Building Hellfire Pass in World War II

Chungkai Cutting

It seems to run without much regard to the landscape as though someone had drawn a line on a map!

[EE Dunlop, The War Diaries of Weary Dunlop, 1989, p 212.]

The Burma-Thailand Railway was built in 1942 and 1943 to supply the Japanese forces in Burma (now Myanmar). It would allow the Japanese to bypass the sea routes that had become vulnerable since mid-1942. Japanese naval strength was reduced after battles in the Coral Sea and at Midway Atoll.

Once the railway was completed, the Japanese planned to attack the British in India. Particularly, the roads and airfields used by the Allies to supply China over the Himalayas.

Begun in October 1942 and completed on 16 October 1943, the railway stretched 415 km between Nong Pladuk in Thailand and Thanbyuzayat in Burma.

A rail connection between Burma and Thailand had been proposed decades before World War II. In the 1880s, the British had surveyed a possible route. But they abandoned the project due to engineering challenges including:

• thick jungle
• endemic disease
• lack of adequate roads.

The Japanese surveyed the project in the 1920s. Then, after completing another survey in early 1942, they decided in June 1942 to go ahead with the build. They would use the large workforce of Allied prisoners of war (POWs) at their disposal.

In June 1942, a small number of POWs worked with Japanese engineers, marking and roughly clearing the route of the railway.

Aiming to finish the railway as quickly as possible, the Japanese decided to use a workforce of POWs and Asian labourers (rōmusha).

The terrain the railway crossed made its construction very difficult. However, its route was not entirely through the dense, inhospitable jungle of popular imagination. At either end, in Burma and Thailand, the railway track ran through gentle landscape before entering the rugged, mountainous jungle on the border between the 2 countries.

When the track reached Wampo, about 112 km from the Thai terminus, it began crossing jagged limestone hills dotted with streams and gullies. During the wet season from May to October, the land became waterlogged and unstable. This posed problems for construction, transport and supply.

As far as possible, the railway track proceeded at a gentle gradient, as steam trains could only climb a slight incline. Where the railway met unavoidable hills, cuttings were dug to allow the line to proceed. Often, the line emerged from a deep cutting onto a series of embankments and bridges.

The project included building 688 bridges and more than 60 stations, as well as refuelling and watering points.

More than 60,000 Allied POWs were used in the Burma-Thailand Railway project, including British Empire troops, Dutch and colonial troops from the Netherlands East Indies (now Indonesia) and a small number of United States (US) troops. About 13,000 were Australian POWs.

The Japanese also enticed or coerced about 200,000 rōmusha to work on the railway. These included Burmese, Chinese, Javanese, Malay and Tamil people.

AWM P00406.026

Despite being repeatedly bombed by the Allies, the Burma-Thailand Railway operated as a fully functioning railway after its completion.

Between November 1943 and March 1944, over 50,000 tonnes of food and ammunition were carried to Burma, as well as 2 complete divisions of troops for the Japanese offensive into India. This attack, one of their last, was defeated by British and Indian forces.

The Japanese used the railway in Burma until the end of the war. They used POWs and rōmusha for maintenance and repair tasks along the line.

Burma-Thailand railway map

For much of its northward route through Thailand to the Burmese border past Songkurai, the map shows the railway following the Kwae Noi river. Other major rivers nearby are the Mae Khlaung in Thailand, which joins the Kwae Noi at Kanchanaburi, and the Ataran further north in Burma. An arrow on the map above indicates the direction north from Thanbyuzayat to the town of Moulmein in Burma. Other arrows indicate the directions to Bangkok (east) and Singapore (south) from Nong Pladuk. The Burmese coastal towns of Ye and Tavoy are shown on the Andaman Sea to the west.

Why the railway was built

The Japanese advance in the Asia-Pacific region in late 1941 and early 1942 was a dramatic period of the war.

Rapid Japanese advance

In just 5 months, Japanese forces occupied territory that stretched from British Burma in the west to the US-administered Wake Island in the east.

The Japanese invasion of Manchuria in the Republic of China in 1931 was the start of an expansionist policy aimed at creating the Greater East Asia Co-Prosperity Sphere. In 1937, Japan attacked China. In the following 2 years, Japan occupied much of northern China and key coastal regions.

When Nazi Germany defeated France in 1940, Japan also occupied the French colonies in Indochina.

The US imposed an oil and economic embargo in response to Japanese aggression in 1941. In turn, the Japanese decided on a southward expansion to gain strategic resources from South-East Asia and the Netherlands East Indies.

The Japanese planned to capture other areas, including the Australian-mandated territories of New Guinea and Papua, as well as various Pacific Islands, to create a protective military barrier against Allied counterattacks.

