A. MINIMUM STANDARDS FOR ROADS AND STREETS.

Item	CLASS OF ROAD OR STREET
	Local	Collector or Commercial	Primary & Secondary Arterial
Cul-de-sac maximum length (1)	600'	600'	n.a.
Cul-de-sac curb radius	50'	50'	n.a.
Maximum grade	7% 2	5%	5%
Minimum grade (6)	0.50%	0.50%	0.50%
Design speed - mph	25	40	55
Horizontal curve radius	150'	200'	300'
Tangent between reverse curves	50'	200'	200'
Intersection angle - degree	60	75	75
Intersection offset	150'	200'	200'
Curb return radius	20'	30'	35'
Sight distance	250'	650'	900'
AASHTO design values:
Reliability	70–80	80–90	90–95
Standard overall deviation
Concrete	0.35	0.35	0.35
Flexible	0.45	0.45	0.45
PSI loss due to traffic
Concrete	2.2	1.7–2.2	1.7
Flexible	2.2	1.7–2.2	1.7
Minimum pavement thickness on prepared subgrades:
		(Min.)	(Min.)
H.A. Surface	1-1/2"	Designed (1")	Designed (1-1/2")
H.A. Binder	4"	Designed (4") 3	Designed (5") 4
Stone Base	9" (5)	Designed (12")	Designed (14")
or
H.A. Surface	1"	Designed (1")	Designed (1")
H.A. Binder	2"	Designed (3")	Designed (2")
H.A. Base	7"	Designed (8") 3	Designed (10") 4
or
Plain Concrete (7)	6"	Designed (8") 3	Designed (10") 4
Stone Base    on Lime Injected sub-base	6"	Designed (6")	Designed (6")

 

 

Notes: 1.   Cul-de-sac length measured from center of through-street to center of cul-de-sac. 2.   Subject to AASHTO Standards relating to intersection proximity. 3.   Add 1" HAC binder or base or concrete for truck traffic > 10% of ADT. 4.   Add 2" HAC binder or base or concrete for truck traffic > 10% of ADT. 5.   Shall consist of 9" of #53 stone or a combination of 5" of #2 stone and 4" of #53 stone. 6.   This minimum grade requirement shall apply to the curbline of cul-de-sacs and other special pavement considerations. 7.   Concrete pavements utilizing a subbase material having an AASHTO Soil Classification of A-2-6, A-2-7, A-4, A-5, A-6, A-7-5 OR A-7-6 shall have a base course of 4" of #8 stone.