Here’s something most U.S. state and county road commissions never have had an opportunity to test out: Can you build a road on top of an active lava flow?
Officials in Hawaii County, facing the ongoing threat from a slowly moving—but recently stalled—lava flow that’s been targeting the small village of Pahoa on Hawaii’s Big Island, have been trying out different materials that would be used to create a new road surface on top of the molten material that’s been oozing from Hawaii Volcanos National Park since June 27.
Aggregate material would be used on top of an active flow that has a “fairly well-formed crust and solid layer,” however there may be lava underneath. “It’s a very hardened supported shell that can sustain the weights of pedestrian traffic and maybe even work its way up to traffic,” Oliveira explained on Thursday.
“We’re testing for temperature, stability and safety,” Hawaii Department of Transportation Highway Division civil engineer Sterling Chow told KHON-TV, “but we’re concerned with what kind of temperatures to anticipate, because these materials are not made for high temperatures.”
The lava flow has already cut off one local roadway just outside Pahoa and, although the lava flow has been mostly stalled recently, is on a trajectory to sever a major state highway.
Lava moves along Cemetery Road / Apa'a Street outside Pahoa, Hawaii. A steel power pole has been surrounded by cinder pile to protect it from the lava. (Photo via Hawaii Volcano Observatory / USGS)
The county has been preparing emergency bypass routes in anticipation of that state highway being cut off. But one of those bypass routes, via the Chain of Craters Road through the national park—which itself was covered by a previous lava flow—but that route has raised environmental concerns, according to The Associated Press.
Below, check out the video of the lava road testing and a map of the flow's location as of Nov. 7 ...