use of regional models can economize on re- 

 sources required for site-specific studies. In the ab- 

 sence of a regional model, estimate use by one of 

 the site-specific methods described below. If a use 

 estimating model has already been developed for 

 the region in which a proposed project is to be lo- 

 cated, use estimates should be obtained by the fol- 

 lowing procedure: 



(i) Delimit the areas of origin for the proposed 

 project (use of counties or parts of counties as 

 origin areas will facilitate gathering of data in sub- 

 sequent steps). 



(ii) Compute measures of the explanatory varia- 

 bles in the use equation for each origin area and 

 for each year for which an estimate is required. 



(iii) Calculate use from each area for each year. 



(iv) Aggregate use from each area to get estimat- 

 ed annual use. 



(2) Site-specific use estimating models. The pre- 

 ferred site-specific method of estimating use is a 

 use estimating model (UEM) that relates use per 

 1,000 of origin population to distance traveled, so- 

 cioeconomic factors, and characteristics of the site 

 and alternative recreation opportunities. Use esti- 

 mating models yield regression coefficients estimat- 

 ed from data gathered at a comparable existing site 

 or cross section of existing sites. The coefficients 

 are used to estimate visitation at a proposed site in 

 the same way as described for regional models. 

 Factors that influence demand for recreation, such 

 as characteristics of user populations and availabil- 

 ity of alternative opportunities, are explicitly taken 

 into account by variables in the model. Because of 

 the influence of congestion during heavy use peri- 

 ods, it is desirable to distinguish use during summer 

 weekends and holidays. If data limitations do not 

 permit disaggregation, explain treatment of season- 

 al use variation and any simplifying assumptions. 



(3) Application of information from a similar pro- 

 ject (i) If a UEM is not available and cannot be es- 

 timated because of data limitations, use may be es- 

 timated by the similar project method. This method 

 assumes that recreation demand for a proposed 

 project can be estimated from observations of visi- 

 tation patterns at one or more existing projects with 

 similar resource, operations, and use characteris- 

 tics. The alternatives under study are compared 

 with water resource projects and recreation re- 

 source areas for which trip generation and other 

 statistics are known. It is important to obtain as 

 close a match as possible in type, size, and quality 

 of project; market area demographic and socioeco- 

 nomic characteristics; existence and location of 

 competing recreation opportunities; and other varia- 

 bles that influence demand. 



(ii) The most efficient and technically sound simi- 

 lar project procedure is based on per capita use 

 curves (i.e., regression curves relating per capita 

 rate of use to travel distance) from which use esti- 

 mates are derived. The similar project method in- 

 volves the following steps: 



(A) Evaluate the characteristics of a proposed 

 project or other area under study. 



(B) Select a similar project or area by comparing 

 characteristics of the proposed project with availa- 

 ble information for existing sites; include evaluation 

 and comparison of the respective recreation market 

 areas. 



(C) Adjust the per capita use curve to account for 

 the differences between the similar project and the 

 proposed project. 



(D) Determine the county populations within the 

 market area for the years in question, and derive 

 per capita use rates for each county population by 

 measuring road mile distance from the project to 

 the center of the most populated city within the 

 county (proxy for centroid of county population). 



(E) fvlultiply each county per capita rate by county 

 population and sum to get total use. 



(F) Determine the percentage of total use that 

 the foregoing estimate represents; if 100 percent, 

 use as is; if less, adjust accordingly. 



(iii) Justify assumptions used to adjust or modify 

 per capita use curves. 



(4) Capacity method of determining use. If data 

 on use determining variables are unavailable and 

 are not cost effective to obtain, and if it can be 

 demonstrated that sufficient excess demand exists 

 in the market area to accommodate the additional 

 capacity supplied by a proposed project, use may 

 be assumed to be equal to capacity. Since this 

 method provides no information on trip generation, 

 willingness to pay cannot be evaluated by the travel 

 cost method. 



2.8.10 Evaluation procedure: Estimate value of 

 use with the project. 



As noted in 2.8.2, three alternative methods can 

 be used to estimate recreation benefits: 



(a) Travel cost estimate of willingness to pay 

 based on use estimating model or per capita use 

 curves— (^) Conditions under which TCM may not 

 be used, (i) Use was not estimated by a technique 

 relating trip-generation to distance to the site; 



(ii) There is insufficient variation in travel dis- 

 tances to allow parameter estimation (for example, 

 urban sites); or 



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