alone or in combination with other structural or non- 

 structural measures. 



(3) Project alternatives can differ in their timing 

 as well as in their physical characteristics. Consider 

 the optimal timing of projects and of individual pro- 

 ject features in project formulation, so as to maxi- 

 mize net benefits over time. 



(4) Consider improvements in alternative trans- 

 portation modes as part of the without-project con- 

 dition only, as specified in 2.6.3(a)(5). 



(5) A change in the watenway system that is cur- 

 rently authorized but not yet under construction 

 may be included if an appropriate share of its asso- 



ciated costs is included in the costs of the alterna- 

 tive under study and its incremental contribution to 

 benefits is explicitly identified. 



2.6.4 Evaluation procedure: General. 



Use the following 10 steps to estimate navigation 

 benefits. (See Figure 2.6.4.) The level of effort ex- 

 pended on each step depends upon the nature of 

 the proposed improvement, the state of the art for 

 accurately refining the estimate, and the sensitivity 

 of project formulation and justification to further re- 

 finement, especially as applied to steps 6, 7, and 8. 



51 



