Federal Highway Research Institute


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Environmental protection, Emissions

Investigation of habituation effects when using fluorescent materials (03.0612)
Around 90 percent of all information in road traffic is conveyed visually. In the research project "Safety effect of fluorescent materials for guidance systems in workplaces" it was proven that especially in critical visual conditions - for example twilight, fog during the day - the use of fluorescent materials (selective yellow) for guidance systems in workplaces leads to better recognisability of the guidance systems. This leads to an earlier reduction of speed and thus to a lower entry speed into the transition area. However, habituation to the conspicuous fluorescent traffic signs could compensate for the proven effect in the long term. This question of habituation effects has not yet been conclusively clarified. The aim of this research project is to investigate the habituation effects when used in various special application areas, for example for the signs “sharp deviation of route” (sign 625), in the area of workplaces or as background signs for sign 136 (children) as well as sign 142 (Wild animals crossing), in order to ensure safe visual communication in the long term.

Development of street lighting concepts using LED technology to improve the visual perception of cyclists (82.0761)
Previous studies on accidents involving cycling have shown that higher accident rates can occur on cycle paths separated from the carriageway compared to mixed traffic on the carriageway in shared road space. Nevertheless, the significant increase in mixed traffic poses a safety risk, especially since it does not show a lower accident severity. Dangerous conflict situations between cycling and motor vehicle traffic also frequently occur at junctions, where more than half of the accidents involving cyclists take place. These safety risks are attributed to various causes, with reduced visibility of cycling traffic from the point of view of motor and pedestrian traffic being of great importance. This could be due to the fact that fixed street lighting does not allow sufficient visibility of cycling traffic at all points on the illuminated road surface. The aim of the present research project is therefore to develop and test both lighting parameters and their selection technique according to DIN EN 13201 as well as design parameters for fixed street lighting systems with increased visibility of cycling traffic.

Glare assessment for the reduction of light immissions caused by road lighting (03.0619)
In the case of glare caused by light sources, a distinction is made between disability and discomfort glare. Whereas disability glare, which describes a reduction in visual performance due to scattered light in the eye, does not tend to occur in normal immission situations, road users or residents are often affected and annoyed by discomfort glare. In this research project, different evaluation models are analysed with regard to their applicability for describing the discomfort glare of road users and residents. Based on this, a new, unified glare formula and the associated glare and immission limiting values will be developed with the help of laboratory and field tests.

Development of a digital tool for nationwide wildlife accident screening (WILUS) (03.0610)
In order to improve road safety at wildlife accident spots, new approaches need to be developed, because despite an overall decrease in the number of accidents, the number of accidents involving wildlife has remained at approximately the same level of over 270,000 accidents per year for years. The basis for the development of suitable countermeasures is the most comprehensive knowledge possible of the existing interrelationships between the various influencing factors that shape the occurrence of accidents involving game. The aim of the project is to identify possible causes for the increased number of accidents and suitable measures on a sufficient number of wildlife accident spots by analysing various wildlife accident-relevant environmental data and characteristics of the road infrastructure in order to be able to avoid wildlife accidents in the future under the given conditions. For this purpose, all information relevant to road safety with regard to wildlife accidents at the identified wildlife accident spots is to be compiled, mapped and evaluated in a geographical information system (GIS). In the final result, the knowledge gained is to be processed for integration into the web-based catalogue of measures against accident spots – MaKaU, so that it is available in a practice-oriented manner for those involved in road safety work (www.bast.de/makau).

Adaptation of the CPX method to ensure the determination of correction values for road surface types – conversion of the measuring tyre (04.0340)
The reduction of road traffic noise is a central issue in the field of environmental protection. The assessment level for roads is calculated according to the Guidelines for Noise Protection on Roads (RLS). The correction values for road surface types applied here are determined according to TP KoSD-19, in which the 2 measurement methods Statistical Pass-By Method (SPB) and Close Proximity Method (CPX) are used. The measuring tyre H1 (DIN ISO/TS 11819-3) prescribed for the CPX measuring method is no longer available on the market. The aim of the research project is to develop a methodology so that the measurement procedure (CPX) can be used accurately in the future when changing over to new measurement tyres. After successful development of a methodology for finding new measuring tyres, the procedure is to be made available to the responsible ISO working group in order to incorporate the results into the revision of ISO/TS 11819-3.

Simplified photometric survey of fixed road lighting of accident sites in case of darkness accidents (82.0791)
Local accident investigation serves to improve road safety in Germany. It is carried out by the traffic police, the accident commissions or by research teams of the German In-Depth Accident Study (GIDAS). The recording of lighting data at the scene of an accident has so far played a subordinate role because only a few features such as the clothing of the unprotected road users or the natural ambient lighting conditions are recorded. Concrete lighting characteristics, for example from the fixed street lighting or from other lighting equipment in the vicinity, are not taken into account. The aim of the study is to enable practical recording of lighting characteristics during accident recording in order to classify the lighting quality on site and the associated lighting class according to DIN EN 13201. The result is to demonstrate the practical applicability of a simplified measurement procedure for police accident recording and technical GIDAS surveys.

