The decision to use POW labor to build the TBR was actually made late in the planning stages. The British were the first to explore the concept of connecting Thailand and Burma — and in doing so forming a rail network that linked to Singapore and even Phnom Penh. They had mapped portions of two possible routes. One ran west from central Thailand starting at Pitsanulok, but the mountains along the border were a formidable obstacle.
The somewhat easier route that the Japanese finally adopted ran along the path of the Kwae Noi river from Kanchanaburi to the border crossing at Three Pagoda Pass. In Burma, it traversed a series of mountain ranges and crossed rivers in the valleys between them before flattening out as it approached within 50 Kms of Thanbyuzyat.
All of this area had been aerial mapped but it fell to a small group of intrepid Railway Engineer survey teams to walk and map the entire route.
The original concept was to hire tens of thousands of indigenous laborers, but in FEB-MAR 1942 the IJA suddenly found itself in possession of well over 150,000 Allied POWs mainly in Singapore and the Dutch East Indies. The majority of the US POWs were taken as POWs on the island of Java. They and their fellow Dutch and Australian POWs were then trans-shipped to Burma to work the TBR.
I have yet to see it formally written or even speculated upon, but it does seem that just as the two sectors of the Railway were assigned to the 5th and 9th IJA Railway Regiments, the provision of workers was divided as well. For the most part (if not exclusively) the POWs who worked the Burma Sector originated in Java. It was incumbent upon Singapore to supply the workers to the 9th Regiment. The most prominent exception to this division was the portion of H Force that was commanded by Ltc Dunlop.
From the Mansell website:
Dunlop Force: Under the command of Lt Col Edward Dunlop a noted Australian surgeon, 895 made up of 15 Officers 12 WOs and 868 ORs left Bandoeng, they were joined before boarding the ship by other prisoners, Australian mainly with 159 Dutch, departed from Batavia, in January 1943 first by Hellship Usa Maru to Singapore then by rail to Non Pluduc. They were the first Australians to arrive in Thailand; they were transported by trucks to Konyu and later to Hintock where they remained for the duration of the construction, working on a particular difficult section involving cuttings and embankments. In February Dunlop commanded a force of 1873 prisoners including 623 Dutch. Cholera also took a huge toll of this force with 66 deaths.
In a similar manner, the vast majority of the romusha were ‘recruited’ in Malaya and Singapore arrived by train and worked the Thai Sector. The 5th Railway Regiment ‘recruited’ exclusively native Burmese and other local hilltribesmen. The relatively small (as yet undefined) number of Thais who laid the first 50 Kms of track from NongPlaDuk to Kanchanaburi from Sep-Nov 42 worked under conditions vastly superior conditions that the Asian Laborers who followed them.
Responsibility for the surveying, design and construction of the entire system fell to two Railway Regiments: the 5th working in the Burma Sector and the 9th in Thailand. In reality, however, the joining point was at Konkoita in Thailand. So the Burma Sector was 152 Km in length and extended about 44 Km beyond Three Pagodas Pass (at Km 108) into Thailand. That leaves the Thai Sector at 263 KM at Konkoita.
This might sound a bit crass when one considers the ordeal of the slave laborers, but I think that the unsung heroes of the TBR were the small survey teams that were sent into the raw jungle to literally map and mark each meter of the railway. There were no roads, no bridges, no way around the limestone out-croppings that were to be ‘cut through’.
These small teams of 5 -10 men spent months in the jungles living off the land; trekking out each day to map and record the route that the rails would take. We know almost nothing of them except a mention by Railway Engineer Futamasu who visited one such group early in their effort.
Another little known aspect of the construction is that the IJA Engineers relied heavily on a US ARMY Field Engineering manual (aka Merriman’s Manual) for the design and construction of many of the wooden trestles and bridges.
The logistics of the TBR are mind-boggling. IJA Engineers calculated that its construction involved building a total of 688 bridges for a combined distance of 14 Kms. These consumed 60,000 cubic feet of timber. 7 million cubic meters of rock (cuttings) and earth (filling) were moved. 300 tons of explosives were also consumed. The logged timber was moved by 400 elephants. 700 boats and barges plied the Kwae Noi river ferrying supplies.
These are reportedly the documents in which the Thai gov’t transferred the usage of the land — a right of way of sorts — for the IJA to build the TBR from BanPong to Kanchanaburi:
It is of historical significance that at roughly the same time, a road was being built over 1,726 kilometers (1,072 miles) to link to the Burma Road that had been cut by the Japanese invasion:
Based on a 19th Century British survey, it was constructed largely by Afro-American Engineer troops.
