Evaluation of Rapid Repair of Concrete Pavements Using Precast Concrete Technology: A Sustainable and Cost-Effective Solution

Concrete and asphalt are the two competitive materials for a highway. In Sweden, the predominant material for the highway system is asphalt. But under certain conditions, concrete pavements are competitive alternatives. For example, concrete pavements are suitable for high-traffic volume roads, roads in tunnels, concentrated loads (e.g., bus stops and industrial pavement). Besides the load-carrying capacity, the concrete pavement has many advantages such as durability (wear resistance), resistance against frost heave, environment (pollution, recycling, and low rolling resistance leading to fuel savings), fire resistance, noise limitations, brightness, evenness and aesthetics. Concrete pavements are long-lasting but need final repair. Single slabs may crack in the jointed concrete pavement due to various structural and non-structural factors. Repair and maintenance operations are, therefore, necessary to increase the service life of the structures. To avoid extended lane closures, prevent traffic congestions, and expedite the pavement construction process, precast concrete technology is a recent innovative construction method that can meet the requirement of rapid construction and rehabilitation of the pavement. This paper evaluates rapid repair techniques of concrete pavement using precast concrete technology by analysing three case studies on jointed precast concrete pavements. The study showed that the required amount of time to re-open the pavement to traffic is dramatically reduced with jointed precast concrete panels.

KAJIAN PERBANDINGAN KELAYAKAN EKONOMI PADA PERENCANAAN TEBAL PERKERASAN LENTUR DAN PERKERASAN KAKU

<p align="center"><strong>ABSTRAK</strong></p><p>Jalan Magelang-Purworejo merupakanijalanilintasiyangimenghubungkan Kabupaten MagelangidenganiKabupaten Purworejo diiProvinsi Jawa Tengah. Di ruas jalan ini termasuk jalanidenganivolumeilaluilintas yang tinggiidan dilalui oleh kendaraaniberat. Kondisi eksisting jalan yang mengalami banyak kerusakan yang disebabkan oleh beban berlebih dari kendaraan. Sehingga perlu adanya penelitian mengenai perencanaanitebal perkerasaniyang dibutuhkan dan sesuaiidenganikondisi di ruas jalan tersebut untuk meminimalisir kerusakan dan memberikan pelayanan jalan yang baik.</p><p>Metode yang digunakan dalam penelitian yaitu dengan merencanakan tebal perkerasanilenturidan tebal perkerasanikakuidengan mengacu pada BinaiMarga Tahun 2017. Dataiprimer yangidibutuhkanidalamipenelitianiini yaitu data laluilintas harianidanidataiCBR untuk mengetahuiidayaidukungitanahipadairuasijalan tersebut. Sedangkan untuk menghitung perbandingan kelayakan ekonomi menggunakan metodei<em>Internal</em>i<em>Rate</em>i<em>of Return</em>i (IRR).</p><p>Berdasarkan penelitian inilaii<em>Internal</em>i<em>Rate</em>i<em>of</em>i<em>Return</em>i (IRR) sebesar 16,3 % sedangkan untuk perkerasan kaku 21,8%. Keduanya memenuhi kelayakan ekonomi karena memiliki nilai yang melebihiitingkatisukuibungaipadaitahuniiniiyaitu sebesar 3,5%.Perkerasan kaku memiliki nilai IRR lebih tinggi dibandingkan dengan perkerasan lentur, sehingga jenis perkerasan kaku lebih sesuai untuk diterapkan.</p><p><strong>Kata Kunci</strong> : Perkerasan Lentur, Perkerasan Kaku, Kelayakan Ekonomi<em>, Internal Rate of Return </em>(IRR)</p><p> </p><p align="center"><strong><em>ABSTRACT</em></strong></p><p><em>Magelang-Purworejo street is a highway that connects Magelang Regency with Purworejo Regency in Central Java Province. This street includes road with high traffic volume and transferred by heavy street. The existing condition of the</em>i<em>road is</em>i<em>caused</em>i<em>by</em>i<em>the excessive load of the vehicle. So there is a need for research on the required pavement thickness planning and</em>i<em>in</em>i<em>accordance</em>i<em>with</em>i<em>the</em>i<em>conditions</em>i<em>of</em>i<em>the axle to minimize damage and provide a good service.</em></p><p><em>The methodology used in this research is to plan the</em>i<em>thickness</em>i<em>of</em>i<em>the</em>i<em>flexible pavement</em>i<em>and</em>i<em>rigid</em>i<em>pavement with reference of Bina Marga 2017. The primary data needed in this research are daily</em>i<em>traffic</em>i<em>data and</em>i<em>CBR value to</em>i<em>determine the bearing capicity of the soil on the segment. Calculate the comparison of economic feasibility using Internal</em>i<em>Rate of</em>i<em>Return</em>i<em>(</em>i<em>IRR</em>i<em>).</em></p><p><em>Based on the research</em><em>, the Internal Rate of Return value is 16,37% and for rigid pavement 21,8%. Both of pavement occupy economic feasibility because they have a value that exceeds the interest rate of this year which is 3,5%. The rigid pavement has a higher IRR value than flexible pavement, so rigid pavement is more suitable to be applied.</em></p><p><strong><em>Keywords</em></strong><em> : Flexible Pavement, Rigid Pavement, Economic Feasibility, Internal Rate of Return (IRR)</em></p>

