HomeMy WebLinkAboutTIA - Amberleigh South Amberleigh Shores Phase II – Traffic Impact Analysis
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TABLE OF CONTENTS
1. INTRODUCTION .............................................................................................................. 1
1.1. Site Location and Study Area ................................................................................................1
1.2. Proposed Land Use and Site Access .....................................................................................2
1.3. Adjacent Land Uses ...............................................................................................................2
1.4. Existing Roadways ................................................................................................................2
2. EXISTING (2016) PEAK HOUR CONDITIONS ........................................................... 7
2.1. Existing (2016) Peak Hour Traffic ........................................................................................7
2.2. Analysis of Existing (2016) Peak Hour Traffic .....................................................................7
3. BACKGROUND (2018) PEAK HOUR CONDITIONS ................................................. 9
3.1. Ambient Traffic Growth ........................................................................................................9
3.2. Adjacent Development Traffic ..............................................................................................9
3.3. Future Roadway Improvements .............................................................................................9
3.4. Background (2018) Peak Hour Traffic Volumes ................................................................10
3.5. Analysis of Background (2018) Peak Hour Traffic Conditions ..........................................10
4. TRIP GENERATION ...................................................................................................... 12
4.1. Site Trip Distribution and Assignment ................................................................................12
5. COMBINED (2018) TRAFFIC CONDITIONS ............................................................ 17
5.1. Combined (2018) Peak Hour Traffic Volumes ...................................................................17
5.2. Analysis of Combined (2018) Peak Hour Traffic ...............................................................17
6. TRAFFIC ANALYSIS PROCEDURE ........................................................................... 20
6.1. Adjustments to Analysis Guidelines ...................................................................................21
7. CAPACITY ANALYSIS .................................................................................................. 22
7.1. Market Street and Marsh Oaks Drive / Mendenhall Drive .................................................22
7.2. Marsh Oaks Drive and Site Drive #1 ..................................................................................23
7.3. Market Street and Site Drive #2 ..........................................................................................24
7.4. Market Street and Alexander Road / Site Drive #3 .............................................................26
Amberleigh Shores Phase II – Traffic Impact Analysis
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8. CONCLUSIONS ............................................................................................................... 28
9. RECOMMENDATIONS ................................................................................................. 30
Amberleigh Shores Phase II – Traffic Impact Analysis
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LIST OF FIGURES
Figure 1 – Site Location Map ...................................................................................................... 4
Figure 2 – Preliminary Site Plan .................................................................................................. 5
Figure 3 – Existing Lane Configurations ..................................................................................... 6
Figure 4 – Existing (2016) Peak Hour Traffic ............................................................................. 8
Figure 5 – Background (2018) Peak Hour Traffic ..................................................................... 11
Figure 6a-b – Site Trip Distribution .......................................................................................... 13
Figure 7a-b – Site Trip Assignment ........................................................................................... 15
Figure 8a-b – Combined (2018) Peak Hour Traffic................................................................... 18
Figure 9a-b – Recommended Lane Configurations ................................................................... 32
Amberleigh Shores Phase II – Traffic Impact Analysis
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LIST OF TABLES
Table 1: Trip Generation Summary ........................................................................................... 12
Table 2: Highway Capacity Manual – Levels-of-Service and Delay ........................................ 20
Table 3: Analysis Summary of Market Street and Marsh Oaks Drive / Mendenhall Drive ...... 22
Table 4: Analysis Summary of Marsh Oaks Drive and Site Drive #1 ....................................... 23
Table 5: Analysis Summary of Market Street and Site Drive #2 .............................................. 24
Table 6: Analysis Summary of Market Street and Alexander Road / Site Drive #3 ................. 26
Amberleigh Shores Phase II – Traffic Impact Analysis
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TECHNICAL APPENDIX
Appendix A: Approved Scoping Letter
Appendix B: Traffic Counts
Appendix C: Signal Plans
Appendix D: TIP U-4902 Plans
Appendix E: Capacity Calculations – Market Street and Mendenhall Drive / Marsh Oaks
Drive
Appendix F: Capacity Calculations – Marsh Oaks Drive and Site Drive 1
Appendix G: Capacity Calculations – Market Street and Site Drive 2
Appendix H: Capacity Calculations – Market Street and Alexander Drive / Site Drive 3
TRAFFIC IMPACT ANALYSIS REPORT
AMBERLEIGH SHORES PHASE II
WILMINGTON, NORTH CAROLINA
1. INTRODUCTION
The contents of this report present the findings of the Traffic Impact Analysis (TIA) conducted
for the proposed Amberleigh Shores Phase II to be located east of Market Street at its
intersection with Alexander Road and south of Marsh Oaks Drive in Wilmington, North
Carolina. This phase of the project is proposed to be adjacent to the already complete first
phase of Amberleigh Shores. The purpose of this study is to determine the potential impacts
to the surrounding transportation system created by traffic generated by the proposed
development, as well as recommend improvements to mitigate the impacts.
