102 RAILWAY CONSTRUCTION. 



the great height and simplicity of the piers. The rail-level over 

 the top of the pier is 301 feet above the level of the water in the 

 Kinsua stream. The width of this pier on the top is 10 feet (for 

 single line), and the width at the bottom 103 feet. 



Fig. 100 is a sketch of the Loa Viaduct on the Antofagasta 

 Railway, Bolivia, stated to be the highest railway viaduct in the 

 world. The arrangement of spans and piers is very similar to 

 the Kinsua Viaduct. The main spans are 80 feet, and the pier 

 spans 32 feet. The width of the pier on the top is 10 feet 

 C inches (for single line), and the width at the bottom of the 

 highest pier is 106 feet 8 inches. 



In contrasting these light iron piers with what would have 

 been required if constructed of masonry, an idea may be formed 

 of the enormous amount of material, labour, and time, which 

 would have been expended* to erect the work in stone. 



Before the principle of lofty iron piers had been thoroughly 

 developed, many high piers had been built of timber both at 

 home and abroad. More particularly was this the case in the 

 United States of America, where the presence of magnificent 

 timber close to hand offered special inducements for the use of 

 wood. Like a mammoth scaffolding, each pier was constructed 

 with a most liberal supply of material, judiciously selected and 

 carefully put together, but the danger of destruction by fire was 

 ever present from the beginning. Probably more timber piers 

 and bridges have been destroyed by fire than have been removed 

 on account of natural decay. 



One of the most notable of these timber-pier constructions 

 was that of the Old Portage Viaduct, on the Erie Eailway, 

 U.S.A. Fig. 101 is a sketch of one or two of the piers. This 

 viaduct was more than 800 feet long, and 234 feet high from the 

 bed of the river to the rail-level. The spans were 50 feet each. 

 Masonry piers were carried up to about 25 feet above the ordi- 

 nary water-level of the river, and upon these the timber super- 

 structure was erected. Each timber pier consisted of three 

 complete sets of framework, securely connected together, and 

 also well stayed and braced to the adjoining piers. This viaduct 

 was destroyed by fire in 1875, and was reconstructed with piers 

 and girders of iron. 



Railway bridges over or under public roads of primary or 

 secondary importance must be constructed to the widths and 

 heights prescribed for such works in the fixed regulations of the 



