188 COMMISSION ON BUILDING DISTRICTS 



the walls are light in color the reflected light is a considerable part of the 

 total illumination. The importance of light colored walls in the daylight 

 illumination of buildings cannot be too strongly emphasized. 



Statement b^ Herbert S. Swan, Expert Investigator, Committee on 



City Plan, May 19, 1916 

 Relation of high buildings to street congestion 



Buildings in the downtown section of Manhattan have been erected 

 without any reference to the street width. The average frontage height 

 nil Trinity J 'lace and Church Street, between Morris and Chambers, is 

 9.18 stories; on Nassau Street, between Wall and Frankfort, 9.21 stories; 

 on New Street, 12.24 stories; on Broadway, below Chambers, 13.92 stories; 

 and on Exchange Place, 14.90 stories. On Trinity Place and Church Street 

 this is 1.8 times the average street width; on Broadway. 2.5 times; on 

 Nassau Street, 3.0 times ; on New Street, 4.6 times, and on Exchange Place, 

 5.6 times. 



The effect of these extreme heights is to render the street width 

 absolutely inadequate to care for the traffic accompanying such heights. 



The ordinary lot in New York is 100 feet deep. The average net 

 rentable floor space per occupant in an office building is about 75 square 

 feet. The approximate number of occupants on any given street, assum- 

 ing the street to be used entirely for office purposes with a rentability of 

 100 per cent may he ascertained by using these factors in connection with 

 the average frontage height in stories. Proper allowance must, of course. 

 be made for the progressive diminution of net rentable floor area accom- 

 panying each increment in height. 



To make one street comparable with another, proper allowance must 

 also be made for any space occupied by parks, public spaces, public build- 

 ings, churches and cemeteries. In making these estimates, the portion of 

 the street frontage devoted to such purposes has been deducted from the 

 total frontage. The street intersections have, however, been regarded as 

 belonging exclusively to the street under consideration in each case. These 

 might more appropriately have been apportioned between the particular 

 street under consideration and its bisecting streets, but the difficulty encoun- 

 tered in doing this made it in feasible. Each street is considered as a unit. 

 The inclusion of the street intersections makes the congestion appear smaller 

 than is actually the fact. 



Estimated on this basis. New Street has at present an office population 

 of 16.952: Exchange Place, 18,401; Nassau Street, 26,109; Trinity Place 

 and Church Street. 37,702, and Broadway, below Chambers Street, 55,540. 

 The total office population of these five streets is 154,704. 



What the office population on these five streets would be at different 

 average frontage heights may be summarized as follows : 











Broadway, 





Increase 



1 [eight 





Trinitv Place 





Below 





Over 



in 



Nassau 



and Church 



New 



Chambers 



Exchange Total 



Present 



Stories 



Street 



Street 



Street 



Street 



Place Population 



Population 



15 



40.230 



58.080 



20.415 



50.580 



18.525 



196,830 



42,126 



20 



51960 



75,000 



26,360 



76.940 



23.9S0 



254.240 



99,536 



25 



62.S2S 



90,275 



31.725 



92.625 



28.875 



306,025 



151,323 



30 



72,150 



104.190 



36,630 



106,860 



33,330 



353,160 



201,840 