Despite having feared war with the Japanese in the Pacific for some time, Australia and the United Kingdom were unprepared to meet the growing threat. They were preoccupied with the war against Germany and Italy in Europe and the Middle East.

In 1941, 2 brigades of the 8th Division of the 2nd Australian Imperial Force were based in Malaya (now Malaysia) alongside British and Indian troops. Another 3 battalions of the 8th Division's third brigade were divided between the islands of Ambon, New Britain and Timor.

On 7 December 1941, the Japanese launched a surprise attack on the US naval base at Pearl Harbor in Hawaii. This attack brought the US into the war on the Allies' side. At the same time, Japanese forces landed in Thailand and Malaya and began rapidly advancing down the Malay Peninsula. They also attacked the British colony of Hong Kong and the US-controlled islands of Guam, Midway Island and Wake Island.

The better-led and more experienced Japanese troops rapidly pushed the British, Indian and Australian troops southward towards Singapore. Despite some local tactical successes, such as at Gemas, Bakri and Jemaluang, the Allied forces could not stop the Japanese advance.

Singapore fell to Japanese forces on 15 February 1942. Over 130,000 Allied troops, including over 15,000 Australians, became POWs.

From late 1941 onwards, Japanese forces successfully attacked:

• the Philippines
• New Guinea
• the Netherlands East Indies
• Burma.

In mid-February 1942, some units of the Australian 7th Division landed in Java to stop the Japanese advance. They were captured as POWs after brief fighting. The men were joined by the survivors of the sinking of HMAS Perth and USS Houston in the Sunda Strait on the night of 28 February to 1 March 1942.

By early March 1942, the Japanese had conquered Rangoon in Burma and were threatening the British in India.

US resistance in the Philippines all but ended in April, after which Japanese forces moved to consolidate their conquests by capturing a buffer zone of territory in New Guinea, Papua, Solomon Islands and the wider Pacific region.

Japanese naval losses

During the Battle of the Coral Sea from 5 to 8 May 1942, Australian and US naval forces turned back Japanese transports and warships aiming to capture Port Moresby. This reversal forced the Japanese to try to take Port Moresby by land, over the Owen Stanley Ranges along the Kokoda Track.

From 4 to 7 June 1942, the US Navy won a massive battle near the Pacific island of Midway Atoll. This was a severe blow to Japanese naval power. While not defeated, the Imperial Japanese Navy was now stretched in its ability to control the seas around the territories it had conquered.

The shipping lane through the Malacca Strait off the coast of Malaya was one of these vulnerable routes.

The Japanese decided to construct a railway to connect their front in Burma with Japanese forces and supplies in Thailand and Malaya. This would reduce the need for naval escorts.

To free up military resources for other fronts, the Japanese decided to use POWs and local labourers to build the railway.

Why it's called 'Hellfire Pass'

The place earned the title of Hellfire Pass, for it looked, and was, like a living image of hell itself.

[Jack Chalker, Burma Railway: Images of War, 2007, p 59.]

Hellfire Pass (Konyu Cutting) was the deepest and longest cutting along the entire length of the Burma-Thailand Railway. The site is a formidable combination of solid limestone and quartz rock, described as 'semi-marbleised limestone'. It was not easy to excavate.

The name 'Hellfire Pass' came from the appalling working conditions at and around the site, located about 150 km from the start of the railway at Nong Pladuk.

Over the years, Hellfire Pass came to symbolise the suffering and maltreatment of Australian prisoners of the Japanese across the Asia-Pacific region.

AWM ART25081

Speedo period

In mid-1943, the Japanese introduced a 'Speedo' to meet tight deadlines for completing the railway.

During the Speedo period, POWs were forced to work long hours into the night to speed up construction. Oil lamps and bamboo fires lit their worksite. The flickering light, the noise from the drilling of the rock and the shuffling of hundreds of poorly fed prisoners seemed the very image of hell.

Around 1,500 British and 2,000 Tamil workers started work on the Konyu section of the railway from November 1942. Some 400 Australians from the T Battalion of D Force began work in the region of Konyu Cutting in late April 1943.

By June 1943, work had fallen behind schedule, and the Konyu area had become a bottleneck. It held up work further along the railway.

The Japanese brought in an extra 600 POWs, including British and Australians of H Force. Around 1,000 rōmusha also worked in the vicinity of Konyu Cutting.

Hellfire Pass is a dramatic cutting, some 75 m long and 25 m deep. The approach to this cutting has a longer series of excavations, creating a bench on the hillside that follows the contour line. Whether POWs thought this too was 'Hellfire Pass' is unclear, but working conditions here were harsh.

