The longest railway tunnel in north Africa, the Gantas tunnel in Algeria, saw a successful breakthrough on Monday after six and a half years of construction, setting the foundation for the completion of the country's first fast railway artery. Hazardous geological conditions in the mountainous area posed challenged to the construction process and the project was once suspended for over a year. It was only resumed after the China Civil Engineering Construction Corporation conducted free test drills and persuaded the proprietor to adopt Chinese standard construction plans.