WASHINGTON -- After four people were killed and more than 40 injured when two commuter trains collided near Darien, Conn., in August 1969, the National Transportation Safety Board recommended an automatic speed control system to prevent future collisions.

The same recommendation was made more than 45 years later -- when an Amtrak passenger train derailed in Philadelphia, killing eight people in May 2015.

A 1988 study of every truck accident in New Jersey and seven other states in which the driver found that more than 3 in 10 crashes were caused by driver fatigue.

The same cause was cited after a tractor-trailer slammed into a limo bus on the New Jersey Turnpike in Cranbury in June 2014, killing comedian James "Jimmy Mack" McNair and seriously injuring comedian Tracy Morgan.

In both cases, the National Transportation Safety Board had to repeat itself after more people died because its recommendations either fell on deaf ears or action was delayed in Washington.

Despite its expertise and reputation, the only power the safety board has is the power of persuasion. If government regulators or industry officials don't listen, there is nothing the safety board can do but make another call for change.

"We know the answer," Board Vice Chair Bella Dinh-Zahr said. "If the industry and the government would listen, we can save lives."

While about 80 percent of the board's recommendations are followed, installing "positive train control" that would automatically slow trains in trouble and reducing driver fatigue have yet to be put in place.

Positive train control has been mentioned 31 times in safety recommendations and driver fatigue eight times, safety board records show.

Former NTSB Managing Director Peter Goelz said the safety board offers the best solutions it can think of without worrying about cost.

"The genius of the NTSB is that they're not a regulatory agency, which allows them to make recommendations that are based solely on the facts," Goelz said. "A lot of what they recommend is awfully difficult to do and involves significant rethinking of how you approach transportation safety."

Such recommendations, however, can run into trouble because of cost and difficulty, some say.

For example, Congress voted in 2008 to require positive train control by Dec. 31, 2015. Lawmakers extended the deadline to Dec. 31, 2018, with possible additional delays, when it became apparent that the industry couldn't meet the deadline, threatening freight lines and commuter rail systems.

The railroad industry had to build such a system from scratch at an estimated cost of $10.6 billion, said Ed Greenberg, a spokesman for the Washington-based Association of American Railroads.

"It isn't about plugging in or turning on components," Greenberg said.

Railroads spent $29 million to lobby in 2015, according to the Center for Responsible Politics, a Washington-based research group.

Almost 40 years after the Connecticut accident, two light rail trolleys collided in Newton, Mass., in May 2008, killing one, injuring eight and and causing an estimated $8.6 million in damage. The safety board called for automatic speed control.

Ditto in 2015.

While the board blamed last year's Amtrak derailment on the fact that the engineer lost track of his surroundings, members said that the accident would have been prevented with positive train control.

"We can't blame it on human error all the time," Dinh-Zarr said. "We have the technology to stop that."

Board Chairman Christopher Hart reiterated the agency's support for the technology.

"This shows any human, even on their best day, can make a mistake," Hart said. "As far as we're concerned, the deadline is not 2018. It's the next preventable crash. We're going to be in this room again looking at another (positive train control)-preventable accident."

Positive train control remains one of the board's most wanted safety improvements, as it has been since the list first was issued in 1990.

Preventing driver fatigue was added this year.

The 2014 crash near Turnpike Exit 8A occurred when a Wal-Mart tractor-trailer crashed into a limo bus carrying Morgan and others, killing McNair.

The truck driver, Kevin Roper, had not slept for more than 28 hours, driving 800 miles overnight from his home in Georgia to a distribution center in Delaware before setting out on his delivery route.

There are federally mandated limits as to how long a driver can be on the road each day, but that doesn't include the time getting to the pick-up location.

Following the crash, the safety board asked the Federal Motor Carrier Safety Administration, which regulates the trucking industry, to require companies to set up fatigue management programs for drivers and supervisors.

The agency said such a program would cost several hundred million dollars a year for two or three years and "be extremely difficult to quantify the safety benefits."

Separately, the FMCSA has proposed new rest rules that have been blocked by Congress with industry support. Trucking companies spent $9 million to lobby in 2015.

The American Trucking Associations, an Arlington, Va.-based industry group, said the rules would force more truckers onto the road during congested times.

Exacerbating the problem: Drivers are "encumbered by the lack of available rest areas," said Rob Abbott, the ATA's vice president for safety policy.

An August 2015 Federal Highway Administration survey named New Jersey, New York and Pennsylvania among the 17 states reporting the "most severe challenges" in providing adequate parking for truckers.

Congress at one point set aside money to expand truck parking areas but the funds instead went for programs designed to help drivers find existing spaces, not to build new ones, said Darrin Roth, the trucking group's vice president for highway policy.

"There just aren't enough spaces available," Roth said. "After 5:00, they all fill up."

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant. Find NJ.com Politics on Facebook.