HomeMy WebLinkAboutSite Access Requirements
PERMIT CENTER
HANDOUT ON
ACCESSING CITY STREETS
Informational Brochure
May 2007
Prepared by
Development Section
Engineering Division
Public Works Department
25 West Main St.
Auburn, WA 98001-4998
(253) 931-3010
FAX (253) 931-3053
The intent of this handout is to provide an informative summary of selected sections of
the City of Auburn’s Design Standards dealing with site access. This handout is
intended to aid in understanding the City’s Design Standards manual, not replace or
supercede any portion of the Manual or good engineering practices.
Driveway Locations
While no property will be denied access to the City streets, direct street access is
not guaranteed. Properties may be required to access the street via an alley, or two
or more contiguous properties may be required to share a single driveway. When a
property has frontage on two or more streets, the driveway shall be located on the
street with the lowest classification unless safety considerations dictate otherwise.
Multiple access points to a property will be allowed only after City review and
approval.
Properties located on arterials where no alternate access is available may be
restricted to a right-in right-out driveway. Additionally, these properties may be
required to construct street improvements, including but not limited to C-curb, to
preclude left turning traffic.
The redevelopment of a property will not guarantee that the existing driveways be
retained. The City may eliminate or require modification to any existing driveway not
in conformance with City standards.
The spacing of driveways and their separation from intersections is critical to
maintain traffic flow while providing safe ingress and egress. For all streets except
local residential streets, the “Functional Intersection Boundary” rules apply.
Functional Intersection Boundary See Table 10-4 & Figure 10-3
A functional intersection boundary is the portion of the street leading up to the
intersection required to allow vehicle movements and storage. This is the area
within which drivers identify the situation, change lanes, come to a stop, and wait
before proceeding through the intersection. The minimum maneuvering distance
assumes the driver is in the proper lane and only needs to change lanes for a right
or left turn pocket. The functional length of an intersection is measured from the
stop bar or point of curvature/point of tangency (PC/PT) of the curb return.
Parameters that must be evaluated in the determination of the maneuvering distance
include the following:
d : Decision Distance. The distance traveled during the reaction time required by
1
the driver for preparing to brake or to change lanes and brake.
d : Lane Change Distance. Braking while moving laterally is a more complex
2
maneuver than braking alone.
d : Braking distance traveled during full deceleration and coming to a stop or to a
3
speed at which a turn can be comfortably executed.
d : The storage length of the intersection. This length will depend on the volume of
4
traffic the intersection was designed for.
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Table 10-4
Distance Requirements for Functional Intersection Boundaries
Functional
Lane
Decision Braking Storage Intersection
Reaction Change
Speed Speed Distance Distance Length* Boundary
Time Distance
mph ft/sec (ft) (ft) (ft) Length
(sec) (ft)
”d” ”d” ”d” d+d+d+d
1341234
”d”
2
(ft)
25 mph 37 1 37 25 60 100 222
30 mph 44 1 44 40 86 100 270
35 mph 51 1 51 60 118 100 329
40 mph 59 1 59 85 154 100 398
45 mph 66 1 66 105 194 100 465
50 mph 73 1 73 140 240 100 553
The preceding table lists the minimum distances required. The numbers shown are for
the average passenger vehicle. Intersections with exceptionally high volumes of truck
traffic will require longer distances in all categories.
* Minimum storage distance has been set at one hundred feet (100’). Intersections that
exhibit high volumes of traffic on a consistent basis will be required to design storage
distances based on a traffic study.
Figure 10-3
Functional Length Diagram of an Intersection with Right and Left-Turn Lane
dddd
4 3 2 1
Storage Braking Lane Change Decision
Distance Distance Distance Distance
Physical Length
Functional Intersection Boundaries Length
For intersections where left and right turns are not provided with their own turn pockets,
the lane change distance (d) will become zero (0).
2
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Street intersections will heavily influence driveway locations. Driveways will not be
allowed within the physical length (d+d+d) portion of the “Functional Intersection
432
Boundary” for the side of the street where traffic is entering the intersection.