Carving cuttings by hand and removing rubble were back-breaking, exhausting tasks for hungry, ill workers.

A large workforce was needed to excavate Hellfire Pass and to build the bridges and embankments beyond it. The POWs and rōmusha lived in a network of camps below and above the railway line. Even before starting work, they might walk several kilometres up or down steep and treacherous mountain slopes to the site each day.

As the line-laying parties neared Hellfire Pass, Japanese engineers increased the pace of work, leading to the infamous Speedo period from April to August 1943.

During the Speedo period, a POW was expected to drill 2 m to 3 m each day into solid rock, instead of 1 m per day. The workday extended to 15 hours, or sometimes 18. If the pace of work seemed too slow, the Japanese resorted to physical punishment.

Wet season deaths

The wet season rains worsened conditions. It turned worksites and camps into quagmires and made steep hill faces impossibly slippery.

It is difficult to know precisely how many men, Australians and others, died at Hellfire Pass itself. However, the graves in the Kanchanaburi War Cemetery show a concentration of deaths not just at Konyu and Hintok but across the length of the railway from June to August 1943.

Constructing the railway

The Japanese will carry out [their] schedule and do not mind if the line is dotted with crosses

[Brigadier A Varley, A Force, 24 May 1943, quoted in Lionel Wigmore, The Japanese Thrust, 1957, p 554.]

The 415 km of the Burma-Thailand Railway were completed in a remarkably short period of 12 months. The 2 sections of the line met at Konkoita, in upper Thailand, in October 1943.

The Japanese desire for speed was reflected in every aspect of the railway's construction. Addressing the project's engineering challenges cost the lives of around 102,000 people through:

• rugged terrain, dense jungle and limestone rock
• remoteness of many worksites
• lack of adequate roads
• logistics (transporting materials, supplies and workers)
• inhospitable climate, particularly the wet season
• the lack of modern equipment
• endemic disease.

Japanese construction crew

The Japanese didn't follow a traditional plan of progressing the line's construction from one end. They constructed the line simultaneously at many points along its entire length. Only the track-laying progressed from each end.

The Southern Army Railway Corps commanded the railway's construction, with:

• the 5th Railway Regiment supervising the Burma section of the line
• the 9th Railway Regiment supervising the Thailand section.

Around 12,000 Japanese were employed on the Burma-Thailand Railway, primarily as engineers and guards.

The guards included some 800 Koreans who were conscripted into the Imperial Japanese Army.

Workforce organisation

The workforce was organised into groups of between 2,000 and 12,000 men:

• 2 groups operated in Burma
• 4 groups operated in Thailand
• another 10,000 POWs in Malaya were administered by Japanese forces.

Before leaving Singapore, the POWs were formed into 'forces', named variously after a letter of the alphabet or the name of their commanding officer. Dunlop Force, D Force, F Force and H Force worked in Thailand, while A Force and others worked in Burma.

Most forces were multinational, although they were organised into battalions that usually followed national lines. Once on location, the forces were broken up, and the men were assigned to work parties required by the construction schedule.

There was little consistency in the forces' structure and size. They depended on the scale and difficulty of the task at hand. Conditions also varied greatly between working parties because units within the Imperial Japanese Army often operated with little day-to-day coordination.

Manual labour

No other nation in the world in 1943 would have bashed and bullied, and sweated and slaved prisoners to such fantastic lengths for such an object.

[John Coast, quoted in Lionel Wigmore, The Japanese Thrust, 1957, p 569.]

The limited availability of modern construction equipment drove the need for large numbers of workers. Cuttings like Hellfire Pass were often excavated by hand-drilling holes into the rock for explosives. Teams of men hauled up pile drivers used in bridge construction.

As far as possible, materials were sourced from the surrounding countryside. Little shipping space could be spared for transporting materials to worksites, although some rolling stock was brought from dismantled railways in Burma, Malaya and Java.

The wood for bridges was extracted from the jungle. Cut and hauled to the construction site.

Embankments were constructed from stone and earth. Laboriously gathered and carried by POWs, often up steep, slippery hills.

On the Thai side of the railway, the Kwae Noi river was an important supply line for the railway. The river was navigable to Tha Kanun during the dry season and to Konkoita during the wet. However, the logistics system broke down as the workforce moved to remote sites farther from the supply base. In mid-1943, the wet-season rains made the single road impassable and the river torrential.

Life as a worker on the railway project was incredibly challenging. While working long hours on construction projects, the POWs and rōmusha also had other tasks. They built their camps, including accommodation, sanitary systems and hospitals, and prepared meals.

