The promise by the Delaware River Port Authority brass to use future revenues only for transportation-related projects is an acknowledgment that an experiment in "economic development" that began 15 years ago has ended badly.

Unfortunately, toll payers on the DRPA's four bridges will be paying off the mistake for years. Indeed, toll hikes could come before the end of 2008 unless action to forestall them is taken.

But any delay is unlikely to prevent an eventual increase, so DRPA should make permanent its promise to stop spending on economic development and provide a full accounting of what it has spent so far.

This mess began in 1992, when the legislatures of both Pennsylvania and New Jersey; their governors (Democrats Bob Casey and Jim Florio, respectively); Congress; and President George H.W. Bush all signed off on giving the DRPA economic-development powers.

Until then, DRPA's mission - despite having "port" in its name - had been limited to building and maintaining bridges over the Delaware River and operating the PATCO High-Speed Line.

Within a decade of getting its expanded power, and with Republican Govs. Tom Ridge and Christie Whitman at the helm in Harrisburg and Trenton, the DRPA went on a borrowing spree, floating a total of $1.2 billion in bonds on Wall Street.

Most of the debt - backed by tolls that are paid largely by New Jersey motorists - was earmarked for needed work on the bridges and PATCO. But more than $300 million - the actual figure is not clear - was spent on what were called "economic development" projects.

Some of the money was put to good use, supporting cultural institutions that bring visitors and tourist dollars to the region. But all too frequently, the beneficiaries were favorites of the governors or powerful DRPA commissioners.

And there never was a satisfactory answer to the nagging question of why motorists paying to use a bridge - often to go to work - also were supporting the Battleship New Jersey or the Philadelphia Orchestra, to name just two beneficiaries.

One result of all of the borrowing and spending is that DRPA now pays 42 cents of every dollar it collects for debt maintenance, considerably more than similar agencies in other states.

The much bigger Port Authority of New York and New Jersey pays to debt service only 14 cents of every toll dollar collected; that's what DRPA pays just for its economic-development debt.

Many of those now in charge at DRPA weren't around during the free-spending days, but they are stuck with the bill and the need to keep four bridges and a commuter railroad in good working condition.

Last week, the agency passed a $229 million operating budget that aims to use $62 million in cash reserves to delay a toll increase until at least the middle of next year. Tolls could jump from the current $3 to up to $5.

DRPA could delay the toll hike even longer by ditching from its budget the $57 million line-item for a tramway linking Camden and Philadelphia. The tram seemed like a good idea when plans were unveiled in 1999, but its price tag has increased each year even as the likelihood of it ever being constructed has grown remote.

Only the tram's foundations have been built. They stand as monuments to the lavish spending DRPA embarked upon after gaining economic-development powers. It used that power to create a slush fund for use by whoever was in control in each state to pay for projects when money could not be obtained by regular government channels.

As history has shown, spending the people's money without real accountability has seldom benefited the public. DRPA needs to stick to its core business of operating bridges and a commuter railroad. And it should make a full accounting of how $1.2 billion was spent on "economic development."