HomeMy WebLinkAboutEx 15 - SGM Traffic Impact Study Final2017Exhibit 15 I Traffic Impact Study (SGM)
Lake Springs Ranch
Filing 2 Final Plat Application
April 2018
6SGM
1 1 8 W Sixth St, Suite 200
Glenwood Springs, CO 81601
970.384.9044
www.sgm-inc.com
Lake Springs Ranch
Traffic Impact Study
Garfield County, Colorado
Dan Cokley, PE
License No. 29799
6/1/2017
Table of Contents
Section Page No.
1.0 Introduction 1
1.1 Project Overview 1
1.2 Site Location and Study Area Boundaries 2
1.3 Description of Site 2
2.0 Traffic Analysis Methodology 3
3.0 Existing Traffic Conditions 3
4.0 Future Traffic Conditions without Lake Springs Ranch 9
5.0 Proposed Development Traffic 11
5.1 Traffic Generation 11
5.2 Adjustments to Trip Generation Rates 12
5.3 Trip Distribution 12
5.4 Project Trip Assignment 13
5.5 Traffic Forecasts with the Proposed Development 14
6.0 Total Traffic Analysis and Project Impacts
6.1 Peak Hour Intersection Level of Service
6.2 Access Permit Requirements
6.3 Turn Lane Storage Requirements
6.4 Road Impact Fee Calculation
7.0 Construction Phasing and Traffic
8.0 Summary of Findings
9.0 References
Figures (1 & 2)
Appendix
15
15
16
16
16
17
17
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Lake Springs Ranch Traffic Impact Study
June 2017
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List of Figures
Figure Page No.
1. Vicinity Map END
2. Site Plan END
3. 2016 AM Peak Hour Volumes 4
4. 2016 PM Peak Hour Volumes 4
5. Southbound Approach of CR 114 to SH 82 7
6. Westbound Approach of SH 82 at CR 114/154 8
7. Eastbound Approach of SH 82 at CR 114/154 8
8. Eastbound Approach of North Frontage Road at CR 114 9
9. 2036 Future Background AM Peak Hour Volumes 10
10. 2036 Future Background PM Peak Hour Volumes 10
11. Project Traffic Distributions at SH 82 13
12. Project Traffic Assignments at SH 82 13
13. 2036 Total Traffic AM Peak Hour Volumes 14
14. 2036 Total Traffic PM Peak Hour Volumes 14
List of Tables
Table Page No.
1. 2016 Signalized Intersection Level of Service and Queuing Summary 6
2. 2016 Signalized Intersection Queuing Summary 6
3. 2036 Future Background Traffic Level of Service and Queuing Summary 11
4. 2036 Future Background Intersection Queuing Summary 11
5. Estimated Traffic Generation 12
6. Future Traffic Level of Service and Queuing Summary 15
Lake Springs Ranch Traffic Impact Study
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Lake Springs Ranch PUD
Traffic Impact Study
LAKE SPRINGS RANCH PUD
TRAFFIC IMPACT STUDY
Garfield County, Colorado
1.0 INTRODUCTION
1.1 Project Overview
This report assesses the expected traffic demands of the proposed Lake Springs Ranch Planned
Unit Development (LSR) that will be located along both sides of County Road 114 (CR 114) in
Spring Valley, south of Glenwood Springs. The approximately 460 -acre site is located just south
of the intersection with County Road near the existing Rivendell sod farm. The development is
proposed to contain a maximum of 118 single-family homes and 12 multi -family affordable
units. Access to the site will be provided at four new roadways intersecting CR 114.
This report was prepared in accordance with the criteria set forth in the Garfield County Land
Use Development Code 2013, the State Highway Access Code (SHAC Section 2.3(5)), and follows
nationally accepted traffic engineering procedures for site impact analysis. This report contains
the following analyses:
• An analysis of existing (2016) roadway and traffic conditions in the vicinity
of the site.
• A determination of the volume of daily and peak hour traffic that would be
generated by the proposed development.
• A forecast of long-term future (2036) traffic volumes on the adjacent street
system with and without Lake Springs Ranch traffic demand.
• An evaluation of future traffic impacts caused by the proposed
development. These impacts are based on the total volume of traffic on the
surrounding roadway system and the resulting levels of service (LOS) at the
adjacent intersections and site access driveway.
• A determination of intersection and access improvements that would be
necessary to mitigate the traffic impacts caused by the proposed Lake
Springs Ranch development.
• A calculation of the County's road impact fee for the development.
• A discussion of the probable construction phasing plan and associated
traffic impacts during construction.
Lake Springs Ranch PUD has received prior approvals from Garfield County in 2006 that allow up
to 194 single-family lots and 16 multi -family units. During the intervening years since the
current Preliminary Plan/PUD approvals were granted, the Applicant has recorded several
conservation deeds that have resulted in a net reduction of 76 single-family lots and 4 multi-
family lots when compared to the originally approved plan.
