1. Utilization of Highway Air Space Definitions: “Air space” A specific, legally described area, which lies under or over another structure, such as a highway facility, railroad tracks, etc. “Air rights” The right to use and control open space above the property owned by another party. Field research data point to a three-pronged investigation:

2. Utilization of Highway Air Space Incentives: Intense urbanization of cities Scarcity of developable sites of a substantial area downtown Urban highway corridors as extensive empty spaces dividing the city Opportunity for shaping city form Untapped source for unlocking revenue for metropolitan development Definitions: “Air space” A specific, legally described area, which lies under or over another structure, such as a highway facility, railroad tracks, etc. “Air rights” The right to use and control open space above the property owned by another party.

3. Historical Context First significant project – Ponte Vecchio exterior and interior views; Florence, 14 th century. First case in U.S. – before and after views of New York Central Railroad and newly decked Park Avenue, New York City, 1900s.

4. Linear Cities Le Corbusier – plan for Algiers, 1930-34. Edgar Chambless – “Roadtown,” 1910. Tokyo’s “Linear City,” 1964

5. An Evolving Case Study Urban Development Goals: Renewed interest if air rights utilization as a catalyst for urban development. New Memorandum of Understanding between the Massachusetts Turnpike Authority (MTA) & the Boston Redevelopment Authority (BRA) resulting in a corridor master plan known as “Civic Visions” Central Artery Massachusetts Turnpike

6. The Pioneers: Hancock & Copley Place Vital Statistics: Area (S.F. + %USE) Hancock (garage-retail) Parking: 734,000 (97%) Retail: 26,000 (3%) Office: N/A (0%) Copley Place Parking: 340,000 (25%) Retail: 360,000 (27%) Office: 640,000 (48%) Indicators (%) - respectively ROTA: 11.21 / 9.62 % ROE: 11.79 / 7.37 % IRR: 22.04 / 21.73 % Hancock (garage-retail), 1976 Copley Place, 1984

7. Return Measures Return Measures – trends

8. Air Rights Development Premium A = V- P, in which, A = the residual value of the air rights V = the value of a comparable fee parcel P = the air rights construction premium A = V- (D + T + P + O), in which, D = Deck (Structural) T = Tunneling Expenses P = Parking (Above Ground) O = Other, i.e. soft costs/carrying costs/etc. A = V- (D + T + P + O) + LA + BD + SV +ZT, in which, LA = Land Assembly savings BD = Minimal or no Building Demolition costs SV = Site Visibility marketing gains ZT = Zoning Treatment (Taxation) benefits

9. Air Rights Development Premium Air rights costs vary according to the scope of air rights construction – usually structure up to the deck – compared to conventional work – structure upwards from the deck. Diagram – Copley Place structural grid in preparation of air rights deck

10. AASHTO & Metro Surveys Lessons Learned Joint development of transportation corridor air space is viable in dense urban locations where the demand for space and related land values have reached levels where, in spite of the increased construction costs. Revenue expectations can be met and can still render the value of the air rights competitive to adjacent sites on terra firma. An expanded view of cost-benefit analysis must be adopted, one that takes into account not only the immediate monetary returns, but also, the health and vitality of a community that has been knit together again.

11. Construction Challenges Highway air space projects often exhibit increased risk due to site restrictions: Allow for continued/safe corridor use Phase the work for least disruption Strain to adjacent businesses/residents Form w/ long spans/transfer beams Unfamiliar/special building assembly Limited space for staging/storage Limitations imposed on the construction have a negative impact on labor cost: Cost for labor raised significantly as amount of work that is scheduled in nights and weekends increases. Construction time prolonged as amount of work that can be scheduled in a 24- hour period is reduced Extended time and budget increase project financing costs and the associated project market timing risk

12. Urban Regeneration Potential Socioeconomic indicators (before and after air rights development show positive effects in terms of household value, rent and income. * Tracts No. 105, 106 and 107 for Back Bay; No. 703, 706, 707 and 708 for South End Joint development of highway air space is viable in dense urban locations where the demand for space and related land values have reached levels where, in spite of the increased construction costs. Revenue expectations can be met and can still render the value of the air rights competitive to adjacent sites on terra firma. An expanded view of cost-benefit analysis must be adopted, one that takes into account not only the immediate monetary returns, but also, the health and vitality of a community that has been knit together again.