The proposed development is expected to consist of 288 apartment units and will have a future
analysis year of 2018. The study analyzes traffic conditions during the weekday AM and PM
peak hours for the following scenarios:
Existing (2016) Traffic Conditions
Background (2018) Traffic Conditions
Combined (2018) Traffic Conditions
Two access scenarios are considered as a part of this study. The first is limiting the proposed
site drive to a right-in / right-out (RIRO) driveway, and the second is considering the same
driveway as an unsignalized left-over (LO).
1.1. Site Location and Study Area
The development is proposed to be located east of Market Street and south of Marsh Oaks
Drive in Wilmington, North Carolina. Refer to Figure 1 for the site location map.
Amberleigh Shores Phase II – Traffic Impact Analysis
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The study area for the TIA was determined through coordination with the North Carolina
Department of Transportation (NCDOT) and the City of Wilmington (City) and consists of the
following existing intersections:
Market Street and Alexander Road
Market Street and Marsh Oaks Drive / Mendenhall Drive
Market Street and Amberleigh Shores Phase 1 Site Drive
Marsh Oaks Drive and Amberleigh Shores Phase 1 Site Drive
Scoping for the project was coordinated with the City through a scoping checklist. This, as
well as the approved scoping letter, can be found in Appendix A.
1.2. Proposed Land Use and Site Access
The proposed development, anticipated to be completed in 2018, is expected to consist of 288
apartment units. Access will be provided with a direct connection to Market Street, as well as
interconnectivity with the completed phase 1. Two access alternatives are considered for the
direct access to Market Street: a RIRO drive and a LO drive.
1.3. Adjacent Land Uses
The proposed development is located south of the Amberleigh Shores Phase 1. The site is also
surrounded primarily by wooded land and residential development.
1.4. Existing Roadways
Market Street is a five-lane roadway running in a north-south direction with a posted speed
limit of 45 miles per hour (mph) within the study area. Based on the most recent data (2013)
from the NCDOT, Market Street had an AADT volume of 32,000 vpd within the study area. It
is worth noting that STIP project U-4902 is currently in the design process, and will convert
Market Street to a four-lane median divided facility.
Alexander Road is a two-lane roadway running in an east-west direction with no posted speed
limit in the study area. For the purpose of this study, it was analyzed to have a speed limit of
Amberleigh Shores Phase II – Traffic Impact Analysis
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25 mph. Based on the most recent data (2013) from the NCDOT, Alexander Road had an
AADT volume of 730 vpd within the study area.
Marsh Oaks Drive / Mendenhall Drive are a two-lane roadway running in an east-west
direction with no posted speed limit in the study area. For the purpose of this study, it was
analyzed to have a speed limit of 35 mph. Based on the current traffic counts from 2016, and
assuming that the peak hour volume is 10% of the average daily traffic, Marsh Oaks Drive has
an AADT volume of approximately 2,600 vpd within the study area.