He is a brief account of the concept and construction of the TBR as written in 1953.
Construction of the Burma-Thailand Railway —
Difficult Project Abandoned by GREAT BRITAIN
[as written by Takoshiro Hattori]
In early November of 1942, an important plan was formulated and its execution commenced. In other words, it was the epoch-making construction of the Burma-Thailand Railway. The supply to BURMA was mainly conducted by long sea transportation. In regard to the land supply route, there was only a poor mountain road which was constructed by the Fifteenth Army when it had advanced from THAILAND to BURMA in February 1942. It was highly possible that the sea transportation would be subjected to enemy submarine attack while over the road a maximum of 10 to 15 tons of supplies could be sent daily. To make matters worse, the strength in BURMA increased to more than four divisions in June 1942, and it was natural to estimate a further increase in strength with the increase in possibility of counter-offensive by the Allied Forces. It was anticipated that transportation to BURMA would become very critical.
Such being the situation, the plan to lay the Burma-Thailand Railway was discussed since June 1942, and the preparations commenced between the Southern Army and the Imperial General Headquarters.
Originally, GREAT BRITAIN had planned this railway construction but abandoned the project because of the extreme difficulty. This was a very difficult project.
An outline of the Burma-Thailand Railway construction plan, which was formulated in accordance with the preparation order given by the Imperial General Headquarters in June 1942, was as follows:
1. Course: 400 kilometers extending from NONGPLADUK TH to THANBYUZAYAT in BURMA through the KWAE NOI Valley.
2. Transportation capacity: Approximately 3,000 tons a day (one way).
3. Construction period: To be completed by the end of 1943.
4. Strength to be used in construction: The force with one railway inspectorate, two railway regiments and one railway stores depot as nucleus.
5. Necessary labor: Indigenous laborers and prisoners of war to be used.
In autumn of 1942, the activities of enemy submarines in the Indian Ocean Area and enemy air attacks on ports and harbors in BURMA intensified. Furthermore, there was an indication of counterattack by the Allied Forces upon BURMA, and the increase in our strength in that area became urgent. The situation being such, the construction of the Burma-Thailand Railway became increasingly necessary. Although the Imperial General Headquarters foresaw serious difficulties in this construction it decided upon the construction and issued the order in late November.
Second Inspector General MAJ Gen SHIMODA NOBUE, who was under the assigned command of the Southern Army Commander in Chief, took charge of this construction.
The construction was finally started in earnest in January 1942. At that time the war situation in BURMA became aggravated, and it was absolutely necessary to complete the construction of this railway by the end of the monsoon season of 1943.
The Imperial General Headquarters ordered the Southern Army to reduce the construction period by four months and complete It by the end of August. On 24 February, the activation of the Southern Army Railway Unit was ordered to expedite the construction. This unit was organized with the units which were formerly engaged in the construction and consisted of the 2d Railway Inspectorate, the 5th and the 9th Railway Regiments as the nucleus.
Maj Gen SHIMODA was killed la an air mishap in late January and Maj Gen TAKASAKI succeeded him.
This construction work was smoothly conducted until about April. In the middle of April, however, the monsoon season set in one month earlier than usual. This was a fatal blow to the construction. Supply was disrupted because the roads and bridges were destroyed by floods. As a result, some units were compelled to discontinue the work temporarily and conduct withdrawal.
To make matters worse, as a result of malnutrition many cases of dysentery and malaria broke out among the engineering personnel. Under such a situation, an epidemic of cholera suddenly broke out and more than 4000 personas died. Consequently, the laborers were panic-stricken and there were many eases of desertion.
The Imperial General Headquarters was aware of this fact and in the middle July it ordered the construction period to be extended two months.
The enemy air attack upon BURMA was suddenly intensified. More than 2,000 enemy aircraft raided BURMA during April 1943. In the first half of 1943, it was possible to conduct uninterrupted railway transportation in BURMA only 10 days during a month and the amount of goods transported decreased to one-third that of the preceding year. The strengthening of the defense of the Burma Area was just started, but in view of the extremely poor supply transportation, considerable difficulties were anticipated.
Along with the railway construction, the construction of three roads across the mountains along the Burma-Thailand border was expedited with a view to open them by the end of 1943.
Listed from the north, these roads were from LAMPHUM and KENG TAUNG to TAKAW, CHIANG MAI to TOUNGOO, and RAHAENG to MAE SOT.