San Francisco city council has ordered a US contractor to rip up more than 5km of track on a light rail project and lay it again.
The council claimed the track rails were made from "standard strength" steel, rather than the "high strength" material required in the contract’s specifications.
The letter was sent by the San Francisco Municipal Transportation Agency (SFMTA) to Los Angeles-based Tutor Perini and subcontractor Con-Quest.
The rail had to be "high-strength, control cooled or vacuum treated carbon steel tee rail", the letter said.
A copy of the letter can be seen here.
The project in question is the Central Subway, an extension to an existing light rail system, which was begun in 2010.
The tunnel boring element of the works was completed in 2014, but completion has been delayed by a year, to December 2019, and its costs have increased beyond the original $1.6bn budget.
The SFMTA is presently in negotiations with Tutor Perini over the issue, but according to reports in the US media, it is expecting Tutor Perini pay all costs for removing and replacing the track.
The SFMTA said it did not know how much the replacements would cost Tutor Perini. The SFMTA has said it may evaluate whether any of the existing track can be retained.
Tutor Perini has a large number of underground rail projects on its order books. They include the $1.4bn Los Angeles Purple Line extension, a viaduct replacement tunnel on the $1.4bn Seattle subway and the $1.3bn California High-Speed Rail stage between Madera and Fresno.
Image: Work on the project has been under way since 2010 (Tutor Perini)