But it is the Immigrantes that is, in the contemporary context, the engineering marvel. The road has more than four miles of tunnels, some longer than the longest highway tunnel in North America (Eisenhower in the Colorado Rockies). There are more than three miles of bridges. At one point the two roadways cross over (picture). This unusual design duplicates that of the Grapevine between Los Angeles and Bakersfield, where the northbound roadway is to the left of the southbound, with perhaps 1,000 feet in between, for a few miles north of Castaic. The motorway approaching Chamonix from the west (on the way to the Mount Blanc Tunnel) also does such a crossover. The two roadways on the Imigrantes are also separated by a comparatively large distance, with, again, the northbound roadway being to the left of the southbound roadway. Both of these roadways, and others, are concessioned to Ecovias dos Imigrantes. The tolls are expensive by North American standards, but not by European, and, o course, the road is paid for directly by users based entirely on the extent of their use of the particular roadways (as opposed to the user fee system in the United States where all of the fees go into a large fund that is divided, o ften politically, without regard to where the funds were collected or the extent of use).