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Dr. Saša Ahac
University of Zagreb - Faculty of Civil Engineering

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0 Drainage Design
0 Roundabouts
0 Sustainability
0 Traffic Noise
0 Infrastructure Engineering

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Roundabouts
Traffic Noise
Sustainability

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Entry
Published: 05 August 2021 in Encyclopedia
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A modern roundabout is an intersection with a circulatory roadway at which the vehicle speed is low, and the traffic is continuous and circulating in one direction around the central island towards the exits at the approach legs. Modern roundabout design is an iterative process that is composed of the following steps: (1) the identification of the roundabout as the optimal traffic solution; (2) the definition of the number of lanes at the intersection based on the required capacity and the level of service; (3) the initial design of the roundabout geometry; (4) design vehicle swept path, the fastest path analysis, and visibility performance checks; and (5) detailed roundabout design if the results of the performance checks are in line with the design recommendations. Initial roundabout geometry design elements are not independent of each other; therefore, care must be taken to provide compatibility between them. An overview and a comparative analysis of the initial geometric design elements for suburban single-lane roundabouts defined in roundabout design guidelines and norms used in Croatia, Austria, France, the Netherlands, Germany, Serbia, and Switzerland is given in this entry.

ACS Style

Saša Ahac; Vesna Dragčević. Geometric Design of Suburban Roundabouts. Encyclopedia 2021, 1, 720 -743.

AMA Style

Saša Ahac, Vesna Dragčević. Geometric Design of Suburban Roundabouts. Encyclopedia. 2021; 1 (3):720-743.

Chicago/Turabian Style

Saša Ahac; Vesna Dragčević. 2021. "Geometric Design of Suburban Roundabouts." Encyclopedia 1, no. 3: 720-743.

Journal article
Published: 12 May 2021 in Sustainability
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Challenges that emerge in roundabout design are mostly related to space constrictions and provision of appropriate deflection around the central island. This can result in speed profiles on roundabouts that might reduce their potential as a noise abatement measure. Because of this, the impact of a roundabout on noise levels and its applicability as a traffic calming device and a noise abatement measure should be investigated in the early design stage, by modeling noise levels. In this paper, the following hypothesis is tested: vehicle movement trajectories, defined during the fastest path performance check in roundabout early design phase, can be used as the road traffic noise sources when modeling noise at roundabouts using static noise model. This procedure (1) simplifies the preparation of the noise model, (2) results in a model that is closer to the real-world in terms of traffic flow conditions, (3) allows the noise calculations in the early stages of roundabout design, and (4) includes the influence of roundabout deflection on calculated noise levels. The abovementioned simplifications of the road traffic noise modeling process should encourage the optimization of roundabout geometry in terms of its noise reduction capabilities in the preliminary design phase of these intersections.

ACS Style

Saša Ahac; Maja Ahac; Josipa Domitrović; Vesna Dragčević. Modeling the Influence of Roundabout Deflection on Its Efficiency as a Noise Abatement Measure. Sustainability 2021, 13, 5407 .

AMA Style

Saša Ahac, Maja Ahac, Josipa Domitrović, Vesna Dragčević. Modeling the Influence of Roundabout Deflection on Its Efficiency as a Noise Abatement Measure. Sustainability. 2021; 13 (10):5407.

Chicago/Turabian Style

Saša Ahac; Maja Ahac; Josipa Domitrović; Vesna Dragčević. 2021. "Modeling the Influence of Roundabout Deflection on Its Efficiency as a Noise Abatement Measure." Sustainability 13, no. 10: 5407.

Review
Published: 08 January 2021 in Sustainability
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Despite the long-term experience in the application of noise walls, the uncertainty in wall panel service life efficiency is almost equal between panels built from established and new materials, which are—because of the desire to increase the sustainability of noise walls—developing at an ever-faster pace. The presented meta-analysis of data collected during a systematic review of concrete, metal, and wood panels’ acoustic and non-acoustic characteristics, long term performance, and cradle-to-gate sustainability aims to reduce this uncertainty and support the process of noise wall design and management by shifting the emphasis in decision making from construction costs to the long-term sustainability of the road traffic noise mitigation project. The multi-criterial analysis showed that when choosing a panel, preference should be given to those using lightweight concrete materials. A further comprehensive cradle-to-grave assessment of lightweight concrete panels with expanded clay and recycled tire rubber aggregates, which was performed to fill a knowledge gap observed in the literature and identify opportunities for the improvement of lightweight concrete sustainability, showed that the main environmental impacts of these panels are due to their production processes and that the way to reduce such impacts is to use panels made with aggregates from secondary raw materials.

ACS Style

Maja Ahac; Saša Ahac; Stjepan Lakušić. Long-Term Sustainability Approach in Road Traffic Noise Wall Design. Sustainability 2021, 13, 536 .