Existing lane configurations (number of traffic lanes on each intersection approach), lane
widths, storage capacities, and other intersection and roadway information was collected
through field reconnaissance by Ramey Kemp & Associates, Inc. (RKA). Refer to Figure 3 for
an illustration of the existing lane configurations within the study area.
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
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LEGEND
Proposed Site Location
Study Intersection
Study Area
Site Location Map
Figure 1
4
Bayshore
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PROPOSED
SITE
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Marsh Oa
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Alexander Road
Mendenhall Drive Marsh Oaks Drive
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Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 3
Existing
Lane Configurations
N
LEGEND
Signalized Intersection
Unsignalized Intersection
Existing Lane
X'Storage (In Feet)
TW
L
T
L
TW
L
T
L
TWLTL Two Way Left Turn Lane
6
TW
L
T
L
50
0
'
TW
L
T
L
Right-In/Right-Out Intersection
17
5
'
Amberleigh Shores Phase II – Traffic Impact Analysis
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2. EXISTING (2016) PEAK HOUR CONDITIONS
2.1. Existing (2016) Peak Hour Traffic
Existing peak hour traffic volumes were determined based on traffic counts conducted at the
study intersections listed below, in April of 2016 by RKA during a typical weekday AM (7:00
AM – 9:00 AM) and PM (4:00 PM – 6:00 PM) peak periods:
Market Street and Marsh Oaks Drive / Mendenhall Drive
Market Street and Amberleigh Shores Phase 1 Site Drive
Marsh Oaks Drive and Amberleigh Shores Phase 1 Site Drive
Market Street and Alexander Road
Traffic volumes were balanced between intersections, where appropriate. Refer to Figure 4 for
existing (2016) weekday AM and PM peak hour traffic volumes. A copy of the count data is
located in Appendix B of this report.
2.2. Analysis of Existing (2016) Peak Hour Traffic
The existing (2016) weekday AM and PM peak hour traffic volumes were analyzed to
determine the current levels of service at the study intersections under existing roadway
conditions. Signal information was obtained from NCDOT and the City of Wilmington and is
included in Appendix C. The results of the analysis are presented in Section 7 of this report.
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Alexander Road
Mendenhall Drive Marsh Oaks Drive
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1
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 4
Existing (2016)
Peak Hour Traffic
N
LEGEND
Signalized Intersection
Unsignalized Intersection
X / Y AM / PM Peak Hour Traffic
8
33/14
12
3
4
/
1
7
2
7
9/
3
4
18
2
4
/
1
9
8
8
108/50
8/4
129/81
25
/
5
1
12
1
2
/
1
6
1
1
30
/
7
9
18/19
2/3
21/23
6/
9
16
7
4
/
1
8
8
4
50
/
1
7
5
34
/
3
7
19
/
1
7
12
4
1
/
1
7
6
0
2/1
35/29
7/
6
18
1
7
/
1
9
8
2
199/108
0/3
46
/
2
7
0/
3
74/215
8/42
Right-In/Right-Out Intersection
Amberleigh Shores Phase II – Traffic Impact Analysis
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3. BACKGROUND (2018) PEAK HOUR CONDITIONS
In order to account for growth of traffic and subsequent traffic conditions at a future year,
background traffic projections are needed. Background traffic is the component of traffic due
to the growth of the community and surrounding area that is anticipated to occur regardless of
whether or not the proposed development is constructed. Background traffic is comprised of
existing traffic growth within the study area and additional traffic created as a result of
adjacent approved developments.
3.1. Ambient Traffic Growth
Through coordination with the City and NCDOT, it was determined that an annual growth rate
of 1% would be used to generate projected (2018) weekday AM and PM peak hour traffic
volumes.
3.2. Adjacent Development Traffic
Through coordination with the City, it was determined that no adjacent developments are
located within the study area.
