An Integer Programming Formulation for Optimal Mode-Specific Route Assignment

To read the full-text of this research, you can request a copy directly from the authors.


Traffic in developing countries has a heterogeneous vehicular mix that uses all the network links and lacks lane discipline. Modeling and controlling such a mixed traffic system are challenging since most of the well-established models were developed for homogeneous traffic. It is hypothesized that segregating the mixed traffic by assigning a unique mode to each link will enhance system capacity. Towards achieving it, this paper proposes optimal mode-route assignment formulations with the objective of minimizing the total system travel time. However, perfect segregation is not always possible since the solution depends on the network topography. A viable solution is to make some links multi-modal. Another formulation is also presented in this paper to address this issue. Both the formulations are demonstrated using sample networks. Linear and nonlinear integer mathematical programming methods are used to explore the qualitative characteristics of optimal mode-route assignment using the single-path routing method. The results indicate that, in the worst case where perfect segregation is not possible, proposed formulation II can identify network with the least number of the multi-modal links. This research will help to develop effective strategies to model, control, and enhance the safety of mixed traffic networks.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

ResearchGate has not been able to resolve any citations for this publication.
In this paper we study the Multicommodity Fixed-Charge Network Design problem. We propose an Iterative linear programming-based heuristic for solving this NP hard problem. The proposed heuristics have been tested on the benchmark instances from the literature. The quality of solutions obtained by each of them has been disclosed comparing them with corresponding solutions of the current state-of-the-art heuristics, i.e., Cycle-Based Evolutionary algorithms.
This paper is concerned with the economics of reserved right of way, i.e. assigning separate facilities (roads or lanes within roads) to automobiles and buses in congested urban areas. The discussion of this issue appears frequently in conjunction with second-best considerations. The reserved right of way is judged as a device for changing the relative attractiveness of mass transportation vis-à-vis the automobile, when the warranted congestion toll is not levied (see Vickrey, 1963). We show in this paper that assigning different facilities (roads or lanes) may be optimal both when a congestion toll is charged from automobile drivers (hereafter ‘first-best’) and when no such toll is charged (hereafter ‘second-best’).
We propose new cycle-based neighbourhood structures for metaheuristics aimed at the fixed-charge capacitated multicommodity network design formulation. The neighbourhood defines moves that explicitly take into account the impact on the total design cost of potential modifications to the flow distribution of several commodities simultaneously. Moves are identified through a shortest-pathlike network optimization procedure and proceed by redirecting flow around cycles and closing and opening design arcs accordingly. These neighbourhoods are evaluated and tested within a simple tabu search algorithm. Experimental results show that the proposed approach is quite powerful and outperforms existing methods reported in the literature.
Numerous transportation applications as diverse as capital investment decision-making, vehicle fleet planning, and traffic light signal setting all involve some form of (discrete choice) network design. The authors review some of the uses and limitations of integer programming-based approaches to network design, and describe several discrete and continuous choice models and algorithms. The objectives are threefold - to provide a unifying view for synthesizing many network design models, to propose a unifying framework for deriving many network design algorithms, and to summarize computational experience in solving design problems. The authors also show that many of the most celebrated combinatorial problems that arise in transportation planning are specializations and variations of a generic design model.
: Each year more than 40,000 people die as a result of highway crashes, and 1 in 8 of those fatalities involve commercial motor vehicles. USDOT has set an ambitious goal of a 50 percent reduction in truck-related facilities by the end of this decade. Meeting that goal will involve finding ways of improving the performance of all elements of the system – the driver, the roadway, and the vehicle. This research deals with the roadway aspect, by investigating the safety and operational aspects of exclusive truck facilities. Determining the need for truck facilities established criteria such as the vehicular volumes, safety elements, and financial feasibility. This paper only deals with the first two. The research approach developed level of service relationships using the simulation software VISSIM. The safety investigation consisted of an evaluation of crashes on the New Jersey Turnpike comparing car-only lanes with mixed flows of trucks and cars. Results of the safety investigation indicate that the crash rate in the outer lanes (mixed flow of cars and trucks) is almost double that in the inner lanes (cars only), given the same exposure. Although inconclusive, this outcome may indicate that truck traffic had an influence on crashes. Results of the operational analysis indicate that the capacity of a two-lane exclusive truck roadway under ideal conditions approaches 1,500 trucks (defined as 3-or more axle vehicles) per lane per hour.
Truck-only lanes and tollways are under study as tools to combat road congestion, enhance safety and reduce other external costs of road traffic. This paper investigates the potential benefits from separating cars and trucks onto different lanes or routes while treating road infrastructure as given. The benefits are found to depend on several factors: the relative volumes of cars and trucks, the congestion delay and safety hazards that each vehicle type imposes, values of travel time for each type, and lane capacity indivisibilities. The optimal assignment of vehicles to road capacity can be supported using tolls that are differentiated by vehicle type and lane. Lane access restrictions usually cannot support the optimum and may well provide no benefit at all. Creating a toll lane for one vehicle type is generally more effective. The benefits of all forms of intervention are sensitive to whether the proportions of cars and trucks are commensurate with lane capacities.
Road pricing, traffic congestion and the environment: issues of efficiency and social feasibility
  • R Arnott
  • A De Palma
  • R Lindsey
Issues in the financing of truck-only lanes
  • D J Forkenbrock
  • J March
Recent developments in the bottleneck model
  • R Arnott
  • A de Palma
  • R Lindsey
  • KJ Button
  • ET Verhoef