Why Is That Bridge Too Narrow for a Cart? It Was Never Meant for One

The bridges are typically one to two metres wide between the parapets, arched, built of local stone, and carry no road wide enough for a wheeled vehicle. The parapets are low or absent entirely, which looks like neglect and is deliberate, since a loaded pannier projecting from each side of a horse needs clearance and a high wall would catch it. The approaches are frequently steep and paved with large stones, and the whole structure sits on a route that is now a footpath or a track.

The choice was forced by the state of the roads:

• •Upland tracks were too steep and rough for wheels
• •Surfaces turned to deep mud for much of the year
• •A horse carries a load a cart cannot reach at all
• •Horses travel in trains of a dozen or more with one driver
• •Bridges for them are far cheaper than bridges for vehicles
• •So the whole transport system was built around the load a horse carries

The trade these routes carried was substantial rather than local. Wool and finished cloth moved out of the Pennines and the West Country to ports and markets. Lead, copper and tin moved from upland mines. Salt travelled inland from coastal workings along routes whose names still record it. Lime for improving fields, coal for domestic fires and malt for brewing all moved this way. The trains were organised commercially, with operators covering fixed routes on a schedule, and a large train could run to forty animals under a handful of drivers.

The bridges are fragments of long distance routes that can still be traced across country. Hollow ways worn deep into hillsides mark where generations of hooves passed. Guide stoops, meaning inscribed stone posts at junctions, were erected by law in some counties from the early eighteenth century and survive with the names of destinations carved on their faces. Causeways of large flat stones, laid end to end across boggy ground, carried the same traffic and are known as causey paths. Wayside inns at the standard day's distance apart mark the stages, and many survive as pubs.

The survival rate is high and the reason is that these bridges were bypassed rather than replaced. When turnpike roads and then modern highways were built for wheeled traffic, they took new alignments with gentler gradients, leaving the old routes and their bridges on ground nobody needed. Being stone, arched and small, the bridges required almost no maintenance to stand. Many are now protected structures and carry footpaths. Their narrowness, which made them obsolete, is exactly what preserved them, since widening was never worth the cost.

A stone arch a metre or two wide with low or absent parapets was built for trains of loaded horses, and the parapets are low so that panniers clear them. Upland tracks were too steep and muddy for wheels, so an entire transport system was built around what a horse carries. New roads took different alignments, which is why so many of the bridges survive.