Ernst-Reuter-Platz Study Traffic analysis using GIS software Human Movements in Urban and Rural Landscapes University of Copenhagen Matthias Lieb
Introduction Ernst-Reuter-Platz is a big roundabout in Berlin-Charlottenburg and an important traffic node. Because of its multiple lanes, it is more complex to drive on than traditional roundabouts. It reports more yearly traffic accidents than any other place in Berlin. In my study about Ernst-ReuterPlatz, I hope to identify areas that are more dangerous than others. Therefore, I want to look at user volume, speeding and lane changes among other things. The architecture department of the Berlin Institute of Technology is located directly at Ernst-ReuterPlatz and therefore provides an optimal spot for observations. My evaluation of the traffic situation is completely based on video recordings from the top level of the TUB‘s architecture building. Even though these recordings are perspectival and thus rather inappropriate for further GIS analysis, I hope to give ideas and rudiments how this is possible, nevertheless.
Collecting Data
Framework For reference and later representation, I traced the outlines of the roundabout from the first frame of my recordings into a new shapefile and later added some buildings and other structural elements. In a different file, I traced the individual lanes of the roundabout. Those become especially important for my later analysis. In a third shapefile, I saved the five streets that lead to Ernst-Reuter-Platz as points.
Tracks In the next step, I entered 60 individual tracks based on the video recordings. After the framerate was reduced to about 2 frames per second, I determined the position of each car at each frame. This way, every route has roughly 10-30 key points. Afterwards, the points could be linked to create a line shapefile. As additional information, I added the size of the car (divided in five defferent classes) and the color of the car to the attribute table.
Analysis
User volume There is very simple data that can be taken directly from the input without further GIS analysis. This includes the total car count. At any given point, there are about 1020 cars on the roundabout, the maximum in the recorded tracks was 23 at a time.
x46
x10
x2
x2
turquoise 3,3% red 5,0%
black 40,0%
silver 15,0%
blue 10,0% white 10,0% grey 8,3%
green 1,7%
yellow 3,3% taxi 3,3%
Track length The entered amount of points per route can easily be converted to the track length. Given one frame equals 0,5 seconds, the average driver spends only 17 seconds in the roundabout. The shortest time measures to be only 4,5 seconds, the longest just above a minute. Seven tracks stayed in the roundabout for less than 10 seconds and eight drivers lasted longer than half a minute.
Speed Due to the camera angle, this diagram showing the speed of the vehicles at every individual point is not very insightful. Different areas cannot be compared because their speed (as measured through GIS software) appears different depending on their distance and angle towards the point of view. Cars in the front appear to move faster, resulting in more red dots than in the back. However, it shows wheather cars move at the same speed at certain points or if there is a high variance.
slow only three lanes slow traffic lights
high variance entering and leaving cars create confusion
Lane changes The police of Berlin names sudden lane changes on the roundabout as one of the main reasons for accidents. With the previously entered lanes (as a line shapefile) and the individual positions from the track, the closest of the lanes in each point can be determined. This represents the lane which the car is on at that moment. Shifting the whole dataset by one feature and comparing the resulting lanes with the previous ones shows the points where a driver changed the lane.
many lane changes change from five to three lanes entering the roundabout lane changes near the entrances are least concerning
Lane precision Luckily, the Near-function in ArcGIS not only outputs which lane is the closest, but also calculated the exact distance to that lane. The drawn lanes are set in the middle of the street lane, so the distance to it shows how far off a car is at a certain point. After a correction calculation (mostly) erased the issue of perspectival distortion, the value for all points at the roundabout (not outside) are comparable.
orange Lane changes and confusion, unclear guidance
orange/green indecisive drivers
mostly green wide lanes and good overview
Origin/Destination The OD analysis shows an interesting result. The roundabout at Ernst-ReuterPlatz is an important connection between Bismarckstraße and Straße des 17. Juni. Almost 44% of the total car traffic only serves this connection. On the other hand, the connection to Marchstraße in the North seems rather unimportant; only about 7% of the total traffic comes from there and merely one out of 60 cars destinates there.
0 Marchstraße 1 Otto-Suhr-Allee 2 Bismarckstraße 3 Hardenbergstraße 4 Straße des 17. Juni
Origin/Destination The comparison of Ins and Outs furthermore shows that the East-West connection is slightly more important in the direction of StraĂ&#x;e des 17. Juni. This direction leads towards the city center and therefore supposed to be more frequently travelled in the morning and afternoon than the opposite direction. Even though I do not dispose of the applicable data, I expect the results for measurements in the evening to be the other way around.
Hardenbergstraße In-Count: 13 Out-Count: 12 Straße des 17. Juni In-Count: 14 Out-Count: 26
Bismarckstraße In-Count: 18 Out-Count: 14 Otto-Suhr-Allee In-Count: 11 Out-Count: 7
Marchstraße In-Count: 4 Out-Count: 1
Conclusion
Critical part My analysis showed that this part in the South might be the most dangerous part at Ernst-Reuter-Platz. Also, because this is where five lanes are reduced to only three.
Conclusion At a certain point, the amount of lanes is suddenly reduced from five to three. This results in people abruptly changing lanes to not accidently exit the roundabout. Better signage is needed here. A possible approach at a solution could also be the use of the space at the outer border at this point to create a fourth lane. The same lane-problem might occur in the evenings on the other side of the roundabout. An additional lane here is imaginable. The strong East-West-connection could be facilitated even more. A tunnel or bridge as an alternative to the highly trafficked roundabout may be a realistic option. Since MarchstraĂ&#x;e is very little used at this point, the street width could even be reduced here to create more public space. Ernst-Reuter-Platz continues to be an important traffic node and the rising number of users calls for alterations to keep the place functioning. How decisive those changes ought to be will depend on Ernst-Reuter-Platz‘s social role.