Honolulu Mayor Kirk Caldwell made it official Monday: Rail will keep chugging along.

The mayor held a brief signing ceremony at Honolulu Hale for Bill 23, which extends for five years a 0.5 percent general excise tax surcharge that pays for the $6.6 billion project.

Officials have said that the tax extension was necessary to keep construction going on the 20-mile rail line.

The project has faced a number of hurdles already, including delays, cost overruns and a shortage of revenues.

It’s estimated that the five-year tax extension will raise an additional $1.2 billion to $1.8 billion for the project.

The GET surcharge, which is only collected on Oahu, is now scheduled to sunset on Dec. 31, 2027.