throughout Sonoma County. But construction on the bike path -#8212; envisioned as the spine of a growing bike network in the two North Bay counties -#8212; remains largely suspended, troubling bike advocates and enthusiasts.

The agency has yet to build one segment of the pathway and has no estimate for when it expects to finish the project, though officials have said they are aiming to complete the first phase of the rail project, from Santa Rosa to San Rafael, by the end of 2016.

"The fact that they haven't established a date for completion (of the pathway) gives me concern about a lack of commitment," said Gary Helfrich, executive director of the Sonoma County Bicycle Coalition. "We feel that the bike path should be happening quicker. We want to seemore of a -#8216;can do' attitude."

SMART officials say they can't do work on most of the pathway until federal environmental regulators give the go-ahead. That approval should happen later this year, SMART spokeswoman Carolyn Glendening said.

In some places, the pathway will follow the rail; in others, it will veer off onto existing bike paths and city streets. Where the path runs along the rail, construction can happen only after the rail line is built, SMART officials say. Otherwise heavy machinery used to lay the rails would tear up the asphalt path.

A total of 17 miles of path will be on bike lanes along city streets.

Cities and other jurisdictions will build some segments of the trail. The city of Santa Rosa finished 0.3 miles of the path from West