Metro riders will have to wait another year for enhanced cell phone service across the transit system.

Verizon Wireless, AT&T, T-Mobile and Sprint missed their self-imposed fall 2010 deadline for installing underground infrastructure to boost coverage in Metro stations. Congress called for the companies to complete the project by October 2012, a deadline the companies are now working toward.

Metro safety officials must accompany the workers from the carrier companies while they install cables in tunnels and at stations, Washington Metropolitan Area Transit Authority spokesman Dan Stessel said.

“We are aware and working towards the goal of finishing up the project by October 2012,” Stessel said.

The four companies completed 80 percent of the wiring work at stations, Stessel added.

The law required Metro to outfit the top 20 busiest stations by October 2009, a task that is already complete. Foggy Bottom and Farragut West are among the stations that have service, but 27 out of the 47 stations have yet to finish the wiring process.

Stessel said 75 percent of the underground fibers are installed and half the above-ground work is also finished.