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Tachograph chart computer-linked microscopic analysis
Forensic Science International, Elsevier Scientific
Publishers
TACHOGRAPH ANALYSIS
211
36 (1988) 211-218 Ireland Ltd.
CHART COMPUTER-LINKED
MICROSCOPIC
PETER NEEDHAM
Lucas Kienzle Instruments, 36, Gravelly Industrial Park, Birmingham B24 HTA (U.K.)
Summary Microscopic evaluation of tachograph charts is used to determine vehicle speeds, interval distances and retardation of a vehicle prior to an accident. The process of analysis has been further developed by a computer-linked system which significantly reduces evaluation time and eliminates potential transcription errors. The software has been designed to offer the analyst detailed calibration and case data information including the facility to generate speed, time and distance graphs.
Key words: Tachograph
chart: Microscopic
evaluation;
Computer-link
Introduction
Accident investigation using microscopic analysis of tachograph charts from vehicles involved in road accidents has become an important source of objective evidence to accident investigators. The tachograph is an accurate recording instrument which is compulsorily fitted to goods vehicles and passenger service vehicles throughout Europe. In addition, tachographs are in use in most countries throughout the world. The instrument (Fig. 1) is a device which indicates and records speed, time and distance and provides va,luable information on the progress of a vehicle’s journey. The chart provides a wealth of information relating to a road traffic accident. The speed and distance recordings are so accurate that under a binocular microscope it is possible to determine the vehicle speed and retardation immediately prior to an, accident (Fig. 2). The chart is the essential part of the tachograph and there are many optical checks taken into consideration. For instance chart quality, printing concentricity and accuracy of recorded traces are important factors (Fig. 3). The recordings on a tachograph chart are made automatically, hence they are of far greater value than the statements of eyewitnesses, the accuracy of which can be affected by so many distractions. The evidential and documentary value of the chart has been clearly confirmed by the effective use of the chart by forensic scientists throughout the U.K. and the rest of Europe in Courts of Law. The operation
of the tachograph
0379-0738/88/$03.50 Q 1988 Elsevier Scientific Publishers Printed and Published in Ireland
is also important and the tachograph
Ireland Ltd.
meets
Fig. 1.
Fig. 2.
213
Fig. 3.
all the requirements for the provision of exact recordings concerning driving activity. Even if the instrument is subjected to unauthorised interference, it is, as a rule, possible to detect this and take it into account in the &ml evaluation. The calibration of the vehicle must also be taken into consideration when evaluating the final result. Microscopic evaluation The chart is microscopically evaluated using a specially built microscope made in Germany by Mannesmann Kienxle. The time dependent recordings are measured to the accuracy of one second, with the aid of a reference line having a thickness of three microns. This reference line would need to be set perpendicular to the path of the recording prior to analysis. Figure 4 shows the procedure used for evaluation. The critical points of the trace are marked t,, t2 and t,, which represent intervals in time, while ul, u, and u3 indicates speed. Computer-linked microscope equipment Recently this laboratory has developed a computer-linked microscope system has been developed to eliminate any potential transcription errors and significantly reduce evaluation time. Now direct reading of polar co-ordinates
214
I
Fig. 4.
Fig. 5.
I
215
representing speed and time are possible. The equipment consists of a suitably modified microscope, microcomputer, interface module, printer and plotter (Fig. 5). The modified microscope incorporates a rotary transducer which is attached to the micrometer for direct measurement of time (accuracy being 0.5 s). The speed is measured using a linear transducer which is attached to the microscope table and driven by a hand wheel at the side of the microscope (Fig. 6) (accuracy being f l/4 Km/h). By placing a crosswire to each respective measuring point the information can be accepted by pressing the appropriate button on the interface module. Each point is displayed on the microcomputer and can be read in any order (Fig. 7). The capabilities of this computer-linked microscope system is illustrated by a recent case. Two articulated vehicles were involved in a fatal multiple accident in fog. One of the vehicles braked sharply due to a vehicle which had stopped ahead. The other vehicle collided with it and a number of vehicles were considerably damaged. Figure 8 illustrates the chart segments from both vehicles. When evaluating both charts from the accident the results were
Fig. 6.
216
Fig. 7.
processed on the computer and displayed in various columns on a printout (Fig. 9). These columns include speed in Km/h or mph, distance in metres and yards, and acceleration and deceleration in ‘g’ or m/s’. The computer system further allows the analyst to select a graph relevant to: speed versus distance, speed versus time and time versus distance. The graph (Fig. 10) displays vehicle movement from evaluation start point to accident point. The results indicate that the articulated vehicle which collided with the vehicle travelling in front braked severely and caused the drive wheels to lock. The analyst if required can select the plotter to combine both vehicles concerned and therefore indicate clearly their trajectory during the journey.
t -i Ii _A=d ,60-J. ---__ -_ -we
J--a__
_‘-,
_I”“:
_
-_
_ _!__I-
-
I,
-
-7
-
--__
‘ , _* .-----_
.!-
--__
-3k --Lz i
_..
