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The standard highway assignment problem is solved by using a volume delay function (VDF). The primary link impedance is travel time, which increases with an increasing degree of saturation. VDFs contain link-specific input parameters, such as capacity and free-flow speed, as well as coefficients depending on VDF type. The coefficients either are taken from guidelines or are estimated from site-specific data. Because free-flow speed can be measured directly, mean values usually are used for particular links or link types. Capacity is not easy to determine because of its stochastic nature and large variations. VDFs for traffic assignment are presented that assume stochastically distributed capacity. These VDFs are suitable for two- and three-lane freeways in urban and non-urban areas. The stochastic capacity depends on the probability of traffic breakdowns and is determined with the use of the product-limit method and the Weibull distribution. The Bureau of Public Roads (BPR) function was chosen as a typical representative of a VDF for highway assignment models. Two models were applied. First, one coefficient was fixed, and then both BPR coefficients were estimated by regression analyses with the least squares method. The regression analyses provide suitable results at all measurement points for the model with one fixed coefficient; results differ when both BPR coefficients are estimated. The calibration of widely applied VDFs in travel demand models benefits from stochastic capacity analysis as applied in the field of traffic engineering. These results are unique to measurement points in Austria, but the method can be transferred to other countries where long-term data from freeway detectors are available.

The emissions of a blast furnace and the separation efficiency of the top-gas scrubber were investigated for the gaseous components HCl, H 2 S, SO 2 , COS, CS 2 , CH 3 SH, HCN and NH 3. The clean gas emission of sulphur was dominated by COS which accounted for about 85% of the total sulphur emissions. From the hydrogen halides only HCl was present above the detection limit and the concentrations of NH 3 and HCN were also low. The average separation efficiency for HCl, SO 2 and NH 3 was 96%, 81% and 46%, respectively. COS was not separated in the scrubber system. The concentrations of the weak acids HCN and H 2 S were higher in the off-gas after the scrubber compared to the concentration before the scrubber. This phenomenon was explained by the release from the scrubber water into the gas of un-dissociated H 2 S and HCN originating from cyanides and sulphides contained in the separated dust. Separation efficiencies similar to those of the scrubber system are expected to be achieved also by dry sorption gas cleaning processes. However, this has to be verified in experiments. In the case of applying a dry gas cleaning system, the concentrations of H 2 S and HCN in the clean gas would be even less.

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-In this paper, the feasibility of air classification of dusts from iron and steel production for improved recycling is investigated. By air classification a dust can be separated into a coarse fraction and a fine fraction. According to literature data some components which are usually unwanted in recycled material like alkali chlorides and the heavy metals Zn and Pb are enriched in the fine dust fraction. Therefore, air classification of dust before recycling would allow recycling of an increased amount of dust and reduce landfill. However, the benefits have to be measured against the cost of air classification. In order to be able to study the feasibility of such treatment the investment costs and the operating costs of a classification facility were calculated for three different dust treatment capacities. The results show that the three main factors affecting the feasibility of such a treatment are the capacity of the unit, the cost of landfill of the respective dust and the fraction of dust which can be recycled after the treatment. A cost curve per ton of processed dust is presented and shown for annual capacities of 2.370, 7.000 and 23.000 t. For the higher capacities it is shown that good feasibility is probable even if rather low landfill costs are assumed.