Most of my posts have been about bridges over rivers, primarily because the oldest bridges predate modern transport. That all changed with the industrial revolution. The canals arrived first and although they often incorporated sections of existing rivers, canals cut new paths across the country. The local road networks were interrupted by the low lying canals and new bridges had to be built over them, and like the packhorse bridges of old, these were often narrow, hump-back bridges that worked for single carts, but not modern vehicles.
The heyday of the canals as a major transport network lasted a century or so before the invention of the locomotive. Railways had similar requirements to canals, they ran straight, as sharp bends are not workable, avoided sleep inclines, and needed to cross the same rivers, and canals, as well as the road system. Many railways were constructed alongside the canals, and in turn, the motorways that came later also joined them in parallel.
These early railway bridges now present many problems. There are about 30000 of them, and many predate the arrival of the horseless carriage – the car. Where they go over the roads, they were not constructed high enough for the tall trucks and lorries of today. High sided vehicles and double decker buses must go on detours. Or they were built too narrow, allowing only one tall vehicle to pass in the middle section, creating one way systems. Those bridges going over railways do not have sufficient load requirements for modern vehicles, and again, detours are necessary.
Railway lines are still being lowered to avoid rebuilding bridges and to accommodate taller freight cars. Then came electrification, and this presented new issues due to the use of overhead cables that have to be incorporated into bridges.
Having said all this, some railway bridges have stood the test of time, including the world’s oldest railway bridge in continuous operation, the Skerne Bridge. The bridge spans the River Skerne near Darlington on the Stockton to Darlington line. George Stephenson, the ‘Father of railways’, was instructed to build a stone and iron bridge, but given the price of iron rose and issues with the reliability of the design, there was a change of plan. A three arch stone bridge over the river was designed by the local surveyor of bridges, Ignatius Bonomi, instead.
On the opening day of the railway on 27 September 1825, Locomotive No 1, built by George and Robert Stephenson, crossed the bridge pulling carriages of coal and passengers. Traffic grew rapidly and within three years repairs to the embankments were needed, saving the railway.
The bridge ranks as one of the hundred irreplaceable places designated by Historic England and featured on a previous version of the five pound note. It has been cleaned and weeded recently, and the Darlington to Bishop Auckland line still runs over it. A truly grand achievement.