Abteilung Straßenverkehrstechnik
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This study aimed to better understand nitrate transport in the soil system in a part of the state of North Rhine-Westphalia, in Germany, and to aid in the development of groundwater protection plans. An advection-diffusion (AD) cell was used in a miscible displacement experiment setup to characterize nitrate transport in 12 different soil samples from the study area. The three nitrate sorption isotherms were tested to define the exact nitrate interaction with the soil matrix. Soils varied in their properties which in its turn explain the variations in nitrate transport rates. Soil texture and organic matter content showed to have the most important effect on nitrate recovery and retardation. The miscible displacement experiment indicated a decrease in retardation by increasing sand fraction, and an increase in retardation by increasing soil organic matter content. Soil samples with high sand fractions (up to 94 %) exhibited low nitrate sorption capacity of less than 10 %, while soils with high organic matter content showed higher sorption of about 30 %. Based on parameterization for nitrate transport equation, the pore water velocity for both sandy and loamy soils were significantly different (P < 0.001). Pore water velocity in sandy soil (about 4 x 10 high 3 m/s) was about 100 to 1000 larger than in loamy soils (8.7 x 10 high 5 m/s). On the other hand, the reduction in nitrate transport in soils associated with high organic matter was due to fine pore pathways clogged by fine organic colloids. It is expected that the existing micro-phobicity increased the nitrate recovery from 9 to 32 % resulting in maximum diffusion rates of about 3.5 x 10 high 5 m/s2 in sandy soils (sample number CS-04) and about 1.4 x 10 high 7 m/s2 in silt loam soils (sample number FS-02).
Non-point sources of traffic-related pollution become a major concern as they " compared to the point-source inputs " are more difficult to be defined or controlled. It is crucial to evaluate the fraction of traffic-related contamination that is transported to the road surroundings as it could negatively impact soil, surface water and groundwater. This study describes two means through which pollutants leave the road to the surrounding environment. Three German motorways were selected (A4, A555, and A61), where runoff and deposits were analyzed to determine pollutant load moving into the roadside soil or into the drainage system. Each of the three motorways carries approximately 70,000 vehicles a day on 4 to 6 driving lanes; and they cover a broad range of truck participation in the total traffic load ranging from 5.4% to 19.8%. The three motorways represent several topographical and landscape features as forest with noise barrier and parallel as well as perpendicular orientation to the main wind direction. Sampling of runoff and deposition was done on monthly basis. Bulk deposition was collected in Bergerhoff vessels at two heights (1.5 m and 0.3 m above the ground) and in 1 m, 2.5 m, 5 m and 10 m distances from the road edge. The results showed that heavy metals as well as large amounts of mineral compounds are moving from the driving lanes into the roadside environment. This includes sodium from applying deicing salts in winter seasons, which could be found in soil, dust and water samples. Calcium and iron were also detected in almost comparable concentrations. The annual deposition flow (bulk deposition) measured at a height of 1.5 m was higher than the comparative values for urban areas and background measuring points. The spatial distribution of material deposition showed clear differences between the three motorways. The pollutant load in deposition measured near the ground surface was higher than those measured at 1.5 m above the land surface. At all three sites, a clear negative correlation between pollutant load and the distance from the roadside could be found. Nearly 90% of the concentration values of heavy metals in road runoff were below or in the range of the test values for seepage water in the German Soil Protection and Contamination Ordinance. The pH-values around 7 in runoff and adjacent soil provide a good retention capacity in the soil for the heavy metal input.
