Improving Traffic Flow at Long-term Roadworks

Abstract

Long-term roadworks on highways are vital as part of carriageway and bridge renovations. They generate bottlenecks and consequently congestion and accidents. If the number of lanes is reduced, it can also lead to significant capacity decrease. Even if it is ensured that all lanes are kept operative, narrow lanes and transitions will affect the capacity. The impact of roadworks on capacity have been analysed in detail by [BECK_2001]. Therefore, intelligent solutions to support the traffic flow at long-term roadworks bottlenecks have to be evaluated. For this purpose the TrafficChange concept was developed. TrafficChange describes the modules of tidal flows on long-term roadworks: - Module 1: Tidal Flow basic set - TrafficChange SE (quickly repositionable moveable safety barriers, so-called Quick-Change Moveable Barriers (QMB)) - Module 2: Attached Traffic Safety Equipment for Tidal Flow - TrafficChange VT including data collection, traffic monitoring, communication, energy supply and displays - Module 3: Repositionable congestion warning systems to safeguard congestion - Module 4: Core system for data analysis, monitoring and managing traffic (TrafficChange Center) as cloud-based service With these components, a dynamic assignment of lanes to higher demanded direction can be reached. Main application fields of TrafficChange are: - Maintenance of bridges - Renewal of road pavement, road surface restoration (entire carriageway) - Tunnel renovation with two-way traffic in the operational tube - Temporarily adaption of the number of operational lanes in dependency of the traffic demand in order to enlarge working space of a roadworks The use of TrafficChange has beneficial effects on capacity and thus on traffic flow. In case of traffic lane reduction due to roadworks, TrafficChange can dynamically assign the remaining traffic lanes according to the demand of both driving directions. Even if all traffic lanes are kept operational during the roadworks, TrafficChange provides several advantages. In case of roadworks on a six lane facility (three lanes in both directions), usually one lane has to be managed separately on the carriageway of the construction field. This has a massive negative impact on the roadworks progress and the completion timetable. When applying TrafficChange this single separate lane is not necessary. Simultaneously this leads to significant capacity increase for this lane, since all lanes are managed on one carriageway and overtaking opportunity is provided. Evaluations of roadworks in Germany have shown that using TrafficChange will enhance the capacity by 10-15% for the driving direction of the construction site. One the other hand, for the direction with low demand, capacity is reduced temporarily, since one lane less is available. When demand for this period is low and can be managed by using the remaining lanes, the traffic flow quality stays efficient. For an economically efficient use of TrafficChange, the demand peaks should not occur simultaneously in both directions. Therefore, for each roadworks it needs to be evaluated individually whether TrafficChange can efficiently improve the traffic flow. For evaluation of the effects, the TrafficChange system is implemented in a microscopic traffic simulation tool, which can be adapted easily for different settings of the roadworks to be evaluated. As input values, the number of available lanes, roadworks design, traffic demand for each required scenario (such as weekday, weekend, holiday) and the length and planned duration of the roadworks are required. As key values, the simulation determines the congestion length, congestion duration and delay times. With these values, the benefit of TrafficChange can be determined. The efficiency estimation is determined by accumulation of total delay times for each required scenario, multiplied by the amount of days this scenario occurs during the roadworks is active, for both the comparison case (roadworks without TC) and target scenario (roadworks with TC). By using current travel time expenses for passenger cars and heavy vehicles, the benefit can be expressed in costs. By the use of TrafficChange, the entire carriageway can be closed so that considerable savings of working period and economic losses could be achieved although the number of operative lanes is lower than in the comparison case. The TrafficChange concept leads to improved traffic safety and optimized traffic flow at roadworks as well as reduced roadworks duration and therefore high economic efficiency that can be determined by the simulation tool TCSim. Literature [BECK_2001] - Beckmann, A., Zackor, H. (2001): Study and calibration of procedures for current estimation of the duration and length of traffic jams as a result of single-day and long-term construction sites on motorways; Forschung Straßenbau und Straßenverkehrstechnik, Volume 808, Bonn, Germany, 2001 [EASY_2009] - Easyway (2009) : Mobile Congestion Warning Systems at lorm term roadworks increase traffic safety – Efficiency of Mobile Congestion Warning Systems, Offprint of the ‘Landestelle für Straßentechnik Baden-Württemberg’, Stuttgart, 2009, www.easyway-its.eu [SUEM_2012] - Sümmermann, A. (2012): Examination of traffic safety and traffic flow in work zones on German Motorways, Aachener Mitteilungen Straßenwesen, Erd- und Tunnelbau, Volume 59, Aachen 2012 [VOLK_2014] - Volkenhoff, T. (2014): Model-based derivation of operating conditions of a video-aided incident and work zone management system in construction sites on German motorways, Aachener Mitteilungen Straßenwesen, Erd- und Tunnelbau, Volume 61, Aachen 2014 [HMSV_2012] – HMSV (2012): Congestion Evaluation 2011. Hessen Mobil – Straßen- und Verkehrsmanagement. URL: http://www.staufreieshessen2015.de , requested on 04.07.2012

Keywords

capacity management at long-term roadworks ; tidal flow management ; Quick-Change Moveable Barriers ; traffic safety and optimized traffic flow at roadworks ; determination of economic efficiency ; microscopic traffic simulation

References

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