FORTH RAIL BRIDGE FACTS & FIGURES

General Dimensions

Imperial 

Metric

Overall length

8296 ft

2528.7 m

South approach

10 spans of 168 ft.

10 spans of  51.2 m

North approach 

5 spans of 168 ft. 

5 spans of  51.2 m

Length portal to portal

5350 ft

1630.7 m.

Length tower to tower

1912 ft.

582.8 m.

Cantilever length

680 ft

207.3 m.

Simply supported spans

350 ft.

106.7 m.

Main spans

[ 2 x 680ft. +350ft.]   = 1710 ft.

[ 2 x 207.3 m. +106.7 m.]  = 521.3 m.

Height of towers

330 ft.

100.6 m

Rail level above high water mark

158 ft.

48.2 m.

Clear navigation headway

150 ft  

45.7 m.

Weight of 1710 ft. span

11571 tons

11754 tonnes

Total number of rivets

 6,500,000 nos.   weighing 4200 tons

6,500,000 nos. weighing 4267 tonnes

Total cost

£3.2m [foundations £0.8m; abandoned suspension bridge £0.25m.]

Each double-cantilever tower is founded on 4 piers consisting of 90 ft. [27.4 m.] tall steel caissons filled with concrete up to the topmost 36 ft. [11 m.] which consists of a core of Arbroath stone faced granite.

Quantities of Steel in Main Spans

Queensferry

Inchgarvie

Fife

Total (Tons)

Central towers (3)

4815.8

7036

4815.8

16667.6

Cantilevers (6)

1 fixed 1 free

2 free

1 fixed 1 free

Bay 1

4235.2

4312.6

4235.2

12783.0

Bay 2

2626.1

2658.6

2626.1

7910.8

Bay 3

1764.3

1724.8

1764.3

5253.4

Bay 4

1034.15

1009.8

1034.15

3078.1

Bay 5

665.9

620.2

665.9

1952.0

Bay 6

490.1

423.6

490.2

1403.8

Central girders (2)

410.75

821.5

410.75

1643.0

Posts and castings

51.45

51.45

51.45

154.35

Ladders

36.0

40.0

36.0

112.0

Totals (Tons)

16129.75

18698.55

16129.75

50958.05

Summary of Progress in Erecting the Superstructure

The engineers for the design and execution of the bridge were Sir John Fowler and (Sir) Benjamin Baker assisted by Mr. Allen Stewart, Mr. P.W.Meik - Resident Engineer 1883-6 and Mr. F.E.Cooper – Resident Engineer 1886-90, and others.

Messrs T.E.Harrison and W.H.Barlow approved the design.

The contractors were Sir Thomas Tancred, (Sir) William Arrol, Mr. T.H. Falkiner and Mr. Joseph Phillips. (Sir) William Arrol personally supervised the work, assisted by Mr. Thomas Scott, Manager, Mr. W. Westhofen, who was specially engaged on the works at Inchgarvie; Mr. A.S.Biggart, who was in charge of the drawing offices, shops and yards; and numerous others.

Operational Use

On 21 January 1890 two trains of about 1000 ft. in length entered on to the bridge side by side from the south end. Each train had two locomotives of 72 tons each pulling 50 wagons. The gross weight of each train was 900 tons making a total load of 1800 tons in all. The varying structural displacements under this load were well within the calculated amounts. [See Westhofen W. The Forth Bridge, 1890].

During 1894 the bridge carried 26,451 passengers, 18,777 goods trains and 2678 light engines. The total weight carried was 7,492,833 tons. By 1899 the average weight of a passenger train had risen from 188 to 200 tons and that of goods train from 388 to 400 tons. In 1907 29,675 passenger trains crossed the bridge with a gross weight of 14,674,750 tons.

This usage contrasts with the present day when during 2000 the bridge carried 54,080 passenger and 6240 freight trains with a gross weight of 10,500,000 tons.