Cost estimates to build the Honolulu rail project have been skyrocketing and officials are trying to figure out the best plan for finishing the line.

The Honolulu Authority for Rapid Transportation, the agency overseeing construction, has been revising estimates as new bids come in.

As recently as last year, the price for the 20-mile line from East Kapolei to Ala Moana Center with 21 stations was estimated at $5.26 billion. The cost is now estimated by HART to be nearly $8 billion. The Federal Transit Administration, which initially agreed to contribute $1.55 billion to the project, recently said the final price tag could be more than $10 billion.

With only about $6.8 billion thought to be available for the project, HART – and Mayor Kirk Caldwell – presented cheaper alternatives during a meeting earlier this summer, which are shown above. HART is currently in the process of creating a new financing plan in response to demands from the FTA.

Explore the graphic above to learn more about the alternatives.