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1.2 Site Location and Study Area Boundaries
The proposed Lake Springs Ranch Planned Unit Development (LSR) will be located approximately
3.5 miles east of the intersection of State Highway 82 & CMC Road (County Road 114). The
vicinity map is shown on Figure 1, which follows this report. The limits of the study include the
intersections of State Highway 82 & CMC Road and the frontage road intersection on the CR 114
(north) side.
Major roadways in the immediate vicinity of the site are described below:
• CMC Road/County Road 114 is the primary two-lane roadway that connects the Roaring
Fork Valley/Highway 82 corridor with Spring Valley, where the Colorado Mountain
College campus and mostly limited residential development exist. The speed limit on
CMC Road in the vicinity of the site is 35 mph. The roadway generally provides two 12'
travel lanes and 2' gravel shoulders.
• State Highway 82 is a four -lane median divided highway with a posted speed of 55 mph
in the vicinity of the CMC Road intersection. Classified as an expressway (Category E -X)
by the State Highway Access Category Assignment Schedule (SHACAS), SH 82 provides
two 12' travel lanes in each direction with acceleration and deceleration lanes required
at intersections. Garfield County Road 154 is the minor leg at the CMC intersection that
accesses southwest of SH 82.
• North Frontage Road, is a two-lane collector roadway that intersects CR 114 just north
of SH 82 and provides frontage road access to Marand Road.
• Marand Road, is a two-lane collector roadway that loops to and from the north frontage
road, providing local access to numerous businesses. The intersections with the North
Frontage Road and SH 82 are controlled by stop signs.
1.3 Description of the Site
The proposed Lake Springs Ranch PUD will be located in rural Garfield County above the Roaring
Fork Valley floor and just below the Colorado Mountain College Spring Valley campus. Figure 2
shows the site plan. LSR is about 3.5 miles from SH 82 on CR 114. The approximately 460 -acre
site is proposed to contain a maximum of 117 single-family homes and 12 multi -family
affordable units (plus the existing home on the property).
There are four proposed access points to the site. Lakeside Lane is planned south of the existing
pond along CR 114, and will provide access to five homes east of CR 114. Spring Valley Road is
south of the Kindel) Road intersection and will provide access north of CR 114, while Lake
Springs Drive will provide access south of CR 114. The third access is proposed south of the CR
115 intersection serving both sides of CR 114, as High Alpine Circle to the north and Lake Springs
Drive to the south. High Alpine Drive is planned along CR 115, located across from the proposed
Spring Valley Ranch PUD main entrance on CR 115. An easement has been established through
SVR for High Alpine Drive.
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Lake Springs Ranch PUD
Traffic Impact Study
The multi -family affordable housing units are planned to be located off the eastern leg of Lake
Springs Drive, in the southern part of the site. The property owner's house currently sits on the
site and will become one of the lots accessed by the western leg of Spring Valley Road. The
owner's house has not been included in the trip generation calculations for this PUD, since the
traffic from this existing home is included in the traffic counts collected last December.
2.0 TRAFFIC ANALYSIS METHODOLOGY
This traffic analysis has been prepared in accordance with the Garfield County Land Use
Development Code 2013 and Section 2.3(5) of the State Highway Access Code (Code). For this
study, an existing conditions and a 20 -year buildout plan will be analyzed. The assumptions and
methodology were discussed with CDOT and are documented in the December 16, 2016 memo
attached as Appendix Al.
Intersection analysis was performed using the Synchro/Simtraffic 8 traffic modeling and analysis
package to estimate the operations of the signalized intersection at CMC Road and SH 82 and
the adjacent unsignalized frontage road intersection. The measures of effectiveness (MOE's)
that are compared for this study include:
• Level of Service (LOS),
• average delay per vehicle, and
• 95th percentile queue lengths.
The estimated 95th percentile queue lengths will be reported for the existing and future buildout
analysis to determine if the current auxiliary turn lanes are adequately sized or need extensions
today or in the future. All signalized and unsignalized analyses contained in this report are
consistent with Highway Capacity Manual 2010 (HCM 2010) methodology. The results of the
Simtraffic model runs are provided in the Operational Summary Tables since Simtraffic analyzes
the intersections as a system, rather than individually (in Synchro module). This allows for the
results to better represent the influence of closely spaced adjacent intersection operations.
Peak hour factors, heavy vehicle percentages, turning movement percentages and other inputs
were developed based on existing traffic counts taken in December 2016. CDOT considers 180
seconds the maximum cycle length allowable on SH 82, with a maximum of 120 seconds
provided to the eastbound and westbound signal timing during peaks.
CDOT's OTIS (Online Traffic Information System) website indicates a 20 -year factor for this
section of SH 82 south of Blake Avenue in Glenwood Springs of 1.26. All seasonally adjusted
turning movement volumes at the intersection were increased by the 20 -year factor to develop
future background volumes for analysis of a future condition without Lake Springs Ranch. The
OTIS information is contained in Appendix A2.