I
Fig. 8.
I
-
---___ - --___
A I
Datez 14/05/1885 Caeez MRw47QV Celibratiom LK Calculated Speed ,dt ,,Dietence (metree)---Diet (yde) _ -Reader,Mean Time Speed km/h m/a m/s sets incr sum sumA part. incr sum
Spd Accel mph
g
0
58
6.6
2.38
25
576
40.5
11.26
6.82
13
65
85
7541
93
93
25.2
+ .07
36
774
52.6 14.60 12.93
7
84
169
7456
B2
185
32.7
+ .05
59
912
61.1
11
166
335
7372
181
366
37.9
+ .02
16.96 15.78
Fig. 9.
90
v(km/h)
23aec
lO_lll_ 0 600
-Direction
500
I
400
I
300
I
200
I
100
I 0 m&es
of travel -
Fig. 10.
Conclusions
The microscopic computer-linked system offers accurate and verifiable data from the tachograph for use by Police Forces and forensic scientists where every commercial vehicle in a case of multiple pile-up could be individually logged metre by metre down to the last multiple points of impact, solicitors, barristers and insurance companies where the burden of liability can be much more accurately established. A whole new area of factual evidence has now been released for everyday use. Up to the arrival of the tachograph we have had to rely on the statements made by drivers which would almost certainly be subjective and possibly biased, the eye-witness account of people who have probably heard the accident and did not see it, the mechanical evidence of skid
218
marks, measurement followed by inference and calculation. We now have available to us the important data from an objective and accurate recording instrument which, thanks to the application of modern technology, can be used to release its data quickly. Acknowledgements
The techniques described in this paper have involved the work of many people including the staff from Mannesmann Kienzle (F.R.G.), Lucas Kienzle (Birmingham, U.K.) and the scientists from the Forensic Laboratories throughout the United Kingdom. The author would also like to acknowledge the advice and and assistance given during the development of the computerlinked microscope from the Home Office Forensic Laboratory in Birmingham.
Publishers
TACHOGRAPH ANALYSIS
211
36 (1988) 211-218 Ireland Ltd.
CHART COMPUTER-LINKED
MICROSCOPIC
PETER NEEDHAM
Lucas Kienzle Instruments, 36, Gravelly Industrial Park, Birmingham B24 HTA (U.K.)
Summary Microscopic evaluation of tachograph charts is used to determine vehicle speeds, interval distances and retardation of a vehicle prior to an accident. The process of analysis has been further developed by a computer-linked system which significantly reduces evaluation time and eliminates potential transcription errors. The software has been designed to offer the analyst detailed calibration and case data information including the facility to generate speed, time and distance graphs.
Key words: Tachograph
chart: Microscopic
evaluation;
Computer-link
Introduction
Accident investigation using microscopic analysis of tachograph charts from vehicles involved in road accidents has become an important source of objective evidence to accident investigators. The tachograph is an accurate recording instrument which is compulsorily fitted to goods vehicles and passenger service vehicles throughout Europe. In addition, tachographs are in use in most countries throughout the world. The instrument (Fig. 1) is a device which indicates and records speed, time and distance and provides va,luable information on the progress of a vehicle’s journey. The chart provides a wealth of information relating to a road traffic accident. The speed and distance recordings are so accurate that under a binocular microscope it is possible to determine the vehicle speed and retardation immediately prior to an, accident (Fig. 2). The chart is the essential part of the tachograph and there are many optical checks taken into consideration. For instance chart quality, printing concentricity and accuracy of recorded traces are important factors (Fig. 3). The recordings on a tachograph chart are made automatically, hence they are of far greater value than the statements of eyewitnesses, the accuracy of which can be affected by so many distractions. The evidential and documentary value of the chart has been clearly confirmed by the effective use of the chart by forensic scientists throughout the U.K. and the rest of Europe in Courts of Law. The operation
of the tachograph
0379-0738/88/$03.50 Q 1988 Elsevier Scientific Publishers Printed and Published in Ireland
is also important and the tachograph
Ireland Ltd.
meets
Fig. 1.
Fig. 2.
