A proposal to extend I-526 across Johns and James islands has been rejected by Charleston County Council and the S.C. Department of Transportation, and yet the project still has a pulse. That’s largely because of support from the State Infrastructure Bank and Charleston Mayor Joe Riley.

In a last-ditch effort to get his version of the highway — Alternative G — under way during his last term in office, Mayor Riley is taking the controversial project to City Council on Tuesday.

Mayor Riley continues to be dismissive of the I-526 plan’s critics, describing the five public hearings in 2010 as being “hijacked” by a “well-funded and well-orchestrated” effort aimed at derailing the project. He cited a DOT mail-in survey and anecdotal evidence of public support as reasons to persist.

We’d prefer to think that the hundreds of opponents who turned out at those hearings recognized the flaws of Alternative G, which fundamentally changes the existing 60 mph elevated expressway into a 45 mph at-grade highway with additional intersections that will encourage new development on both James and Johns islands.

As former state transportation secretary H.B. “Buck” Limehouse told us when Alternative G was first presented: “What’s the point of building a road to relieve congestion when you are encouraging development?”

Very likely, opponents were also displeased with the transparent attempt to limit public input on the project by the initial plans for just two hearings at Burke High School, nowhere near the project’s route. After The Post and Courier criticized the plan, the DOT agreed to expand the number of hearings by three, which were held in the project area.

After first rejecting the project, County Council reluctantly agreed to keep it alive when a member of the SIB board insisted the county would otherwise have to repay $11.6 million already spent on it.

County Council has thoroughly vetted this project and heard the pros and cons. As the original sponsor, County Council has the responsibility to vote the project up or down, not pass it off to the city like a hot potato.

And the SIB threat to force repayment of the $11.6 million should not be central to that decision. A lawyer with the Southern Environmental Law Center has persuasively argued in a brief that the county cannot be held responsible for project costs when its “no” decision followed the requisite federal process of public review.

If County Council reaffirms its opposition to the project, the city could then pursue its options with the SIB, assuming that City Council concludes the county acted unwisely.

While there are mixed views about the I-526 extension among County Council, it’s worth noting that council rejected Alternative G unanimously. It is reasonable to ask why it would agree to a request that could ultimately reverse that long-considered decision.

Before City Council decides to take up the project, it has the responsibility to raise some serious questions:

» Who would cover potential cost overruns of a massive project projected to cost $558 million?

The SIB has approved that amount. The mayor says if the costs exceed that figure, the SIB would pay them.

Yet SIB board member Eddie Adams, who’s also chairman of the state highway commission, told our reporter that he thinks the city would have to pay any extra expense.

» Would the project live up to its billing as a major solution for wide-ranging problems of intense local traffic congestion?

The number of interchanges will encourage more development, and more traffic. And it’s reasonable to worry that the James Island Connector, which would join the I-526 extension at Folly Road, would dump much more traffic onto the Charleston peninsula where the connector ends at Calhoun Street. That location is already highly congested during morning rush hour.

» Is there sufficient public support to justify spending more than half a billion public dollars on the project?

The public hearings on the I-526 extension sounded alarms about its negative impacts on the environment and its potential role as a trigger for more population sprawl, with low-income residents bearing the consequences.

And in a long letter to the editor published Wednesday, County Council member Henry Darby wrote:

“If I-526 is completed, properties of African-Americans (as well as many less affluent whites) on James and Johns Islands could become much like those of Hilton Head, Daniel Island, Mount Pleasant, and various areas of Cainhoy. The very people who own the land will find it difficult to continue living there; and as a result, the completion of I-526 will inevitably and irreversibly eviscerate cultures which took more than 300 years to foster.”

Mayor Riley insists that those concerns are misguided, and that state money now available for the project will be lost if the project is further postponed. As he puts it, “If it’s not built now, it will never be built.”

He might be right about that.

And despite the mayor’s single-minded support for the project, there is plenty of evidence to show that a significant number of local residents would be satisfied with that no-build outcome.