If you wish to enter Laos via the Friendship Bridge at Nong Khai, the visa-on-arrival fee for foreigners is US $35 and entitles you to 30 days in Laos You must have two passport photos available. Thais pay a different fee of their own. Air conditioned buses to Vientiane depart six times daily from Udon Thani. The fare is 80 baht one way.