The Alar del Rey to Santander Railway is 87 miles long. It has twenty-one short tunnels upon it, the total length of which is 4,808 metres.
The length of the Palencia and Astorya Line is 110 miles. It runs from Palencia to Gigon, on the Bay of Biscay. This railway is only in course of construction. There are several tunnels upon it, of which the particulars have not yet been published.
The Saragossa and Barcelona Line is 230 miles in length. In the section between Cervara and Tarrassa, 59 miles long, there are sixteen tunnels. As their aggregate length is only 3,591 metres, it will be observed that they are all very short ones. The other portions of the line are of comparatively easy construction.
The Ciudad Real to Badajoz Railway, 213 miles long, is a line presenting scarcely any difficulties of construction, and it has no tunnel upon it from one end to the other.
The principal difficulty connected with the Tudela and Bilbao Line is that at its terminus at Bilbao, it is barely above the level of the sea; but it has to ascend 2,060 feet in 29½ miles. There are no heavier works in all Spain than those upon this section. For more than half a mile the principal branch of the Ebro has been deviated, and the railway has been constructed upon the old bed of the river.
On the Barcelona to Santa Coloma Railway there are seven tunnels, very short in length; the longest is 443 metres long.
The Tarragona to Barcelona Line is 64 miles long; though passing through a level country for the greater part of its extent, it has one section—that between Villa-franca and Marterello, in which the rise is 540 feet in 15 miles. There are five tunnels upon this length, all short ones; but they were very difficult as regards construction, and they are very troublesome in maintenance.
The Lerida Reus and Tarragona Line is 63 miles. It has only one tunnel upon it, that of Terres, 700 metres long.
The Cordova to Malaga Railway, 121 miles, is extremely easy in point of construction, except for 6¼ miles at the passage of the Guitanas, where there are no less than twelve tunnels and six great bridges. In one of the tunnels a singular circumstance was discovered during construction. The miners suddenly came upon a crevasse or split in the mountain which extended from its lofty and precipitous summit to a great depth beneath the part bored through. The space is traversed by a bridge, the only one in the records of tunnels that we remember to have met with.
There is one very long canal tunnel in Spain—the Canal of Urgel—between the Ebro and one of its affluents, the Segro. This canal is 90 miles long and the tunnel is of the length of 5,230 metres.