142 MASS. EXPERIMENT STATION BULLETIN 170. 



towiis. Many of these old towns are arranged with exceptionally wide 

 streets that from earlj^ times were systematically planted with shade 

 trees. Some of these streets are 300 feet wide and have two rows of shade 

 trees on either side of the street. On the other hand, many towns are 

 poorly laid out, with no proper provision, or at any rate very poor pro- 

 vision, for planting trees. 



Fk;. 12. — Narrow avenue, showing trees planted alternately 

 about 45 feet apart. 



Most towns will not accept a highway under 40 feet wide, which is 

 narrow enough for tree planting; in fact, it would be much better if towns 

 would not accept avenues less than 50 or 60 feet in width. Some of our 

 modern cities, when laying out avenues, now make provision for a tree 



Fiii. 13. — Plan of modern avenue provided with a 40-foot roadbed, 

 6-foot sldewaliis, 23-foot tree belts, with alternating rows of trees 

 60 feet apart. 



belt or a space between the curbing and the sidewalk where trees may be 

 planted. This space should be at least 4 feet wide, and 20 or even 30 feet 

 %vide is better. A tree belt 2 or 3 feet wide is far better than none, 

 since this allows some space for planting. In case the sidewalk comes 

 next to the curbing, and a special tree belt is lacking, it is always advis- 



