Baulk road facts for kids
Baulk road is a special type of railway track. Instead of using many short wooden blocks (called sleepers or ties) under the rails, baulk road uses long, continuous wooden beams. These beams are called 'baulks'. The rails sit on top of these long wooden baulks.
This design was made popular by a famous engineer named Isambard Kingdom Brunel. He used it for his broad gauge railways in the UK, especially the Great Western Railway. While most railways today use cross-sleeper tracks, you can still find modified baulk road in some special places.
Contents
What is Baulk Road?
Baulk road is different from the railway tracks you usually see. Most tracks have rails resting on many short wooden or concrete blocks called sleepers or ties. These sleepers are placed across the track.
With baulk road, the rails sit on long wooden beams that run continuously along the track. Imagine two long wooden planks, one under each rail, stretching for miles. These planks are the 'baulks'. Smaller wooden pieces called 'transoms' connect the baulks across the track to keep the rails the right distance apart.
How Baulk Road Was Developed
Isambard Kingdom Brunel was a brilliant engineer. He wanted to build a better railway for the Great Western Railway (GWR), which was planned to connect London and Bristol in 1835.
Brunel didn't just follow old ideas. He thought the usual railway track, which was narrower, wasn't good enough for his fast trains. He wanted a wider, more stable track. He chose a very wide track width, called a 7 ft 1⁄4 in (2,140 mm) broad gauge. This allowed his trains to have wider carriages, which could be more stable and comfortable.
Early railways used short, brittle cast iron rails on stone blocks. These often broke and gave a bumpy ride. Brunel decided to use stronger wrought iron rails. He chose a special shape called a 'bridge rail'. This rail looked like an upside-down 'U' and was bolted onto the long wooden baulks.
To make the track even better, small wooden pieces were placed between the rail and the baulk. When these small pieces wore out, they could be replaced easily. This saved money because they didn't have to replace the whole long baulk.
The long baulks were kept at the correct distance apart by 'transoms'. These were wooden beams placed across the track. Iron bars also helped keep the baulks from spreading too far apart.
On the first part of the GWR, Brunel tried to make the track extra firm by tying it down to wooden piles. But this made the track bumpy! They fixed it by cutting the ties to the piles.
The rails used on the GWR were quite heavy, around 62 lb/yd (30.8 kg/m). The wooden baulks were usually about 12 in (305 mm) wide and 5 in (127 mm) deep. The transoms were about 6 by 9 in (152 by 229 mm) and were placed every 11 feet (3.35 m).
Even though Brunel loved baulk road, the GWR also used regular cross-sleeper track, especially on its 4 ft 8 1⁄2 in (1,435 mm) standard gauge lines. The last broad gauge baulk road was changed to standard gauge in 1892. To change a broad gauge baulk road to standard gauge, workers would cut the transoms and move one of the long baulks closer to the other.
Later, some parts of the Great Western Railway had 'mixed gauge' tracks. This meant they had three rails, so both broad gauge and standard gauge trains could use the same track. This made baulk road more complicated and expensive to build than cross-sleeper tracks.
Other Types of Track Systems
Engineers tried different ways to build railway tracks:
- Vignoles rail: This was a lighter, flat-bottomed rail. It could be used on baulk road, similar to the bridge rail.
- Barlow rail: Invented in 1849, this rail was designed to be laid directly into the gravel without any wood. It had a special V-shape. However, it was hard to keep the track stable, so it wasn't used much. Some old Barlow rails were even used as girders to build Clevedon Pier!
- MacDonnell plate track: The Bristol and Exeter Railway used Brunel's bridge rail but placed it on iron plates instead of wood. These plates had ridges to hold the rail in place. But it was difficult to keep these tracks straight.
- Seaton rail: This was similar to Vignoles rail but had an angled foot. It was used on triangular wooden supports.
Where Else Was Baulk Road Used?
Baulk road was also used by engineer John Coode for building large harbour breakwaters. For example, at Portland and Table Bay. The wide space between the rails and transoms allowed him to support the tracks on piles. This meant he could drop rocks directly from wagons between the rails to build the foundations of the breakwaters.
You can still see a type of baulk road today on some old railway bridges. Here, the long wooden timbers are placed directly on the bridge's main beams, without any gravel underneath. Transoms and tie-bars still keep the rails at the right distance. Modern rails are then placed on top. This design is useful where good drainage is needed or where workers need to get under trains for maintenance.
See also
- Permanent way (history)
- Rail tracks
- Ladder track
- Slab track
