This paper proposes alternative approaches for the prediction of short-term traffic flow using three branches of computational intelligence techniques, namely linear genetic programming (LGP), multilayer perceptron (MLP) and fuzzy logic (FL). Different LGP, MLP and FL models are developed for estimating the 5-and 30-min traffic flow rates. New LGP-and MLP-based prediction equations are derived for the traffic flow rates in the 5-and 30-min time intervals. The models are established upon extensive databases of the traffic flow records obtained from Iran's Rasht-Qazvin highway. The results indicate that the proposed models are effectively capable of predicting the target values. The LGP-based models are found to be simple, straightforward and more practical for predictive purposes compared with the other derived models.

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This paper considers the issue of air pollutants emission for the optimal and sustainable determination of cordon location, toll level, and price of park and ride (P&R). Although air pollutants emission decreases within the cordon by the implementation of cordon pricing scheme, it may increase INTRODUCTIONTraffic congestion has become one of the most severe social problems in modern societies. For years, adding additional capacity has been the solution for the rising level of congestion [1]. However, such an approach is subject to many spatial and financial constraints. Furthermore, providing more road space has been proven to be self-defeating in congested areas, because increased capacity will soon be occupied by induced travel demands [2,3]. Thus, in order to alleviate roadway congestion, road congestion pricing has been introduced.Congestion pricing was first suggested by investigating a sample of a congested road and expressing some ideas about externalities and optimal congested charges by Pigou (1920). The fundamental concept of pricing is so simple: prices should be higher under congestion conditions and lower at less congested times and locations in order to prevent excessive use [4].Recently, road pricing issue has widely attracted the attention of economists and transportation researchers, due to growing prominence and changing nature of urban transportation problems faced by modern cities [5][6][7].Road pricing theory is based on the fundamental economic principle of marginal cost pricing. It indicates that the users who use congested roads have to pay a toll which is equal to the difference between marginal social cost and marginal private cost in a way that social surplus increases [8]. The marginal cost pricing, unlike its full theoretical basis, is of little practical interest. Therefore, the second-best pricing method has attracted interest recently [4]. In the second-best pricing method, toll is only charged over a subset of links of the network. Four types of toll charging scheme in road network seem to be more popular: travel-distance based charging, travel-delay based charging, linkbased charging, and cordon-based charging [9].Recently, in some countries, a cordon pricing scheme has been used, instead of pricing on separate individual links, in order to reduce traffic demand in central congested urban areas [10][11][12][13]. In the second-best pricing, simultaneous determination of toll locations and toll level on a network is practically important [14][15][16]. In addition, the effect of value of time (VOT) on the pricing problems has been investigated in some of the previous studies [17]. In the presence of heterogeneous users with different VOTs, various network equilibrium models have been developed either by assuming a discrete set of VOTs for several distinct user classes or by a continuously distributed VOT across the whole population [18][19][20][21][22][23]. Moreover, in other studies, equity issues and revenue redistribution in congestion pricing have been investigated [24...

Congestion pricing strategy has been recognized as an effective countermeasure in the practical field of urban traffic congestion mitigation. Despite the positive effects of congestion pricing, its implementation has faced problems. This paper investigates the issue of environmental equity in cordon pricing and a park-and-ride scheme. Although pollution decreases inside the cordon by implementation of cordon pricing, air pollutants emission may increase in some links and in the whole network. Therefore, an increase in air emissions in the network means more emission outside the cordon. In fact, due to the implementation of this policy, air pollutants emission may transfer from inside to outside the cordon, creating a type of environmental inequity. To reduce this inequity, a bi-level optimization model with an equity constraint is developed. The proposed solution algorithm based on the second version of the strength Pareto evolutionary algorithm (SPEA2) is applied to the city network in Tehran. The results revealed that it seems reasonable to consider environmental equity as an objective function in cordon pricing. In addition, we can create a sustainable situation for the transportation system by improving environmental inequity with a relatively low reduction in social welfare. Moreover, there are environmental inequity impacts in real networks, which should be considered in the cordon pricing scheme.

As roadway and development factors are identified as the most effective factors contributing to road traffic accidents, investigating these factors could lead to reducing the accident frequency rate. However, previous works focused on investigating the effect of roadway factors on the accident frequency rate using statistical analysis. The present study aimed to evaluate the effect of roadway and development factors on the accident frequency rate using ANOVA and Chi-square tests on a rural road. Secondly, it aimed to develop a rural road safety risk index based on K-means clustering and Gaussian models. The findings indicated that the operating speed and the differences between posted speed limits and the operating speed are the pivotal influencing factors on the accident frequency rate. Moreover, clustering analysis of the roadway and development factors on the two-lane, two-way road of Borujerd-Khorramabad indicated six clusters which were identified as highly, relatively highly, moderately, relatively lowly, lowly risky, and not risky (safe) clusters. Regarding clusters, the accident frequency rate increased by decreasing the difference between the posted speed limits and the operating speed from the safe cluster. In addition, the risky index model based on the Gaussian model showed that the average reducing factor of accident frequency rate reached 0.99 by increasing per km/hr in the difference between the posted speed limits and the operating speed among low risky and safe clusters, while it was equal to 1.17 in risky and unsafe clusters. The comparison of the clusters revealed that accident occurrence probability in risky clusters was more than the ones in low risky or safe clusters. Therefore, the maximum and minimum values of the safety risk index were observed in the sixth and the third clusters, respectively.

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