A proposed bill in Congress would throw a wrench into transportation safety standards, just in time for many families' summer travel plans.

Sen. John Thune's (R-SD) bill would eliminate the deadline for railroad companies to adopt important accident-prevention technology. The bill would also permit the rental of recalled cars that haven't been fixed yet – including those with faulty airbags responsible for at least eight fatal malfunctions. Car rental companies would need to only include an additional waiver to the pile of papers customers already sign at the rental counter.

Both provisions would make train and rental car travel more risky. Thune, who chairs the Senate Commerce, Science and Transportation Committee, seems more concerned with protecting industry profits than with the health and safety of American travelers.

Thune's bill is an attack on vital rail safeguards.

The National Transportation Safety Board has been advocating for the adoption of Positive Train Control (PTC) and similar accident-prevention technology for more than 45 years. PTC automatically slows or stops a train when a conductor fails to respond to signals. Considering that human error contributes to around 40 percent of all rail accidents, this technology is a huge step forward in train safety.

In 2008, Congress passed a bill requiring all rail companies carrying passengers or hazardous materials to adopt PTC by the end of 2015. But with less than six months until the deadline, most railroad companies will fail to meet it. The industry is begging for more time, despite experiencing a recent surge in profits that could cover the costs of implementation several times over.

Thune introduced a bill this spring that would have extended the deadline to implement PTC to 2020. But the fatal Amtrak derailment outside of Philadelphia in May weakened support for the extension, especially after Amtrak's CEO admitted that PTC could have prevented this catastrophe.

Now, just two months after the tragedy, Thune is trying to delay PTC implementation again.

Under the new bill, companies would have until the end of 2018 to install PTC equipment, but it removes the deadline for implementation. After installation, companies still need to run numerous tests to ensure that everything is working as planned.

With the railroad industry already failing to meet deadlines, granting them unlimited time to implement PTC is mind-numbingly irresponsible.

Oil train safety regulations are experiencing similar attacks.

Last May, federal agencies released rules for trains carrying Bakken crude oil that would help prevent fiery derailments. Among the provisions is a requirement for advanced breaking systems that significantly reduce breaking distances. Yet Republicans in Congress are considering a measure that would drop this requirement in order to spare companies the costs of installation.

This opposition to proven safety measures may be better understood in the context of campaign contributions from railroad companies. Over the past 20 years, railroad companies have contributed over $50 million dollars to congressional candidates, with nearly two-thirds of this going to Republicans. Thune received nearly $300,000 of this money and ranks fourth for total contributions to senators over the past 20 years.

The technology exists to significantly reduce accidents on passenger and freight trains. Railroad companies are already required to adopt them. Let's not let special interests get in the way of safer cars and trains for all Americans.