INDUSTRIAL ENGINEERING APPLICATIONS IN TRANSPORTATION:TECHNOLOGY

TECHNOLOGY

Vehicle Routing

For solving transportation problems, the use of computers plays an important role in the development of models, schedules, network plans, and delivery and pickup routes. As described in previous sec- tions, the complexity and magnitude of the transportation problems discussed in this chapter require extensive computation times. Making transportation decisions is a complex process. Dispatch man- agers in package-delivery companies must assess a variety of factors before making dispatch deci- sions. Some of those factors were discussed in previous sections. They include vehicle capacity, time windows, demand fluctuations, labor productivity, and the dynamic changes in pickup and delivery characteristics of customers, geographies, and traffic conditions.

Vehicle-routing problems fall into one of three basic segments: routing of service vehicles, pas- senger vehicles, and freight vehicles (Hall and Partyka 1997). Service vehicles are used to support jobs in the field and are generally used by service technicians. In this type of problem, the primary constraints are service time, time windows, and travel time. Because there is no major variation in the merchandise carried by any given vehicle, capacity constraints are not included in the formulation of service routes. Passenger-transportation services such as bus service face an additional constraint: capacity. The size of the vehicle determines the number of passengers that can be safely carried from one point to another. Freight vehicles are also constrained by their capacity. When completing pick- ups, a vehicle may run out of capacity at a certain customer location. At this point, the dispatcher must either dispatch another vehicle to the customer’s location to complete service or ask the current driver to return to the depot, obtain an empty vehicle, and return to the customer’s location to complete the service. It is clear from this example that the decision made by the dispatcher can have different cost and service implications and may affect more than one customer. A few years ago, the only way to make these dispatch decisions effectively was through human knowledge and experience. The ability of the dispatcher to make numerous decisions based on a few pieces of information could make or break the dispatching process. Today, things have changed. With the increasing implemen- tation of technologies such as the geographic information systems (GIS) and global-positioning sys- tems (GPS), dispatchers have new tools that automate and improve the vehicle-routing process.

Routing pickup-and-delivery vehicles does not end with the development of routes prior to the drivers’ departure from the depot. Once drivers have left the depot, in-vehicle communications and route-information systems offer mechanisms not only to improve their performance but to meet on- demand customer requests. When dispatchers have the ability to communicate routing instructions and customer requests to drivers in the field, the opportunities for improving the overall efficiency of a dispatch plan increase substantially. However, the initial development of an efficient and effective dispatch plan is still critical.

Several software vendors have developed vehicle-routing software. In 1997, Hall and Partyka surveyed several vendors in order to compare the characteristics of their respective software systems. Table 4 presents an extract of this survey. The complete survey appeared in the June 1997 issue of OR / MS Today.

Information Gathering and Shipment Tracking

As indicated earlier in this chapter, the information associated with the goods being moved is as important as the transportation process itself. Today, transportation companies use a variety of tools to track, manage, and control the movement of goods from pickup to delivery. In addition, sophis- ticated electronic devices are being used by drivers not only to record the status of deliveries and pickups, but also to keep track of vehicle usage, time cards, and sales information.

New Trends: Intelligent Transportation Systems (ITS)

The transportation community has turned to the deployment of intelligent transportation systems (ITS) to increase the efficiency of existing highway, transit, and rail systems. One of the key variables in the vehicle-routing models described above is travel time. With the use of information from ITS, dispatchers can make better decisions. The U.S. Department of Transportation (DOT) has indicated that ‘‘ITS uses advanced electronics and information technologies to improve the performance of vehicles, highways, and transit systems. ITS provides a variety of products and services in metro- politan and rural areas.’’

As ITS evolves from pure research, limited prototyping, and pilot projects into routine usage, decision makers at ‘‘the corporate, state, regional, and local levels seek reliable information about the contribution that ITS products can make toward meeting the demand for safe and efficient move- ment of people and goods.’’ Literature indicates that substantial benefits have already been realized in areas such as accident reduction, travel-time savings, customer service, roadway capacity, emission reduction, fuel consumption, and vehicle stops. Greater benefits are predicted with more extensive

deployment of more mature products. Freight-transportation companies face new constraints and challenges not only in meeting service commitments but in remaining competitive and cost effective while meeting governmental regulations. The use of ITS offers new opportunities to use information in the development of routes and schedules.

The ITS program is sponsored by the DOT through the ITS Joint Program Office (JPO), the Federal Highway Administration (FHWA), and the Federal Transit Administration (FTA).

ITS, formerly known as the intelligent vehicle highway systems (IVHS), were created after the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 was established. ISTEA helped authorize larger spending for transit improvement. In January 1996, then Secretary of Transportation Frederico Pen˜a launched Operation TimeSaver, which seeks to install a metropolitan intelligent trans- portation infrastructure in 75 major U.S. cities by 2005 to electronically link the individual intelligent transportation systems, sharing data so that better travel decisions can be made.

A projected $400 billion will be invested in ITS by the year 2011. Approximately 80% of that investment will come from the private sector in the form of consumer products and services.

The DOT has defined the following as the components of the ITS infrastructure:

• Transit fleet management: enables more efficient transit operations, using enhanced passenger information, automated data and fare collection, vehicle diagnostic systems, and vehicle posi- tioning systems

• Traveler information: linked information network of comprehensive transportation data that directly receives transit and roadway monitoring and detection information from a variety of sources

• Electronic fare payment: uses multiuse traveler debit or credit cards that eliminate the need for customers to provide exact fare (change) or any cash during a transaction

• Traffic signal control: monitors traffic volume and automatically adjusts the signal patterns to optimize traffic flow, including signal coordination and prioritization

• Freeway management: provides transportation managers the capability to monitor traffic and environmental conditions on the freeway system, identify flow impediments, implement control and management strategies, and disseminate critical information to travelers

• Incident management: quickly identifies and responds to incidents (crashes, breakdowns, cargo spills) that occur on area freeways or major arteries

• Electronic toll collection: uses driver-payment cards or vehicle tags to decrease delays and increase roadway throughput

• Highway–rail intersection safety systems: coordinates train movements with traffic signals at railroad grade crossings and alerts drivers with in-vehicle warning systems of approaching trains

• Emergency response: focuses on safety, including giving emergency response providers the ability to pinpoint quickly the exact location of an incident, locating the nearest emergency vehicle, providing exact routing to the scene, and communicating from the scene to the hospital

The use of information from all of these system components will enhance the planner’s ability in designing efficient transportation networks and delivery routes. In addition, as this information is communicated to the drivers, they will also have the capability of making better decisions that will enhance customer satisfaction and reduce overall costs.

For additional information, visit the DOT’s website on ITS: http: / / www.its.dot.gov / .

Acknowledgments

The authors wish to thank Professor Mark S. Daskin of Northwestern University and Professor Ching-Chung Kuo of Pennsylvania State University for their constructive comments. They also thank their colleagues Ranga Nuggehalli, Doug Mohr, Hla Hla Sein, Mark Davidson, and Tai Kim for their assistance. They also thank Dr. Gerald Nadler of the University of Southern California for all his support.