The 6 worst tunnels in the world have leaking walls and slippery roads — take a look

• Most of the world's tunnels are considered safe for drivers, but a few are still decaying rapidly.  
• The world's worst tunnels are often plagued by leaking walls, corroding infrastructure, and collapsing or uneven roads.
• We've rounded up six tunnel systems that are in desperate need of repair — including two in New York City. 
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Elon Musk may have moonshot dreams of building high-speed loops that whiz passengers from city to city, but the world's tunnels are a far cry from this vision. 

Read more: 7 of the most dangerous roads in the world

Rather than serving as oases from traffic, many modern tunnels suffer from congestion and corroding infrastructure. A select few are even becoming dangerous, posing a threat to the daily operations of thousands — in some cases, millions — of residents.

Here are six tunnels that are in such desperate need of repair, they might easily be considered the world's worst.

China's Guoliang Tunnel consists of a steep road with no barriers.

In the 1970s, the Guoliang Tunnel was chiseled into the Taihang Mountains by 13 villagers — a genesis that doesn't exactly bode well for its safety. The tunnel is wide enough to fit cars, but its walls are uneven and its road is one of the steepest in the world.

There are also no barriers or street lamps, which could pose a hazard for drivers. Locals now refer to it as "the road that does not tolerate mistakes."

Boston's Storrow Drive Tunnel will eventually have to be rebuilt.

In 2017, Travel and Leisure analyzed data from the Federal Highway Administration (FHWA) for nearly 700,000 bridges in the US. Their analysis awarded each bridge a "sufficiency rating" based on four FHWA categories: structural adequacy, safety, functionality, and whether it was used often by the public.

Boston's Storrow Drive, which includes the Storrow Drive Tunnel, received the worst rating possible: a zero on a scale of zero to 100. Over time, the tunnel's cracked beams, drooping ceiling, and leaks have mandated immediate repairs, but the entire structure will likely have to be rebuilt someday, an engineering professor told the Boston Globe. 

New York's Hudson River tunnels are running out of time for repairs.

The Hudson River tunnels in New York City aren't just old — they're also falling apart. After Superstorm Sandy flooded the tunnels with saltwater in 2012, the walls have begun to crumble and leak, and steel and electrical cables have corroded rapidly.

The tunnels' owner, Amtrak, has estimated that the tunnels have about a decade before at least one of them fails. New York legislators are still seeking federal funding for the renovations. At the moment, the tunnels are still considered safe, but time to repair them could be running out.