Major Traffic Roads Research Articles

Variability of particulate matter concentrations along roads and motorways determined by a moving measurement unit

The spatial variability of aerosol number and mass along roads was determined in different regions (urban, rural and coastal-marine) of the Netherlands. A condensation particle counter (CPC) and an optical aerosol spectrometer (LASX) were installedin a van along with a global positioning system (GPS). Concentrations were measuredwith high-time resolutions while driving allowing investigations not possible with stationary equipment. In particular, this approach proves to be useful to identify those locations where numbers and mass attain high levels (‘hot spots’). In general, concentrations of number andmass of particulate matter increase along with the degree of urbanisation, with number concentration being the more sensitive indicator. The lowest particle numbers and PM1-concentrations are encountered in a coastal andrural area: o5000 cm 3 and6 m gm 3 , respectively. The presence of sea-salt material along the NorthSea coast enhances PM>1-concentrations comparedto inlandlevels. High-particle numbers are encounteredon motorways correlating with traffic intensity; the largest average number concentration is measuredon the ring motorway aroundAmsterd am: about 160 000 cm 3 (traffic intensity 100 000 veh day 1 ). Peak values occur in tunnels where numbers exceed10 6 cm 3 . EnhancedPM 1 levels (i.e. larger than 9m gm 3 ) exist on motorways, major traffic roads and in tunnels. The concentrations of PM>1 appear rather uniformly distributed (below 6m gm 3 for most observations). On the urban scale, (large) spatial variations in concentration can be explainedby varying intensities of traffic andd riving patterns. The highest particle numbers are measuredwhile being in traffic congestions or when behind a heavy diesel-driven vehicle (up to 600 10 3 cm 3 ). Relatively high numbers are observedduring the passages of crossings and, at a decreasing rate, on main roads with much traffic, quiet streets and residential areas with limited traffic. The number concentration exhibits a larger variability than mass: the mass concentration on city roads with much traffic is 12% higher than in a residential area at the edge of the same city while the number of particles changes by a factor of two (due to the presence of the ultrafine particles (aerodynamic diameter o100 nm). It is further indicated that people residing at some 100 m downwind a major traffic source are exposed to (still) 40% more particles than those living in the urban backgroundareas. r 2004 Elsevier Ltd. All rights reserved.

Analysis of broadband seismic noise at the German Regional Seismic Network and search for improved alternative station sites

The German Regional Seismic Network (GRSN) comprizes now 16 digital broadband stations equipped with Wieland-Streckeisen STS-2 seismometers, 24-bit dataloggers and a seismological data center at Erlangen. It covers the whole territory of Germany with station-spacings between 80 km to 240 km. The stations are sited in very different environments ranging from near shore at the Baltic Sea coast up to distances of about 700 km from the coast, both within cities and up to about 10 km away from any major settlement, industry or traffic roads. The underground varies from outcropping hard rocks in Hercynian mountain areas, sedimentary rocks in areas of Mesozoic platform cover to up to 1.5 km unconsolidated Quarternary and Tertiary subsoil. Accordingly, seismic background noise varies in a wide range between the upper and lower bounds of the new global noise model. The noise conditions at the GRSN have been investigated systematically by means of displacement power spectral analysis within the frequency range 10-2 5 for RUE and > 10 for BSEG have been confirmed for frequencies between about 0.6 Hz 3 Hz. Strong lateral velocity and impedance contrasts between the outcropping Triassic/Permian sedimentary rocks and the surrounding unconsolidated Quarternary/Tertiary sediments are shown to be the main cause for the strong noise reduction and signal-to-noise ratio improvement at RUE and can account for about 50% of the noise reduction at BSEG.

Carbon monoxide distribution around Cairo‐Alexandria highway

Simultaneous measurements of carbon monoxide were conducted on both sides of the major traffic road in Egypt. These values were used to test and validate the highway line source model against a real air quality set of data. A non‐zero value was assumed to account for the initial vertical dispersion that occurs due to the turbulence wake behind moving vehicles. The model initially was found to overestimate carbon monoxide concentrations detected around the highway. However, the consideration of each lane as an individual source resulted in reasonable agreement between measured and predicted concentrations with a correlation coefficient of more than 0.8.