GG 541 Professor T. R. Lakshmanan September 23, 2008
Key Components of CBA ◊ User benefits (times, fares, vehicle operating costs, safety etc.) ◊ Investment costs ◊ Operator costs and revenues ◊ Impacts on government - taxation subsidies ◊ Externalities (environmental, congestion)
User Benefit Estimation Three concepts underlying the definition of user benefit: ◊ Willingness to Pay (WTP) ◊ Consumer Surplus (CS) ◊ Generalized Cost (GC)
WTP is the maximum amount of money an individual is willing to pay for the change in his/her circumstances, e.g to make a trip from i to j using mode m. If the price (p) of the trip is less than or equal to WPT, the individual is assumed to make the trip. If P is > WTP, the traveler will find an alternative, which may be not the travel at all.
WTP is grounded in the acceptance of Consumer Sovereignty, so that it does not apply to goods subject to per se social or moral judgment. WTP can still be applied to cases of externalities (negative spill overs). However, if a community places extra value on social interactions promoted by public transit, that value will not be captured by the sum of individual willingness to pay for transit trips (only if one could also separately measure and include individual WTP for a better social milieu likely to result for more social interactions)
Continued… Note - different individuals have different levels of WTP for the same ijm trip. One can construct the demand function for ijm trips, linking the price to number of trips demanded - a downward sloping demand curve.
CBA is a comparative tool, involving a comparison of alternative states of the world. A do-something scenario - Where a link or facility is included in the transport network. these will be a separate do-something scenario for each alternative version of the project. A realistic do-minimum scenario - With the project not implemented. The do-minimum scenario will include a realistic level of maintenance and a minimum set of minor improvements to avoid the transport deterioration.
DD, the demand function represents the number of trips that would be made at different levels of generalized costs - a few trips with large economic benefit made at high costs, and less beneficial trips at lower costs. The intersection of the supply function s yields the number of trips made. CS, consumer surplus is a measure of the excess of willingness to pay over the generalized cost of the trip - the area CS under the demand curve and above a horizontal line indicating the current price (GCo).
Operationalizing the concept in transport poses some problems. For most goods, the vertical axis indicates price . In the case of transport, prices and money costs are not only one part of the composite. Cost of transit, which in principle incorporates travel times, access times to public transport, discomfort, perceived safety risk and others. Hence price is replaced by Generalized Cost (GC).
GC represents the money equivalent of the overall cost and inconvenience to the transport user engaged in travel between origin (i) and destination (j) by a particular mode (m). While in principle, it includes all aspects of ‘quality’ factors, in practice GC is limited to three elements. GCC ijm = time cost ijm + user charges ijm + VOC ijm Value of time costs vary among individuals and even for the same individual depending upon the trip purpose and their factors.
The User Benefit 1 0 • CSijm (=CSijm – CSijm) is estimated by the rule of a half • (ROH) on assumption that the demand curve between • (Q1GC0) and (Q1GC1) is linear approximately • ∆CS= 1/2 (GCo - GC1)(Q1 - Q) • This procedure repeated for transport users as well • as for freight users. 1
Components of GC will vary by mode * Public Transport users - fare plus costs of time of travel * Car users - costs of time, toll charges, fuel costs plus VOCs Differences in repeated user benefits for users of different modes (e.g. Public transport users do not have VOC benefits)
Producer Surplus PS - TR - TC where TR is total revenue and TC is total costs ∆PS = ∆ TR - ∆ TC
In the case of diagram (a) there is a rail journey time improvement, but marginal costs and fares (which are above marginal costs) stay constant [benefits] The change in the producer surplus ( DPS) is “net revenue gain”
continued… Figure 3a is the case in which the benefits are fully passed through to the travelers Figure 3b – there is complete “pricing up” by the railway operators. Thus the size of the revenue and user benefits effects (as well as their distribution) depends upon pricing policy.
Operating Costs Costs of infrastructure operation (e.g. signaling/traffic control) Maintenance costs (cleaning, minor repairs, winter services) Costs of renewals (road/rail reconstruction) Changes in VOCs of Public Transport Services
Investment Costs Some adjustments to Investment Costs include: Mitigation Measures (EIS, etc.) Disruption (effect of disruptions on traffic revenues and on service quality) Consistent Account (Market prices or factor costs basis)
Travel Time Savings • Dominant item of benefits, especially for air travel, • urban community and surface freight shipping • - Big time savings occur when there is • A new high speed rail service • A new highway through previously underdeveloped land • Congestion relief from expanding capacity • Improved rail switching facilities • Upgrade a line haul facility to permit higher speeds
An extensive literature based on demand models suggests that people and firms make reasonably predictable trade-offs between travel time and other factors when they make travel choices. From these studies, attempts to estimate WTP for travel time savings, a quantity known as the ‘Value of Time’ (VOT).
VOT Varies Across - population subgroups and also on individual circumstances e.g. people WTP more on average to avoid time walking to a bus stop or waiting there than they are willing to pay to avoid the same amount of time riding on the bus. Also willing to pay more to avoid driving in congested conditions.
These variations not surprising as time is not fungible: time saved in one circumstance cannot be automatically used in another – examples: These variations must be considered: Predicting travel time savings often complicated by offsetting behavioral shifts as a result of unpriced congestion. The case of latentdemand Amount of travel time savings overstated
The Case of Land Use Distortions Failure to price highway congestion leads to the city being inefficiently decentralized. New highways exacerbate this effect by creating housing locations which create longer trips and more traffic. So congestion will be reduced by a project less than predicted.
