit projects for the price of that one interchange. For less than $500 million, you could extend the Broad Street Subway to the Navy Yard, a proven economic generator that just passed the 10,000-jobs mark.

With the leftover money, you could continue the subway to the airport. That would make the Navy Yard even more attractive as a corporate center because employees would be internationally mobile.

Compared to road projects, transit improvements can serve many more people. The improvements to the I-295 interchange will make life smoother for about 600,000 vehicles each month.

As for that tunnel project that Christie canceled? Well, more than 1.5 million people travel between Jersey and New York's Penn Station every week on NJ Transit alone.

Certainly, spending $900 million on the interchange will reduce accidents there. In the end, it might also boost travel to the Jersey Shore - by encouraging more people to drive the already crowded roads.