Two ultramodern drones from Vias institute are to be used by the Federal Traffic Police in the wake of accidents that occur on our motorways. These drones mean that the scene of an accident can be examined more quickly after the incident has taken place. They will enable the motorway to be re-opened more quickly and help dissipate traffic jams. They will also help avoid a number of additional accidents in both directions.
A ‘photogrammetry’ traffic accident team has been operating in the Federal Traffic Police in Antwerp since 1st January 2010. Since then, this team of specialists has been deployed regularly to investigate serious road accidents on the motorway network in the province of Antwerp and occasionally also beyond. The team has been using 2D photogrammetry in their work, as well as 3D more recently.
The main reasons for using photogrammetry are as follows:
- faster completion of police findings in road accidents.
- high-quality observations in which the positions of the vehicles involved and their tracks can be established with pinpoint accuracy down to the last centimetre. Because it can do this, findings can be checked and reproduced at all times.
From 2D to 3D photogrammetry
At the time, the use of 2D photogrammetry was revolutionary, but 2D is only possible at locations where there are no significant height differences in the terrain. That is because 2D photogrammetry is unable to take the third dimension – height – into account. Given that most of the tracks and traces from road accidents are on the driving surface itself (which is flat), this does not usually cause a problem. But when there are height differences involved, a special measuring device (a “total station”) is used with 2D photogrammetry to measure marks and traces from the accident, but then a full photogrammetric work-up is not possible. However, by using 3D photogrammetry, everything can be perfectly measured from every angle. Using 3D photogrammetry gives the police the following advantages
Using 3D photogrammetry gives the police the following advantages:
- From 2D to 3D photogrammetry
- using photogrammetry, finding evidence located away from the road surface is possible.
- taking photogrammetric photos is possible without the need to hoist vehicles out of the way.
- setting up measuring points is no longer necessary (which saves time in the field).
- there’s no need to take measurements on the ground because the work is done using known fixed reference measurements (which saves time in the field).
- further processing of the findings is faster back in the office because some processes are automated.
Why are drones necessary?
In view of the fact that major accident sites on motorways often extend over an area of hundreds of metres and that processing using 3D photogrammetry requires multiple photos, there is a need to work from a bird’s eye perspective.By using drones, the police are able, once they are on-site, to overfly the whole site immediately in a matter of minutes and establish all the facts so that taking any further measurements is not required. It also means that the police don’t have to wait until all of the vehicles have been hoisted out of the way and they are able to establish all of the other traces of the accident away from the road surface in one go. With the drone and 3D photogrammetry, in many cases we are able to halve the time required to observe the entire accident site, compared with 2D.
If the use of a drone is not possible in line with the principles of deployment stated above (e.g. poor weather conditions, low tunnels, technical defects, etc.), the police can always fall back on conventional methods, for example by using the photogrammetry vehicle with the camera on a retractable boom.
But the accident investigators only have one chance to establish what actually happened in an accident. Once all of the debris has been cleared and the vehicles involved have been towed away, all of the essential information has gone. There is also the need to open up the motorway again as quickly as possible – not least to avoid any further accidents, both at the tail of the jam already caused, but also by rubberneckers passing by the scene on the other carriageway. And the economic damage and harm to the environment caused during long waiting times also calls for the incident to be dealt with as swiftly as possible. Using a drone is a very useful solution and the police know that 3D photogrammetry has become virtually standard in combination with a drone
Drones also of value of in-depth investigations.
However, in order to gain a good understanding of how accidents actually come about – and especially how they can be avoided – in-depth investigations will also be essential in the future. With this in mind, drones are able to provide relevant and accurate information about the accident scene. Over the years, Vias institute has gained a great deal of expertise in in-depth investigations. For example, investigators from Vias institute have been involved on the ground in France and they are also monitoring practices and developments in Germany, which is a pioneer in this area and where in-depth investigations have been carried out for many years already. Vias institute is part of the international IGLAD consortium, which gathers knowledge and data internationally on in-depth investigations. At the current time in Belgium there is not yet any legislation on accidentology. Vias institute hopes that things will speed up in that area so that in-depth investigations can soon be carried out in practice.