Photos

A picture taken three weeks ago at South Queensferry, formerly in the county of West Lothian but now part of the City of Edinburgh. From here you can have fine views of both the Forth Bridge (the rail bridge) and this, the Forth Road Bridge.

From the website of the Forth Bridges Visitor Centre Trust:

The Forth Road Bridge when opened, on 4 September 1964 by Her Majesty Queen Elizabeth II, was the largest suspension bridge in Europe, and, together with the approach viaducts is over 2½ km. (over 1½ miles) long.

The bridge has a spectacular central span of over 1 km. (3300 ft.) between its two main towers. The side spans, which carry the deck to the side towers, are each 408 m. (1340 ft.) long and are flanked by approach viaducts.

At the side towers the supporting cables turn down towards the anchorages which are, essentially massive wedges built by tunneling into the rock. The cables are 610 mm. (2 ft.) in diameter and were spun on site using 11618 parallel high tensile steel wires 5 mm. (0.196 ins.) in diameter.

The main towers extend 156 m. (512 ft.) above mean river level and the sag of the cables between the towers is approximately 91 m. (300 ft.). The clearance for shipping below the deck of the main span is 46 m. (150 ft.) close to the towers and this increases to 50 m. (163 ft.) at mid-span.

The above dimensions of span, sag, tower height and shipping clearance give the bridge its basic sense of fitness for purpose, and result in a structure of slenderness and elegance combined with strength.

The dual 7.3 m. (24 ft.) wide roadways on the bridge are flanked by two cycle paths 2.74 m. (9 ft.) wide and two footpaths 1.83 m. (6 ft.) wide. Since the bridge was opened the permitted weight of commercial vehicle using the roads in this country has been increased from 24 tons to 44 tonnes. In order to accommodate these heavier vehicles and the large increase in the number of vehicles using the bridge; certain parts of the structure have been strengthened in recent years.

Some 39,000 tons of steel and 115,000 cubic metres (150,000 cubic yards) of concrete were used in the construction. The total cost of the bridge including the approach roads consisting of 13 kilometres of dual carriageway, 13 kilometres of minor access roads and 24 minor bridges was £19,500,000 (~£250,000,000 today).

In the recent past collision protection has been provided to the main tower piers at river level (£7.5M), the structure has been painted, all of the hanger ropes supporting the bridge deck have been renewed and the towers have been strengthened (£12.75M). Currently, the carriageway is in the process of being resurfaced (£3.5M).

On 3 April 2001 the Forth Road Bridge was listed as a category 'A' building.

However, some of you might have read or seen on television that the two main supporting cables are suffering from corrosion and gradually weakening. Special microphones have been installed on the the cables to "listen" to and count the "pings" as individual steel strands within the cables snap: by analysing data from recordings, engineers will be able to assess the rate of corrosion and weakening of the cables. Because of such worries about the longterm survival of this bridge, planning is under way for a second road bridge across the Forth estuary.

In the foreground is a Victorian pillar box which I believe you can actually just see if you look at the Map:[view].

Shot in RAW and converted and edited in PSE6.

All comments/critiques/advice welcome!