HomeMy WebLinkAboutSILVER OAKS - PRELIMINARY - 14-88F - SUBMITTAL DOCUMENTS - ROUND 1 - TRAFFIC STUDY0 0
HORSETOOTH WEST
SITE ACCESS STUDY
FORT COLLINS, COLORADO
AUGUST 1992
Prepared for:
Tri Trend Homes
1505 Timberline Road
Fort Collins, CO 80524
Prepared by:
MATTHEW J. DELICH, P.E.
3413 Banyan Avenue
Loveland, CO 80538
Phone: 303-669-2061
EXECUTIVE SUMMARY
. Horsetooth West is a proposed commercial and residential
development located near the intersection of Taft Hill Road and
Horsetooth Road. This traffic impact study involved the steps of
trip generation, trip distribution, trip assignment, capacity
analysis, traffic signal warrant analysis, signal progression
analysis, and accident analysis.
This study assessed the impacts of Horsetooth West on the
short range (1995) and long range (2010) street system in the
vicinity of the proposed development. As a result of this
analysis, the following is concluded:
- The development of Horsetooth West is feasible from a
traffic engineering standpoint. At full development as proposed,
approximately 6100 trip ends will be generated at this site daily.
- The Taft Hill/Horsetooth intersection currently operates
acceptably with signal control and the existing geometrics. The
Taft Hill/Bronson intersection operates acceptably considering the
recent delay criteria research.
- By 1995, given development of the residential portion of
Horsetooth West and an increase in background traffic, the
signalized intersection of Taft Hill/Horsetooth will operate
acceptably. The existing geometrics will be adequate at the Taft
Hill/Horsetooth intersection. The stop sign controlled
intersections will operate acceptably.
- By 2010, the Taft Hill/Horsetooth intersection will operate
acceptably in the morning and afternoon peak hours with a typical
four lane cross section with left -turn lanes on each leg. The stop
sign controlled intersections will operate acceptably.
- In the long range future (2010), the proposed stop sign
controlled right-in/right-out access to Taft Hill will operate
acceptably. A right -turn deceleration auxiliary lane is warranted.
This right -turn lane would remove vehicles from the through traffic
stream on Taft Hill, providing a safer condition. This right -turn
lane should be at least 240 feet long including taper and assuming
a 15 mph turn radius.
- With the recommended control and geometrics, the accident
rate should be at an acceptable level for typical urban conditions.
0 0
I. INTRODUCTION
This traffic impact study addresses the capacity, geometric,
and control requirements at and near a proposed development known
hereinafter as Horsetooth West. It is located near the
intersection of Taft Hill Road and Horsetooth Road in Fort Collins,
Colorado.
During the course of the analysis, numerous contacts were made
with the project planning consultant (Gefroh Hattman, Inc.), the
project engineering consultant (Stewart & Associates), and the Fort
Collins Traffic Engineering Department. This study generally
conforms to the format set forth in typical traffic impact study
guidelines. The study involved the following steps:
C _ Collect physical traffic and development data;
Perform trip generation, trip distribution, and trip
assignment,
- Determine peak hour traffic volumes and daily traffic volumes;
- Conduct capacity and operational level of service analyses on
key intersections;
- Analyze signal warrants and signal progression;
- Analyze potential changes in accidents and safety
considerations.
II. EXISTING CONDITIONS
The location of Horsetooth West is shown in Figure 1. It is
important that a thorough understanding of the existing conditions
be presented.
Land Use
Land uses in the area are primarily vacant
or residential.
Residential development exists to the east, across Taft Hill Road,
and to the south of Horsetooth West. A small parcel
of vacant land
exists to the southeast across the Taft
Hill/Horsetooth
I
intersection. To the west of the site, land is
vacant. Land to
the north of this site is large lot residential.
Land in the area
is essentially flat. Beginning at approximately
Horsetooth Road,
Taft Hill Road climbs a small grade to the south.
This small grade
has little effect on traffic operations and no
effect on sight
distance. The center of Fort Collins lies to:
the northeast of
Horsetooth West.
Roads
in Figure
The primary streets near Horsetooth West are shown
2. Taft Hill Road is east of Horsetooth West. It
is a north -south
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SITE LOCATION Figure 1
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11 PRIMARY STREETS Figure 2
street designated as an arterial on the Fort Collins Master Street
Plan. In this area, it has a two lane cross section, with right -
and -left -turn lanes at the Taft Hill/Horsetooth intersection. The
curb locations are established for an eventual four lane urban
cross section adjacent to the site. The posted speed limit is 35
mph. Sight distance is generally not a problem along Taft Hill
Road. The Taft Hill/Horsetooth intersection is signalized. The
nearest other signal along Taft Hill Road is at Drake to the north.
