The value of time one important component of Boston's big dig project mentioned at the beginning of this chapter was a 3.5-mile stretch of highway that cost $6.5billion it was estimated that with the new highway in place the ride from downtown to the airport would be reduced from 45 minutes to 8 minutes was this a good deal even though it is true that "time is money" to do cost -benefit analysis we need to know how much money. A common way to estimate the value of time is to take advantage of the theory of leisure -income choice. People who have control over the amount they work do so up to the point where the subjective value of leisure is equal to the income they gain from one more hours of work -the after -tax wage rate thus the after -tax wage can be used to value the time that is saved.