AMA Style

Maja Ahac, Saša Ahac, Stjepan Lakušić. Long-Term Sustainability Approach in Road Traffic Noise Wall Design. Sustainability. 2021; 13 (2):536.

Chicago/Turabian Style

Maja Ahac; Saša Ahac; Stjepan Lakušić. 2021. "Long-Term Sustainability Approach in Road Traffic Noise Wall Design." Sustainability 13, no. 2: 536.

Journal article
Published: 20 March 2020 in Transportation Research Procedia
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The main factors that affect the choice of the intersection type when constructing a new or reconstructing an existing intersection are desired traffic flow rate and achievable traffic safety. At the same time, a significant challenge is to find optimal solutions for (re)construction and traffic organization at intersections in settlements, especially in agglomeration centers, due to their specific and, in most cases substantial, spatial and traffic constraints. This paper presents the examination of the functional efficiency of the introduction of roundabouts in the road network of Našice Town. As the location for the analysis, a section of county road 4168 is selected, which includes two consecutive 4-legged signalized intersections. For the purpose of the investigation presented in this paper, these signalized intersections are to be substituted with two single lane roundabouts. Conceptual design of these roundabouts includes prescribed performance checks: swept path analysis, speed and visibility checks. Finally, the rating of the analyzed road corridor functional efficiency and dynamics of intersections reconstruction is given based on the defined levels of service for the current state and the intersection reconstruction proposals.

ACS Style

Maja Ahac; Saša Ahac; Mihael Devald; Šime Bezina. Analysis of the functional efficiency of small town arterial thoroughfare (Case Study of Našice Town). Transportation Research Procedia 2020, 45, 242 -249.

AMA Style

Maja Ahac, Saša Ahac, Mihael Devald, Šime Bezina. Analysis of the functional efficiency of small town arterial thoroughfare (Case Study of Našice Town). Transportation Research Procedia. 2020; 45 ():242-249.

Chicago/Turabian Style

Maja Ahac; Saša Ahac; Mihael Devald; Šime Bezina. 2020. "Analysis of the functional efficiency of small town arterial thoroughfare (Case Study of Našice Town)." Transportation Research Procedia 45, no. : 242-249.

Journal article
Published: 01 June 2019 in Journal of the Croatian Association of Civil Engineers
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ACS Style

Ivica Stančerić; Saša Ahac; Šime Bezina; Filip Vlaović. Design limits for intersection angles between approach legs of suburban roundabouts. Journal of the Croatian Association of Civil Engineers 2019, 71, 389 -399.

AMA Style

Ivica Stančerić, Saša Ahac, Šime Bezina, Filip Vlaović. Design limits for intersection angles between approach legs of suburban roundabouts. Journal of the Croatian Association of Civil Engineers. 2019; 71 (5):389-399.

Chicago/Turabian Style

Ivica Stančerić; Saša Ahac; Šime Bezina; Filip Vlaović. 2019. "Design limits for intersection angles between approach legs of suburban roundabouts." Journal of the Croatian Association of Civil Engineers 71, no. 5: 389-399.

Journal article
Published: 01 February 2017 in Tehnicki vjesnik - Technical Gazette
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ACS Style

Tamara Džambas; Saša Ahac; Vesna Dragčević. Geometric design of turbo roundabouts. Tehnicki vjesnik - Technical Gazette 2017, 24, 1 .

AMA Style

Tamara Džambas, Saša Ahac, Vesna Dragčević. Geometric design of turbo roundabouts. Tehnicki vjesnik - Technical Gazette. 2017; 24 (1):1.

Chicago/Turabian Style

Tamara Džambas; Saša Ahac; Vesna Dragčević. 2017. "Geometric design of turbo roundabouts." Tehnicki vjesnik - Technical Gazette 24, no. 1: 1.

Journal article
Published: 01 July 2016 in Journal of Transportation Engineering
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This paper describes a turbo roundabout design procedure based on the rules of design vehicle movement geometry. Previous studies carried out on various junction types have shown that this design approach ensures the usage of optimal roundabout element dimensions as well as safety and comfort during driving. A five-step design procedure is suggested, including a detailed description of relevant influential parameters. They are choosing a design vehicle, implementing the initial roundabout scheme on which the vehicle swept path is analyzed, choosing a method of assigning input parameters for swept path requirements testing procedure, choosing optimal design elements of a standard turbo roundabout, and fastest path vehicle speed analysis.

ACS Style

Tamara Džambas; Saša Ahac; Vesna Dragčević. Design of Turbo Roundabouts Based on the Rules of Vehicle Movement Geometry. Journal of Transportation Engineering 2016, 142, 05016004 .

AMA Style

Tamara Džambas, Saša Ahac, Vesna Dragčević. Design of Turbo Roundabouts Based on the Rules of Vehicle Movement Geometry. Journal of Transportation Engineering. 2016; 142 (7):05016004.