3.0 EXISTING TRAFFIC CONDITIONS
Traffic counts were collected in early December 2016. A turning movement count was collected
at the SH 82/CMC intersection that showed the AM peak hour occurred between 8:30 and 9:30
AM and the PM peak hour occurred between 5:15 and 6:15 PM. Since the count was collected
in December, a seasonal factor of 1.19 was applied to all peak hour turning movement volumes
to account for higher traffic volumes that occur in July. The July volumes or "seasonally
adjusted" volumes are the baseline inputs for the intersection analysis.
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Two 24-hour volumes were collected on CMC Road; one about % mile from the intersection with
SH 82 and the other just north of the Rivendell Sod Farm entrance above the CMC campus. No
turning movement counts were collected at the intersections along CMC Road at Kindel) Road or
Red Canyon Road due to the low 24-hour traffic volume found on CMC Road above the sod
farm. All traffic counts are contained in Appendix A3 -A6.
The volumes on CMC road ranged from 2,007 vehicles per day east of SH 82 to 402 vehicles per
day above the sod farm. According to Garfield County's Capital Improvement Program Volume
II, CMC Road has a design capacity of 6,850 vehicles per day (for its entire length), so the existing
volumes are well below the County's stated design capacity. Garfield County recorded a volume
of 1,408 in 2014, although it was not clear what month or day of week this volume was
collected. The existing seasonally adjusted peak hour turning movements are shown on Figures
3 and 4 below.
cg A54
Figure 3
2016 AM PEAK HOUR VOLUMES
cg A"
Figure 4
2016 PM PEAK HOUR VOLUMES
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The turning movement volumes at the North Frontage Road intersection were approximated
using volumes previously collected in 2009 and balancing them through the signalized
intersection.
AM and PM level of service estimates were analyzed in the Simtraffic program and prepared in
accordance with the Highway Capacity Manual (Transportation Research Board, 5th Edition,
2010). For signalized intersections, the HCM measures level of service in terms of seconds of
delay per vehicle. This is also a measure of driver discomfort, fuel consumption, and lost travel
time. The table below relates the LOS to seconds of delay per vehicle at a signalized
intersection.
LEVEL OF SERVICE CRITERIA
SIGNALIZED INTERSECTIONS
Level of Service
A (Highly Desirable)
B (Desirable)
C (Acceptable)
D (Acceptable in Urban Areas)
E (Unacceptable)
F (Unacceptable)
Source: Highway Capacity Manual, 2010
Delay (seconds)
< 10.0
10.1 to 20
20.1 to 35
35.1 to 55
55.1 to 80
> 80
For unsignalized intersections, the Highway Capacity Manual defines level of service and delay
for unsignalized intersections in terms of seconds of stopped delay per vehicle, which is based
on the number of acceptable gaps in the conflicting traffic stream. In general, the traffic
movements analyzed are those controlled by stop signs or yield signs, and the left turn
movements from the uncontrolled major street. The following table represents the level of
service criteria for unsignalized intersections:
LEVEL OF SERVICE CRITERIA
UNSIGNALIZED INTERSECTIONS
Level of Service Delay (seconds)
A (Highly Desirable) < 10.0
B (Desirable) 10.1 to 15
C (Acceptable) 15.1 to 25
D (Acceptable in Urban Areas) 25.1 to 35
E (Unacceptable) 35.1 to 50
F (Unacceptable) > 50
Source: Highway Capacity Manual, 2010
The "overall" intersection level of service at unsignalized intersections corresponds with the
highest delay experienced on a minor street approach.
The results of the unsignalized analysis that was completed for this study for the North Frontage
Road/CR 114 intersection are not reported in a table but can be found in Appendix A7 which
contains the output results from the Simtraffic models. The intersection operations at the stop -
controlled approaches to CR 114 are directly related to the intersection operations at the
adjacent signal. As delays increase at the signal in the future, so too will delays on the stop -
controlled approaches to the North Frontage Road intersection.
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The results of the capacity analysis based on the seasonally adjusted existing volumes are shown
in the following table. The acceptable level of service standard used by most jurisdictions is LOS
"C" in rural/suburban areas and LOS "D" in urban areas. CDOT and Garfield County consider the
LOS "D" rating as acceptable for the SH 82 corridor.
Table 1
2016 Signalized Intersection Level of Service and Queuing Summary
SH 82 j CR 114 Intersection -
Approach Performance
2016 INTERSECTION
2016 AM Peak
PERFORMANCE
OVERALL
SUMMARY
AM
PM
SH 82 Eastbound Left
Eastbound
westbound
Northbound Southbound
LEFT THRU RIGHT
LEFT THRU RIGHT
LEFT THRU RIGHT
LEFT
THRU
RIGHT
LOS B
C B A
C C A
B B B
C
C
A
Baseline (My) Delay 19.2
32.4 17.9 7.1
32/ 20.4 6.3
19.9 19.2 12.9
20.8
20.1
5.6
Queue
115 284 59
66 168 40
112 112 57
96
96
72
2016 PM Peak
LOS C
❑ B A
D C 9
C C B
C
C
B
Baseline (luly)
Delay 25.1
46.9 14.9 5.3
36.6 29.2 11.3
25.8 28.3 11.2
22.8
25.5
17.6
Queue
112 189 30
152 358 119
129 129 65
121
121
92
Signal runs actuated -uncoordinated with
protected -only phasing for SH 82 left turns and permissive phosing for side streets
95th Percentile Queues exceeding available storage shown in BOLD
Simtraffic Results - Optimized cycle length and splits
12:19+2016
As shown in Table 1, the signalized intersection currently operates at level of service "B" during
the morning peak hour and LOS "C" during the afternoon peak hour. Under existing operations,
the stop -controlled approaches to the North Frontage Road intersection operate acceptably.
