Global warming and air pollution are hot issues and important topics on everyone’s agenda. The challenges we are facing can only be addressed with a bundle of complementary actions. Austria is taking a lead here in the traffic management domain.
As in numerous other locations, acceptable thresholds for NO2 according to immission protection law were  exceeded in Tyrol during 2006 at various places. This required immediate action, including the consideration of speed limits. An algorithm has been developed that to avoid an inconvenient permanent speed limit, which allows to switch on speed limits dynamically based on air quality sensor measurements.
Heusch/Boesefeldt has implemented this algorithm for ASFiNAG and implemented it as an additional control algorithm into the Tyrolean sub control centre of the VMIS traffic management and information system.
The system had been commission in Tyrol just in time for the 2007/2008 winter season on 1 November 2007.
First evaluation results of the system have been published (in German) by the Tyrolean local government at
www.tirol.gv.at/themen/verkehr/verkehrsplanung/dynamischestempo100/.
To visualise the high potential for reduction, we quote a few key findings from this report:
“Nitrogen oxide exhaust in car traffic was reduced by -23% (these are approx. 82 tons), respirable dust in exhaust emissions reduced even further by -27% (equivalent to a reduction by -3.4 toms PM10).
Improvements could also be made in immissions, i.e. the measured air quality. Without a speed limit of 100 km/h during this winter, NO2 emmissions would have been increased by an additional 4,5 µg/m³. This is equivalent to a reduction by -6%. Due to this reduction because of the speed limit during last winter, the annual increases of the last two years could be compensated.”
There’s also a well received side effect in traffic safety: compared to the average reduction rate of accidents in Austria (20%), accidents with damage to persons on the Kufstein to Zirl West section were reduced by 61%.


Another dedicated installation of immission controlled speed limits – recently deployed in Upper Austria – is currently in a trial operations phase. Further deployments are scheduled for 2008. These systems are known in Austria as “VBA Umwelt” (environmental active traffic management systems).