In estimating VOT, distinction is made between: 1. travel in working time 2. travel in non-working time (e.g. shopping, commuting, education, personal business, leisure) 3. freight travel time
Working time value is easy to analyze because there is a market (labor market) where working time is valued Two approaches Adapt the gross wage rate (wage plus employee - related overheads) as a measure of the marginal product of labor minutes of travel time savings in working time VOT = gross wage/min X
Second approach by Hensher qualifies the previous approach in two ways: 1) The ability to work while traveling (varies by mode) The ability to use productively any travel time saved also varies, depending upon the extent to which work tasks are divisible and flexible.
Non-working Time Savings Value No market exists A WTP value based on market research Both revealed preference (RP) and stated preference (SP methods used for VOT in different situations - including route choice, mode choice etc.
Value of Non-working Time Varies with Disposable Income • - Disposable income • - Employment status • Type of activity (walk and wait higher than in • vehicle time, congestion) and with mode (comfort, • privacy) • Journey purpose and journey lengths • Pragmatic use of standard values
Freight Travel Time Savings • Most important savings in drivers time • Not only VOC savings but those resulting from trip • rescheduling which leads to total labor cost reduction • Also the ability to adapt more efficient logistics - the • process and service innovations and the resulting • productivity in access.
Appraisal Values for Travel Time Savings - an example: UK Official Values Notes: (a) all values have been converted to 1999 US$, (b) Other goods vehicles include heavy goods vehicles. c) PSVs are public service vehicles, principally buses. (d)Walking, waiting and, cycling in non-working time are given double this value.
CBA with Externalities Transport provision often leads to a variety of negative or positive external effects (e.g. Air pollution, congestion, accidents and fatalities and airport noises are negative externalities. External economies of agglomeration is an example of positive externalities.
CBA with Externalities Here the private cost of travel is increased by an external cost e.
Because of the upward sloping nature of the s + e functions, the estimated benefit (a social benefit here) will be lower than the user benefit (in the simple user benefit case) by the amount E, which represents the extra external cost imposed by the increase in trips. If one wants to reduce pollution, a positive adjustment is needed. To implement this adjustment, it must be possible to calculate the net change in external cost in monetary terms and subtract it from the calculated user benefits.
Congestion is a reciprocal externality. When the traffic exceeds design capacity, all vehicles experience congestion. As congestion increases, travel time is an increasing function of the number of users of the transport link. As a consequence, the horizontal supply function is to be replaced by an upward sloping segment. Infrastructure improvement leads to an increase in design capacity, thus shifting the upward sloping segment to the right as in previous figure.
continued… Calculation of congestion costs must not be on a link basis but on a transport network basis. Please note that trips induced by the transport improvement may negate much of the benefit that might otherwise have accrued to freight users.
Value of Safety Impacts Some of the safety projects are market driven, while some safety proposals are government mandated. Changes in the risk of injuries, fatal or otherwise can be assessed based on WTP. Decisions are made implicitly placing values on additional risks incurred. A reliable method to value risk of death appears to be comparing wages for jobs that are similar in all respects except occupational risk.
Review of such studies suggest that on average people in affluent industrialized countries are willing to pay (early 1990s) $3 - $7 for each reduction of one in a million in the risk of death. Take $5, and a million people, their aggregate WTP for saving one life is $5 million. - “value of life” (VOL) 5 million
Most government agencies use a value of VOL of much less than $5 million. Canada $1.4 million (Canadian) (1991). [Even this amount is higher than those the average person’s personal wealth or the discounted sum of future earnings] No one is paying to avoid a sure death; rather people are paying to lower the probabilities slightly.
Risk of serious injuries or illnesses evaluated in a similar fashion. WTP to reduce the risk of typical serious (but non fatal) traffic injury is 10% of WTP (for traffic fatality). Note that the government borne costs of medical treatment must be added.
Some Countries Public Official Values for CBA Purposes
Environmental Impacts of Transport The challenge for CBA is to find ways to bring these impacts (air pollution, noise, or regional long run problems such as acid rain and global warming) into the CBA framework in a consistent way, given the greater uncertainty associated with environmental problems. Noise: Hedonic analysis of rental property to get the impact of noise.
Values generated by the approach are typically of the order of 30 Euros/person per dB per annum in year 2000 prices (Grant-Muller). This value adjusted to other countries using PPP exchange rates
Particulates most Significant Air Pollutant Damage costs much higher /unit mass of pollutant emitted in urban (US non urban areas) - 50 times as much in London vs. rural areas. 46-740 Euros/kgm. High level of uncertainty - sensitivity testing necessary.
CBA Process Inputs - modeling & forecasting all inputs (time, cost and time). Estimates of investment costs, safety and environmental impacts. Consistent Benefit Estimation - Use ROH for user benefits and simple do-minimum vs. do-something comparison for other cost and benefit items initially for one or two years. Interpolation and Extrapolation - using growth rates for quantities and unit values, to arrive at cost and benefit streams over the entire appraisal period.
continued….. Discounting - Discount future costs and benefits in line with public sector conventions on discount rates. Summary Measures - over all measure in CBA terms.