costs while traveling to and from the project, so the 

 cost per mile is doubled. Since more than one user 

 may arrive in each vehicle, a second adjustment 

 must be made to distribute the travel costs of the 

 trip between the number of users traveling in each 

 vehicle. This is readily accomplished by using the 

 average number of users per vehicle determined 

 from the survey of the existing sites used to devel- 

 op the per capita use curve or regional estimator. 



(E) The variable travel costs are the proxy for 

 price associated with the simulated increase in dis- 

 tance used to derive the resource demand curve. 

 Using the average variable cost for all three types 

 of automobiles (6.8 cents per mile) and using a hy- 

 pothetical average of 2.7 persons per vehicle, the 

 proxy for price for a simulated increase in distance 

 of 10 miles in the above example would be equal to 

 $0.50 (6.8 cents per mile times 2 for round-trip 

 mileage, divided by 2.7 persons per vehicle, times 

 10-mile increment). 



(ii) An adjustment for ttie opportunity cost of time. 

 (A) The use of variable travel costs alone in the de- 

 velopment of the demand schedules ignores the ef- 

 fects of time on recreation decisions. If time is ig- 

 nored, the demand schedules are constructed 

 under the hypothesis that increasing distance de- 

 creases use only because of higher money cost. 

 However, the additional time required to travel the 

 increased distance would seem to be a deterrent 

 equal to or greater than the out-of-pocket money 

 costs. The exclusion of the time factor introduces a 

 bias into the derived demand schedule, shifting it to 

 the left of the true demand schedule and resulting 

 in an underestimation of the recreation benefits. 



(B) The opportunity cost of time is the value of 

 work or leisure activities foregone to travel to and 

 recreate at the site. The opportunity cost for a 

 person whose work time is variable is measured as 

 income foregone during the recreation visit and as- 

 sociated travel. Most people, however, are con- 

 strained by a fixed work week and receive paid va- 

 cation days. Recreation occurring during periods 

 where no working time is lost incurs only leisure 

 time costs. This value may range between (if the 

 recreationist would not have engaged in any other 

 leisure activity in the absence of the observed rec- 

 reation) and the wage rate (if the alternative leisure 

 activity was valuable enough to forego earnings, 

 given that opportunity). 



(C) Where direct survey data on time costs are 

 not available, published statistics or studies of 

 work-leisure choices and wage rates may be used 

 to justify particular assumed values. One procedure 

 that may be used to accommodate the disutility of 

 time is to assume a known tradeoff between time 

 and money; however, but no universally accepted 

 formulation of this tradeoff has been established 



and empirically tested. In one proposed formulation, 

 time is valued as one-third the average wage rate 

 in the county of origin for adults and one-fourth of 

 the adult value (one-twelfth of the wage rate) for 

 children. Any method used to value time should be 

 supported by documenting evidence. Both travel 

 and onsite time costs should be included in the 

 derivation of total willingness to pay for access to 

 the site. 



(iii) Benefit computation. (A) The final computa- 

 tional step in the travel cost approach is to meas- 

 ure the area under the demand curve. This area is 

 equal to the amount users would be willing to pay 

 but do not have to pay for the opportunity to partici- 

 pate in recreation at the resource being evaluated. 

 Any user charges or entrance fees should be 

 added to this value to determine the gross value of 

 the resource associated with the specified manage- 

 ment option. 



(B) The travel cost approach can be used for 

 evaluating either the with-project or without-project 

 conditions as long as a use estimating model or a 

 per capita use curve is available for estimating use 

 under the specified condition. To evaluate the with- 

 out-project condition, estimate the value of the rec- 

 reation that would be lost at a site if a water re- 

 source development project were developed. To 

 evaluate a with-project alternative, estimate the 

 value of the new recreation opportunities that 

 would be created. If a use estimator is not available 

 for evaluating either the without-project conditions 

 or one of the with-project conditions, the tech- 

 niques described in other portions of this manual 

 should be used. 



(C) The procedure described above is applicable 

 to any type of activity or groups of activities for 

 which use can be described by a use estimating 

 equation or per capita use curve. The separation of 

 day use from overnight use or sightseeing from 

 other day use activities, for example, is dependent 

 upon the specificity of the survey data and the 

 model formulation. 



(c) Data requirements. (1) The development of 

 use estimator models as described above requires 

 that data from existing areas be systematically col- 

 lected. The major requirement is that the data on 

 use and users of a range of facility types and loca- 

 tions span the proposed types and locations for 

 which estimates are to be made. A series of sur- 

 veys at existing sites can provide such basic data, 

 which would normally include total use, timing and 

 patterns of use, characteristics or users, and users' 

 areas of ongin. 



(2) Methods of data collection that have proved 

 fairly satisfactory involve a short handout question- 

 naire or interviews of a small sample of randomly 



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