FORT McMURRAY, Alberta — At a camp for oil workers here, a collection of 16 three-story buildings that once housed 2,000 workers sits empty. A parking lot at a neighboring camp is now dotted with abandoned cars. With oil prices falling precipitously, capital-intensive projects rooted in the heavy crude mined from Alberta’s oil sands are losing money, contributing to the loss of about 35,000 energy industry jobs across the province.

Yet Alberta Highway 63, the major artery connecting Northern Alberta’s oil sands with the rest of the country, still buzzes with traffic. Tractor-trailers hauling loads that resemble rolling petrochemical plants parade past fleets of buses used to shuttle workers. Most vehicles carry “buggy whips” — bright orange pennants attached to tall spring-loaded wands — to help prevent them from being run over by the 1.6-million-pound dump trucks used in the oil sands mines.

Despite a severe economic downturn in a region whose growth once seemed limitless, many energy companies have too much invested in the oil sands to slow down or turn off the taps. In addition to the continued operation of existing plants, construction persists on projects that began before the price fell, largely because billions of dollars have already been spent on them. Oil sands projects are based on 40-year investment time frames, so their owners are being forced to wait out slumps.

“It really is tough right now,” said Greg Stringham, the vice president for markets and oil sands at the Canadian Association of Petroleum Producers, a trade group that generally speaks for the industry in Alberta. “We see kind of a lot of volatility over the next four or five years.”