All existing acceleration and deceleration lanes at the highway intersection do not meet current
length requirements specified in the State Highway Access Code. The following table
summarizes the existing highway deceleration turn lane lengths and the model's AM and PM
95th percentile queue estimates from Simtraffic. Lengths shown in bold indicate where existing
queue lengths exceed the turn pocket lengths that exist today.
Table 2
2016 Signalized Intersection Queuing Summary
As the table shows, the eastbound left turn lane and both approaches to the highway from CR
114 and CR 154 are shorter than the current 95 percentile queue demand. Current observations
confirmed that the westbound left turn lane and the north and south approaches to the
highway frequently fill or extend past their existing limits during peak hours. The existing
eastbound deceleration lane for left turns from SH 82 to CMC Road is excessively short,
providing 100' of storage for vehicles queued to turn left. The existing westbound acceleration
lane for westbound CMC Road traffic at the SH 82 intersection is approximately 400' long,
providing less than standard acceleration length (approximately 1180') for this classification of
highway.
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Existing Turn
Lane Length
95th % Queue
Lane
AM
PM
SH 82 Eastbound Left
100'
115'
112'
SH 82 Eastbound Right
145'
59'
30'
CR 114 Southbound Approach
50'
96'
121'
SH 82 Westbound Left
380'
66'
152'
SH 82 Westbound Right
205'
40'
119'
CR 154 Northbound Approach
50'
112'
129'
As the table shows, the eastbound left turn lane and both approaches to the highway from CR
114 and CR 154 are shorter than the current 95 percentile queue demand. Current observations
confirmed that the westbound left turn lane and the north and south approaches to the
highway frequently fill or extend past their existing limits during peak hours. The existing
eastbound deceleration lane for left turns from SH 82 to CMC Road is excessively short,
providing 100' of storage for vehicles queued to turn left. The existing westbound acceleration
lane for westbound CMC Road traffic at the SH 82 intersection is approximately 400' long,
providing less than standard acceleration length (approximately 1180') for this classification of
highway.
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These turn lane deficiencies, coupled with the close spacing of the frontage road on both sides
of this intersection and heavy peak hour volumes will show that certain movements at the
intersection may operate below local standards during peak hour traffic conditions, but the
intersection as a whole operates at acceptable levels. Similar to other intersections in the SH 82
corridor with closely spaced frontage road intersections (i.e. Aspen Airport Business Center and
Basalt Avenue), the adjacent stop -controlled intersections may get blocked during each cycle,
but generally clear with each green phase on these minor approaches.
Below are several photos of the intersection showing the short turn lanes on the highway,
closely spaced adjacent intersections, and bus stops serving the RFTA Valley route.
Figure 5
SOUTHBOUND APPROACH OF CR 114 TO SH 82
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Figure 6
WESTBOUND APPROACH OF SH 82 AT CR 114/154
Figure 7
EASTBOUND APPROACH OF SH 82 AT CR 114/154
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Traffic Impact Study
Figure 8
EASTBOUND APPROACH OF NORTH FRONTAGE ROAD AT CR 114
Park and ride parking for RFTA exists on both sides of the highway at this intersection. South of
the highway, there's a driveway to a lot that serves about 35 — 40 spaces, while north of the
highway there's head -in parking along the North Frontage Road adjacent to the gas station that
can handle about 18 — 20 vehicles. Generally, these spaces were fully occupied during weekday
traffic observations (as seen in photos above). Striped pedestrian crossings exist on all legs of
the signalized intersection with pedestrian actuated push buttons on all corners. RFTA's Valley
Local route stops at this intersection two times per hour in each direction during peak times.
4.0 FUTURE TRAFFIC CONDITIONS WITHOUT LAKE SPRINGS RANCH
For this analysis, background traffic forecasts for the 20 -year planning period were developed
based on forecasts for SH 82 traffic found on CDOT's website. The future traffic volumes are
calculated using the 20 -year growth factor of 1.26, and applying this to all the seasonally
adjusted turning movements. No additional specific traffic generated by future developments
such as Spring Valley Ranch has been included in this report. It is assumed that the CDOT
growth factor includes all potential development occurring in the coming 20 years. Based on
this growth factor, CR 114 is forecast to carry 2,529 vehicles per day in 20 years without LSR.