3.3. Future Roadway Improvements
Based on coordination with the NCDOT and the City, the TIP Project (U-4902 D along the
Market Street corridor), is to be considered as a future roadway improvement. As part of the
project, a median will be constructed, restricting some movements to a right-in/right-out, while
others will be provided with a median cross-over in order to make a left turn from Market
Street will still restricting the side streets to right turns only onto Market Street.
It is worth noting, according to the plans acquired; the signalized full movement intersection
of Market Street with Mendenhall Drive and Marsh Oaks Drive is proposed to remain a full
movement signalized intersection. A median cross-over is currently planned for the
intersection of Alexander Road and Market Street in the study area, converting this
intersection from an unsignalized full movement intersection to an unsignalized LO
intersection.
Amberleigh Shores Phase II – Traffic Impact Analysis
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Refer to Appendix D for the TIP plans through the study area.
3.4. Background (2018) Peak Hour Traffic Volumes
The background (2018) traffic volumes were determined by projecting the existing (2016)
peak hour traffic to the year 2018. Refer to Figure 5 for an illustration of the background
(2018) peak hour traffic volumes at the study intersections.
3.5. Analysis of Background (2018) Peak Hour Traffic Conditions
The background (2018) AM and PM peak hour traffic volumes at the study intersections were
analyzed with future geometric roadway conditions and traffic control. The analysis results are
presented in Section 7 of this report.
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Mendenhall Drive Marsh Oaks Drive
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#
1
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 5
Background (2018)
Peak Hour Traffic
11
N
LEGEND
Signalized Intersection
Unsignalized Intersection
X / Y AM / PM Peak Hour Traffic
34/14
12
5
9
/
1
7
6
2
9/
3
5
18
6
1
/
2
0
2
8
110/51
8/4
132/83
26
/
5
2
12
3
6
/
1
6
4
3
31
/
8
1
18/19
2/3
21/23
6/
9
17
0
8
/
1
9
2
2
51
/
1
7
9
35
/
3
8
19
/
1
7
12
6
6
/
1
7
9
5
2/1
36/30
7/
6
18
5
4
/
2
0
2
2
203/110
0/3
47
/
2
8
0/
3
75/219
8/43
Right-In/Right-Out Intersection
Amberleigh Shores Phase II – Traffic Impact Analysis
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4. TRIP GENERATION
The proposed development is expected to consist of approximately 288 apartment units.
Average weekday daily, AM peak hour, and PM peak hour trips for the proposed development
were estimated using methodology contained within the ITE Trip Generation Manual, 9th
Edition. Table 1 provides a summary of the trip generation results for the site.
Table 1: Trip Generation Summary
Land Use
(ITE Code) Intensity
Daily
Traffic
(vpd)
AM Peak Hour
Trips (vph)
PM Peak Hour
Trips (vph)
Enter Exit Enter Exit
Apartments (220) 288
dwellings 1,900 29 116 114 62
It is estimated that the proposed development will generate 1,900 total site trips on the
roadway network during a typical 24-hour weekday period. Of the daily traffic volume, it is
anticipated that 145 trips (29 entering and 116 exiting) will occur during the AM peak hour
and 176 (114 entering and 62 exiting) will occur during the PM peak hour.
4.1. Site Trip Distribution and Assignment
Trip distribution percentages used in assigning site traffic for this development were estimated
based on a combination of existing traffic patterns, population centers adjacent to the study
area, and engineering judgment. It is estimated that residential trips will be distributed as
follows:
40% to/from the north via Market Street
60% to/from the south via Market Street
The trip distribution is shown in Figures 6a and 6b for the two analysis scenarios. The total
site trips are shown in Figures 7a and 7b.