213
Fig. 3.
all the requirements for the provision of exact recordings concerning driving activity. Even if the instrument is subjected to unauthorised interference, it is, as a rule, possible to detect this and take it into account in the &ml evaluation. The calibration of the vehicle must also be taken into consideration when evaluating the final result. Microscopic evaluation The chart is microscopically evaluated using a specially built microscope made in Germany by Mannesmann Kienxle. The time dependent recordings are measured to the accuracy of one second, with the aid of a reference line having a thickness of three microns. This reference line would need to be set perpendicular to the path of the recording prior to analysis. Figure 4 shows the procedure used for evaluation. The critical points of the trace are marked t,, t2 and t,, which represent intervals in time, while ul, u, and u3 indicates speed. Computer-linked microscope equipment Recently this laboratory has developed a computer-linked microscope system has been developed to eliminate any potential transcription errors and significantly reduce evaluation time. Now direct reading of polar co-ordinates
214
I
Fig. 4.
Fig. 5.
I
215
representing speed and time are possible. The equipment consists of a suitably modified microscope, microcomputer, interface module, printer and plotter (Fig. 5). The modified microscope incorporates a rotary transducer which is attached to the micrometer for direct measurement of time (accuracy being 0.5 s). The speed is measured using a linear transducer which is attached to the microscope table and driven by a hand wheel at the side of the microscope (Fig. 6) (accuracy being f l/4 Km/h). By placing a crosswire to each respective measuring point the information can be accepted by pressing the appropriate button on the interface module. Each point is displayed on the microcomputer and can be read in any order (Fig. 7). The capabilities of this computer-linked microscope system is illustrated by a recent case. Two articulated vehicles were involved in a fatal multiple accident in fog. One of the vehicles braked sharply due to a vehicle which had stopped ahead. The other vehicle collided with it and a number of vehicles were considerably damaged. Figure 8 illustrates the chart segments from both vehicles. When evaluating both charts from the accident the results were
Fig. 6.
216
Fig. 7.
processed on the computer and displayed in various columns on a printout (Fig. 9). These columns include speed in Km/h or mph, distance in metres and yards, and acceleration and deceleration in ‘g’ or m/s’. The computer system further allows the analyst to select a graph relevant to: speed versus distance, speed versus time and time versus distance. The graph (Fig. 10) displays vehicle movement from evaluation start point to accident point. The results indicate that the articulated vehicle which collided with the vehicle travelling in front braked severely and caused the drive wheels to lock. The analyst if required can select the plotter to combine both vehicles concerned and therefore indicate clearly their trajectory during the journey.
t -i Ii _A=d ,60-J. ---__ -_ -we
J--a__
_‘-,
_I”“:
_
-_
_ _!__I-
-
I,
-
-7
-
--__
‘ , _* .-----_
.!-
--__
-3k --Lz i
_..
I
Fig. 8.
I
-
---___ - --___
A I
Datez 14/05/1885 Caeez MRw47QV Celibratiom LK Calculated Speed ,dt ,,Dietence (metree)---Diet (yde) _ -Reader,Mean Time Speed km/h m/a m/s sets incr sum sumA part. incr sum
Spd Accel mph
g
0
58
6.6
2.38
25
576
40.5
11.26
6.82
13
65
85
7541
93
93
25.2
+ .07
36
774
52.6 14.60 12.93
7
84
169
7456
B2
185
32.7
+ .05
59
912
61.1
11
166
335
7372
181
366
37.9
+ .02
16.96 15.78
Fig. 9.
90
v(km/h)
23aec
lO_lll_ 0 600
-Direction
500
I
400
I
300
I
200
I
100
I 0 m&es
of travel -
Fig. 10.
Conclusions
The microscopic computer-linked system offers accurate and verifiable data from the tachograph for use by Police Forces and forensic scientists where every commercial vehicle in a case of multiple pile-up could be individually logged metre by metre down to the last multiple points of impact, solicitors, barristers and insurance companies where the burden of liability can be much more accurately established. A whole new area of factual evidence has now been released for everyday use. Up to the arrival of the tachograph we have had to rely on the statements made by drivers which would almost certainly be subjective and possibly biased, the eye-witness account of people who have probably heard the accident and did not see it, the mechanical evidence of skid
218
marks, measurement followed by inference and calculation. We now have available to us the important data from an objective and accurate recording instrument which, thanks to the application of modern technology, can be used to release its data quickly. Acknowledgements
The techniques described in this paper have involved the work of many people including the staff from Mannesmann Kienzle (F.R.G.), Lucas Kienzle (Birmingham, U.K.) and the scientists from the Forensic Laboratories throughout the United Kingdom. The author would also like to acknowledge the advice and and assistance given during the development of the computerlinked microscope from the Home Office Forensic Laboratory in Birmingham.