Pai Bridge

The Pai River bridge is often cited as the most visible evidence of the presence of Japan's Army in Northern Thailand during WWII.
But the bridge was actually built after the war. This website attempts to correct both that misconception and others about the period.


Japan in Northwest Thailand during World War II

N20°16.58 E100°05.22[1] Chiang Saen (Th: เชียงแสน / Jp: チャンセン )
Williams-Hunt (W-H) Aerial Photomosaics
Page 1 of 1

Route 1016
Station 00x[2]


Text Notes


This page discusses a World War II aerial photo taken by the Royal Air Force (RAF) and provided on-line by the Geo-spatial Digital Archive Project (GDAP) in its Williams-Hunt Aerial Photograph Digital Collection.[2a]

"Chiang Saen" is penciled-in on an aerial photo of Mae Chan[3] and a penciled-in circle implies the location of Chiang Saen:

Chiang Saen markup

There is a problem, however --- the photo does not 'scale out'. The distance between Mae Chan which is clearly visible in the photo and the circle measure only about 3.2 km:[4]

Aerial photo of Mae Chan markup

In actuality, the distance between the two towns is about 28 km:[5]

Chiang Saen location

In addition, there is a peculiarity about the two towns in that their shapes as viewed from the air are generally similar. In the photos below, the scale and true north are the same; hence, while similar, there are discernable differences between the two towns:[6]

Comparison of shapes of Mae Chan and Chiang Saen

But primarily, the presence of the Mekong River to the right (east), which forms part of the old defense line for Chiang Saen, clearly differentiates the two; and it is this which strongly implies that the aerial photo is of Mae Chan and the penciled-in information is in error.


GDAP, the source of these photos, has asked that the following information be included regarding the aerial imagery shown above:

  • Williams-Hunt Aerial Photos Collection
  • Original from the School of Oriental and African Studies (SOAS), University of London
  • Digital Data from Center for Southeast Asia Studies (CSEAS), Kyoto University
  • Digital Archive from Chulachomklao Royal Military Academy (CRMA), Thailand



Revision List
2012 Oct 05
First published on Internet




See Key for interpreting page content.

Revision list. See bottom of Text column on this page.

Bibliography supports notes.

1.^ Source: Google Earth fix on apparent center of town.

2.^ Stationing needed.

2a.^ The collection and its origin are described in detail in:

Lertlum, PhD, Col Surat, and Dr Elizabeth Moore, Williams-Hunt Aerial Photograph Collection, (undated); available as here linked.

Moore, Elizabeth, The Williams-Hunt Collection, Sari - International Journal of the Malay World and Civilisation, 27(2)(2009), pp 265-284.

Periasamy, Makeswary, "A View from the Top",  biblioasia, 5(1) (Apr 2009), pp 38-42.

3.^ 02509.jpg


4.^ Extract from 02509.jpg. Annotations are by author using Microsoft Publisher.











5.^ "Terrain" map from  Nations Online Project: Searchable Map and Satellite View of Thailand using Google Earth Data. Annotation (red & blue colored items) placed with Microsoft Publisher by author.














6.^ Both images from Google Earth, with annotations added by author using Microsoft Publisher.