No signals exist south of this site.
Horsetooth Road is south of this site. It is an east -west
street designated as an arterial on the Fort Collins Master Street
Plan. Adjacent to the site, Horsetooth Road is improved to its
future four lane width, but it is striped as a two lane street both
east and west of Taft Hill Road. The excess width is used for
turning lanes approaching the Taft Hill/Horsetooth intersection.
Horsetooth Road is posted at 35 mph. The nearest signalized
intersection along Horsetooth Road is at Shields Street to the
east. No signals exist west of this site.
Existing Traffic
Peak hour traffic is shown in Figure 3. These counts were
obtained in July 1992. Due to the time of year, Olander Elementary
School trips are not included in these counts. Olander School
trips were added to the system as part of the traffic assignment
process shown later in this report. Raw traffic count data is
provided in Appendix A.
Existing Operation
The Taft Hill/Horsetooth and Taft Hill/Bronson intersections
were evaluated regarding operational efficiency. The Taft Hill/
Horsetooth intersection was evaluated using the existing signal
control with existing geometrics and the volumes shown in Figure
3. The peak hour operation is shown in Table 1. Calculation forms
are provided in Appendix B. Appendix C describes level of service
for signalized and unsignalized intersections from the 1985 Highway
Capacity Manual (1985 HCM). Operation at this intersection is
acceptable during the peak hours. Acceptable operation is defined
as level of service D or better.
At the Taft Hill/Bronson intersection, operation is acceptable
except for left -turn exits from Bronson during the afternoon peak
hour. According to the unsignalized intersection technique from
the 1985 HCM, the level of service for the left -turn exits in the
afternoon peak hour is in category E. Based upon recent research,
contained in Appendix D, the delay is estimated at 14-24 seconds
per approach vehicle. This delay is more appropriately defined as
level of service C/D. Table 1 also shows the level of service for
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HORSETOOTH
AM/PM
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1992 PEAK HOUR TRAFFIC
Figure 3
Table 1
1992 Peak Hour Operation
Intersection
Horsetooth/Taft Hill (signal)
Taft Hill/Bronson (stop sign)
WB LT
WB RT
SB LT
Level of Service
AM PM
B B
D (A/B)* E (C/D)*
A B
A A
( )* Level of service considering recent research related vehicle
delay.
these left turns based upon this research. This type of operation
is typical where minor streets intersect with arterials. It is
considered to be acceptable as long as alternative means of access
are provided in the same general area. The Rossborough area has
numerous alternative means of both ingress and egress.
III. PROPOSED DEVELOPMENT
Horsetooth West is a proposed commercial/residential
development located near the intersection of Taft Hill Road and
Horsetooth Road in Fort Collins. Olander Elementary School was a
part of the previous Horsetooth West Overall Development Plan.
This school has been built and is in operation. Figure 4 shows a
schematic of the site plan of the Horsetooth West Overall
Development Plan, indicating location of the uses shown in Table
2, Trip Generation. The short range analysis (1995) included the
existing school and the residential portions of the overall
development plan. The long range analysis (2010) included full
build out of the Horsetooth West Overall Development Plan and an
increase in background traffic in general accordance with the
"North Front Range Corridor Study."
Trip Generation
Trip generation is important in considering the impact of a
development such as this upon the existing and proposed street
system. Trip Generation, 4th Edition, ITE was used to project
trips that would be generated by the proposed uses at this site.
Table 2 shows the expected trip generation on a daily and peak hour
basis. No adjustments were made for transit or ridesharing.
Therefore, the trip generation can be considered conservatively
high.
Trip Distribution
A number of directional distributions of the generated trips
were determined for Horsetooth West. The trip distributions are
shown in Figure 5.
Traffic Projections
Traffic projections for the short range time period (1995)
were obtained by factoring the existing traffic by 102 percent per
year. A school trip assignment was also performed since the
existing traffic was counted in the summer.
The long range projections (2010) used daily traffic obtained
from the North Front Range Transportation Planning Process. These
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TAFT HILL ROAD
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SITE PLAN Figure 4
Table 2
Trip Generation
Daily
A.M.
Peak
P.M.