Restricted access, right-in right-out, may be allowed within the decision distance (d)
1
portion of the “Functional Intersection Boundary” along the direction of traffic. For
the side of the street where traffic is exiting the intersection, restricted access will be
allowed a distance equal to half the stopping distance (½d) plus the decision
3
distance (d) from the intersection. (See Figure 10-4)
1
Figure 10-4
Functional Intersection Boundary Driveway Restrictions
d+d+dd
4321
B
A
C
C
A
B
d+d
32
+d
1
2
A PROHIBITED ACCESS
B RESTRICTED ACCESS
C UNRESTRICTED ACCESS
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Driveway Layout
Driveways shall be designed in such a manner as to allow for efficient and safe
ingress and egress from the City streets. Driveways and on-site parking, other than
that for single-family residences on unclassified roads, shall be designed such that
vehicle-backing maneuvers will not occur onto the street. A properly designed
driveway shall allow the largest typical vehicle that will use the driveway (i.e. tractor-
trailers at large warehouses, beer trucks at mini marts) to enter and exit the site
without encroaching into opposing traffic.
Driveways for adjacent properties should be separated by a minimum of ten feet
(10’) for residential and fifty feet (50’) for commercial/industrial. This distance should
be measured from the outside edge of the driveway apron. When this separation is
not obtainable, a single driveway centered on the property line may be required.
When designing site layout and driveway access, internal circulation shall be such
that onsite traffic will not backup the driveway impeding vehicles in the public street.
The City may require sites with internal traffic congestion to design driveways with
long throat lengths to provide extra storage to avoid impacting City streets.
Driveway Alignment (Horizontal & Vertical)
Driveways should be aligned horizontally to as near perpendicular to the City street
as possible. The angle of intersection to the City street may not be less than
seventy-five degrees (75°). Right-in-right-out driveways where the entering and
exiting lanes are separated by a raised “pork chop” may reduce the angle to forty-
five degrees (45°).
The vertical grade behind the driveway shall not exceed twelve percent (12%) and
shall be designed in such a way as to preclude vehicles dragging when entering or
exiting the site.
Driveway Widths
Residential See Standard Detail Traffic-07 & -08
Residential driveways shall be used when serving four (4) or fewer living units.
Driveway widths shall be a minimum of ten feet (10’) and a maximum of twenty-
four feet (24’). Residential driveways shall be constructed using a minimum
thickness of six inches (6”) of non-reinforced concrete.
Commercial/Industrial See Standard Detail Traffic-09 & 10
Commercial and industrial driveway widths shall be based on the number of lanes
used on the driveway and the type of use. Commercial driveways shall be
constructed using a minimum thickness of eight inches (8”) of reinforced concrete.
The three categories described below will be determined based on the vehicles
expected to use the site.
A. Light commercial/industrial driveways should be used for sites where the
average vehicle use will range from passenger vehicles to small size delivery
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trucks. Examples include mini marts, strip malls, fast-food restaurants,
triplexes, and small apartment buildings. Driveways will have one entering
lane and up to two exiting lanes with the lane widths restricted to a maximum of
twelve feet (12’).
B. Medium commercial/industrial driveways should be used for sites where the
average vehicle use will range from medium to high volumes of passenger
vehicles to multiple medium delivery trucks per day and the occasional large
tractor/trailer delivery truck. Examples include supermarkets, large outlet
stores, shopping malls, large apartment buildings, and busy retail stores
located on arterials. Driveways will have one entering lane and up to two
exiting lanes with the lane widths restricted to a maximum of fourteen feet (14’).
C. Heavy commercial/industrial driveways should be used for sites where high
volumes of medium to large tractor/trailer trucks enter and exit every day.
Examples include manufacturing and storage warehouses. Driveways will have
one entering lane and one exiting lane with the lane widths restricted to a
maximum of sixteen feet (16’).
Driveway uses discussed above may be subject to change based on the street
classification on which they are located. For example: a site use that may
normally fall under the light commercial/industrial classification may be upgraded
to a medium commercial/industrial classification if it is located on a principal or
minor arterial to facilitate moving vehicles off the right-of-way in a more efficient
manor.
Restricted Access Driveways
Restricted Access driveways are typically driveways that do not allow left-hand turns
out of or into the driveway. Development or redevelopment of properties where the
required setback from an intersection cannot be achieved in any direction and
without other ways to access the site will be allowed a restricted access driveway.
The installation of the driveway may require the developer to install “C-curb” at the
road centerline or at the edge of the center turn lane to prevent left turns. In some
cases a raised median may be required.
Restricted Access Driveways will only be allowed upon City approval. The existence
of other driveways in the vicinity that do not meet the above standards will not be
grounds for allowing further substandard driveways.
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NOTE: At the present time the City is working on revising the commercial driveway details
contained herein. Please contact Costa Philippides at 253-804-5063 for the most current
information.
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