2. Traffic Accident Site and Close-Range 
Photogrammetry 
2.1 Introduction 
The first technique for measuring traffic 
sites was adopted in Japan at the police 
headquarter in Saitama Prefecture, one of 
47 administrative divisions in 1967,fol- 
lowed by Kanagawa,Osaka,Hiroshima. In 1971 
the national police agency in Japan for- 
mally adopted this method and established 
an organization at each prefecture police 
headquarters. At the same time, they allo- 
cated the necessary funds for the program 
and offered a training course in Tokyo in 
Tokyo,twice a year, for leaders in the 47 
prefecture. The course continued for about 
10 days and included lectures and practi- 
cal applications. 
As of 1987,there were 303 stereo-camera,68 
stereo-plotters and several analytical 
plotters for performing measurements at 
the traffic sites and also special police 
cars in which all necessary instruments 
were set up.The photogrammetric methods 
proved to be superior to the conventional 
one, using direct measurements. The posi- 
tive points using this method are (1) the 
necessary time for stopping traffic vehi- 
cles at accident sites can be reduced 
drastically, (2) The drivers pay special 
attention to their driving because of the 
psychological effect that this very accu- 
rate system generates. 
Nowadays, the use of photogrammetry is 
expanding to more and more areas within 
the police bureau,because the high accura- 
cy of the results. this technique is used 
not only at traffic accident sites but 
also at criminal sites, airplane and train 
accident sites and great fire sites. It 
has also a special use for estimating car 
speed from the results of measuring the 
body strain caused by the auto collisions. 
Due to the increasing number of accidents, 
these sites of fatal accidents were mapped 
photogrammetrically and sent to the court 
with field survey documents and in the 
case of slight injury, photos are submit- 
ted with this conventional documentation. 
Frequently, accident sites were mapped 
beforehand for later use for actual acci- 
dent reporting. 
2.2 Organization and System 
At the first stage, the National Police 
Agency had the initiative to organize 
police activities, system development and 
distribution for. the national budget. 
Since the general training course was 
completed in each prefecture. the tech- 
nique of measuring at the accident sites 
had been executed in each prefectural 
police agency and application programming 
has been also promoted at several prefec- 
ture police headquarters. Therefore, the 
National Police Agency is now the liaison 
and planning office of each prefecture and 
the office to promote new advanced tech- 
nology and abso to carry out training 
seminars. 
The accuracy of the field direct measure- 
ments with tapes relies upon personal 
skill,but the photogrammetric method 
comparatively does not include personal 
errors and constantly maintains accurate 
mapping. As the authors have described 
here,the time of traffic congestion at an 
accident site is minimized. 
2.3 Stereomicroscope Camera and Plotting 
Instrument 
Stereometric cameras used by the police in 
Japan are short-base dual cameras which 
are rigidly fixed at the two ends of a 
bade-tube. The camera are arranged with 
parallel axes which are normal to the 
base-tube. When the clamps holding the 
base-tube can be rotated and tilted, i.e., 
he direction of photo-taking can be chosen 
at will, with the camera axes still re- 
maining normal to the base. Such camera 
setups are found to be convenient and 
almost universal for police applications. 
The camera pointings are equipped with 
viewfinders provided with cameras. the 
vehicle, manned by two officers, is fully 
equipped with photo-taking and photo- 
processing facilities along with flood- 
lighting equipment as may be necessary for 
photo-taking in darkness. 
Presently, there are a total 3038 cameras 
being used in police work of which arounf 
70 cameras are made by Zeiss, Wild and 
Sokkisha and about 230 cameras by Asahi 
Co.Ltd. The distribution of these cameras 
in the various prefectures depends on 
their workload. Some examples of such 
distributions are (as in 1986) Osaka 
Prefecture, 21;Saitama Pre.,32;kanagawa 
Pre. ,18:Tokyo. Metroplitan,8: and “Aichi 
Pre. 13. Most of these cameras have a 
120-cm base and are generally used in jobs 
requiring stereoplotting. For providing 
additional information and in circum- 
stances requiring very close-range data 
acquisition and documentation, camera with 
20-cm and 40-cm based are also used. 
Of the total 68 stereoplotting instruments 
used by the police in Japan, around 42 
were made by Asahi Co. Ltd. with trademark 
of Asahi-Wild,45;Sokkisha,16; Nikon,4; and 
Zeiss ,3. All of these instruments are 
capable of yielding three dimensional data 
of continuous map compilation. Currently, 
because of the need for a more fully 
digital type, Pentax Co. developed 
PAMS (Photogrammetric Analytical Measure- 
ment System) and Koei Densi Co. developed 
PHOCAS (Photogrammetric Coordinate Analiz- 
ing System). The both use only a metric 
camera, but also a 35-mm camera specially 
developed for this schemes. 
  
Photo. 1. Specially designed poliice motorcar for photo-taking 
(Courtesy of Saitama Prefecture Police Headquarters)