The Blanka tunnel complex, a part of the Prague City Ring Road, is with a length of about 5.5 km the longest road tunnel in the Czech Republic and the longest city tunnel in Europe. Designed to relieve the historic center of Prague from heavy traffic, it connects the area west of Prague Castle with the Trója district in the northeast. The construction of Blanka started in 2007. Initially due to open in 2011, the tunnel complex was officially opened to the public in September 2015. Model calculations have shown that starting Blanka operation will significantly increase traffic on a connected main road, the V Holešovičkách street, which passes through a compact populated area in the length of 1.6 km.
To study changes in the dust fallout near the highly exposed V Holešovičkách street, expected to appear with road traffic intensification after opening the Blanka tunnel complex, two sets of dust samples collected in the street vicinity were used: a set collected long before Blanka opening between December 2012 and September 2013, and a set collected immediately before Blanka opening and during its pilot operation between February 2015 and April 2016. The study included characterization of elemental composition of the collected dust samples by means of instrumental neutron activation analysis, and SEM/EDX for further compositional characterization and identification of particles of the particulate air pollution. The relationship of compositional variation in the studied dust samples to the traffic intensification, regarding probable seasonality effects, will be discussed.
The study has been supported by the Czech Science Foundation within the project P108/12/G108, and by the Ministry of Education, Youth and Sports of the Czech Republic within the projects LM2015056 (CANAM - Center of Accelerators and Nuclear Analytical Methods) and LM2015074 (Nuclear Research Reactors LVR-15 and LR-0).