Peak
Land Use
Trips
Trips
Trips
Trips
Trips
in
out
in
out
PARCEL A
43 S.F. D.U.
430
9
24
27
16
PARCEL B
78 S.F. D.U.
780
16
43
23
29
PARCEL D
61 S.F D.U. &
710
14
41
45
26
16 M.F. D.U.
PARCEL E
C-store/gas
2000
54
54
63
63
Day Care
420
38
34
37
40
Retail
610
5
2
31
29
Office
230
24
4
5
20
PARCEL F
Elementary School
590
63
42
6
8
PARCEL G
58 M.F. D.U.
350
6
25
27
12
TOTAL
6120
229
269
264
243
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RESIDENTIAL TRIPS
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5% �10%—
HORSETOOTH
ae
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CONVENIENCE STORE
75% Passby
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SITE
10%
HORSETOOTH
olae
SCHOOL TRIPS
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10%/5%
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SITE
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30%/5%
25%/40%
HORSETOOTH
a°
ae
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9
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Ln
RETAIL -DAY CARE / OFFICE
TRIP DISTRIBUTION
Figure 5
daily volumes were factored to obtain the expected peak hour
traffic.
Trip Assignment
Trip assignment is how the generated and distributed trips are
expected to be loaded on the street system. The assigned trips are
the resultant of the trip distribution process. Figure 6 shows the
short range morning peak hour assignment and the afternoon peak
hour assignment of the residential portion of the Horsetooth West
generated traffic plus background traffic. Figure 7 shows the long
range peak hour assignment of full development of Horsetooth West
with the background traffic.
Signal Warrants
As a matter of policy, traffic signals are not installed at
any location unless warrants are met according to the Manual on
Uniform Traffic Control Devices. Using the traffic forecasts shown
in Figures 6 and 7, it is not likely that a signal will be
warranted at any of the key intersections near Horsetooth West.
Signal Progression
Signal progression was not evaluated since no new signals are
anticipated in this area.
Operations Analysis
Capacity analyses were performed on key intersections adjacent
to Horsetooth West. Using the traffic volumes shown in Figure 6
and the existing geometrics, the intersections operate in the short
range condition as indicated in Table 3. Calculation forms for
these analyses are provided in Appendix E. The Taft Hill/
Horsetooth signalized intersection operates acceptably. The Taft
Hill/Bronson stop sign controlled intersection operates acceptably
considering the vehicle delay research cited earlier. The two stop
sign controlled intersections along Horsetooth Road operate
acceptably.
Using the traffic volumes shown in Figure 7, the intersections
operate in the long range future as indicated in Table 4.
Calculation forms for these analyses are provided in Appendix F.
It is expected that by this future date (2010), Horsetooth West
will be at full development. It is assumed that both Taft Hill
Road and Horsetooth Road will have four lane urban cross sections
with auxiliary lanes at appropriate locations. It is also assumed
that Horsetooth Road will connect to Overland Trail to the west of
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18/29
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HORSETOOTH) j
23/81
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j 103/212
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105/75
249/
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123/78
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AM / PM
SHORT RANGE PEAK HOUR TRAFFIC Figure 6
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Lo
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Lo
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r-
20/25
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HORSETOOTH)
1
—25/85
10/15
15/25
285/265
405/340 —g-
5/10�`
Lo0 �
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CD
AM / PM
0
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15/10
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35/50 —�
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BRONSON
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5/10
35/25
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25/30
�n o
0000
N co m
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1"*�— 105/310
55/80 f— 130/280
265/440 J 1 -/ 140/285
190/ 140 —�
210/175 —�
70/90
LONG RANGE PEAK HOUR TRAFFIC Figure 7
Table 3
Short Range Peak Hour Operation
Level of
Service
Intersection
AM
PM
Horsetooth/Taft Hill (signal)
B
C
Taft Hill/Bronson (stop sign)
EB LT/T
D (C/D)*
E (C/D)-
EB RT
B
B
WB LT/T
D (C/D)*
E (C/D)-
WB RT
A
C
SB LT
A
B
NB LT
A
A
Horsetooth/Local Street (stop sign)
SB RT/LT
A
A
EB LT
A
A
Horsetooth/Auntie Store (stop sign)
NB LT/T
A
A
NB RT
A
A
SB LT/T
A
A
SB RT
A
A
EB LT
A
A
WB LT
A
A
( )* Level of service considering recent research related vehicle
delay.
•
Table 4
Long Range Peak Hour Operation
Level of
Service
Intersection
AM
PM
Horsetooth/Taft Hill (signal)
C
D
Taft Hill/Bronson (stop sign)
EB LT/T
E (D)*
F (D)*
EB RT
A
A
WB LT/T
E (C/D)*
E (D)*
WB RT
A
B
SB LT
B
D
NB LT
C
D
Horsetooth/Local Street (stop
sign)
SB RT/LT
C
C
EB LT
A
A
Horsetooth/Auntie Store (stop
sign)
NB LT/T
B
C
NB RT
A
A
SB LT/T
C
D
SB RT
A
A
EB LT
A
A
WB LT
A
A
Taft Hill/right-in/right-out
(stop sign)
EB RT
A
A
( )* Level of service considering recent research related vehicle
delay.
