WASHINGTON (NYTimes)- President Donald Trump is expected to unveil on Monday (Feb 12) a plan that would fulfill one of his signature campaign promises: a US$1.5 trillion (S$2 trillion), once-in-a-generation proposal to rebuild, restore and modernise the nation's ageing infrastructure.

"We will build gleaming new roads, bridges, highways, railways and waterways all across our land," Trump said in his State of the Union address on Jan 30.

But while the proposal represents one of the administration's main legislative ambitions, it could directly clash with one of its defining regulatory principles, which is to question the risk from global warming and roll back regulations addressing climate change.

The Trump infrastructure blueprint is almost certain to call for expensive new roads, bridges, airports and other projects in areas that are increasingly vulnerable to rising waters and other threats from a warming planet.

Engineers and researchers say that construction plans should consider these design constraints at the outset. Their concern is that a plan led by a White House that has both discounted climate science and weakened climate change regulations could mean that costly projects may be vulnerable to damage or, in a worst-case scenario, quickly rendered obsolete by the changing environment.

"The impact of not considering climate change when planning infrastructure means you end up building the wrong thing, in the wrong place, to the wrong standards," said Michael Kuby, a professor of geographical sciences and urban planning at Arizona State University and contributing author to the National Climate Assessment, the federal government's most comprehensive scientific study of the effect of global warming on the United States.

"That's a whole lot of waste."

Climate change already poses one of the most significant threats to the nation's infrastructure, according to dozens of scientific and engineering studies, including several prepared by the federal government.

A 2017 report by the Environmental Protection Agency concluded that, through the end of the century, up to US$280 billion will be needed to adapt the nation's roads and railways to the effects of a warming climate.

A White House spokeswoman, who asked to remain anonymous because the plan was not yet public, declined to discuss whether climate change reports were considered in the preparation of Trump's blueprint.

"The president's team spent almost a full year formulating his infrastructure plan and all relevant scientific data was considered," she said in an e-mailed statement.

Since the beginning of his administration, Trump and his appointees have steadily worked to roll back climate change regulations.

Trump's EPA chief, Scott Pruitt, has taken the lead role in the administration's efforts to undo climate policies and question the validity of climate science.

On Wednesday, Pruitt suggested that global warming could benefit humanity. Those views are contradicted by research conducted by his own agency.

The 2017 EPA report warned that some 6,000 bridges nationwide face a greater risk of damage in coming decades from the effects of a warming climate.

It provides analysis showing that "proactive adaptation" - essentially, planning for global warming before you build - could save the government up to 70 percent in future costs of repairing damage caused by climate change-driven weather events such as deluges, coastal flooding and heat waves.

A spokeswoman for the EPA did not respond to requests to interview the study's lead scientist, Jeremy Martinich.

An academic colleague of Martinich's, who has worked with him on several climate reports, including the EPA study published last year, described in practical terms what the findings mean for federal infrastructure planners.

"Say you're going to build a new road in Denver that's designed to last for 25 years," said the colleague, Paul Chinowsky, a professor of civil engineering at the University of Colorado, Boulder.

"What climate science tells us is that, over the next 25 years, the climate in Denver is going to look more like the climate in Albuquerque" - meaning, he said, that the asphalt will have to be designed to withstand much higher levels of heat than a Denver road might historically have experienced.

"If you don't do that," he said, "It could double the cost of maintenance and the amount of delays on that road."

In New England and the Upper Midwest, Chinowsky said, failing to account for climate change when planning the asphalt mix for roads there could mean that more rapid cycles of winter freezes and thaws could cause more potholes.

"If you think places like Wisconsin, Minnesota and New England have potholes now, just wait," he said.

Chinowsky also pointed to a 2015 study he helped write that focused on the Southeast, in particular an 18-mile stretch of Interstate 85 between Atlanta and Alabama. Over the next 50 years, stronger rainstorms were estimated to cause up to US$118 million in damage to the highway and surrounding feeder roads, the study found.

Other scientific and engineering studies make the case that rising sea levels will erode coastal highways in Florida, stronger rains will send rivers flooding bridges in Iowa and more powerful heat waves will melt asphalt across the Southwest.

For instance, the 2014 National Climate Assessment concluded climate changes will disrupt the reliability and capacity of the nation's transportation systems, including an increase in flooding of airports, harbors and tunnels.

It found that runways in 13 of the nation's largest airports are vulnerable to flooding from higher storm surges driven by climate change.

It also found that, absent planning, municipal drainage systems will overflow.

The impact of climate change on Alaskan infrastructure is expected to be particularly severe.

Already the Alaska Highway, built atop permafrost that was never expected to go away, has started buckling as the permafrost melts.

A 2010 study concluded that the highway is one of the state's 4,576 miles of paved road, 5,000 miles of unpaved road, 253 airports, 853 bridges, 131 harbours, and 819 miles of railroad that could be damaged by a warming climate in coming decades.

The study concluded that the impact of climate change on Alaska's infrastructure could reach up to US$7.6 billion by through 2080. In Iowa, meanwhile, a 2008 rainstorm sent the waters of the Cedar River pouring over the Interstate 80 bridge, closing it for four days and sending drivers on a 120-mile detour.

The impact of climate change in the Hawkeye State will threaten nearly 3,000 bridges in coming years, according to the author of a 2015 report by the Iowa Department of Transportation.

"With climate change and infrastructure, it's pay me now, or pay me later," said Eugene S. Takle, a co-author of that study and director of the climate-science program at Iowa State University.

"Pay a lot more later."