According to a report in today's Examiner, the cost of repairing the Sunset Tunnel will increase from $13 million to $16 million after a contractor discovered that the tunnel's walls, structural supports and electrical conduits were in worse shape than expected after more than a year of construction. Inspectors have theorized that leaks in the tunnel may have caused more damage than was previously believed.

The tunnel, which opened in 1928, has been the focus of a seismic retrofit that has caused numerous weekend shutdowns on the N-Judah, Muni's most-traveled light rail line. The project has taken significantlylonger than expected due to weather delays, as well as noise complaints from residents who live near construction areas. 

According to the Examiner, Muni approved the additional expense because following the initial plan would have created a "high probability" of damage that could potentially prevent the agency "from using the tunnel at all." For the moment, it's still unclear whether the added construction will lead to more weekend shutdowns or other delays on the N-Judah.