HomeMy WebLinkAboutVILLAGE COOPERATIVE FORT COLLINS - PDP - PDP160036 - SUBMITTAL DOCUMENTS - ROUND 2 - VARIANCE REQUESTDecember 7, 2016
City of Fort Collins Development Review
Marc Virata
281 N. College Ave.
Fort Collins, CO 80524
(970) 221-6567
Project # 1284-001
Village Cooperative Utility Plans
Variance Request for Section 9.3.3.a Adequate Intersection Sight Distance
Variance description:
This is a request for variance to Standard contained in Section 9.3.3.a of the Larimer County Urban Area
Street Standards which pertains to the Adequate Intersection Sight Distance at driveways.
Variance to this standard will allow for the use of AASHTO’s interpretation in quantifying adequate
intersection sight distance which will provide drivers a comparable degree of safety as with the Larimer
County Standards.
Technical Design Criteria:
Section 9.3.3 A: Adequate Intersection Sight Distance. To the extent possible, all openings for driveway
shall be located at the point of adequate sight distance along the street. Accesses to commercial, office
and multifamily residential establishments shall have sufficient space reasonably clear of and
obstructions to provide drivers entering the property sufficient sight distance for proper and safe
movements.
Variance Justification Criteria:
The professional Engineer must determine and state that the variance will not be detrimental to the
public health, safety and welfare, will not reduce design life of the improvement nor cause the Local
Entity additional maintenance costs. The proposed plan (as varied) must advance the public purpose of
the standard sought to be varies equally well or better than would compliance with such standard.
Identifying the Issue:
Due to various site constraints, the on-site private drive has been placed along the northern boundary of
the proposed development parcel while the building is in the southwestern corner. Having any building
located in this corner would be challenging due the existing alignment of Stanford drive. From the
intersection with Horsetooth, Stanford veers east with a radius of approximately 332’, shortly thereafter
arching to the east in a compound curve of approximately 310’ radius. The existing radii do not comply
with the roadway classification of a minor collector. This existing geometry and posted speed limit of 25
mph is more consistent with a local commercial roadway. Utilizing the sight distance requirement
associated with a minor collector would result in a substantial encumbrance across this site.
Justification:
The AASHTO Geometric Design of Highways and Streets is a highly-regarded guidebook that has been
used for Civil Engineering design for multiple decades. We request the City refer to the AASHTO
Geometric Design of Highways and Streets for the Intersection Sight Distance requirement.
It is our understanding that for the classification of Stanford Road, the design speed is 40 mph. Based on
a design speed of 40 mph, per Figure 7-16 of the Larimer County Urban Street Standards, a minimum
sight triangle of 660’ is required. The driveway is approximately 350’ north of Horsetooth Road.
The variance we are requesting is that the sight distance triangle for the driveway be reduced from 660’
to 335’. This reduced distance provides AASHTO’s requirements for a design speed of 35 mph (see
attached AASHTO table 9-6 and 9-8). This virtually ensures visibility into the northerly edge of the
intersection of Horsetooth Road as well as most of the proposed free right turn lane.
This also provides more than the minimum required sight distance for a design speed of 30 mph per
Larimer County Urban Area Street Standards. This design speed is, in fact, what LCUASS requires in the
design of Local Commercial Roadways. As stated above, the geometry of Stanford Road more generally
conforms to a Local Commercial Roadway. Stanford Road is currently signed for 25 mph.
We do not feel that this variance will be detrimental to the public health, safety or welfare, nor will it
reduce the design life of any public roadway or cause the City of Fort Collins additional maintenance
costs.
Please call if you have any questions.
Sincerely,
Adam Boese, E.I. Stephanie Thomas, P.E.
Project Engineer Project Engineer
Calculated
(ft)
Design
(ft)
LCUASS
(Figure
7-16)
15 80 165.4 170 210
20 115 220.5 225 210
25 155 275.6 280 260
30 200 330.8 335 310
35 250 385.9 390 520
40 305 441 445 660
45 360 496.1 500 830
50 425 551.3 555 1030
55 495 606.4 610 1240
60 570 661.5 665 -
65 645 716.6 720 -
70 730 771.8 775 -
75 820 826.9 830 -
80 910 882 885 -
Calculated
(ft)
Design
(ft)
LCUASS
(Figure
7-16)
15 80 143.3 145 210
20 115 191.1 195 210
25 155 238.9 240 260
30 200 286.7 290 310
35 250 334.4 335 520
40 305 382.2 385 660
45 360 430 430 830
50 425 477.8 480 1030
55 495 525.5 530 1240
60 570 573.3 575 -
65 645 621.1 625 -
70 730 668.9 670 -
75 820 716.6 720 -
80 910 764.4 765 -
AASHTO Table 9-6 Design Intersection Sight Distance - Left Turn from Stop
Intersection Sight Distance for Passenger Cars
Intersection Sight Distance for Passenger Cars
AASHTO Table 9-8 Design Intersection Sight Distance - Right Turn from Stop
Note: Intersection sight distance shown is for a stopped passenger car to turn right onto a two-lane highway
with no median and grades 3 percent or less. For other conditions, the time gap should be adjusted and the
sight distance recalculated.
Design
Speed
Stopping
Sight
Distance
Design
Speed
Stopping
Sight
Distance
Note: Intersection sight distance shown is for a stopped passenger car to turn left onto a two-lane highway
with no median and grades 3 percent or less. For other conditions, the time gap should be adjusted and the
sight distance recalculated.