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Mendenhall Drive Marsh Oaks Drive
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Site Drive #3
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 6a
Site Trip Distribution
Alternative 1
X%
(Y%)
XX%
Entering Trip Distribution
Exiting Trip Distribution
Regional Trip Distribution
N
LEGEND
Signalized Intersection
Unsignalized Intersection
Site
Right-In/Right-Out Intersection
13
60%
40%
(5%)
(5
0
%
)
(3
5
%
)
5%
(1
0
%
)
(10%)
(4
0
%
)
40
%
5%
55
%
(6
0
%
)
(1
0
%
)
40%
(85%)
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Alexander Road
Mendenhall Drive Marsh Oaks Drive
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#
1
Site Drive #3
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 6b
Site Trip Distribution
Alternative 2
X%
(Y%)
XX%
Entering Trip Distribution
Exiting Trip Distribution
Regional Trip Distribution
N
LEGEND
Signalized Intersection
Unsignalized Intersection
Site
Right-In/Right-Out Intersection
14
60%
40%
(5%)
(5
0
%
)
(3
5
%
)
5%
30
%
(
1
0
%
)
(10%)
(4
0
%
)
30
%
10
%
5%
55
%
(6
0
%
)
30
%
(1
0
%
)
10%
(85%)
Left-Over Intersection
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Alexander Road
Mendenhall Drive Marsh Oaks Drive
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#
1
Site Drive #3
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 7a
Primary Site
Trip Assignment
Alternative 1
N
LEGEND
Signalized Intersection
Unsignalized Intersection
X / Y AM / PM Peak Hour Traffic
Right-In/Right-Out Intersection
15
Site
6/3
57
/
3
1
41
/
2
2
1/
6
12
/
6
12/6
47
/
2
5
12
/
4
6
1/
6
16
/
6
2
69
/
3
7
12
/
6
12/46
98/53
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Alexander Road
Mendenhall Drive Marsh Oaks Drive
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Site Drive #3
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 7b
Primary Site
Trip Assignment
Alternative 2
N
LEGEND
Signalized Intersection
Unsignalized Intersection
X / Y AM / PM Peak Hour Site Trips
Right-In/Right-Out Intersection
16
Site
6/3
57
/
3
1
41
/
2
2
1/
6
20
/
4
0
12/6
47
/
2
5
9/
3
4
3/
1
2
1/
6
16
/
6
2
69
/
3
7
9/
3
4
12
/
6
3/12
98/53
Left-Over Intersection
Amberleigh Shores Phase II – Traffic Impact Analysis
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5. COMBINED (2018) TRAFFIC CONDITIONS
5.1. Combined (2018) Peak Hour Traffic Volumes
To estimate traffic conditions with the residential site developed, the total site trips for the
residential site were added to the background (2018) traffic volumes to determine the
combined (2018) traffic volumes. Refer to Figures 8a and 8b for an illustration of the
combined (2018) peak hour traffic volumes with the proposed Residential Phase developed.
5.2. Analysis of Combined (2018) Peak Hour Traffic
Study intersections were analyzed with the combined (2018) traffic volumes using the same
methodology previously discussed for existing and background traffic conditions.
Intersections were analyzed with improvements necessary to accommodate future traffic
volumes. The results of the capacity analysis for each intersection are presented in Section 7 of
this report.
