BOISE - A megaload of oil refinery equipment finally arrived in Idaho after a tortuous, three-week journey through Oregon, but isn't likely to roll toward its final destination in the Canadian tar sands until later this week.

The 380-foot, 450-ton load left Vale, Ore., Sunday night, traveled across the border and was parked Monday at the junction of U.S. Highway 95 and Idaho Highway 55. It took about 20 days for the load to travel 315 miles through Oregon, where it was plagued by protesters and poor weather before finally arriving at Idaho's far western border.

The Idaho Transportation Department has issued a permit to Omega Morgan, the trucking company that's transporting the equipment, to complete its 500-mile journey across the state before it crosses into Montana and eventually to the Kearl oil sands of Alberta. It will be allowed to travel in Idaho only between 10 p.m. and 6 a.m., and won't move again until at least Friday.

"The shipment will resume travel this Friday... after 10 p.m.," said Adam Rush, an ITD spokesman Monday afternoon, adding the agency had been informed of no delays, efforts to block the Idaho roads or arrests before the equipment came to its resting point on a rural highway pullout.

Previously, however, this megaload has been the target of protests for weeks.

In mid-December, for instance, foes of the refinery equipment - a large heat exchanger for a piece of water purification equipment manufactured in Portland - and its future role in extracting energy from Canadian soil chained themselves together in a disabled car and a trailer for roadblocks in John Day in eastern Oregon.

The obstacles were cleared in about two hours, but not before 16 people from Oregon, Washington, Alaska and California were arrested.

This is just the first in what are expected to be three big shipments soon to be transported by Omega Morgan from the Port of Umatilla. The second of the three megaloads left the Port of Umatilla on Sunday night and parked one mile south of Pendleton in eastern Oregon on Highway 395.

That transport is also loaded with refinery equipment, said Holly Zander, spokeswoman for Omega Morgan, though it's about 100,000 pounds lighter than this first one, with the total weight calculated for the hauling trucks, as well as the refinery equipment.

Indian tribes and conservation groups have been trying to block the movement of the megaloads since 2011, but some have gotten through. Last month, a judge blocked shipments through Northern Idaho on scenic U.S. Highway 12 from Lewiston, Idaho, to Missoula, Mont.

That route was favored because it allowed transporting the loads on barges up the Columbia and Snake rivers to Lewiston.

But with U.S. 12 currently off limits, Omega Morgan is now using this alternative.

Officials at the Idaho Transportation Department are also considering a permit for another route for a separate tar sands delivery.

The Dutch-based hauling company Mammoet wants to move three large pieces of equipment, each of which is 1.6 million pounds, 472-feet-long, 27-feet wide and 16-feet tall, from a Washington state port on the Snake River, north on U.S. Highway 95, and then eastward toward Montana on U.S. Interstate 90.

This is largely the same route that Exxon Mobile used in 2012 to transport about 32 shipments of tar sands equipment.

"If everything goes as is planned at this time, the first shipment should be able to start in January," ITD's Rush said. "The Federal Highway Administration needs to grant its approval before ITD can issue any permits."

- AP writers Matt Volz in Helena, Mont., and Tim Fought in Portland, Ore., contributed to this story.