HomeMy WebLinkAboutBEST WESTERN TRANSMISSION PUD LOT 1 FINAL - 15 93A - CORRESPONDENCE - CITY STAFFIV Design Elements
Radii and Width
The swept path diagram on
Figure 4 shows that a 15-foot
A critical element of driveway de- (5 m) flare would give operational
sign is the radius of the curb re- results equally as effective as a
turn or amount of flare or taper of curb return with a 15-foot (5 m)
the curbing connecting the edge radius. For single-family residen-
or throat of a driveway with the tial driveways, flares are probably
edge of the nearest travel lane. just as good as radii. On the larger
The radius should be related to swept path radii needed for com-
the swept path of a vehicle mak- mercial and industrial driveways,
ing a right turn in or out consider- however, the curved area of pav-
ing the width of the adjacent
street lane and the width of the
driveway. Figure 4 shows the path
of a passenger car entering drive-
ways of two different designs,
both with 30-foot (9 m) throats,
measured at a point 15 feet (5 m)
from the curbing. A 12-foot (4 m)
roadway lane has been assumed,
with the vehicle beginning its
turn from the outer edge of the
lane. In the upper portion of this
figure, a flare of only two feet (60
cm) has been used. Obviously, a
vehicle would occupy a substan-
tial portion of the throat in enter-
ing the driveway, and a vehicle ex-
iting from the driveway would be
in direct conflict with an entering
vehicle. If an exiting vehicle is
waiting in the driveway, the enter-
ing vehicle would have to stop in
the traveled lane until the other
vehicle was able to leave. The po-
tentials for congestion and acci-
dents could be serious, depending
on general traffic conditions.
Operation at a two-way drive-
way with a 30-foot (9 m) throat is
greatly improved if the radii of the
curb returns on both sides of the
driveway are more adequate, as
illustrated in the lower part of
Figure 4. In this case, a vehicle is
able to enter or leave by a right
turn without lane encroachment
at a speed which reduces inter-
ference with through vehicles,
and without conflicting with
other vehicles entering or leaving
the driveway.
ing reduces the total cost of a
driveway and looks better. It may
also facilitate turning move-
ments.
In the Recommended Guide-
lines section, the minimum radii
range from 5 to 20 feet (2 to 6• m),
depending on type of land use
served. Greater radii are often de-
sirable, such as 20 feet (6 m) for
commercial driveways.31
Front overhang
T
I
Cli Inner \ \
— `ear \
\the
Flare 2`� -- 30' 2' Flare
Throat
POOR DESIGN
N
io
15, -T-1 — 30' / — 15'
Radius Throat Radius
GOOD DESIGN
1ft=0.3m
Figure 4. Swept path of passenger car nuns to and tram 12-foor curb lane for 2-way
commercial or industrial driveways.
9
a
have the driveway blocked by vehicles stacked in the left turn lane
on Stuart Street.
Turning templates for passenger vehicles placed on the P.U.D. plan
show that the existing driveway is adequate for passenger vehicle
access. However, adding a curb radius of 15 feet to either side of
the driveway, as shown on the attached sketch, improves the
situation. Engineering staff would consider the addition of such
radii, however the throat of the driveway would be subject to the
35 foot maximum. If turning templates for a 40' long bus (similar
to that for an RV which is apparently associated with the proposed
use on the site) are placed on the plan, it is not the curb cut
location which limits the use of the site, but rather the location
of the existing building in relation to both College Avenue and
Stuart Street.
These comments are based on the informal request you have received.
If the applicant wishes to further pursue the request for
modifications to the curb cut design and location shown on the
preliminary P.U.D., a formal letter should be submitted along with
documentation from a registered professional traffic engineer for
our consideration. A complete traffic study, including an analysis
of the driveway and intersection operations, will be required with
the final P.U.D. and/or any amendment to the preliminary P.U.D.,
regardless of the proposed use.
ti
Commu .y Planning and Environmental rvices
Planning Department
City of Fort Collins
M E M O R A N D U M
DATE: June 30, 1993
TO: Ted Shepard, Senior Planner
FROM: Kerrie Ashbeck, Civil Engineer I Gt-&
THRU: Mike Herzig, Development Review Engineering Manager
RE: REQUEST FOR 45' WIDE CURB CUT ON THE OLD AMOCO SITE
SOUTHEAST CORNER OF SOUTH COLLEGE AVENUE AND STUART STREET
In response to the informal request you have received to widen the
existing eastern most curb cut to 45 feet, the Engineering
Department has the following comments. Current City standards
allow a maximum commercial curb cut width of 35 feet. However,
even if the design standards are being met, all commercial curb
cuts are evaluated and approved by both the Engineering and
Transportation Departments. Among other conditions shown on the
plans and in the staff report, the preliminary P.U.D. was approved
based on the curb cut remaining at 30 feet wide. Therefore, any
new P.U.D. would have to show that widening the curb cut would
create a situation equal to or better than the existing in terms of
safe and efficient operation of the driveway as well as the
intersection of Stuart and College.
Engineering staff has discussed the request for a 45 foot wide curb
cut and determined that the maximum allowable width of 35 feet on
this site cannot be varied. This is due to the proximity of the
existing curb cut to the intersection, especially once the standard
30' radius on the southeast corner is constructed. Stuart is a
collector street and College Avenue is a major arterial. The
volume of traffic and the number of turning movements at such an
intersection makes it important not to compromise the space
available between the driveway and the intersection. For example,
traffic flow on College Avenue cannot be impeded by vehicles
slowing down or stopping on College to wait for a vehicle to
negotiate a right turn into the driveway. In addition to being a
major arterial within the City limits, College Avenue is a limited
access State Highway with a posted speed limit of 40 mph.
Efficient traffic flow is maintained by signalization and
controlled access points. Neither College Avenue nor Stuart Street
can function as the area in which vehicles make, or are impacted
by, maneuvers which should be accommodated by good site design.
Nor is it desirable from the commercial site user's standpoint to
281 North College Avenue • P.O. Box 580 • Fort Collins, CO 80522-0580 • (303) 221-6750