HomeMy WebLinkAboutFOX GROVE - PDP - PDP130029 - SUBMITTAL DOCUMENTS - ROUND 2 - VARIANCE REQUESTJune 17, 2014
City of Fort Collins Development Review
Tyler Siegmund
281 N. College Ave.
Fort Collins, CO 80524
(970) 221-6573 Project # 335-008
Fox Grove Utility Plans
Variance Request for Section 8.2.14 Intersection Sight Distance
Variance Description:
This is a request for Variance to Standard contained in Section 8.2.14 of the Larimer County Urban
Area Street Standards which pertains to the minimum sight distance allowed at intersections.
Variance to this standard will allow the existence of 1 lot along Kit Den Drive in the Fox Grove
development.
Technical Design Criteria:
Section 8.2.14 Intersection Sight Distance.
Street intersections shall be designed so that adequate sight distance is provided along all streets.
The required sight distance shall be determined by the design speed and grades of the street and
the acceleration rate of an average vehicle as prescribed below.
A. Minimum Requirements
All designs must provide minimum safe stopping sight distance in accordance with Chapter
7, Street Design and Technical Criteria, and AASHTO. In addition, for all streets that
intersect with Arterial and Collector streets, the sight distance must be large enough to allow
a vehicle to enter the street and accelerate to the average running speed without interfering
with the traffic flow on the Arterial or Collector street. The design sight distance values to
be used are provided in Figure 7-16.
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 varied equally well or better than would compliance with such
standard.
Identifying the Issue:
The proposed Carriage Parkway alignment ties directly to existing features northeast of the site
making it the controlling horizontal geometry on site. Carriage Parkway makes a large sweeping
bend starting from the Northeast corner heading south to make a perpendicular intersection with
the southern property boundary, thus allowing the future (minor collector) connection between
Mulberry and Prospect and connecting the future development to the South.
This bend creates sight distance issues at the intersection of Carriage Parkway and Tod Drive.
Using the LCUASS standards for an intersection with a minor collector (40 mph), the sight distance
measurement would be 660’. This sight distance bisects one proposed lot, creating a lot that is
unusable.
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.
For a design speed of 40 mph, on a 2 lane collector, AASHTO requires a 385 ft sight distance
measurement for Case B2 (Right Turn from Stop and Crossing Maneuver), and a 445 ft sight
distance measurement for Case B1 (Left Turn from Stop).
This standard would allow these 2 proposed lots to have fences and be more utilized. No safety
issues are expected with this adjustment.
Please see the attached exhibit showing the differences between the AASHTO standard sight
distance and the LCUASS standard.
Sincerely,
Stephanie J. Thomas
Professional Engineer