Carving the cuttings

I was on the hammer and tap, drilling rock, as my comrades were … We started off having to drill 80 centimetres a day; we finished up having to do 3 metres …

[Tom Uren, quoted in Gavan McCormack and Hank Nelson, The Burma–Thailand Railway, 1993, p 53.]

Cuttings such as Hellfire Pass were critical to the success of the Burma-Thailand Railway. They allowed the rail track to climb at a steady gradient.

The task of carving deep, wide cuttings to allow a steam train to pass through mountainous terrain was colossal. Much of the excavation was done without modern equipment.

The railway route needed many cuttings, including:

• small incisions in a hill, to form a 'bench' or level out a stretch of track
• deep chasms in the rock, such as Hellfire Pass.

The excavation of these cuttings was done mainly by hand, although some working parties used jackhammers powered by a compressor.

The first step in excavating a cutting was to clear the area of vegetation. Then, loose soil could be removed relatively quickly using hand tools. Where the ground was semi-marbleised limestone, such as Hellfire Pass, the clearing work was more difficult and time-consuming.

Hammer and tap

A common method of drilling a series of holes into the rock was 'hammer and tap'.

One man would hold a metal drill or 'tap'. Another man hit the tap's head with an 8-to-10-pound hammer (3 to 4 kg). After each blow from the hammer man, the tap man would rotate the drill to prevent it from becoming stuck in the rock. Three progressively longer lengths of tap were used as the POWs drilled deeper into the rock.

The rock powder was then extracted by pouring water into the hole and scooping out the resulting mud with a long spoon.

Dynamite would be placed and detonated after a series of drilled holes had been finished.

Hugh Clarke, an Australian POW, recalled:

The engineers would plug it with dynamite, get six or seven of us out and give us a cigarette. We would light a cigarette each. We would have to light four or five fuses and then go for our lives up into the bush before the charges blew.

['Of elephants and men' in Gavan McCormack and Hank Nelson (ed.), The Burma–Thailand Railway: memory and history, p 40.]

After the dust had settled, the hammer-and-tap pair would move to another section while other gangs of POWs moved the resulting rubble.

After breaking up the rubble with shovels, picks and chunkels (hoes), the POWs would carry it out using sacks or bamboo baskets. Where a cutting was deep, the workers would form human chains to carry earth up ladders and over the side of the cutting.

At some worksites, the workers used skips (bins) on light rail to move the earth.

Jackhammers

At some worksites, jackhammers powered by compressors were used to dig through the rock. But these were bulky, in short supply and often broke. Compressor Cutting, about 4 km beyond Hellfire Pass, was named after these machines.

Workers sometimes used elephants. For example, to carry water for use in extracting dust from the hammer-and-tap holes.

Work on cuttings was exhausting and dangerous.

It was easy for a tired and malnourished hammer man to slip and hit his partner holding the tap, crushing his fingers.

Rock splinters from the drilling and the explosives could easily cause skin and eye injuries.

Sharp rubble was also a hazard to men whose shoes and clothes had long since worn away in the humid climate.

Any injury incurred in constructing a cutting was compounded by the lack of medicine available to doctors and the poor food provided to POWs. Even a small cut from a sharp rock could become infected and turn into a tropical ulcer.

Hintok Cutting

Building the bridges

Standing precariously on the sill, you swing your hammer and the whole trestle shook, especially nerve wracking doing it in the dark with only fire light to see with.

[AE Field and LJ Robertson, 'The gap is bridged', AWM MSS0956]

The Burma-Thailand Railway travelled through a region containing many rivers, streams and gullies. Some 688 bridges were constructed along the line, totalling about 14 km of its overall length.

Only 8 bridges were constructed from steel, one being the famous 'Bridge on the River Kwai' that spans the Kwae Yai at Kanchanaburi. Most bridges were built from local wood.

Bridges could range from small spans crossing a stream or gully to large multi-levelled structures. For instance, the Wampo viaduct hugging the cliffs along the Kwai Noi was 200 m long and 8 to 9 m high in places.

Wooden 'trestle' bridges had several short spans supported by a frame, which was termed the 'trestle'. These were particularly suited to the Burma-Thailand Railway as they were simple to construct.

The terrain, the lack of resources and the speed at which the railway was built meant that bridge construction was often a precarious and dangerous task. One bridge, about 3.5 km along the track from Hellfire Pass, fell 3 times during construction, prompting Australian POWs to call it 'Pack of Cards Bridge'.

This footage was filmed by the Australian War Graves Commission survey party as it travelled up the Burma-Thailand Railway shortly after the war. Here, a truck fitted with rail wheels travels over the Three-Tier Bridge near Hellfire Pass and the Wampo viaduct. At this time, the railway was still relatively intact. The section near Hellfire Pass was removed after the war. The current railway still uses the Wampo viaduct, which has been repaired over the years.

