Passenger and Freight Transport: Transport Planning Models

Transport Planning Models: Passenger and Freight Transport Transportation is a fundamental component of society today, capable of yielding massive economic and social benefits but also equally capable of producing extremely costly negative externalities. Proper policies need to be put in place to minimize the externalities while taking full advantage of the benefits. Proper policies can only be devised through the use of appropriate and well-thought out transportation models.

Freight and passenger transport systems usually move in separate nodes, which implies that their structures are quite different from each other, and so are the designs of their models (Hofstra University, 2014). The differences are, however, more pronounced at the respective terminals, which often concern different locations and different facilities (Hofstra University, 2014). The rationale behind the operational differences between freight and passenger transportation systems is that whereas "each passenger is an independent decision-making unit, each load of freight must be managed from its origin to its destination" (Hofstra University, 2014).

Other significant differences between freight and passenger transportation systems that ought to be taken into account when developing transportation models include; i) freight is 100% passive in nature, and would usually call for specific loading and unloading infrastructure, ii) most freight vehicles are designed specifically for the shipment of a particular goods type, iii) freight transport range from the shipment of single parcels to that of bulk items weighing thousands of tones, iv) unlike passenger transport, where decision-making is largely independent, freight transport travel itinerary is influenced by several actors including the driver, freight-forwarder and carrier, and consignor and consignee, v) in the freight transport market, transport shipment and service frequency costs often remain undefined until a prospective "sender makes an inquiry" (Friedrich, Haupt & Nokel, 2003, p.

2), and vi) whereas a passenger transportation network consists of nodes and links only, freight supply network would often consist of terminal nodes (warehouses, shunting yards, logistic centers, freight hubs), "with specific characteristics concerning capacity and transfer delay time" (Friedrich et al., 2003, p. 2). As has been mentioned elsewhere in this text, transportation models are used to develop and analyze policy options.

Passenger transportation models are regularly applied in both regional and international studies and often distinguish between public passenger transport systems (rail, tram, bus), and private passenger shipment systems (bikes, passenger cars) (Friedrich, Haupt & Nokel, 2003). They manly focus on individuals and model them as homogenous agents or groups. In passenger transport modeling, a developer can choose from a range of commercial software packages that allow for traffic assignments, demand calculations, and network editing (Friedrich et al., 2003).

For passenger models, output is given in terms of points of transfer (nodes), links (routes), and users' travel times and costs (Friedrich et al., 2003). Net changes, on the other hand, "are measured in terms of vehicle miles of travel, passenger miles of travel, vehicle hours of travel, and passenger hours of travel (VMT, PMT, VHT, and PHT respectively)" (CTRE, 2007). Freight transportation, on the other hand, usually involves complex interactions between players, and its models, therefore, ought to reflect the networks' specific supply structures (CTRE, 2007).

A carrier may not ship one, but an array of items to different destinations, which implies that model outputs would be given in terms of origin-destination pairs and trip volumes (CTRE, 2007). Moreover, "traffic patterns, volumes and.