Coach development could only benefit from the improvement in roads. Before turnpike trusts, coaches had been un-sprung and any journey in them was very uncomfortable as there was no suspension. Basically a wooden carriage, aided by four wooden wheels, was used to move people or produce.
By 1800, coaches were suspended on a C-spring. This was as it sounds - a large C-shaped piece of metal from which hanged a carriage. This was a form of suspension. By the 1830's these springs had been improved with the elliptic spring. These were shaped like a rugby ball and each wheel had one. The coach itself was effectively laying on these springs which went up and down as the ride required. They greatly improved the quality of a journey.
One of the benefits of this was that it made the country 'smaller' in that it took less time to do things - mail, for example, was quicker to send for those who could afford to do so.
John Palmer started the first mail coach service from London to Bristol. His service halved the time it usually took to do the journey. Palmer was a great planner - he had his coaches carry a horn to warn toll gate keepers of their arrival so that the gates were already opened when the coaches arrived. The toll was paid at a later date direct from Palmer's company - the toll keepers simply kept a record of the number of times his coaches had gone through a toll gate. His coaches also had to carry repair kits to allow basic repairs to be made rather than wait for someone to come out. Mail coaches also carried passengers.
The Bath Mail Coach
To assist the growth in coaches, coaching inns grew up along the route where fresh horses were kept and passengers and drivers could refresh themselves. The time taken to do a journey was greatly cut.
In 1750, it could take 6 days to get from London to York. By 1830, it took a day. London to Manchester fell from 5 days to one day in the same time span.
"Coaches 1750 to 1900". HistoryLearningSite.co.uk. 2005. Web.