While political debate drags on, work has been under way on new Hudson River tunnels

Politicians in New York, New Jersey and Washington haven't figured out how they're going to pay for a new Hudson River rail tunnel — but work on the massive project has been going on for years.

One example is a $185 million start to the tunnel beneath Hudson Yards in Manhattan. The 800-foot-long concrete casing was carved out in the past two years to get ahead of ongoing redevelopment work at the riverside site.

Amtrak is spending $300 million in all on the tunnel project, an amount that also includes preliminary design work based on the assumption the tunnel will someday be approved.

Meanwhile, debate over paying for the rest of the tunnel continues — though officials in both states and the federal government agree that it's badly needed to relieve congestion in the existing 105-year-old tunnel.