Prime Minister Taro Aso's economic stimulus measures are about to unleash the nation's worst highway traffic jams, toll operators and police say.

Aso's ¥5 trillion spending program announced in October included discounted expressway charges on holidays. As workers prepare for Wednesday's start of Golden Week, police expect more than 70 million people to travel within the country, creating traffic jams of 60 km or more.

"If there weren't the discount, I wouldn't be traveling to Aomori," said Takeyuki Nagasawa, 32, who aims to drive 600 km to the prefecture. "I was thinking of going somewhere else, but when I worked out the budget, I found a one-way ticket by train or plane would equal the full cost of the Aomori trip."