Honolulu has arrived at a critical juncture. With the planned fixed-rail project at the point of final approvals and the recent news about a costly federal mandate to improve sewage treatment, the city needs guidance to keep these long-term projects from morphing into special-interest bonanzas that bankrupt the rest of us.

Homelessness, the lack of affordable housing and other hurdles will remain through more than one city administration, but the groundwork laid by the next mayor will be key to success. After vetting contenders for the Sept. 18 special election, the Honolulu Star-Advertiser endorses acting Mayor Kirk Caldwell as the candidate best prepared to take the helm.

Since becoming managing director some 18 months ago, Caldwell has broadened his experience in public service to include the nuts-and-bolts concerns of running city government. His work as majority leader in the state House of Representatives counts as an important credential as well. After years of enmity between Honolulu Hale and the governor’s office, the city should welcome a chief executive with experience in both circles.

As second in command under then-Mayor Mufi Hannemann, Caldwell is seen, for better and worse, as the status-quo candidate. The better part of that is his experience with municipal issues. But the taxpayer also expects fresh ideas from a new administration, so Caldwell’s challenge would be to demonstrate independence and his own brand of leadership, in an electoral field of distinct personalities.

Surveying the contenders: Councilman Rod Tam simply lacks the capacity and track record for the city’s top job. The others are not so easily dismissed.

Peter Carlisle has proven to be a strong and capable leader of the city’s Prosecutor’s Office and his reputation for independence appeals to many voters seeking change. Likewise, engineering professor Panos Prevedouros connects with other voters, primarily for his staunch opposition to rail and as an alternative to professional politicians.

But a mayor needs experience that goes beyond the law-and-order sector or a career in engineering.

And in the few weeks since he took over at Honolulu Hale, Caldwell has begun to strike out on his own. As acting mayor, he is moving to correct, rather than deflect blame, for the recent failure to notify a small sector of homeowners of a drastic spike in their property tax bill.

In a meeting with the Star-Advertiser editorial board, he pledged to bolster the city’s role in fostering more workforce housing. He also pledges continued work toward privatization of the city’s subsidized projects but rightly acknowledges the city’s responsibility to address homelessness. He favors finding a site to house and assist the chronically homeless, and for "safe zones" for those who now gravitate around parks and public places.

On waste management, Caldwell said the city needs to maximize the capacity of H-POWER and other technologies to further reduce the ash that would need to be sent to a landfill. He highlights the request for proposals already out for projects to develop these technologies for the city’s benefit.

In response to questions and on his own website, Caldwell points to the potential for private partnerships in pursuit of his stated top priority of job growth and economic recovery. His ideas — for example, putting a new focus on streamlining permits and encouraging the fledgling high-tech sector to develop projects for the local visitor industry, to help them remain in Hawaii — show a willingness to think creatively about problems that can’t be solved by the public sector alone.

But the dominant item on Caldwell’s to-do list is the rail project, and the acting mayor demonstrates the firmest grasp of the challenges ahead. His connections with officials at state and federal levels should help in maintaining continuity, and given Honolulu’s on-again, off-again approach to mass transit development, the city’s best interests will be served by a steady hand.

That’s what Kirk Caldwell can provide, certainly for the two years that remain in Hannemann’s term. Voters should hold him to his promises of independence and initiative — and give him the chance to keep those promises with their vote this month.