Contrasting wolf responses to different paved roads and traffic volume levels

In some regions of the world, large carnivores, such as wolves, persist in landscapes with dense networks of paved roads. However, beyond the general impacts of roads on wildlife, we still lack information on carnivore responses to different types of roads and traffic volume levels. Using wolves in NW Spain as a case study, we show how wolves respond differently to paved road classes depending on road size, speed limit and traffic volume. All wolves evaluated (25 GPS collared wolves) crossed paved roads. Overall, during 3,915 sampling days, we recorded 29,859 wolf crossings. Wolf crossings of all paved road classes were recorded at a mean rate of 0.022 crossings/day/km (95% CI 0.016–0.027). Wolves crossed low speed and low traffic volume roads more frequently, and more often during the night, in order to lessen the chances of encountering traffic. We found mortality to be highest on roads with high speed and high traffic volume. How wolves interact with paved roads should be considered in landscape planning strategies in order to guarantee wolf long-term persistence in human-dominated landscapes. In our case, our results support an increasing focus on primary roads (class II) to identify segments of these roads where road mitigation efforts should be prioritised. Our study also highlights the importance of considering paved road classes when studying the impact of roads on wildlife.

Balancing the Service Benefits and Mainline Delay Disbenefits of Operating Shorter Freight Trains

Advanced train control systems enabling single-person crews or driverless trains promise to significantly reduce the fixed costs of operating a train, removing a strong incentive for longer trains. For carload freight traffic, operating a given number of railcars in shorter trains enables railroads to improve service quality and revenue through increased train frequencies or more direct trains bypassing intermediate classification yards. However, operating shorter trains increases the total number of trains on existing rail corridors, exacerbating congestion and decreasing network fluidity. Rail Traffic Controller simulation software is used to quantify the potential mainline delay impacts and relative capacity consumption of shorter trains. Different combinations of train length and train type heterogeneity are tested on representative single-track freight corridors. Results indicate that train control systems with moving blocks can mitigate some of the mainline delay impacts of shorter trains, particularly at a high traffic volume, with a mix of train types and a greater proportion of railcars traveling on short trains. Mid-siding crossovers can further boost the effectiveness of moving blocks in managing complex train conflicts caused by train type heterogeneity. Simulation results are used to perform an example railcar transit time estimation illustrating the trade-off between yard connection time benefits and mainline delay disbenefits, and the thresholds at which different operating strategies produce a net transit time benefit. Understanding the mainline delay impacts of shorter trains can assist railroad practitioners formulating long-term capital investment plans, developing future operating strategies, and improving service quality and market share through a short train philosophy.

Evaluating Operational Features of Three Unconventional Intersections under Heavy Traffic Based on CRITIC Method

Conventional four-legged intersections are inefficient under heavy traffic requirements and are prone to congestion problems. Unconventional intersections with innovative designs allow for more efficient traffic operations and can increase the capacity of the intersection, in some cases. Common unconventional designs for four-legged intersections include the upstream signalized crossover intersection (USC), continuous flow intersection (CFI), and parallel flow intersection (PFI). At present, an increasing number of cities are using such unconventional designs to improve the performance of their intersections. In the reconstruction of original intersections or the design of new intersections, the question of how to more reasonably select the form of unconventional intersection becomes particularly critical. Therefore, we selected a typical intersection in Xi’an for optimization and investigated traffic data for this intersection. The traffic operations, with respect to the four solutions of a conventional intersection, USC, CFI, and PFI, were evaluated using the VISSIM software. Then, we evaluated the suitability of each solution under different situations using the CRITIC (CRiteria Importance Through Intercriteria Correlation) method, which is a multi-criteria decision-making (MCDM) method that enables a more comprehensive and integrated evaluation of the four solutions by taking into account the comparative intensities and conflicting character among the indices. The results show that the conventional intersection is only applicable to the case of very low traffic volume; PFI has the advantage in the case of moderate and high traffic volume; CFI performs better in the case of high traffic volume; and USC is generally inferior to CFI and PFI, although it has greater improvement, compared with the conventional solution, in a few cases.

Pavement markings: identification of relevant covariates and controllable factors of retroreflectivity performance as a road safety measure

In this paper we present relevant contributions and important features related to the study of the retroreflectivity performance of pavement markings. The contribution of this paper is threefold. First, we propose an artificial scheme to allow some randomization of the treatments owing to several restrictions imposed on the choice of the experimental units. It is an experiment involving one fixed factor (three types of materials) in a randomized block design executed on a high-traffic-volume highway. Under this condition, the traffic volume works as a stress factor and the degradation of the retroreflectivity of pavement markings is faster than the degradation on rural roads or streets. This is related to the second contribution: the possibility of a reduction of experimental time. The current experiment spent 20 weeks to collect the data. And finally a mixed linear model considering three random effects and several fixed effects is fitted and the most relevant effects pointed out. This study can help highway managers to improve road safety by scheduling the maintenance of pavement marks at the appropriate time, choosing adequate material for the pavement markings and applying the proposed artificial scheme in future studies.