Comprehensive reduction of the guideline values in the Noise Abatement Guidelines-StV (89.0349)
The "Richtlinien für straßenverkehrsrechtliche Maßnahmen zum Schutz der Bevölkerung vor Lärm - Lärmschutz-Richtlinien-StV" (BMVBS, 2007) serves road traffic authorities as a guideline for road traffic measures to protect against noise on existing roads. The aim of the research project is to investigate what influence a lowering of the guide values of the Noise Abatement Guidelines (Lärmschutz-Richtlinien-StV) would have on speed restrictions. The examination covers both urban (speed limit 30/40) and non-urban areas (speed limit 80/120/130) with different types of roads.

Practical application of the methods from ExNet 1.0: Overall noise (69.0004)
In the traffic networks of the different modes of transport, there is an overlapping of the corresponding noise emissions at points where traffic routes cross or run parallel to each other. Especially in dense traffic networks, this means that people are exposed to traffic noise from more than one source. Such an accumulation can be perceived as a nuisance and cause an overall noise situation. In the already concluded project FE 02.0400 "Cross-modal noise accumulation in complex situations", a guideline for dealing with such overall noise situations was developed. With the help of the presentation tools of the guideline, overall noise situations can now be adequately and comparably assessed and efficient and effective measures can be found. The aim of the current follow-up project is to apply the guideline in practice on the basis of specific noise situations: In this way, a review and further development of the methodology is to be achieved with regard to, among other things, informative value, comprehensibility, transparency and practical suitability, and dissemination to relevant user groups is to be promoted. and dissemination to relevant user groups is to be promoted.

Testing psychoacoustic parameters for innovative noise reduction strategies (02.0431)
In complex traffic or development situations, conventional noise reduction measures may be difficult or impossible to apply. In such cases, it would be desirable to have an extended range of measures available. Since the disturbing effect of noise sources on humans does not necessarily correlate only with the sound level, but also depends on the frequency composition and the temporal structure of the sound signal, psychoacoustic parameters have increasingly come to the fore in this respect in recent years. Consequently, different sounds with the same sound level can be perceived differently in terms of annoyance. The aim of this research project is to investigate the applicability of psychoacoustic parameters to traffic noise and to expand the current range of measures aimed at reducing noise immission levels.

Noise weather in practice: Testing and further development of the methodology for applying meteorological corrections to sound propagation (02.0438)
Meteorological influences can cause effects that favour or impair sound propagation. However, for the sake of a better applicability, detailed weather conditions are not explicitly considered in the national acoustic calculation models. Based on a proposed method for applying a meteorological correction, a validation and initial testing by relevant stakeholders is to be carried out and evaluated on the basis of concrete cases on federal roads. This is important in order to examine the practical suitability of the method, identify any need for improvement and create a statistically valid basis for the transfer to general study areas. The method is to be reviewed and further developed with regard to its reliability, comprehensibility and transparency, among other things.

Acoustic effectiveness of buckled and curved noise barriers (02.0419)
In addition to conventional, flat, vertical noise barriers, buckled and curved noise barriers or noise barriers with different impedances are also used to reduce noise levels on motorways. So far, only the position of the diffraction edge is considered in the noise calculation according to the "Guidelines for Noise Protection on Roads - RLS-19". On the one hand, the shape of the noise barrier, especially if it cantilevers over the road, has not been adequately treated in calculation programes for noise prediction so far. On the other hand, the reflection of differently shaped noise barriers or noise barriers with different impedance cannot be calculated. The aim of the research project is to create calculation modules that convert the three-dimensional measurement or calculation results into algorithms for the two-and-a-half-dimensional calculation method. These modules can then be used - in terms of formulas and language - in a revised RLS.