Sourcing timber

Bridge construction used local wood, which was vital given the difficulty in moving materials to worksites.

Teak was preferred for bridge construction because it rotted slower than other, softer woods.

It was not always possible to source teak locally, so parts of bridges were often built with softer, less durable wood.

POWs formed work gangs in the jungle, cutting down wood and hauling it to worksites. Another group of POWs would cut the wood into standard sizes. This was dangerous work, and several prisoners were killed or injured by:

• falling trees
• logs rolling down hills
• infections from splinters.

Bridge building

Once the wood had been readied, the bridge was put together by another group of POWs under the direction of Japanese engineers.

Their first task was to lay the foundations. Where the ground was stable, the footings were constructed out of concrete into which the bridge trestles were inserted. Many of these footings can still be seen along the railway.

In areas with soft soil, the bridge foundations were constructed using pile driving.

Long timber piles were driven into the ground using a heavy weight suspended by a rope from a timber scaffold. A team of POWs below pulled the weight up to the desired height, after which it was dropped onto the pile. The weight would then be lifted again, and the process continued until the pile was driven far enough into the ground. The whole scaffold would then be moved to the next pile on the bridge.

POWs could spend their whole day lifting the weight, often while standing in the river that the bridge would cross.

Once the bridge foundations were laid, the pre-cut timber pieces were assembled at the site. Bamboo scaffolding was created, and the heavy beams were lifted using ropes and pulleys.

As with many tasks on the railway, muscle power was central to the bridge-building process.

Work on bridges was dangerous.

Workers risked falling from tall structures, especially when carrying heavy loads or when the timber was wet and slippery.

Reportedly, POWs tried to sabotage the bridges they were building, placing termite nests on the bridge timbers or substituting poor-quality wood that would make the bridge unstable.

Almost all the wooden bridges on the railway have disappeared, except the Wampo viaduct.

Creating the embankments

Basket by basket, tanka by tanka, we carry the earth which has to be scratched from between the rocks in the jungle, tramping it out to the slowly forming bank.

[Ray Parkin, Into the Smother, 1963, p 77.]

Along the length of the Burma-Thailand Railway, embankments remain stark reminders of the scale of its construction and the efforts of those forced to work on it.

Embankments were the most common type of engineering task along the railway. They could range from minor earthworks levelling out undulating terrain to massive artificial hills rising out of the jungle.

Embankments helped maintain a gentle gradient along the railway for steam trains, which could only climb or descend gentle slopes. They were built where the ground had to be raised to accommodate the railway, but bridges were impractical or unnecessary.

As with all railway work, the first step in constructing an embankment was to clear the jungle along the railway's route.

The width of the land cleared depended on the size of the embankment to be constructed. The larger the embankment, the wider its base would be. One embankment, around 2 km from Hellfire Pass, was 7 m tall and so required a huge base to be cleared.

To speed progress on the railway, Japanese surveyors erected timber guide frames along the route of each embankment. The guards could then direct construction without engineers or surveyors, freeing these men for more complex tasks.

The embankments themselves were constructed from rock and soil. As with bridge construction, the Japanese used local materials for the embankments.

In some places, the excavation of cuttings provided material for nearby embankments.

In other places, rock and soil had to be laboriously carried to the construction site by POWs and rōmusha. In these cases, one group of labourers would be engaged in digging using hand tools, such as shovels, picks and chunkels. These tools were basic, of poor quality, and often broke.

Another group of labourers would carry the material to the embankment site. These men would use baskets or a sack spread between 2 bamboo poles, called a tanka.

The journey from the quarry to the embankment differed from site to site, but could be extremely arduous, especially as the embankment grew in height.

During the wet season, the embankment sides became slippery and unstable, making the climb to the top gruelling for the tired labourers. Once at the top, they had to stamp the earth down and return for another trip.

Initially, the daily quota for each man working on embankments was to move one cubic metre of earth. As pressure to complete the railway increased, so too did the daily quota. Eventually, the quota reached 3 cubic metres each day, which would have been a challenging task even for fit men.

It's a testament to their construction that many embankments along the Burma-Thailand Railway remain relatively intact. Unlike wooden bridges, many of which collapsed or rotted away after the railway fell into disuse after the war, embankments form part of the physical and cultural landscape.

Hellfire Pass was lost to the jungle years after the war, when the railway was demolished. But it was rediscovered in the 1980s. It's now the site of Anzac Day services, the Australian Government's Hellfire Pass Interpretive Centre and a walking trail for visitors.