PM emissions in railway operation - in-situ measurements in an Austrian railway tunnel

Description

Quiet little information is available concerning PM emissions from electrified rail traffic. However, at special locations like in or close to railways stations, rail tunnel portals or similar locations, PM resulting from rail traffic can be a major contributor to local air pollution. The few existing measurements show remarkably high dust loads due to this source (FVT-LUA 2015, INFRAS 2007).
In order to improve the data basis a research project was set up, with the aim of generating non-exhaust particle emission factors for rail vehicles. For this reason the Austrian railway corporation initiated a pilot-project at Unterwalder tunnel on the Schoberpass-track in upper Styria. Although the focus of this project was testing electronical components under real in-situ conditions, dust concentrations inside the tunnel were measured as a side product. Dynamic measurements of particle concentrations, using a gravimetric (TEOM 1400a) and a hybrid (nephalometer/radiometer) measurement system (Sharp 5030) as well as dust composition analysis of PM samples (particle sampler Partisol-PLUS 2025) were performed.
On basis of these investigations emission-factors for railway operation were calculated and assigned to different train types. Usually wear effects on traction wire, breaks and rails are the main sources of particle emissions. The main particle size in this connection is PM10, which is responsible for 75% of the total particles.
Next to wear effects, the loading of railways is essential for particle emissions. Since the Schoberpass track is heavily used by freight trains, this influence is definitely given. For being able to differentiate various loading systems, a video-monitoring system was installed next to the tunnel portal. Although container transport dominated, there were also open wagons transporting bulk freight (e.g. iron ore, gravel) which caused very high particle concentrations in the tunnel air. It can be noted that the measured concentrations also varied depending on the train-type, train speed and on weather conditions. Train type was monitored via the installed video cameras at portal site, train speed was not directly recorded, but the influence was given due to the recorded tunnel air velocity. Additionally a meteorological station was installed near Unterwalder tunnel for recording precipitation.
In total, emission factors for more than four thousand train movements were calculated. This contains passenger and freight trains, which additionally were split into several sub-categories. It can be concluded, that freight trains causes PM non-exhaust emissions roughly 4 times higher than passenger trains. Finally, chemical analysis of the dust composition was made. It was found that iron particles are responsible for about 50 % of the total particle mass.

Period	1 Apr 2021
Event title	24th International Transport and Air Pollution Conference: TAP 2021
Event type	Conference
Location	Virtuell, Austria
Degree of Recognition	International