Baulk road is the name given to a type of railway track

Permanent way

The permanent way is the elements of railway lines: generally the pairs of rails typically laid on the sleepers embedded in ballast, intended to carry the ordinary trains of a railway...

 or 'rail road' that is formed using rails carried on continuous timber bearings, as opposed to the more familiar 'cross-sleeper' track that uses closely spaced sleepers or ties to give intermittent support to taller rails. Baulk road was popularised by Isambard Kingdom Brunel

Isambard Kingdom Brunel

Isambard Kingdom Brunel, FRS , was a British civil engineer who built bridges and dockyards including the construction of the first major British railway, the Great Western Railway; a series of steamships, including the first propeller-driven transatlantic steamship; and numerous important bridges...

 for his broad gauge

Broad gauge

Broad-gauge railways use a track gauge greater than the standard gauge of .- List :For list see: List of broad gauges, by gauge and country- History :...

 railways in the United Kingdom, but has also been used for other railways and can still be found in modified form in special locations on present day railways.

Development

Brunel sought an improved design for the railway track needed for the Great Western Railway

Great Western Railway

The Great Western Railway was a British railway company that linked London with the south-west and west of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament in 1835 and ran its first trains in 1838...

, authorised by Act of Parliament

Act of Parliament

An Act of Parliament is a statute enacted as primary legislation by a national or sub-national parliament. In the Republic of Ireland the term Act of the Oireachtas is used, and in the United States the term Act of Congress is used.In Commonwealth countries, the term is used both in a narrow...

 in 1835 to link London

London

London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 and Bristol

Bristol

Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...

.

He refused to accept received wisdom without challenge. The gauge that had been adopted by most railways at that time had been fine for small mineral trucks on a horse-drawn tramway, but he wanted something more stable for his high-speed railway. The large diameter wheels used in stage coaches gave better ride quality over rough ground, and Brunel originally intended to have his carriages carried in the same way – on large diameter wheels placed outside their bodies. To achieve this he needed a wider track gauge and he settled on a 7 ft (2,134 mm) broad gauge but it was soon eased slightly to . When the time came to build the passenger carriages they were designed conventionally with smaller wheels under the bodies after all, but with the broad track gauge the bodies could be much wider than on the standard gauge. His original intention to have the wheels outside the width of the bodies was abandoned.

Early locomotive-powered railways had used short cast iron

Cast iron

Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 rails carried on stone blocks; a few were trying timber sleepers to give the rails their necessary support and to maintain the gauge between them. These rails were brittle and broke easily, and they gave a very rough ride due to the difficulty of maintaining a smooth line between the blocks or sleepers. Wrought iron

Wrought iron

thumb|The [[Eiffel tower]] is constructed from [[puddle iron]], a form of wrought ironWrought iron is an iron alloy with a very low carbon...

 rails were being manufactured but they were of poor quality due to the difficulty of cooling them evenly during manufacture. Brunel decided to use a continuously supported wrought iron rail, a bridge rail with a smaller rail section that cooled more evenly. This was an inverted-U section with wide flanges that could be bolted to the timber bearer, which was known as a 'longitudinal' baulk. The rail was usually kept off this by small wooden packing pieces that could be replaced when they were worn out by the passage of the trains and therefore avoid the expense of replacing the heavier longitudinals. The rails were bolted to the longitudinals by long fang bolts or coach screws, and the rail joints were later supported by a base plate formed with a plug in the void of the inverted U shape rails so as to keep the rails in line with each other.

The longitudinal baulks, and therefore the rails, were kept to gauge by 'transoms' – transverse timber spacers – and iron tie-bars. The transom kept the longitudinals from getting too close together; the tie rods stopped them spreading too far apart. In later years the tie rods were replaced by strap bolts. These were bolted to the transoms and passed through a hole drilled through the longitudinal to a nut on the outside.

On the first section of line, from London Paddington station to a temporary station at known as 'Maidenhead Bridge', Brunel had the track tied down to timber piles so that the gravel ballast (which was necessary on all railways for drainage) could be packed very firmly. It was packed so firmly, in fact, that the track was forced upwards between the piles and thus gave an undulating ride, just the thing that Brunel had tried to address by using continuous bearings and firm packing! He cut the piles away from the transoms and this solved the problem. The bridge rail for this line weighed 43 lb/yd but this was soon increased, generally to 62 lb/yd. A large quantity of the now redundant 43 lb bridge rail removed from Brunel's "Bath Road" was sold to the Netherlands in 1832, but a small batch was recently found having been used as reinforcement during the demolition of a stable block in Berkshire. The longitudinal baulks were around 12 in (305 mm). wide and 5 in (127 mm). deep or 10 by, but the sizes varied depending on the timber available and the weight of traffic to be carried. Transoms were around 6 by and initially spaced at 15 feet (4.57 m) intervals but this was reduced over time to around 11 feet (3.35 m).