SOPRANOISE (6319014)
The performance of in-situ tests of airborne sound insulation and reflection of noise barriers (DIN EN 1793-5 and -6) is metrologically demanding and time-consuming. Therefore, the methods are only practicable for random checks. Fast measurement procedures for the acceptance of new noise barriers or for testing damaged noise barriers are desirable. The SOPRANOISE project (Securing and Optimising the Performance of Road trAffic NB with New methOds and In-Situ Evaluation) addresses new tools for evaluating the acoustic effectiveness of noise barriers. The primary objective is to develop an innovative, fast and safe method for easy in-situ characterisation of installed noise barriers. For this purpose, a structured recommendation for an inspection procedure is to be established

Glare effects with retro-reflective traffic signs (6319013)
According to experts, 90 percent of information in road traffic is communicated visually. The necessary visual communication is generally made possible by light-effective road equipment and appropriate lighting. Retroreflective traffic signs are an important device for visual communication between road users and the road. Traffic signs can only fulfil their function if they are clearly visible to the road user. The visibility of traffic signs is essentially determined by their photometric properties (reflection value and brightness in daylight) and by the luminous intensity distribution of the motor vehicle headlamp, which are described in detail in European and national regulations. In addition to these photometric properties, location, ageing, soiling, condensation and glare are also influencing factors that should not be neglected. In the present research project, the occurrence of glare as well as other photometric effects (rainbow effect) on retro-reflective traffic signs due to light irradiation is to be investigated in dependence on the reflective sheeting structures commonly available on the market. The results obtained will then be used in national and international regulations to define requirements.

MesSBAR (6319010)
Air quality mitigation strategies and pollution level limitation are important aspects of ensuring quality of life. Air pollutants are typically measured stationary at various locations and predicted by models. The knowledge on the vertical distribution of pollutants can yet only be obtained with a high logistical and financial effort, but plays an important role for transport and distribution models. To improve predictions and verify measures of pollutant reduction, a flexibly deployable mobile measurement system is necessary. In the project MesSBAR, an aerial and modular pollutant measurement system is being developed and deployed in the vicinity of motorways, urban an industrial areas to record the distribution of particulate matter, soot, NOx and O3 up to a height of one kilometre. Several copters measure in a coordinated manner upwind and downwind of emission and immission areas. Deployments are selected by pollutant predictions in order to improve them. The focus is on the usability of the system, the insurance of high data quality and the provision and publication of the data.

Acoustic Efficacy of Vegetation (02.0423)
One aspect that is becoming increasingly important in times of rising traffic volumes is the use of forests and vegetation to protect traffic routes from noise. The guidelines for noise protection on roads (RLS) do not yet take sound level attenuation by vegetation, especially forests, into account. Since the end of the 1940s, the acoustic shielding effect of forests and vegetation has repeatedly been the subject of investigations and studies in order to determine the sound-insulating properties of different forest stands and vegetation structures and to be able to describe them as a function of forest parameters. On the one hand the noise reduction comprises the physical reduction of the sound level, on the other hand the visual screening can already lead to a subjective decrease of the noise perception. The exact attenuation values depend strongly on the meteorological, seasonal and forestal environmental conditions. A simple method for the consideration of the physical sound level reduction during propagation by dense vegetation from trees and bushes can be found in the ISO 9613-2, but for various reasons it is not used in the RLS. The aim of this project is to determine the acoustic effectiveness and frequency-dependent sound insulation by forest and vegetation strips of different vegetation widths (between approx. 40 and 100 m) next to motorways and highways.

Abrasion of road surfaces (02.0424)
Air pollutant measurements throughout Germany show that the immission limit values for some air pollutants laid down in the "Directive 2008/50/EC on ambient air quality and cleaner air for Europe" are in some cases significantly exceeded, especially at locations close to traffic. Although in recent years some measures have already led to a reduction in air pollutant pollution, particularly in the case of particulate matter, in some places the daily limit value has still been exceeded. In addition to engine-related particle emissions from exhaust gases, traffic-generated particles are also diffusely emitted by abrasion from tyres, brakes and road surfaces or by resuspension of road dust. The abrasion of road surfaces causes a significant contribution depending on the state of preservation of the road surface. The worse the road condition, the higher the emission potential. For the planning of pollutant-reducing measures in the course of road construction and new road construction, models are used which must be subjected to continuous improvement of the input data. For the modelling emission factors over the abrasion contributing to the particle fractions PM10 and PM2.5 are required with the highest possible accuracy. At present, however, only fixed emission factors for non-engine-related abrasion emissions from road surfaces, some of which are associated with a high degree of uncertainty, are available in the "Guidelines for determining air quality on roads without or with loose peripheral development" (RLuS). The aim of the project is to carry out a systematic investigation of the abrasion behaviour and thus the particle emission of different road surfaces.

Relationship between reduced noise limits and in-use noise emissions in different traffic situations (02.0402)
Against the background of increasing traffic volumes, noise abatement is an ongoing challenge for all modes of transport. In the past, for example, the type-test limits for the entire vehicle and for tyres have continued to fall, while in the real traffic situation little has been achieved in terms of noise reduction. If real noise emissions are present for different driving situations, any need for changes to the regulations for vehicles and certain components can be specifically defined. The first step in the project is to select road sections that are as representative as possible and on which traffic noise measurements can be carried out. In a second step, level statistics on the road sections are to be collected at a suitable distance within at least one hour. Acoustically conspicuous events are to be documented. In a third step, the measurements are to be evaluated and statistically processed. The investigated in-use noise emissions of different traffic situations (speeds, accelerations, road surfaces, etc.) are to be transferred to the noise immissions in a sound propagation calculation. In addition, comparative considerations with the emission assumptions of the revised RLS-90 (Guidelines for Noise Protection on Roads) are to be carried out.