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Alexander Road
Mendenhall Drive Marsh Oaks Drive
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Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 8a
Combined (2018)
Peak Hour Traffic
Alternative 1
N
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LEGEND
Signalized Intersection
Unsignalized Intersection
X / Y AM / PM Peak Hour Traffic
Right-In/Right-Out Intersection
40/17
57
/
3
1
13
0
0
/
1
7
8
4
10
/
4
1
18
7
3
/
2
0
3
4
110/51
8/4
144/89
26
/
5
2
12
8
3
/
1
6
6
8
31
/
8
1
18/19
2/3
21/23
6/
9
17
0
8
/
1
9
2
2
63
/
2
2
5
35
/
3
8
19
/
1
7
12
6
7
/
1
8
0
1
16
/
6
2
2/1
36/30
7/
6
19
2
3
/
2
0
5
9
203/110
0/3
59
/
3
4
0/
3
75/219
20/89
Site
98/53
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Mendenhall Drive Marsh Oaks Drive
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Site Drive #3
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 8b
Combined (2018)
Peak Hour Traffic
Alternative 2
N
19
LEGEND
Signalized Intersection
Unsignalized Intersection
X / Y AM / PM Peak Hour Traffic
Right-In/Right-Out Intersection
40/17
57
/
3
1
13
0
0
/
1
7
8
4
10
/
4
1
18
8
1
/
2
0
6
8
110/51
8/4
144/89
26
/
5
2
12
8
3
/
1
6
6
8
31
/
8
1
18/19
2/3
21/23
6/
9
17
1
7
/
1
9
5
6
54
/
1
9
1
35
/
3
8
19
/
1
7
12
6
7
/
1
8
0
2
16
/
6
2
2/1
36/30
7/
6
19
2
3
/
2
0
5
9
9/
3
4
203/110
0/3
59
/
3
4
0/
3
76/220
11/55
Site
98/53
Left-Over Intersection
Amberleigh Shores Phase II – Traffic Impact Analysis
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6. TRAFFIC ANALYSIS PROCEDURE
Study intersections were analyzed using the methodology outlined in the 2010 Highway
Capacity Manual (HCM) published by the Transportation Research Board. Capacity and level
of service are the design criteria for this traffic study. A computer software package, Synchro
(Version 9.1), was used to complete the analyses for most of the study area intersections.
Please note that the unsignalized capacity analysis does not provide an overall level of service
for an intersection; only delay for an approach with a conflicting movement.
The HCM defines capacity as “the maximum hourly rate at which persons or vehicles can
reasonably be expected to traverse a point or uniform section of a lane or roadway during a
given time period under prevailing roadway, traffic, and control conditions.” Level of service
(LOS) is a term used to represent different driving conditions, and is defined as a “qualitative
measure describing operational conditions within a traffic stream, and their perception by
motorists and/or passengers.” Level of service varies from Level “A” representing free flow,
to Level “F” where breakdown conditions are evident. Refer to Table 2 for HCM levels of
service and related average control delay per vehicle for both signalized and unsignalized
intersections. Control delay as defined by the HCM includes “initial deceleration delay, queue
move-up time, stopped delay, and final acceleration delay”. An average control delay of 50
seconds at a signalized intersection results in LOS “D” operation at the intersection.
Table 2: Highway Capacity Manual – Levels-of-Service and Delay
UNSIGNALIZED INTERSECTION SIGNALIZED INTERSECTION
LEVEL
OF
SERVICE
AVERAGE
CONTROL DELAY
PER VEHICLE
(SECONDS)
LEVEL
OF
SERVICE
AVERAGE
CONTROL DELAY
PER VEHICLE
(SECONDS)
A
B
C
D
E
F
0-10
10-15
15-25
25-35
35-50
>50
A
B
C
D
E
F
0-10
10-20
20-35
35-55
55-80
>80
Amberleigh Shores Phase II – Traffic Impact Analysis
21
6.1. Adjustments to Analysis Guidelines
Capacity analysis at all study intersections was completed according to the City’s UDO and
NCDOT Congestion Management Guidelines, with one exception.
It should be noted that the signalized intersection of Market Street with Mendenhall Drive and
Marsh Oaks Drive is part of the Wilmington Signal System. Being a part of a coordinated
system, a recall setting is utilized to indicate to the signal system how much green time to
default to once returning to the coordinated phases. According to the signal plans, the signal is
to be set to the minimum recall (C-Min). However, the signal system was analyzed with the
recall mode set to the maximum recall (C-Max), in accordance with the City’s analysis
guidance.
Typically, the level of service and delay calculated for the signal operation are very similar,
with the delay calculations differing by as little as fractions of a second to as much as a few
seconds. Due to the capacity analysis results, found in Section 7, this is not expected to cause
a large increase in the delay calculations.