This background traffic scenario is analyzed to provide a basis for comparing operations before
and after traffic from Lake Springs Ranch is added to the system. The AM and PM future
background traffic volumes used in the Simtraffic models are shown on the following figures.
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Figure 9
2036 FUTURE BACKGROUND AM PEAK HOUR VOLUMES
cRA64
Figure 10
2036 FUTURE BACKGROUND PM PEAK HOUR VOLUMES
The intersection of SH 82 & CMC Road was analyzed in the future conditions assuming the turn
lanes have been extended to meet current Code requirements. Capacity analysis of the
background traffic volumes are shown below on Table 3.
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Table 3
2036 Future Background Traffic Level of Service and Queuing Summary
SH 82/ CR 114 Intersection -
Approach Performance
2036 INTERSECTION PERFORMANCE
OVERALL
SUMMARY
Lane
AM
PM
Eastbound
Westbound
Northbound Southbound
LEFT THRU RIGHT
LEFT THRU RIGHT
LEFT THRU RIGHT
LEFT
THRU
RIGHT
2436 AM Peak LOS C
D B A
D C A
C C C
C
C
A
Background Delay 20.6
36.8 16.9 5.5
44.1 20.9 5.5
292 32A 22.0
29.4
29.5
8.0
169'
Traffic Queue
231 581 46
88 208 38
104 104 148
102
102
70
2036 PM Peak LOS D
F 8 A
E D B
D D A
D
ID
C
Background Delay 38.6
91.9 15.3 4.2
56.2 46.3 13.6
43.5 51.4 9.0
41.5
44.6
24.5
Traffic Queue
275 192 32
473 1049 320
169 169 46
107
107
94
Signal runs actuated -uncoordinated with
protected -only phasing for SH 82 left turns and permissive phasing for side streets
95th Percentile Queues exceeding available storage shown in BOLD
Simtraffc Results - Optimized cycle length and splits
12/19/2016
As the table shows, the intersection is forecast to operate within acceptable standards in the
AM and PM peak hours through 2036, given 20 -year growth of 26% (1.26 factor). In the PM
peak, the eastbound and westbound left turn from SH 82 operates at LOS "E"/"F"; but the
overall operations at the intersection for both peak periods is forecast to be LOS "D" or better.
The critical movement for the unsignalized North Frontage Road intersection is the westbound
left turn movement. This movement experiences a LOS "B" in the AM peak and LOS "D" in the
PM peak under future background conditions.
Table 4
2036 Future Background Intersection Queuing Summary
As the table shows, the eastbound left turn lane, the westbound left and right turn lanes, and
both approaches to the highway from CR 114 and CR 154 are shorter than the forecast 20 -year
95 percentile queue demand. These lanes were modeled as improved to Code standards to
determine what queues would exist in the future with fully developed turn lanes on SH 82.
Without extending these turn lanes, they will continue to impact operations of the through
lanes during times of high congestion.
5.0 PROPOSED DEVELOPMENT TRAFFIC
5.1 Traffic Generation
Trip generation rates for the proposed land uses for the Lake Springs Ranch development were
based on Trip Generation (Institute of Transportation Engineers, 9th Edition, 2012). Trip
estimates shown on Table 5 summarize the total trips expected to be generated by the
development during the AM and PM peak hours and on a daily basis on an average weekday. As
noted previously, the existing property owner's home is not included in the trip generation
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Existing Turn
Lane Length
95th % Queue
Lane
AM
PM
SH 82 Eastbound Left
100'
231'
275'
SH 82 Eastbound Right
145'
46'
32'
CR 114 Southbound Approach
50'
102'
107'
SH 82 Westbound Left
380'
88'
473'
SH 82 Westbound Right
205'
38'
320'
CR 154 Northbound Approach
50'
148'
169'
As the table shows, the eastbound left turn lane, the westbound left and right turn lanes, and
both approaches to the highway from CR 114 and CR 154 are shorter than the forecast 20 -year
95 percentile queue demand. These lanes were modeled as improved to Code standards to
determine what queues would exist in the future with fully developed turn lanes on SH 82.
Without extending these turn lanes, they will continue to impact operations of the through
lanes during times of high congestion.
5.0 PROPOSED DEVELOPMENT TRAFFIC
5.1 Traffic Generation
Trip generation rates for the proposed land uses for the Lake Springs Ranch development were
based on Trip Generation (Institute of Transportation Engineers, 9th Edition, 2012). Trip
estimates shown on Table 5 summarize the total trips expected to be generated by the
development during the AM and PM peak hours and on a daily basis on an average weekday. As
noted previously, the existing property owner's home is not included in the trip generation
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calculation, since traffic from this unit has been included in the existing counts and forecasts.
The Trip Generation Handbook advises use of the regression curve equations to calculate
project traffic from these uses rather than the average trip rates.
