§ 15.01.1900. Access characteristics.

Recommendations for access characteristics discussed in this section include the following:

•

Driveway width

•

Curb return radii

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Vertical profile of driveway

•

Driveway throat length

•

Minimum separation of gate on private access from public street

All recommendations in this section assume the following:

•

The design vehicle for residential and commercial accesses is a passenger car

•

The design vehicle for industrial accesses is a WB-50, with the exception of the North Pointe Business Park including the Price property, which will be designated by the city engineer based on the type of anticipated vehicle usage.

Although some larger vehicles such as delivery vehicles do need access to commercial areas, these types of trips do not typically occur during the peak periods of the day. The entire access (ingress and egress side) can therefore be used by a larger vehicle during off-peak times. This is more efficient than utilizing more area to make larger radii and access widths and is also more ideal for pedestrians. Access driveways that will be heavily utilized by trucks and busses during peak periods should be designed to the industrial recommendations.

Table 5 shows driveway widths and curb radii for various intersection types depending on the functional classification of the adjacent roadway.

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Table 5. Driveway Widths and Curb Return Radii

Access Type	Total Driveway Widths & (Ingress Lane Width) in Feet				Curb Return Radii in Feet
	Arterial	Major Collector	Minor Collector	Local	Arterial	Major Collector	Minor Collector	Local
Residential (SFDU) 1 dwelling unit	n/a	n/a	12 (n/a )	12 (n/a )	n/a	n/a	n/a	n/a
Multi-Family (less than 3 units)	n/a	18 (n/a )	18 (n/a )	18 (n/a )	n/a	n/a	n/a	n/a
Multi Family (more than 3 units)	26 (n/a )	26 (n/a )	26 (n/a )	26 (n/a )	20	20	20	25
Commercial (1 exit lane)	26 (14)	26 (14)	26 (14)	26 (14)	20	20	20	25
Commercial (2 exit lanes)	40 (16)	40 (16)	n/a	n/a	20	25	n/a	n/a
Industrial	36 (22)	36 (22)	36 (22)	n/a	45	45	45	n/a
Notes:
1. This type of access is not striped.
2. This type of access is a "dustpan" style access; therefore, no curb-return radius applies.

 

Table 6 shows the required curb radius measured from top back of curb (TBC) for the various street intersections within American Fork City. Deviation from these standards requires approval in writing from the city engineer.

Table 6. City Street Curb Radii (feet)

Right-of-Way Width (feet)	Right-of-Way Width (feet)
	60	66	82	96
60	25	25	30	30
66	25	30	35	35
82	30	35	45	45
96	30	35	45	45
Notes:
1. All measurements are in feet.
2. Based on currently adopted American Fork City standards.

 

Table 7 contains maximum change in grade between the cross-slope of the roadway and the slope of the driveway. The maximum change in grade reported is the algebraic difference in slope. For example, if a negative two percent cross-slope connects to a positive two percent driveway slope, the algebraic change in grade is four percent. Likewise, if the cross-slope is negative two percent and the driveway slope is negative six percent, the algebraic change in grade is also four percent. Table 6 also shows the maximum change in grade where no vertical curves are required (rounding only) as well as the maximum change in grade with vertical curves provided.

Table 8 shows the recommended driveway throat lengths for various access types and based on what type of conflict is closest to the adjacent road. When an internal intersection will be the first conflict encountered when entering a driveway, a shorter throat is typically needed then for a site where the driver will encounter parking spots after entering the access.

Table 9 shows the minimum separation of a gate on a private access from the edge of traveled way for various design vehicles. This separation is necessary so that a vehicle can park in front of the gate while it is still closed without the rear of the vehicle obstructing the flow of traffic. Where the possibility of queuing exists, such as at a gated residential community, a traffic study should be completed to determine the 95th percentile queue length during the peak hour.

Table 7. Change in Driveway Vertical Profile

Access Type	Maximum Change in Grade No Vertical Curve Required				Maximum Change in Grade Vertical Curve Required
	Arterial	Major Collector	Minor Collector	Local	Arterial	Major Collector	Minor Collector	Local
Residential (SFDU)	n/a	n/a	8%	10%	n/a	n/a	10%	12%
Multi-Family (3 or less units)	n/a	8%	8%	10%	n/a	10%	10%	12%
Multi Family (4 or more units)	4%	7%	8%	10%	5%	7%	10%	12%
Commercial (1 exit lane)	4%	7%	8%	10%	6%	7%	10%	12%
Commercial (2 exit lanes)	4%	7%	n/a	n/a	5%	7%	n/a	n/a
Industrial	4%			n/a	5%			n/a
Notes:
1. Rounding by taking care to avoid abrupt change in grade.

 

Table 8. Recommended Driveway Throat Length (feet)

Access Type	First conflict within the site is:
	Parking	Internal Intersection
Residential (SFDU)	n/a	n/a
Multi-Family (3 or less units)	n/a	n/a
Multi Family (4 or more units)	75	30
Commercial (1 exit lane)	75	30
Commercial (2 exit lanes)	75	50
Industrial	75	75
Notes:
1. For signalized accesses with three egress lanes, throat length should be at least 200 feet long. For signalized accesses with four egress lanes, throat length should be at least 300 feet long. These lengths should also be verified by a traffic study.

 

Table 9. Minimum Setback of a Gate on a Private Access from a Private Street

Design Vehicle	Minimum Distance (feet)
Passenger Car	25
Single Unit Truck	35
Bus	50
Recreational Vehicle	35
Recreational Vehicle Pulling a Trailer	60
WB-40	50
WB-50	60
WB-62	75
WB-67	80
Notes:
1. Measured form the edge of the sidewalk to the gate. Traffic study required if multiple vehicles are expected to use the gate.
2. For a gate controlled access from a public street an SU design vehicle should be able to complete a three-point turn within the throat, see St. Dwg. #15.38A.

 

(Ord. No. 2012-05-15, § 2, 5-8-2012)

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