Finance, Taxation, Pricing, Economic Analysis, Socioeconomics
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122 TRANSPORTATION RESEARCH RECORD 1395 Understanding the Competing Short-Run Objectives of Peak Period Road Pricing DAVID BERNSTEIN AND JEROME MULLER The interest in peak period road pricing has grown considerably 1993 or 1994 and a full-scale program by 1997 (14); and Oslo in recent years both in the United States and abroad. This increase and Trondheim, Norway, and Stockholm and Gothenberg, in interest is usually attributed to worsening congestion and im Sweden, are all considering programs of one kind or another. proved electronic toll collection technologies. However, there may be a third reason as well: peak period pricing can be used Several reasons are usually given for this renewed interest. to generate revenues. This use of peak period road pricing is First, congestion is now much worse than it has ever been in explored and compared with programs that are designed to min the past. As two-income families have become more prevalent imize social cost. Using some simple examples, it is shown that and suburban rings have grown in both absolute population it is possible to increase toll revenues but at a significant cost to and area, the number of commuters using private automobiles society. In addition, it is shown that most of the revenues and in the United States has increased dramatically. In fact, from costs can be attributed to the length and end of the toll period. 1960 to 1980 the number of people driving to work nearly doubled (at a time when the number of people in the work Peak period pricing has been an accepted part of life in the force increased by only 50 percent). In addition, there has United States for many years. For example, most long dis been a continued increase in the amount of truck transport, tance telephone companies charge higher prices during the and hence in highway truck miles, both inside and outside of day than they do during the evening and night. In addition, urban areas. The result is that more than 55 percent of urban many public transit systems (e.g., the Washington, D.C., freeway travel during the peak period takes place during con Metro) also charge higher prices during the peak period. gested conditions (15) and that more than 11 percent of the However, in spite of the urgings of many economists, peak total vehicle miles of travel takes place during recurring period pricing is not yet in widespread use on U.S. highways. congestion (16). Hence, although congestion pricing has been There are, of course, many reasons for this. In the United unpopular in the past, it is needed more than ever before. States, some of these reasons became evident during the 1970s Second, toll collection technology [see for example, Bernstein when UMTA, with the help of the Urban Institute, offered and Kanaan (17)] has now advanced to the point where to assist several cities in establishing programs that would congestion pricing can be implemented. demonstrate that peak period pricing could be used to bring However, in our casual conversations with policy makers congestion levels down to the "socially optimal" level (which who are now considering peak period pricing, it has become is a specific type of peak period pricing that is usually referred apparent that there is another reason for this increase in in to as "congestion pricing"). The response was considerably terest. Many of them seem to view peak period pricing as a less than expected (1,2). Although three cities did agree to mechanism for increasing revenues (which should not, strictly further study (Madison, Berkeley, and Honolulu), all of the speaking, be referred to as congestion pricing). In addition, preliminary studies ended without requests for further funding there ma.y also be increased support for road pricing simply because of public opposition. Congestion pricing was per as a means of reclaiming road space for pedestrians [see Good ceived as being unfafr, discriminatory, regressive, coercive, win (18) ]. and antibusiness. Not surprisingly, the existing literature does not consider Yet, in spite of these past failures, the United States and these aspects of peak period road pricing. Instead, it focuses other countries are again beginning to consider peak period on the inefficiencies that are inherent in (high-volume) road road pricing. In the United States, the recent Intermodal way travel (19-28). Thus, given the possibility that peak pe Surface Transportation Efficiency Act (!STEA) has allocated riod road pricing may be used as a revenue generation mech funding for up to five pilot congestion pricing programs. In anism, it is important to consider the impacts of such policies. the rest of the world, several such programs are now either This paper represents a first step in such an investigation. under way or in the planning stages. For example, Singapore We begin by describing the specific setting we consider has had a program in place since 1975 (3-6); Bergen, Norway, throughout the remainder of the paper and by discussing the has had a program in place since 1986; and Hong Kong tested various competing objectives of peak period road pricing. We a program from 1983 to 1985 and is now considering a full then consider the impacts of pursuing these objectives, first scale implementation (7-12). The Netherlands had planned within the context of tolls that are in place throughout the on having a full-scale program in place by 1996 and is now entire peak period and then within the context of time-varying considering a somewhat scaled-down program instead (13); tolls. We conclude with a discussion of future avenues that Cambridge, England, intends to initiate a trial program by still need to be pursued. We should point out in advance that we do not evaluate any specific road pricing programs in this Massachusetts Institute of Technology, Cambridge, Mass. 02139. paper. Studies of this kind can be found elsewhere (29-32). Bernstein and Muller 123 COMPETING OBJECTIVES by rP(t), and each possible pattern of departures is described by the vectors r(t) = (rp(t) : p E P) and r = (r(t) : t E Road pricing can have several effects on traveler behavior in [O, T]). The total number of commuters between the single the short run. In particular, it can result in changes in route, 0-D pair is denoted by N. Thus, the set of feasible path flow changes in departure time, changes in mode, changes in the vectors is given by total number of trips taken, and changes in the origin and destinations of those trips. As a result, it can be used to achieve a variety of different ends. (It is for this reason that H = {r: L lT rP(t)dt = N} (1) pEP 0 we generally often use the term peak period road pricing rather than congestion pricing in this paper. We use the latter term only to describe programs that are designed to increase The cost on each path ( CP) is a function of the total travel social welfare.) For example, one can imagine policy makers time on the path and the arrival time at the destination (plus making well-reasoned arguments about why road pricing should any tolls). We assume that the time needed to traverse path be used to p when entered at time t can be modeled as a deterministic queueing process in which •Reduce social costs (time, money, etc.), • Reduce out-of-pocket transportation costs, (2) •Reduce travel time, • Reduce the number of vehicle miles, where • Increase toll revenues, •Increase transit revenues, or (fixed) travel time on path p, • Increase total (toll and transit) revenues. service rate of the queue on path p, and number of vehicles in the queue on path p for a vehicle that enters the path at time t Furthermore, these objectives could be either general (e.g., (and hence reaches the queue at time reduce the total number of vehicle miles or reduce out-of pocket transportation costs) or very specific (e.g., reduce the t + dp). total number of vehicle-miles on the Gotham Expressway or Further, because travelers may arrive early or late, we intro reduce out-of-pocket transportation costs for people earning duce an asymmetric schedule cost given by less than $20,000/year). In general, the various objectives of road pricing need not 13[t* - (t + Dp(t))] if[t+Dp(t)]<t* conflict, yet in some cases they may be entirely contradictory. <l>p(t) = 0 p ( (3) { if [ t + D t)] = t * For example, it may be possible to both increase toll revenues -y[(t + Dp(t)) - t*] if [t + Dp(t)] > t* and reduce social costs. On the other hand, it may not be possible to both reduce out-of-pocket transportation costs and where increase total revenues. In either case, it is important that we have some way of comparing these different objectives so that t* desired arrival time, policy makers can make informed decisions. 13 dollar penalty associated with early arrival, and For the purposes of this paper, we will use a relatively -y dollar penalty associated with late arrival. simple technique to conduct the comparison. In particular, Note that we do not include a window of "equally acceptable" we will consider only two different types of policies, one aimed arrival times to simplify the analysis that follows. Also note at minimizing social cost (which in the examples that follow that we will often use the notation F,, to denote the free-flow is simply the total travel cost minus the toll revenue) and the travel cost on path p (i.e., F,, = adP). other aimed at maximizing toll revenues (given certain con Using the preceding definitions, we may now define the straints).