The Firth of Forth was historically crossed by ferry until the opening of the Forth Road Bridge in 1964. Roman boat bridge It is possible that a boat bridge made of around 500 boats across the Forth could have been constructed by Septimius Severus and his son Caracalla during their campaign in Scotland . Divided in the middle by Inchgarvie, a bridge made of boats secured to long mooring ropes was within the capabilities of the Romans at the time, and with several tens of thousands of men campaigning north of the river such an investment may have been worthwhile. Whilst there is no evidence of such a bridge being built at Queensferry, the Romans are known to have built such bridges elsewhere. Regular ferries A regular service is known to have crossed at Queensferry as early as the 12th century, using a series of natural rock landings west of Queensferry Harbour. Small permanent structures existed at both sides of the crossing by 1710, but by 1760 these were considered inadequate for the most trafficked ferry passage in Scotland. A 1772 petition to the Forfeited Estates Commission from an unknown engineer requested for improvements, who in turn consulted civil engineer John Smeaton. Smeaton considered the largely natural landings to be the greatest issue, especially at low water, and recommended an increased number of landings in order to prevent boats having to tack, as well as specific improvements to existing piers. By July 1777, the Royal Burghs of Scotland had given and the Forfeited Estates Commission , the latter on the basis of its importance as a military route. The Board of Trustees for Fisheries, Manufactures and Improvements in Scotland also contributed to the repair of two piers. John Rennie the Elder made improvements worth to a number of piers by 1812, and further works were carried out when expenditure of was authorised in 1814. The harbour at South Queensferry was brought to its present form by an 1817 plan from Hugh Baird, who turned the west pier at a right angle to further enclose the harbour. Robert Stephenson was called by the ferry superintendent in 1817 to advise on how to furnish the passage with lighting. Steamboats In September 1819, a steamboat started operation at the "Broad Ferry" between Newhaven and Dysart, resulting in the Queensferry Passage losing two-thirds of its traffic by the autumn of 1820. The design of