Realistic Vehicular Traces

Here we describe a new source of realistic mobility traces for simulation of inter-vehicle networks These traces are obtained from a multi-agent microscopic traffic simulator (MMTS) that was developed by K. Nagel (at ETH Zurich, now at the Technical University in Berlin, Germany). This simulator is capable to simulating public and private traffic over real regional road maps of Switzerland with a high level of realism. The traces generated by MMTS provide an interesting starting point to study the performance of routing protocols in VANETs.

1. Detailed description of the vehicular traces
2. Download vehicular traces
3. MobiHoc 2006 paper
4. Acknowledgments

Detailed description of the vehicular traces

Since real vehicular traces are not available, a traffic simulator can be used to generate the movement of vehicles. However, driver behavior on a road is very complex. Driving is interactive, drivers must react to changing road conditions. Road conditions (e.g., congestion) depend in turn on the drivers' plans and behaviors. Thus, the choice of the traffic simulator in the end influences the relevance and viability of the obtained results.

Vehicular traffic simulators can in general be classified into microscopic and macroscopic simulators. A macroscopic simulator considers such system parameters as traffic density (number of vehicles per km per lane) or traffic flow (number of vehicles per hour crossing some point, usually intersection) to compute road capacity and the distribution of the traffic in the road net. From the macroscopic perspective, vehicular traffic is viewed as a fluid compressible medium, and, therefore, is modeled as a special derivation of the Navier-Stokes equations. In contrast, microscopic simulators determine the movement of each vehicle that participates in the road traffic. Thus, a microscopic traffic simulator is potentially a better choice for our research.

The multi-agent traffic simulator developed at ETH Zurich is capable of simulating public and private traffic over real regional road maps of Switzerland with a high level of realism. MMTS models the behavior of people living in the area, reproducing their movement (using vehicles) within a period of 24 hours. The decision of each individual depends on the area it lives in. The individuals in the simulation are distributed over the cities and villages according to statistical data gathered by a census. Within the 24 hours of simulation, all individuals choose a time to travel and the mean of transportation according to their needs and environment. E.g., one individual might take a car and go to work in the early morning, another one wakes up later and goes shopping using public transportation, etc. Travel plans are made based on road congestion; congestion in turn depends on the travel plans. To resolve this situation a standard relaxation method is used.

The street network that is used in MMTS was originally developed for the Swiss regional planning authority (Bundesamt fur Raumentwicklung). The major attributes of each road segment are type, length, speed, and capacity. The street network is simulated on a Beowulf Pentium cluster of up to 30 CPUs. With the help of MMTS, the consequences of construction sites, road modifications, new roads, etc. can be simulated and potential economical influence (e.g., travel time and price changes for public and private transport) can be estimated.

For the evaluation of inter-vehicle routing schemes, we use a 24 hour detailed car traffic trace file generated by MMTS. The file contains detailed simulation of the area in the canton of Zurich, this region includes the part where the main country highways connect to the city of Zurich, the largest city in Switzerland. Around 260'000 vehicles are involved in the simulation with more than 25'000'000 recorded vehicles direction/speed changes in an area of around 250 km x 260 km.

Download vehicular traces

ATTENTION: Files are very big, check that you have enough disk space!
On Windows computers sometimes you may experience problems downloading large files, e.g., IE, Mozilla/Firefox browsers start downloading, but then do not do any progress (it's kind of a known issue, e.g., discussed here). Rebooting may help, otherwise try Linux, Mac, Sun, another Windows machine...
Download VANET-traces-ns2.mov.gz (668M, ns-2 movement file format)
Download VANET-traces-ns2.mov.nam.gz (1001M, nam file format)
Download example-different-areas-and-densities.tar.gz (158M, ns-2 movement file format; examples of different highway and city regions)
Note:

The coordinates used in the ns-2 movement files are internal Swiss coordinates.
Free online maps of Switzerland (some examples):

1. http://map.search.ch/index.en.html
   Good map, English version, no coordinates.
2. http://www.gis.zh.ch/gb4/bluevari/gb.asp
   German, shows/searches coordinates.
   (Select "i" in the tools panel, then click on a map, you get coordinates. Or use Search "Binoculars" and the coordinates Tab -- "Koordinaten" in German)

If you need to match Swiss coordinates to GPS, the trasformation formulas can be found here.

MobiHoc 2006 paper:
"An Evaluation of Inter-Vehicle Ad Hoc Networks Based on Realistic Vehicular Traces"

In the MobiHoc'06 paper "An Evaluation of Inter-Vehicle Ad Hoc Networks Based on Realistic Vehicular Traces" we study the behavior of routing protocols in VANETs by using mobility information obtained from a microscopic vehicular traffic simulator that is based on the on the real road maps of Switzerland. The performance of AODV and GPSR is significantly influenced by the choice of mobility model, and we observe a significantly reduced packet delivery ratio when employing the realistic traffic simulator to control mobility of nodes. To address the performance limitations of communication protocols in VANETs, we investigate two improvements that increase the packet delivery ratio and reduce the delay until the first packet arrives.

Download MobiHoc 2006 paper.

Acknowledgments

We thank Kai Nagel, Bryan Raney, and Hinnerk Spindler for providing us with the car traffic simulator output and for their support of our work.

(c) Val Naumov <naoumov**at**inf.ethz.ch>
(Please substitute "**at**" with "@")