ARLINGTON, VA - MARCH 21: Arlington County's new $1 million bus stop on Columbia Pike and Walter Reed Drive Thursday March 21, 2013. (Dayna Smith/For The Post)

OFFICIALS IN Arlington County were surprised in 2006 when school enrollment, holding at around 18,500 for a number of years, began to rise. They’d figured that the erosion of affordable housing in the county, a byproduct of gentrification spurred by Metro, would drive families out of the county and shrink the number of students.

In fact, the opposite happened. Today, a little more than eight years on, school enrollment has soared by about 40 percent, to more than 25,000, and officials project that the system will continue to add almost 1,000 students a year for the foreseeable future. Despite recent economic tremors, Arlington, and its transit-oriented development, are national success stories.

Yet there are signs that the county’s civic harmony, or at least the consensus for continued growth and bejeweled amenities that elected officials had counted on, may be a victim of that success.

A wake-up call came recently with the victory of a thoughtful independent (and former Republican) candidate in a special election for the formerly all-Democratic county board, one who made a forceful case against the assumptions and spending policies that have contributed to the county’s rapid transformation.

John Vihstadt ran successfully on a platform opposing the construction of what he called an unaffordable streetcar line on Columbia Pike. His argument flew in the face of what planners and consultants had recommended (and we supported), but it persuaded many voters who regarded the county’s ambitions and spending habits as mushrooming beyond all logic.

For those who listened closely, Mr. Vihstadt’s critique went beyond the streetcar project to include other gold-plated projects, including a state-of-the-art $80 million aquatic center and a notorious $1 million bus shelter. Fundamentally, he accused county officials of speeding ahead without community buy-in.

Pro-streetcar Democrats, who retain a majority on the board, might have forged ahead anyway. Wisely, they have not. They pulled the plug on the streetcar project two weeks after the November election.

Now they are going further, in recognition that Mr. Vihstadt’s broader assessment — that county government and the residents it serves were not on the same page — should not be shrugged off.

In a New Year’s address, the incoming head of the county board, Mary H. Hynes (D), said she would undertake a broad outreach effort to solicit views from Arlingtonians countywide, including by appointing 20 residents to an advisory panel to study plans in the pipeline and make recommendations to elected officials. “We skipped an important conversation,” said Ms. Hynes, who promised that initiative to engage community more deeply would represent a “new chapter” in the county’s growth.

Growth pains are common in booming localities, and they come as no surprise in Arlington, which has added nearly 40,000 residents since the turn of the century to a population that now approaches 230,000. It’s a good bet that debates over growth and amenities will not end with the election of one new independent-minded board member or the appointment of an advisory panel.

Still, it’s heartening that the county’s elected officials took notice of the shift in public sentiment and, regardless of the obvious successes Arlington has enjoyed, are willing to recalibrate the way they do business.