these mansions. In the Victorian era, with houses creeping further onto the Downs, an Act of Parliament was passed to protect them as a park for the people of Bristol. In 1754 a bridge to span the gorge was proposed, but it was nearly 80 years before work began on Isambard Kingdom Brunel's Clifton Suspension Bridge, and a further 30 years before it was completed. Today the bridge is perhaps the best known landmark in Bristol. Throughout Bristol's history the gorge has been an important transport route, carrying the River Avon, major roads and two railways. It is the gateway to Bristol Harbour, and provided protection against storms or attack. The Bristol Channel and Avon estuary have a very high tidal range of , second only to Bay of Fundy in Eastern Canada; and the gorge is relatively narrow and meandering, making it notoriously difficult to navigate. Several vessels have grounded in the gorge including the SS Demerara soon after her launch in 1851, the schooner Gipsy in 1878, the steam tug Black Eagle in 1861 and the Llandaff City. The phrase "ship shape and Bristol fashion" arises from when the main harbour in Bristol was tidal, the bottom of which was rocky. If ships were not of stout construction then they would simply break up as the tide receded, hence the phrase. A railway, the Bristol Port Railway, was built through the gorge on the east side from Hotwells to Avonmouth between 1863 and 1865. The Portishead Railway was opened on the west side in 1867. The section of the Bristol Port Railway between Hotwells and Sneyd Park junction was closed in 1922, when construction of a major road through the gorge, the Portway, was started. The Portway was opened in 1926. The road is now part of the A4 road, linking Bristol city centre to the M5 motorway, which bypasses the city near Avonmouth. In the late 1990s the wide pavement through nearly all the Avon Gorge was designated to be legally usable by both cyclists and the fewer pedestrians. Two railways still run through the gorge. On the east side the Severn Beach Line to Avonmouth and Severn Beach uses the remaining part of the Bristol Port Railway through part of the gorge, and through a tunnel under the Downs. On the west side the Portishead Railway was closed by the Beeching Axe in the 1960s, but