Perhaps Gaffney is being a little circumspect when he talks of "tapping the rise of rents on lands served by facilities with heavy fixed costs to help pay for those works." Perhaps a good economic policy with regard to public works - including the roads under discussion - would be first to determine whether the increase in land value caused by new construction would pay for the construction. If these estimated values - if collected - were unlikely to handle financing of the improvement, perhaps it shouldn't be built. The Jubilee Line Extension in London cost ???3.5 billion. Jones Lang LaSalle measured the increase in land values around 2 of the 11 stations - Canary Wharf and Southwark. Stripping out other drivers that increase land values they estimated that the land value increase directly caused by the Extension between 1992 and 2002 in the immediate vicinity of these two stations was ???2.8 billion. Maybe collection of the land-value increase around the 11 stations would have provided financing for the entire Jubilee Line Extension moving us toward Gibert M. Tucker's concept of the Self-Supporting City. (The Self-Supporting City. by Gilbert M. Tucker - The Journal of Finance, Vol. 14, No. 4 (Dec., 1959) Harry Pollard