The White House said the new system will provide “an unprecedented level of collaboration in the environmental review process.”

Nick Goldstein, American Road & Transportation Builders Association vice president for regulatory and legal issues, says, "This is probably one of the most ambitious steps in terms of project delivery that I think we've seen." He says that "now EIS's can take anywhere from seven to 13 years."

Don Riley, a senior adviser with water-resources consulting firm Dawson & Associates, says, "It will be significant, in some way. It certainly can help in the long run."

Riley, a former Corps deputy commanding general, says, "But to really implement this MOU...there have to be new processes developed."

As agencies draw up their plans to carry out the memo, a key question is whether they decide formal regulations are needed. If agencies decide not to write regulations, Riley says, "I suspect that any critic of a project that does receive a permit will then litigate."

The new document—13 pages plus individual pages for each signing agency—fleshes out an executive order that Trump signed last August. That directive defines “major” projects as those “for which multiple authorizations by federal agencies will be required to proceed with construction.”

Neither the new memo nor the executive order sets a dollar-value minimum for major projects.

Goldstein says that the memo will apply to projects that have environmental impact statements. They constitute a relatively small subset of all infrastructure projects. "They're going to be new things. They're going to be big things," he says.

The measures in the new memo are "all well and good," Goldstein says. "But we also need to start using this new reformed EIS process, and the way we do that is to stabilize the Highway Trust Fund, have a permanent source of revenue, and then we can embark upon the projects that require these kind of reviews."

The new memo also is similar to project-expediting provisions in the 2015 Fixing America’s Surface Transportation, or FAST, Act.

That statute lays out a process for faster reviews and designates the DOT as the lead agency, but it only applies to surface-transportation projects.

The FAST Act doesn’t set a decision deadline but does say parties seeking to challenge federal review decisions have no more than two years to file their lawsuits.

The memo says the two-year clock will start on the reviews when an agency publishes a notice of intent to develop an environmental impact statement.

There is wiggle room in the decision deadline—the new memo defines the targeted time frame as “an agency average of not more than two years.”

Industry officials and a key Republican lawmaker praised the action but environmentalists criticized it.

"Time is money," said House Transportation and Infrastructure Committee Chairman Bill Shuster (R-Pa.) “Reviewing and approving infrastructure projects in the most efficient way possible is critical to our Nation’s efforts in building a 21^st century infrastructure and keeping project costs from escalating.”

Neil Bradley, U.S. Chamber of Commerce executive vice president and chief policy officer. called the memorandum  “a much–needed step in the process to modernize America’s infrastructure.”

Scott Slesinger, Natural Resources Defense Council legislative director, said in a statement, "President Trump's much-ballyhooed infrastructure plan has been diminished to little more than an ideological attack on environmental safeguards."  Slesinger added, "Local residents should have a say in the projects that will define their communities for decades to come."

Story updated on 4/11 with further comments.