Broad gauge was superseded by standard gauge

Standard gauge

The standard gauge is a widely-used track gauge . Approximately 60% of the world's existing railway lines are built to this gauge...

 in 1892 but baulk road continued to be used for some time afterwards, although new work was already being constructed with conventional cross-sleepered track. Converting broad gauge baulk road to standard gauge involved cutting the transoms and slewing the longitudinal and its rail to its new position. Between 1852 and 1892 an ever-increasing length of the Great Western Railway was laid as mixed gauge that could be used by trains of either gauge. For baulk road this meant laying an additional longitudinal between the existing two (one rail was common to both gauges), but this significantly increased the cost and complexity of the track.

Alternative systems

Vignoles rail was a light section that today would be classed as flat-bottomed rail. In its original form it was only about 4 inches (102 mm) deep and was used on baulk road interchangeably with bridge rail.

William Henry Barlow

William Henry Barlow

On 28 December 1879, the central section of the North British Railway's bridge across the River Tay near Dundee collapsed in the Tay Bridge disaster as an express train crossed it in a heavy storm. All 75 passengers and crew on the train were killed...

’s Barlow rail

Barlow rail

Barlow rail was a rolled rail section used on early railways. It has wide flaring feet and was designed to be laid direct on the ballast, without requiring sleepers...

 was patented in 1849 as a purely metal road. Deep rails with an inverted, curved V section were designed to be laid directly into the ballast; gauge was maintained by iron tie bars between the rails. The rails weighed 93 lb/yd but this was later increased to 99 lb/yd. They were used on lines such as the West Cornwall Railway

West Cornwall Railway

The West Cornwall Railway was a railway company in Cornwall, England, United Kingdom, formed in 1846 to operate the existing Hayle Railway between Hayle and Redruth and extend the railway to Penzance and Truro....

, Wycombe Railway

Wycombe Railway

The Wycombe Railway was a British railway between and that connected with the Great Western Railway at both ends; there was one branch, to .-History:The Wycombe Railway Company was incorporated by an act of Parliament passed in 1846...

, South Wales Railway

South Wales Railway

The South Wales Railway was a broad gauge railway that linked the Gloucester and Dean Forest Railway with Neyland in Wales.-History:The need for the railway was created by the need to ship coal from the South Wales Valleys to London, and secondly to complete Brunel's vision of linking London with...

 and New South Wales Railways. They soon fell out of favour as it proved difficult to pack the ballast properly. A large number were sold to the engineers building Clevedon Pier

Clevedon Pier

Clevedon Pier is a seaside pier in the town of Clevedon, on the English side of the Severn Estuary. It is situated next to the Royal Pier Hotel....

 who bolted them together to use as girders. Other pieces of Barlow rail can occasionally be found in fencing near ex-GWR lines. Discarded samples found buried in ballast being recovered from the Didcot Newbury and Southampton Railway can be seen at Didcot Railway Centre.

The Bristol and Exeter Railway

Bristol and Exeter Railway

The Bristol & Exeter Railway was a railway company formed to connect Bristol and Exeter.The company's head office was situated outside their Bristol station...

 and the Bridport Railway used Brunel’s bridge rail section but laid it on iron MacDonnell plates. These had three ridges to keep the rail in line and were laid directly into the ballast without any timber supports. It proved difficult to keep in alignment.

Seaton rail was similar to Vignoles rail but with the flanged foot angled down to give an inverted V section that was then used on triangular longitudinal.

Other applications

Baulk road was used by John Coode

John Coode (engineer)

Sir John Coode , English civil engineer, was born at Bodmin, Cornwall, the son of a solicitor. After considerable experience as an engineer in the west of England he came to London, and from 1844 to 1847 had a consulting practice in Westminster.In the latter year he was appointed resident engineer...

 for a number of railways that he built as part of large construction schemes for harbour breakwater

Breakwater (structure)

Breakwaters are structures constructed on coasts as part of coastal defence or to protect an anchorage from the effects of weather and longshore drift.-Purposes of breakwaters:...

s at places such as Portland and Table Bay

Table Bay

Table Bay is a natural bay on the Atlantic Ocean overlooked by Cape Town and is at the northern end of the Cape Peninsula, which stretches south to the Cape of Good Hope. It was named because it is dominated by the flat-topped Table Mountain.Bartolomeu Dias was the first European to explore this...

. The great widths between the rails and between the transoms allowed him to support the tracks on piles and discharge rocks from wagons directly between the rails to form the foundations of the breakwaters.

A variant of baulk road can still be seen today on some older under-line bridges where no ballast is provided. The design varies considerably, but in many cases longitudinal timbers are supported directly on the cross-girders, with transoms and tiebars to retain the gauge, and modern rails and base-plates or chairs laid on top. It can also be found in places where easy drainage is required or where access is required under rail vehicles for maintenance.

See also

• Permanent way (history)
• Rail tracks
  Rail tracks
  The track on a railway or railroad, also known as the permanent way, is the structure consisting of the rails, fasteners, sleepers and ballast , plus the underlying subgrade...
  
  
• Ladder track
  Ladder track
  Ladder Track is a type of railway track in which the track is laid on longitudinal supports with transverse connections holding the two rails at the correct gauge distance. Modern ladder track can be considered a development of baulk road which supported rails on longitudinal wooden sleepers...
  
  - generic term for longitudinally supported rails with gauge constraining transverse ties