Table 5
Estimated Traffic Generation
Land Use
# of
UNITS
DAILY
TRIPS
AM
IN
AM
OUT
PM
IN
PM
OUT
Single -Family Detached Homes 1
117
1,213
30
71
76
45
Multi -Family Affordable Units 2
12
102
2
8
7
3
Total Traffic Generation
1,315
32
79
83
48
1— ITE Land Use Code #210 — Single-family Detached Housing, trips based on number of dwelling units
2— ITE Land Use Code #230 — Condominium/Townhouse, trips based on number of dwelling units
As Table 5 shows, the residential units planned for Lake Springs Ranch will generate
approximately 1,315 daily trips on an average weekday. The site is expected to generate
approximately 111 trips in the AM peak hour and 131 trips in the PM peak hour upon buildout
of the current site plan.
5.2 Adjustments to Trip Generation Rates
All traffic generated by Lake Springs Ranch was assumed to be external traffic; meaning that
each trip generated will enter or exit the site at the site's primary access points and all site
traffic is distributed to the SH 82 signal. No trips were reduced to account for transit use or
other modes, allowing a conservative estimate of project traffic generation. Additionally, no
adjustments were made to the trip generation rates used to account for second homes or
vacation homes (which is common to many existing large lot developments in the Roaring Fork
Valley).
5.3 Trip Distribution
Estimates of the directional distribution of site -generated traffic were based on existing traffic
patterns in the vicinity of the site. The existing traffic split (ratio of traffic turning right, thru, and
left) to and from CMC Road onto State Highway 82 was used to estimate the distribution of site
traffic. Figure 11 below shows the distribution assumptions based on existing count
information.
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Figure 11
Project Traffic Distributions at SH 82
5.4 Project Trip Assignment
The assignment of site -generated traffic to the study intersections was made by applying the
directional distribution percentages shown on Figure 11 to the trip generation estimates found
in Table 5. The resulting assignment of traffic to the study intersection is shown on Figure 12.
Figure 12
Project Traffic Assignments at SH 82
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5.5 Traffic Forecasts with the Proposed Development
Traffic forecasts with the proposed Lake Spring Ranch PUD were derived by combining the site -
generated traffic depicted in Figure 12 with the future background traffic volumes developed
using the CDOT growth factor and shown on Figures 9 and 10. The resulting total traffic
forecasts are summarized on Figures 13 and 14 for the SH 82 intersection.
Figure 13
2036 TOTAL TRAFFIC AM PEAK HOUR VOLUMES
cR A54
Figure 14
2036 TOTAL TRAFFIC PM PEAK HOUR VOLUMES
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6.0 TOTAL TRAFFIC ANALYSIS AND PROJECT IMPACTS
Operational analyses of the 20 -year forecast traffic volumes, including full -buildout of Lake
Springs Ranch are contained in this section. The impacts in this section are defined as the
effects of Lake Springs Ranch on the highway intersection to compare them with impacts if no
Lake Springs Ranch development occurs.
6.1 Peak Hour Intersection Level of Service
Buildout AM and PM level of service estimates, which include Lake Springs Ranch traffic
demand, are summarized on Table 6 for the Background and Total traffic scenarios. The table
shows both results to compare performance with and without LSR traffic demand.
Table 6
Future Traffic Level of Service Summary
SH 82/ CR 114 Intersection -
Approach Performance
2036 INTERSECTION PERFORMANCE
OVERALL
SUMMARY
Eastbound
Westbound
Northbound Southbound
LEFT THRU RIGHT
LEFT THRU RIGHT
LEFT THRU RIGHT
LEFT
THRU
RIGHT
2036 AM Peak LOS C
D B A
D C A
C C C
C
C
A
Background Delay 20.6
36.8 16.9 5.5
44.1 20.9 5.5
292 32A 22.0
29.4
29.5
8.0
Traffic Queue
231 581 46
88 208 38
104 104 148
102
102
70
2036 AM Peak LOS C
❑ B A
D C A
C C B
C
C
A
Total Traffic Delay 21.3
37.1 17.8 6.5
422 22.9 67
28.1 2T5 18.6
27.1
29.3
8.5
Queue
267 1102 45
78 212 46
93 93 120
103
103
83
2036 PM Peak LOS D
F B A
E D B
D D A
D
D
C
Background Delay 38.6
91.9 15.3 4.2
56.2 46.3 13.6
43.5 51.4 9.0
41.5
44.6
24.5
Traffic Queue
275 192 32
473 1049 320
169 169 46
107
107
94
2036 PM Peak LOS D
F B A
E D B
E E A
D
ID
C
Total Traffic Delay 44.6
112.7 15.5 4.1
61.4 53.1 16.0
57.1 66.9 8.4
46.8
49.0
25.6
Queue
444 240 25
433 897 324
219 219 60
99
99
95
Signof runs actuated -uncoordinated with
protected -only phasing for SH 82 left turns and permissive phasing for side streets
95th Percentile Queues exceeding avaIable storage shown in BOLD
Simtraffic Results - Optimized cycle length and splits
12/19/2016
As the table shows, the study intersection is forecast to operate within acceptable standards in
2036 with the buildout of Lake Springs Ranch. During the AM peak, all movements will operate
within acceptable LOS standards with and without LSR traffic demand. During the PM peak, the
left turns from the highway in both directions operate at LOS "E/F" and the northbound
approach is LOS "E". However, the intersection operates at LOS "D" overall, with an average
delay of 44.6 seconds per vehicle. Under both Future Background and Total Traffic conditions,
the right and left turn lanes along the highway were extended to their standard lengths.