Cycling and designing for cyclist in Germany: an overview of road safety, research and guidelines
(2016)
Cycling is considered a social, eco-friendly, pollution-free, low noise and healthy activity and mode of transportation. There are currently around 67 million bicycles in Germany. This number is expected to increase in the near future with greater use of electromotive assisted bicycles. Regarding the expected increase, there should be additional attention given to road traffic accidents involving cyclists. In 2014, 396 cyclists were killed in road accidents in Germany, which is 12 % of all road fatalities. Also in 2014, Germany reported over 78,000 injuries to cyclists. The majority of the fatalities (about 58 %) and 83 % of the serious injuries to cyclists occurred in urban areas. This paper will examine three aspects concerning cyclists. First, the paper will show the main current developments, for example the National Cycling Plan 2020, the effects of the road safety programme and provide an analysis of the German national accident statistics. Second, the paper will give an overview of the regulations, guidelines for road traffic and designing of cycling facilities. Lastly, this study will detail the current and completed research in Germany addressing cyclist. For example, the paper will discuss the topic "Accidents between Turning-off Trucks and Cyclists" Accidents between right turning trucks and straight riding cyclists often show massive consequences. Accident severity is much higher than in other accidents. The situation is critical especially due to the fact that, in spite of the six mirrors that are mandatory for ensuring a minimum field of sight for the truck drivers, cyclists in some situations cannot be seen or are not seen by the driver. Either the cyclist is overlooked or is in a blind spot area that results from the turning manoeuvre of the truck. At present driver assistance systems are discussed that can support the driver in the turning situation by giving a warning when cyclists are riding parallel to the truck just before or in the turning manoeuvre. The paper will describe the requirements for turning assist systems for trucks. The outcome of the study is an overview of the accident situation between right turning trucks and straight driving cyclists in Germany as well as a corresponding test procedure for driver assistance systems. Below are several other projects which will be investigated, too: Accident Risk and Acceptance of Traffic-Rules by Cyclists ; Safety Improvement in Terms of Using Bicycle Paths in the Opposite Direction ; Cycling in Mixed-Traffic ; Observation of Pedal Electric Cycles Riders to Identify Safety Concerns. These three aspects will provide the current situation on the topic of cyclist safety in Germany.
The high density of commercial freight transport on motorways makes it difficult for truck drivers to find safe parking places especially for longer rest periods during the night. Even though expansions have been made to satisfy the demand in Germany, overcrowding and dangerous situations still occur as a result of vehicles parking on the entrance and exit roads of rest areas. In 2005 a control procedure called "Convoy Parking" was installed at the rest area Montabaur on the A3 motorway in Germany. Convoy Parking is subject to a patent (EP 1 408 455 B1, 2007). Convoy Parking requires all drivers entering their departure time at a terminal in front of a barrier. Subsequently, on the basis of the input data, the automatically detected vehicle length and the actual situation at the rest area, a free parking row is assigned and trucks can be parked sorted. The German Federal Highway Research Institute (BASt) developed a new control procedure called "Intelligent Controlled Compact Parking" (hereafter referred to as "Compact Parking" for short) to achieve that trucks are parking in a compact way, side by side and without a driving lane between trucks. Convoy Parking and Compact Parking have a very different control procedure and appearance. While Convoy Parking assigns a parking row to the driver, Compact Parking deliberately leaves the choice of the parking row to the drivers themselves. Drivers do not have to disclose their departure time to any system and they are not stopped by any barrier because Compact Parking offers a wide range of departure times on variable message signs. Drivers ought to use the parking row where their intended departure time is offered. With the innovative system Compact Parking the capacity of an existing rest area can be quickly increased without enlarging the area. This also avoids long-term planning approval procedures and is friendly to the environment. Besides, the safety for all users of the rest area can be improved by reducing illegal parking. Compact Parking is supported by the German Federal Ministry of Transport and Digital Infrastructure (BMVI). The first installation of Compact Parking is under construction at the rest area Jura-West on the A3 motorway (Northern Bavaria). The Autobahndirektion Nordbayern (Motorway Directorate for Northern Bavaria) is the central agency to plan, build and run the motorways in Northern Bavaria and got the approval of the BMVI to realize the pilot project. BASt accompanies the pilot project and leads the implementation of the control procedure. The opening is scheduled for summer 2015.