The Status of Air Quality in the United States During the COVID-19 Pandemic: A Remote Sensing Perspective

The recent COVID-19 pandemic has prompted global governments to take several measures to limit and contain the spread of the novel virus. In the United States (US), most states have imposed a partial to complete lockdown that has led to decreased traffic volumes and reduced vehicle emissions. In this study, we investigate the impacts of the pandemic-related lockdown on air quality in the US using remote sensing products for nitrogen dioxide tropospheric column (NO2), carbon monoxide atmospheric column (CO), tropospheric ozone column (O3), and aerosol optical depth (AOD). We focus on states with distinctive anomalies and high traffic volume, New York (NY), Illinois (IL), Florida (FL), Texas (TX), and California (CA). We evaluate the effectiveness of reduced traffic volume to improve air quality by comparing the significant reductions during the pandemic to the interannual variability (IAV) of a respective reference period for each pollutant. We also investigate and address the potential factors that might have contributed to changes in air quality during the pandemic. As a result of the lockdown and the significant reduction in traffic volume, there have been reductions in CO and NO2. These reductions were, in many instances, compensated by local emissions and, or affected by meteorological conditions. Ozone was reduced by varying magnitude in all cases related to the decrease or increase of NO2 concentrations, depending on ozone photochemical sensitivity. Regarding the policy impacts of this large-scale experiment, our results indicate that reduction of traffic volume during the pandemic was effective in improving air quality in regions where traffic is the main pollution source, such as in New York City and FL, while was not effective in reducing pollution events where other pollution sources dominate, such as in IL, TX and CA. Therefore, policies to reduce other emissions sources (e.g., industrial emissions) should also be considered, especially in places where the reduction in traffic volume was not effective in improving air quality (AQ).

A QoS Based Formal Model for Software Defined Network

Background & Objective: Software-Defined Networks (SDN) decouple the responsibility of data plane, control plane and aggregates responsibilities at the controller. The controller manages all the requests generated from distributed switches to get the optimal path for sending data from source to destination using load balancing algorithms. The guarantee of packet reachability is a major challenge in real time scenario of a SDN which depends on components of network infrastructure as switches, a central controller, channel capacity and server load. The success of this aggregation and packet reachability demand is a high Quality of Service (QoS) requirement in terms of throughput, delay and packet loss due to high traffic volume and network size. This QoS has two perspectives one is required other is a computation of real QoS value. Methods: In this paper, we have presented the QoS based formal model of SDN to compute and to investigate the role of the real QoS value. This formal model includes QoS on the basis of packet movement hop by hop which is a real-time QoS. The hop by hop packet movement reliability has been computed using channel capacity and server load which is an abstraction of throughput, delay, and packet loss. The effect of channel capacity and server load can be varying using different values of the weight factor. We have also considered an equal role of channel capacity and server load to compute reliability. This QoS helps to the controller to match with required QoS to decide the better path. Conclusion: Our results finds the reliable path based on channel capacity and server load of the network. Also, results showed that the reliability of the network and controller which are based on the reliability of the packet delivery between two nodes.

A Comparison of Traffic Flow Performance of Roundabouts and Signalized Intersections: A Case Study in Nigde

Background: Intersections affect the safety and capacity of urban traffic. Therefore, the design and selection of the type of intersection need to be made very carefully. According to the demand level, a different intersection can be designed. Signalized intersections are one of the intersection types in which the sequence and duration of the flow at the intersection are provided by the lights. Generally, this type of intersection is used on roads with high traffic volume. Modern roundabouts are one of the types of circular intersections that provide advantages over other types of intersection in terms of smooth operation and safety. Modern roundabouts exist in several types today worldwide. In practice, the distinction about the kinds of roundabouts would not be fully clarified; as a result, queuing and delay can be seen as negative effects. Methods: In this study, to make a distinction and clarify the kinds of roundabouts, first, the roundabouts types are introduced according to geometric and operational aspects. A signalized intersection, where a circular island is placed and also signalized, was investigated in terms of capacity, delay, and emissions located in Niğde. The traffic flow performance of the current state (nested signalized roundabout) was calculated with HCM Method (for signalized intersection) using SIDRA and compared with roundabout solutions of the intersection with HCM6 (for roundabout) method using SIDRA Intersection analysis software. Results: From the results of the intersection capacity analysis study based on HCM6, it was seen that the application of a roundabout scenario (intersection considered as a modern roundabout) showed higher performance at the intersections than the intersection having a secondary signal. Capacity increased to 67.8%, the average delay decreased to 72.8% and 95th percentile queue dropped to 82.2%. Conclusion: Roundabout controlling instead of a nested signal system can be an example of the increase in the performance of traffic flow. This highlights the importance of choosing the appropriate roundabout design.