Building the infrastructure and then operating a railroad which starts on the Pacific coast of South America and which, a few score kilometres inland, must climb close to 4,000 metres above sea level in the Andes mountains has always presented challenges both for the civil engineers responsible for its construction and for the managers in charge of its operation.As at mid-2001, two of the four transandean railroads that ran 20 years ago are out of service, owing to adverse weather conditions, and a third is not operating as a result of institutional problems.Nevertheless, two of the three railroads that are now shut down could resume service soon. Furthermore, there is a possibility that a new transandean railroad could be built that would cross the Andes mountains further south, at an altitude of less than 1,750 meters.