Horsetooth West. The exact location of that intersection and the
future alignment of Overland Trail will be the subject of future
planning and engineering studies by the City of Fort Collins. The
Taft Hill/Horsetooth signalized intersection is expected to operate
acceptably. It is expected that the only auxiliary lanes necessary
will be the left -turn lanes on each leg. The Taft Hill/Bronson
stop sign controlled intersection will operate acceptably
considering the vehicle delay research cited earlier. Minor street
left turns and throughs will find that the delay, particularly
during the peak hours, will increase. However, signals are not
warranted at this intersection. The movements which will
experience this delay do have convenient, alternative routes
through signalized intersections. Even if all the minor street
left turns and throughs use the Taft Hill/Horsetooth intersection,
it will continue to operate acceptably. The stop sign controlled
intersections along Horsetooth Road are expected to operate
acceptably.
At this level of development, the overall development plan
shows a right-in/right-out access approximately 300 feet north of
Horsetooth Road along Taft Hill Road. At the right-in/right-out
driveway access and Taft Hill intersection, the right -turn
entrances warrant an exclusive right -turn lane. According to
Section 1.02.08 of Design Criteria and Standards for Streets, City
of Fort Collins, 1986, this right -turn lane and taper should be 500
feet at a 50 mph design speed. This would require a right -turn
lane extending from the driveway through the Taft Hill/Bronson
intersection. The posted speed on Taft Hill Road is 35 mph. The
distance from the right-in/right-out access to Bronson is just over
300 feet. If the access were designed to accommodate a 15 mph
turn, then the deceleration lane length at 35 mph is 240 feet (from
"Intersection Channelization Design Guide," NCHRPR 279, TRB, 1985,
Pg. 65). This will comfortably fit into the available separation
between the access and Bronson. It is recommended that this
criteria be used in designing this access. A right -turn
acceleration lane is not recommended at this access. Exiting
vehicles should be stopped and required to wait for an acceptable
gap in the southbound traffic on Taft Hill Road. There is already
a median on Taft Hill Road so further channelization is not
necessary.
Typically, the City of Fort Collins requires a "with/without"
analysis to justify a right-in/right-out on an arterial. This
analysis evaluates how other key intersections will operate with
and without the proposed access. A cursory analysis indicates that
this access will have little impact on adjacent intersections. The
access is more one of convenience for the future commercial parcel.
A properly designed right-in/right-out access will not negatively
impact the operation of the through lanes on Taft Hill Road. It
is, therefore, recommended that the City consider allowing the
right-in/right-out access.
5
I
Accident Analysis
_The recommended control devices and geometrics should minimize
vehicular conflicts and maximize vehicle separation. Therefore,
the accident rate should be at its minimum for a typical urban
condition.
IV. CONCLUSIONS
This study assessed the impacts of Horsetooth West on the
short range (1995) and long range (2010) street system in the
vicinity of the proposed development. As a result of this
analysis, the following is concluded:
- The development of Horsetooth West is feasible from a
traffic engineering standpoint. At full development as proposed,
approximately 6100 trip ends will be generated at this site daily.
- The Taft Hill/Horsetooth intersection currently operates
acceptably with signal control and the existing geometrics. The
Taft Hill/Bronson intersection operates acceptably considering the
recent delay criteria research.
- By 1995, given development of the residential portion of
Horsetooth West and an increase in background traffic, the
signalized intersection of Taft Hill/Horsetooth will operate
acceptably. The existing geometrics will be adequate at the Taft
Hill/Horsetooth intersection. The stop sign controlled
intersections will operate acceptably.
- By 2010, the Taft Hill/Horsetooth intersection will operate
acceptably in the morning and afternoon peak hours with a typical
four lane cross section with left -turn lanes on each leg. The stop
sign controlled intersections will operate acceptably.
- In the long range future (2010), the proposed stop sign
controlled right-in/right-out access to Taft Hill will operate
acceptably. A right -turn deceleration auxiliary lane is warranted.
This right -turn lane would remove vehicles from the through traffic
stream on Taft Hill, providing a safer condition. This right -turn
lane should be at least 240 feet long including taper and assuming
a 15 mph turn radius.
- With the recommended control and geometrics, the accident
rate should be at an acceptable level for typical urban conditions.