Monitoring and analysis of the coarse dust incidence (6388004)
International studies of recent years indicate a marked change in climate in the coming decades. Climate models predict a rise in regional strong wind and storm events. They can endanger traffic safety by raising and transporting loose soil material. A temperature-related rise in tyre abrasion particles can also lead to a distinct increase in mass concentration in the particle fraction range from 2.5 to 10 µm and to the overstepping of PM10 thresholds. In addition to endangering traffic safety and exceeding air pollutant thresholds, climate-change-related extreme weather events can also mean that the useful life of road structures is impaired considerably and the road surface abrasion increased. Long-term monitoring will be implemented to quantitatively and qualitatively record the influence of climate change on the development of coarse dust on traffic routes. A corresponding hazard potential and suitable avoidance measures can be determined from the results.

Development of a database to calculate exemplary noise situations including sound emission data from roads as a mode of transport and meteorological data (02.0416)
Meteorological influences can cause special effects which favour the spread of sound and reduce the acoustic effectiveness of existing noise protection measures. The research project firstly serves as a feasibility study with the aim of examining the usefulness of complex meteorological sound propagation models and resultant weather-corrected immission levels for roads as a mode of transport. Secondly, a database is to be provided for an investigation area which contains the necessary inputs to calculate noise situations incorporating weather information so that correlations between defined weather profiles and immission levels can be shown. The consideration of the local microclimate in planning and implementing noise protection measures is intended to assist in making efficient noise protection decisions and to provide additional help in individual cases for optimised noise protection measures.

Network of experts: designing environmentally friendly transport and infrastructure (6316006)
The topic of “Designing environmentally friendly transport and infrastructure” in the Federal Ministry of Transport’s “Knowledge – Ability – Action” network of experts makes environmental science contributions to the National Sustainable Development Strategy from the perspective of mobility and to the National Mobility Strategy from the perspective of sustainability/the environment. The objective is to shape mobility in such a way as to ensure that natural resources and the ecosystem services based on them remain available for future generations. Where possible, the ecosystem services and infrastructure services should be positively coupled. The environmentally friendly design of transport and infrastructure is becoming a central requirement of sustainable development. All modes of transport have common conservation goals when considering harmful effects on the environment.

2D-Array for SPB measurements with reflections (02.0327)
The taking of measurements in accordance with the Statistical Pass-by method (SPB) in order to determine noise emissions from road surfaces is especially difficult in built-up areas. Up to now, only the what is referred to as the “Backing Board“ was available, with which the reverse noise reflections are shielded, enabling measurements to be taken in front of surfaces which reflect noise. The spectrum is falsified however due to the reflection at the board and diffraction around the board edges. With a 1D-Array (distribution of microphones in a line along the carriageway), it is possible to correctly measure the maximum level of vehicles which are being driven close behind each other. In the scope of the project, a 2D-Array with the microphones being positioned in a level which is aligned in keeping with the road axis enables measurements to be taken of the maximum pass-by level in front of reflecting surfaces. A check is also to be carried out in order to determine whether the spectrums are correctly reproduced as is the case with free field measurements, or whether these are falsified as with the backing board.

Air quality on Federal highways (BAB) (6390000)
The EU Air Quality Directive 2008/50/EC was transposed into national law in August 2010 with the introduction of the 39th Ordinance on the Implementation of the Federal Immission Control Act (BImSchV). It requires compliance with limit, target and threshold values for selected air pollutants to protect human health and vegetation. The Federal Immission Control Act (BImSchG) defines air pollutants as changes in the natural composition of the air, whereby emissions from motor vehicles are named as one of their sources. In order to be able to record and evaluate typical traffic emissions, the BASt maintains measuring stations at 2 highly polluted motorway cross-sections, where nitrogen oxides, ozone and particulate matter are continuously recorded within the scope of this project. The measurements began in 1987 and were continued continuously until 2015. Between 2015 and 2017, an extensive redesign and renewal of the measurement cross-section on the A4 took place. In autumn 2019, two further BASt measuring containers were also installed on the A555 federal motorway between Wesseling and Bornheim. The measurement data of the air pollutants recorded are evaluated on a measuring point-related and comparative basis and processed for further analyses in other projects. The results of the measurements also flow into the regular revision and updating of the PC programme RLuS. The data collected over a longer period of time enables the assessment of the effects of new or changed air quality requirements.