Chicago/Turabian Style

Tamara Džambas; Saša Ahac; Vesna Dragčević. 2016. "Design of Turbo Roundabouts Based on the Rules of Vehicle Movement Geometry." Journal of Transportation Engineering 142, no. 7: 05016004.

Journal article
Published: 01 July 2014 in Romanian Journal of Transport Infrastructure
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The paper gives an overview of concrete noise barrier application in several EU countries and in Croatia. It describes a process of introducing different noise protection solutions on Croatian market in the phase of intensive motorway construction in recent years. Namely, an extensive motorway network has been constructed in Croatia in the last 10 years. Following the process of motorway construction, noise protection walls have also been erected. Usage of different building materials and installation processes as well as variations in building expenditures has led to a comparative analysis of several types of noise protection solutions (expanded clay, wood fibre) including a new eco-innovative product RUCONBAR, which incorporates rubber granules from recycled waste tyres to form a porous noise absorptive layer.

ACS Style

Saša Ahac; Ivo Haladin; Stjepan Lakušić; Vesna Dragčević. Croatian Experience in Road Traffic Noise Management - Concrete Noise Barriers. Romanian Journal of Transport Infrastructure 2014, 3, 1 -11.

AMA Style

Saša Ahac, Ivo Haladin, Stjepan Lakušić, Vesna Dragčević. Croatian Experience in Road Traffic Noise Management - Concrete Noise Barriers. Romanian Journal of Transport Infrastructure. 2014; 3 (1):1-11.

Chicago/Turabian Style

Saša Ahac; Ivo Haladin; Stjepan Lakušić; Vesna Dragčević. 2014. "Croatian Experience in Road Traffic Noise Management - Concrete Noise Barriers." Romanian Journal of Transport Infrastructure 3, no. 1: 1-11.

Journal article
Published: 01 December 2013 in Romanian Journal of Transport Infrastructure
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Ensuring sufficient visibility on planned roads by sight distance testing is an integral part of every project, but problems with visibility can emerge when noise barriers are erected on existing roads. Namely, in order to provide sufficient noise protection, high noise barriers are often placed at minimum distance from the carriageway edge, and additional visibility testing in most cases is not carried out. Research described in this paper consists of stopping sight distance tests conducted by means of specialized road design software MX Road, and noise barrier optimization conducted by means of specialized noise prediction software LimA using static noise calculation method RLS 90. The aim of this research is to establish whether the required stopping sight distance on road sections where minimum design parameters are applied can be achieved if the noise barrier is placed at minimum distance from the carriageway edge, and to establish whether the optimized dimensions of planned noise protection barrier will change if the barrier is placed on larger distance from the noise source, which is, in this case, the existing road.

ACS Style

Tamara Džambas; Saša Ahac; Vesna Dragčević. The Influence of Visibility Conditions in Horizontal Road Curves on the Efficiency of Noise Protection Barriers. Romanian Journal of Transport Infrastructure 2013, 2, 22 -32.

AMA Style

Tamara Džambas, Saša Ahac, Vesna Dragčević. The Influence of Visibility Conditions in Horizontal Road Curves on the Efficiency of Noise Protection Barriers. Romanian Journal of Transport Infrastructure. 2013; 2 (2):22-32.

Chicago/Turabian Style

Tamara Džambas; Saša Ahac; Vesna Dragčević. 2013. "The Influence of Visibility Conditions in Horizontal Road Curves on the Efficiency of Noise Protection Barriers." Romanian Journal of Transport Infrastructure 2, no. 2: 22-32.

Journal article
Published: 01 July 2013 in Romanian Journal of Transport Infrastructure
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The paper describes the analysis of tram traffic noise situation in residential areas in the vicinity of Drzic Avenue, one of the major routes between the northern and southern part of the Croatian capital city Zagreb, and the effect of low barriers placed by the tracks on tram noise mitigation. In order to evaluate the effect of planned protection measure, noise models were produced and verified with short-term field measurements. Calculations were conducted by means of noise prediction software, using European interim noise prediction method and 3D model of analyzed area. Finally, the results of noise calculations for existing tram traffic situation and planned measure of protection are presented on noise maps.

ACS Style

Maja Ahac; Stjepan Lakusic; Saša Ahac; Vesna Dragčević. The Analysis of Low Noise Protection Barriers Influence on Tram Traffic Noise Levels. Romanian Journal of Transport Infrastructure 2013, 2, 1 -9.

AMA Style

Maja Ahac, Stjepan Lakusic, Saša Ahac, Vesna Dragčević. The Analysis of Low Noise Protection Barriers Influence on Tram Traffic Noise Levels. Romanian Journal of Transport Infrastructure. 2013; 2 (1):1-9.

Chicago/Turabian Style

Maja Ahac; Stjepan Lakusic; Saša Ahac; Vesna Dragčević. 2013. "The Analysis of Low Noise Protection Barriers Influence on Tram Traffic Noise Levels." Romanian Journal of Transport Infrastructure 2, no. 1: 1-9.