D.C.'s first streetcar line in 50 years may be ready for passengers service by spring or early summer of next year, but an exact date remains elusive.

"We will get passenger service going as soon as can," Nick Nicholson, the District Department of Transportation's chief engineer, told reporters on Tuesday.

But how soon?  "As soon as I can," was his response to repeated questions about when the 2.2-mile streetcar line — the first in D.C. since the 1960s — would be ready to roll.

Nicholson said that he would not estimate a start date because the process of finishing the line contains so many variables -- the most pressing being safety testing. He said he expects that the testing will begin in December along a very busy commercial corridor chock full of jaywalkers and double-parked delivery trucks.

A somewhat similar streetcar project in Tampa took three months to certify as safe and ready to go, but Nicholson opted not to speculate what that would mean for D.C. "There is no precedent in D.C.," he said.

Another issue that remains unresolved is how much fares will cost, the hours of operation and how passengers will pay. All of those are being addressed as the District works with H Street merchants to prepare for the changes to come in parking and deliveries.

The line is the first of what city officials hope will be a 37-mile network crossing from H Street to Georgetown and from Buzzard Point to Takoma or Silver Spring.