In this case where an exclusive movement may experience unsatisfactory delay, CDOT may
require improvements to that approach. The study shows that these approaches operate at
Level of Service "E" or worse with or without the project, except for the northbound approach.
Additionally, the poor level of service for these approaches during the peak hour results more
from the opposing heavy through volumes along SH 82 that conflict with these left turn
movements than from heavy turning volumes on these approaches.
The critical westbound left turn movement for the unsignalized North Frontage Road
intersection operates at LOS "C" in the AM peak and LOS "F" in the PM peak under future total
traffic conditions.
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6.2 Access Permit Requirements
Upon buildout of Lake Springs Ranch, the SH 82/CMC intersection will see a 24% increase in PM
peak hour traffic volumes on the CMC Road approach, when compared to existing traffic
volumes on this leg (131 LSR vs. 554 existing). In the AM peak hour, the buildout of the Lake
Springs Ranch site increases the traffic volume on the CMC approach by 21% (112 LSR vs. 528
existing). Based on the current development plan, this project will require an access permit
with CDOT. If additional lots are put into conservation in the future before any construction has
begun, this percentage should be recalculated to determine if a permit is still required by CDOT
based on the requirements of the State Highway Access Code. In all likelihood, adding any
significant development (more than 10 homes) will trigger an access permit at the SH 82/CR 114
intersection.
County driveway permits will be required for all proposed access points that will be located at
easements established in the site plan. The sight distance along CMC Road for vehicles entering
the roadway is adequate as a result of the site's topography and existing conditions along CMC
Road. As stated in the State Highway Access Code, the required sight distance for Single Unit
Trucks over 10,000 Ib GVM along a two-lane roadway is 455'. This distance is factored by 1.35
to account for the 5-7% downgrade on CMC Road for westbound traffic in the steepest sections
(615'). Vehicles preparing to turn onto CMC Road from any site access point will be required to
have over 455' of clear sight lines to the west and over 615' to the east along CMC Road to make
safe turning maneuvers from the site. For vehicles along CMC Road, the required sight distance
is less than that required for vehicles entering the roadway, so sight distance should be
sufficient for all traffic ingress and egress movements. Confirmation of sight distances should be
done during preliminary design of these access points. Design of all internal roads and any
redesign of the county roads shall be in accordance with the attached agreement between the
Lake Springs Ranch owners and Spring Valley Development.
6.3 Turn Lane Storage Requirements
Turn lanes along the highway affected by LSR traffic include the westbound right turn lane, the
eastbound left turn lane and the westbound acceleration lane. These were all noted to be
shorter than the standards set forth in the Code. The westbound right turn lane should be
extended to 822'; the eastbound left turn lane should be extended to 822' + storage distance
(based on peak hour demand); and the westbound acceleration lane should be extended to
1182'. The turn lanes along the highway could all be extended to full length within existing
right-of-way and with minimal median, shoulder, and drainage improvements required. Turn
lane extensions would significantly improve the safety and capacity at this signal in the short-
term, before more significant and costly solutions are proposed. Based on recent construction
costs to extend an acceleration lane and a deceleration lane at the nearby Cattle Creek
intersection, lane extensions could cost approximately $400,000 per lane, for a total cost of
$1.2M for full extension of these lanes.
6.4 Road Impact Fee Calculation
Using the updated Garfield County Road Impact Fees (2017), the road impact fees were
calculated for Lake Springs Ranch PUD using a few assumptions for unit sizes. The County's
impact fee ranges from $726 to $2,703 per residential unit depending on the size of units. Using
16 SGM, Inc.
Lake Springs Ranch PUD
Traffic Impact Study
12 units at $1,474 (901 — 1,400 sf) and 117 units at $2,703 (2,401 sf and greater), the road
impact fee for Lake Springs Ranch is $333,939. The road impact fee is typically collected at final
plat (first half) and upon building permit (final half) in a phased development.
7.0 CONSTRUCTION PHASING AND TRAFFIC
The current phasing plan consists of a series of phases called "blocks". No temporary access
points will be created for this project. The construction and phasing plan allows for most work
to be completed outside the right-of-way of the adjacent County roads until final connections
are needed. However, LSR will be reconstructing the portion of CMC Road through the site to
the standard set forth in the development agreement for the Spring Valley Ranch PUD. This
work will be completed in conjunction with successive phases, working up CMC Road to the CR
115 intersection. Staging and storage of vehicles and materials will be on the Lake Springs
Ranch property and out of all County right-of-ways. The site grading plan is relatively balanced
so there will be little importing or exporting of excavation materials.
