David Patton, Arlington’s bicycle and pedestrian planner, shows the inside of a bike counting meter to county board member Walter Tejada on April 1 in Arlington. (Patricia Sullivan /The Washington Post)

Arlington County’s newest cyclist-counting device, shrouded and waiting for its ceremonial unveiling, was supposed to record County Board Chairman Jay Fisette as its first passing cyclist.

But when Fisette’s bike pulled the ribbon that pulled the cloth from the shiny new pillar Tuesday morning, he wasn’t the first, or the second, or the 10th bicyclist to be recorded. Some 637 cyclists had triggered the automated counter while the speeches were going on, and the numbers on the digital display kept ticking up.

The new electronic device, called a “bikeometer,” is the only one of its kind on the East Coast. It will tabulate and display the number of cyclists who pass by the busy intersection of Lee Highway and North Lynn Street, just south of the Key Bridge.

A digital read-out will show the daily, monthly and year-to-date totals for the estimated 500,000 cyclists who use this portion of the Custis Trail each year.

“That which doesn’t get counted doesn’t count, and this counts,” Fisette said. “We are in the midst of a transformation that gives people a full range of options for getting around.”

A newly built bike meter, which will count the number of passing bicyclists in real time, is installed in Arlington near the Key Bridge. (Patricia Sullivan /The Washington Post)

It’s this type of investment that officials point to when they explain why Arlington’s population has grown more than 12 percent since 2000, without a parallel increase in road traffic. The county persistently promotes Metrorail, buses, cycling and walking as alternative modes of transportation.

Arlington has 30 other counters that track use of bike and pedestrian trails, but unlike the bikeometer they don’t display the information in real time. Many of the counters are on the National Park Service’s Mount Vernon Trail, which emerges from its riverfront path half a block from the bikeometer’s location. Others are scattered on county and state lands.

“This shows the courage of a community to wear [its bike data] on its sleeve,” said Andy Clarke of the League of American Bicyclists, who bikes to work on a route that will take him past the new counter.

The bikeometer cost $32,000 to buy and install, said David Patton, an bicycle planner for the county. It and the county’s other counters are paid for with a portion of the local vehicle decal fee.

The county will use the data collected for research into how, where and when to address the needs of bikers and walkers, and to improve safety and access, officials said.