The first version of German Highway Capacity Manual was published in 2001. Now, a new version is published in 2015 (HBS 2015). For the new German Highway Capacity Manual, most major chapters are revised and some of them are totally rewritten. The chapter for merge, diverge, and small weaving segments is rewritten in accordance with forthcoming developments in the past 10 years. In this paper, an overview of the chapter in the new German Highway Capacity Manual is presented. Procedures dealing with performance analyses and level of service (LOS) of those segments are introduced both for freeways and rural highways. Differences between the former version and the new version of the chapter in the German Highway Capacity Manual are indicated and discussed. In most of the existing highway capacity manuals, LOS of merge, diverge, and small weaving segments is traditionally defined by speed, volume, or density in critical areas. In that traditional concept several capacity values of different critical areas (merge, diverge, and weaving) as well as upstream and downstream basic segments within the influence areas are evaluated separately. In the new HBS 2015, a new model which considers the total merge, diverge, and weaving segment as an entire object is incorporated. A combined volume-to-capacity ratio (freeways) or a combined density (rural highways) is used for defining the LOS of the total segment. The parameters of the new procedure are functions of the number of lanes of the major road, the number of lanes in the on-ramp or off-ramp, and the predefined geometric design of those segments. The coefficients are calibrated with field data or defined by experts" experiences within a matrix of coefficients. With those procedures, the traffic quality (LOS) can be obtained directly as a function of the volumes or densities on the major road and on the on-ramp or off-ramp respectively. The new procedure has the following advantages: a) a uniform function for all types of merge, diverge, and small weaving segments, b) traffic quality assessment for all critical areas under investigation in one step, and c) the procedure can easily be calibrated. For applications in practice, a set of graphs is provided.
With the introduction of the German Highway Capacity Manual (HBS) in January 2002 (FGSV, 2002), all methods for the evaluation of the performance of highway facilities were, for the first time in Germany, simultaneously updated and consolidated in a single work following the ideas of the American Highway Capacity Manual (HCM). This paper gives an overview of the new 2015 edition of the German HBS and describes the changes as for example the addition of chapters for freeway, rural roads, and major urban street facilities, comprising segments and intersections.
Accidents between right turning trucks and straight driving cyclists often show massive consequences. Accident severity in terms of seriously or fatally injured cyclists that are involved is much higher than in accidents of other traffic participants in other situations. It seems clear that adding additional mirrors will very likely not improve the situation. At ESV 2015, a methodology to derive test procedures and first test cases as well as requirements for a driver assist system to address blind spot accidents has been presented. However, it was unclear if and how testing of these cases is feasible, to what extent characteristics of different truck concepts (e.g. articulated vehicles, rigid vehicles) influence the test conduction and outcome, and what tolerances should be selected for the different variables. This work is important for the acceptance of a draft regulation in the UN working group on general safety. In the meantime, three test series using a single tractor vehicle, a tractor-semitrailer combination and a rigid vehicle have been conducted. The test tools (e.g. surrogate devices) have been refined. A fully crashable, commercially available bicycle dummy has been tested. If used correct, this dummy does follow a straight line quite precisely and it does not cause any damage to the truck under test in case of accidental impact. The dummy specifications are freely available. During testing, the different vehicle categories resulted in different trajectories being driven. Articulated vehicle combinations did first execute a turn into the opposite direction, and on the other hand, single tractor vehicles did behave comparable to passenger cars. A possible solution to take these behaviors into account is to require the vehicles to drive through a corridor that is narrow for a precise straight-driving phase and extends during the turn. Other investigated parameters are the dummy and vehicle speed tolerances. The results from this research make it possible to draft a regulation for a driver assistance system that helps to avoid blind spot accidents: test cases have been refined, their feasibility has been checked, and corridors for the vehicles and for important parameters (e.g. test speeds) have been set. The test procedure is applicable to all types of heavy goods vehicles. In combination with the accidentology (ESV 2015 paper), the work provides the basis for a regulation for such an assistance system.
