Traffic signal timing problems with environmental and equity considerations

Abstract

SUMMARYTraffic signal timings in a road network can not only affect total user travel time and total amount of traffic emissions in the network but also create an inequity problem in terms of the change in travel costs of users traveling between different locations. This paper proposes a multi-objective bi-level programming model for design of sustainable and equitable traffic signal timings for a congested signalcontrolled road network. The upper level of the proposed model is a multi-objective programming problem with an equity constraint that maximizes the reserve capacity of the network and minimizes the total amount of traffic emissions. The lower level is a deterministic network user equilibrium problem that considers the vehicle delays at signalized intersections of the network. To solve the proposed model, an approach for normalizing incommensurable objective functions is presented, and a heuristic solution algorithm that combines a penalty function approach and a simulated annealing method is developed. Two numerical examples are presented to show the effects of reserve capacity improvement and green time proportion on network flow distribution and transportation system performance and the importance of incorporating environmental and equity objectives in the traffic signal timing problems.

A Simultaneous Solution for Reserve Capacity Maximization and Delay Minimization Problems in Signalized Road Networks

“…Thus, a suitable solution has to be found among Pareto optimal solutions. Although there are several efficient methods to find the set of Pareto optimal solutions of biobjective problems, the weighted-sum method can be used as an efficient tool to convert a biobjective problem into single-objective by using convex linear combination of objectives [52]. On the other hand, since each singleobjective problem (delay minimization and reserve capacity maximization) has a different unit, they cannot be directly added.…”

Joint Optimization of Distribution Network Design and Two-Echelon Inventory Control with Stochastic Demand and CO2 Emission Tax Charges

“…The location–inventory problem (LIP) is an extension of the classical facility location problem (FLP), which is also NP-hard [12,13]. LIP is basically an integrated discrete location problem that simultaneously determines location, allocation, and inventory decisions, which has received much attention in the past two decades.…”

Reserve Capacity Model for Optimizing Traffic Signal Timings with an Equity Constraint

“…(7) is related to the link capacity constraint in which p a represents degree of saturation for link a and s a is the saturation capacity on link a.In Eq. (8), σ i is a vector of green-time ratio for intersection i ∈ I , and matrix G i and vector b i are variables, which depend on the stage configuration of a given signalized intersection (see for details [20]). The equilibrium link flows, x a (ξ, σ a ), and corresponding travel costs for O-D pairs, Z w x ξ; σ ðÞ ðÞ , are obtained by solving user equilibrium traffic assignment problem given below:…”

“…The maximum degree of saturation flow p a is assumed as 0.9. Further assumptions are made on the values of travel time and stop delay and they are considered as α 1 =20 and α 2 =40$/hour [20].…”