At this point in the planning process, construction traffic impacts can only be speculated. In
general, traffic generated by a residential site is typically greater at buildout than at any time
during the construction of the residential site. Although there will be some initial mobilizations
of heavy equipment and heavy daily loads for base, paving and concrete construction, the
contractor will be encouraged to carpool workers to and from the site to minimize day-to-day
construction traffic.
8.0 SUMMARY OF FINDINGS
The proposed Lake Springs Ranch Planned Unit Development is an approximately 460 -acre site
planned to contain a maximum of 117 single-family homes and 12 multi -family affordable units.
The entire development is estimated to generate approximately 1,315 vehicle trips on an
average weekday. Of this daily volume, the site will generate approximately 111 trips in the AM
peak hour and 131 trips in the PM peak hour. For conservative purposes, all site traffic was
assumed to access the highway.
No turn lanes are necessary along CMC Road at the intersection of CMC Road and the Lake
Spring Ranch driveways. The driveway approaches will be constructed to allow one exiting lane
and one entering lane. These approaches will be controlled by stop signs. Adequate sight
distance is provided for turning and stopping maneuvers at all access driveways to Lake Spring
Ranch.
The intersection of CMC Road and SH 82 is expected to operate at LOS "D" or better in the long-
term year with or without the development of Lake Springs Ranch. Turn lane extensions for
lanes affected by LSR traffic demand should be completed to bring the westbound right turn
deceleration lane, eastbound left turn deceleration lane, and the westbound right turn
acceleration lane up to current Code standards. The preliminary cost for such lane extensions is
approximately $1.2 million.
Lake Springs Ranch will be required to file for an access permit with CDOT for the SH 82/CMC
intersection. In addition, County driveway permits will be required for the proposed accesses
onto CR 114 and CR 115. The roadways will be located within dedicated rights of way and will
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Lake Springs Ranch PUD
Traffic Impact Study
be designed and constructed to Garfield County geometric standards as contained in Resolution
No. 2016-35 which grants approval for the most recent amendment of the Lake Springs Ranch
PUD.
Lake Springs Ranch has received prior approvals from Garfield County that allow up to 194
single-family lots and 16 multi -family units. This traffic impact study has been prepared as part
of a land use application seeking Final Plat approval for Filing 2.
9.0 REFERENCES
Garfield County Road Impact Fee Updated (website)
https://www.garfield-county.com/community-development/road-impact-fees.aspx
Highway Capacity Manual 2010 (Transportation Research Board, 5th Edition, 2010)
State of Colorado State Highway Access Code (Colorado Department of Transportation, August
1998)
Trip Generation (Institute of Transportation Engineers, 9th Edition, 2012)
18 SGM, Inc.
r
SCHMUESERI GORDONI MEYER
ENGINEERS U R V E Y O R S
SCHMUESER GORDON MEYER, INC.
1 1 8 W. 6TH STREET, SUITE 200
GLENWOOD SPRINGS, COLORADO 81601
(970) 945-1004 FAX (970) 945-5948
ASPEN, COLORADO (970) 925-6727
CRESTED BUTTE, CO (970) 349-5355
Figure 1
Vicinity Map
✓ob No. 2009-351
Dote: 3/23/10 !Drawn by: LMB I Fite: 77SF/gs,
r
ke Springs Ranch PUD Amendment
Proposed Lot Lines
Proposed Bldg Envelopes
LSR Property Boundary
County Roads
County Parcels (GIS)
SCHMUESERI GORDONI MEYER
ENGINEERS U R V E Y O R S
SCHMUESER GORDON MEYER, INC.
I 18 W. 6TH STREET, SUITE 200
GLENWOOD SPRINGS, COLORADO 81601
(970) 945- 1004 FAX (970) 945-5948
ASPEN, COLORADO (970) 925-6727
CRESTED BUTTE, CO (970) 349-5355
Figure 2
Site Plan
Job No. 2009-351 'Dote: 3/23/10 !Drown by: LMB I Fite: 17SFigs,
APPENDIX
Appendix Al — December 2016 Memo to CDOT (3 pages)
Appendix A2 — 2015 and 2036 OTIS data (1 page)
Appendix A3 — AM Peak Hour Turning Movement Counts SH 82/CR 114 (1 page)
Appendix A4 — PM Peak Hour Turning Movement Counts SH 82/CR 114 (1 page)
Appendix A5 — CR 114 Lower ADT count data (1 page)
Appendix A6 — CR 114 Upper ADT count data (1 page)
Appendix A7 — Table Al Trip Generation (1 page)
Appendix A8 — Table A2 Trip Distribution (1 page)
Appendix A9 — Simtraffic Output Files (18 pages)
Appendix A10 — Spring Valley Ranch/Lake Springs Ranch Agreement 2002 (6 pages)
Lake Springs Ranch Traffic Impact Study
June 2017