(AP) -- U.S. Sens. Charles Schumer and Richard Blumenthal have introduced legislation that would require railroads to install additional safety technology by 2018 to help prevent crashes from speed and human error.

The Democrats from New York and Connecticut say delays are unacceptable for adding the communications and signaling system called Positive Train Control. The system helps slow trains in an emergency.

The senators say it could have prevented crashes.

U.S. Sen. Kirsten Gillibrand, another New York Democrat, is also a sponsor.

Congress in 2008 set an implementation deadline at the end of 2015 for a significant portion of the industry.

Schumer says the legislation would also make sure railroads are "transparent" about their efforts and would require regular status updates.