TransCanada's Keystone XL oil pipeline will be manufactured from high-strength, epoxy-coated steel able to withstand high pressure. The 36-in.-dia pipeline will be up to 0.748-in. thick in places and will be monitored constantly for leaks by a computerized system. A physical inspection of the 1,387 miles of line in the U.S. will be required every two weeks. Coatings on the pipes must be inspected before they are joined by double submerged-arc welding, and welds must be inspected afterward.

In addition to meeting U.S. Dept. of Transportation Pipeline and Hazardous Materials Safety Administration regulations as well as other pipeline standards, TransCanada will undertake 57 additional safety measures.

The firm is “doing additional things that would go beyond any pipeline being built today,” says Peter Lidiak, pipeline director for the American Petroleum Institute.

That's simply not enough, says Mohammad Najafi, director of the University of Texas, Arlington's Center for Underground Infrastructure Research and Education.

“Pipelines are one of the safest modes of transportation. I am an advocate of pipelines and support installations of gas, water and sewer pipelines,” Najafi says. “But on the other hand, you need to consider the high-pressure oil [1,308 psig] going through this line. If something were to happen, it would be a disaster. … Considering the length of this pipe and the sensitivity of the area the line is going through, it should be avoided. Accidents happen, and you can not avoid it,” he says. “Pipelines are not 100% safe.”

It's easy for crews to miss a section when coating field welds, and just a minor coating problem can cause corrosion, he says.

Najafi says the line will be prone to breaks because of digging and other activity. The environmental impact statement says Keystone XL will be buried about 4 ft below the surface.