Measuring and characterizing airborne particulate matter (PM) is an important research area because PM can lead to impacts on health and to visibility reduction, material damage and groundwater pollution. In regard to road dust, suspension and re-suspension and the contribution of non-exhaust PM to total traffic emissions are expected to increase as a result of predicted climate scenarios. European environmental regulations have been enforced to reduce exhaust particle emissions from road traffic, but little attention has been paid to reducing non-exhaust coarse particle emissions due to traffic. Therefore, a monitoring program for coarse PM has been initiated in early 2013 to assess the predicted increase in the abundance of non-exhaust particles. Particle sampling was performed with the passive-sampler technique Sigma-2. The subsequent single-particle analysis allows for characterization of individual particles, determination of PM size distribution, and calculation of PM mass concentrations. Two motorways n ear Cologne (Koeln), Germany were selected as sampling sites, and the experimental setup in the field was realized with a so-called twin-site method. The present study reports single-particle analysis data for samples collected between May 31, 2013 and May 30, 2014. Coarse PM, generated through multi-source mechanisms, consists of, e.g., tire-wear, soot aggregates, and mineral dust. The highest mass concentration occurs at both motorways in spring, and the observed PM mainly contains traffic-abrasion particles. The field measurements show that the minimum PM concentration was found in the 5 to 12-°C temperature range, whereas the maximum concentration was observed in both the "5 to 5-°C and the 12 to 24-°C ranges, in agreement with previous laboratory measurements. Correlation between super-coarse (d p 10"80 μm, geometric equivalent diameter) PM concentration and precipitation displays a significant increase in concentration with decreasing number of precipitation events (dry weather periods).
Road markings are an essential component of a safe road. In particular, the optical guidance at night and under wet conditions rates high. Special surface textures of road markings can enhance the nighttime visibility during wetness, but they can lead on the other hand to noise emission during passages of vehicles and thus annoy residents. In the present study the tyre/road marking noise is analysed based on two different measurement methods for traffic noise: Several different road markings with increased nighttime visibility during wetness were overrun and the noise was determined by controlled coast-by measurements as well as close-proximity measurements. For both measuring methods the averaged A-weighted sound pressure levels were determined and an analysis of the third octave spectra was performed in order to identify annoying tonal components. The results of both measurement methods were compared with each other. Limitations of the individual measurement methods were overcome by combining the data. Properties of road marking noise depending on the texture of the marking are discussed in relation to those of road surface noise. The results will help specifying road marking texture types that ensure less annoyance and at the same time good visibility at wetness and night-time.
Rural roads (highways) in Germany have to provide both high road safety and an appropriate level of service in accordance with their function in the road network. Single carriageway rural roads often underperform these expectations. An analysis of severe accidents on rural roads found two main contributing factors. First, high or inappropriate speed leads to accidents caused by the loss of control of the vehicle. Second, unsafe passing manoeuvres related to a misjudgement of sight distance, speed of oncoming vehicles or a misjudgement of the driver vehicle's acceleration capability. On the five roads where unsafe passing manoeuvres were a main contributing factor to accident occurrence, single short passing lanes (600 m to 1.2 km) were built to provide safe passing. On the remaining two-lane sections passing was prohibited by road signs and road marking. This paper investigates the effect of this design change on the accident situation and on traffic flow. The research project is based on a before/after comparison of traffic and accident data. Traffic volume, vehicle types and their velocities as well as the time gaps between the vehicles were recorded at different cross-sections. The result shows a significant improvement in road safety. This improvement was especially noted for severe head-on crashes, which were reduced to almost zero. The analysis of traffic flow on these roads pointed out that the chosen lengths of passing lanes were sufficient for safe passing and thereby reduced the need for dangerous driving behaviour. The recommendations of this research were fundamental for the determination of the design parameters of the second highest design class (EKL 2) in the new German Rural Road Design Guideline (RAL) published in spring 2013.