Amberleigh Shores Phase II – Traffic Impact Analysis
22
7. CAPACITY ANALYSIS
7.1. Market Street and Marsh Oaks Drive / Mendenhall Drive
The signalized intersection of Market Street and Marsh Oaks Drive / Mendenhall Drive was
analyzed under existing conditions with existing lane configurations and traffic control.
Background and combined scenarios were analyzed with background lane improvements
planned as part of the TIP Project. Refer to Table 4 for a summary of the analysis results.
Refer to Appendix E for the Synchro capacity analysis reports.
Table 3: Analysis Summary of Market Street and Marsh Oaks Drive / Mendenhall Drive
ANALYSIS SCENARIO
A
P
P
R
O
A
C
H
LANE
CONFIGURATIONS
WEEKDAY
AM PEAK HOUR
LEVEL OF
SERVICE
WEEKDAY
PM PEAK HOUR
LEVEL OF
SERVICE
Approach Overall
(sec) Approach Overall
(sec)
Existing (2016) Conditions
EB
WB
NB
SB
1 LT-TH, 1 RT
1 LT-TH, 1 RT
1 LT, 2 TH, 1 RT
1 LT, 1 TH, 1 TH-RT
D (47)
E (62)
B (17)
B (18)
C
(21)
D (53)
E (64)
C (26)
C (21)
C
(25)
Background (2018)
Conditions
EB
WB
NB
SB
1 LT-TH, 1 RT
1 LT-TH, 1 RT
1 LT, 2 TH, 1 RT
1 LT, 1 TH, 1 TH-RT
D (46)
E (62)
B (18)
B (19)
C
(22)
D (53)
E (63)
C (27)
C (23)
C
(26)
Combined (2018)
Conditions - RIRO
EB
WB
NB
SB
1 LT-TH, 1 RT
1 LT-TH, 1 RT
1 LT, 2 TH, 1 RT
1 LT, 1 TH, 1 TH-RT
D (45)
E (62)
B (20)
C (21)
C
(24)
D (52)
E (64)
C (28)
C (26)
C
(28)
Combined (2018)
Conditions - LO
EB
WB
NB
SB
1 LT-TH, 1 RT
1 LT-TH, 1 RT
1 LT, 2 TH, 1 RT
1 LT, 1 TH, 1 TH-RT
D (45)
E (62)
B (20)
C (21)
C
(24)
D (52)
E (64)
C (28)
C (24)
C
(28)
Capacity analysis indicates the existing signalized intersection currently operates at LOS C
during both the AM and PM peak hours. This is expected to continue for all analysis
scenarios.
Amberleigh Shores Phase II – Traffic Impact Analysis
23
7.2. Marsh Oaks Drive and Site Drive #1
The existing unsignalized intersection of Marsh Oaks Drive and Site Drive #1 (constructed as
part of Amberleigh Shores Phase 1) was analyzed under existing and background traffic
conditions with existing lane configurations and traffic control. Combined traffic conditions
were analyzed with the addition of the proposed lane configurations. Refer to Table 5 for a
summary of the analysis results. Refer to Appendix F for the Synchro capacity analysis
reports.
Table 4: Analysis Summary of Marsh Oaks Drive and Site Drive #1
ANALYSIS
SCENARIO
A
P
P
R
O
A
C
H
LANE
CONFIGURATIONS
WEEKDAY
AM PEAK HOUR
LEVEL OF
SERVICE
WEEKDAY
PM PEAK HOUR
LEVEL OF
SERVICE
Approach Overall
(sec) Approach Overall
(sec)
Existing (2016) Conditions
EB
WB
NB
1 TH-RT
1 LT-TH
1 LT-RT
--
A2
B1 N/A
--
A2
B1
N/A
Background (2018)
Conditions
EB
WB
NB
1 TH-RT
1 LT-TH
1 LT-RT
--
A2
B1
N/A --
A2
B1
N/A
Combined (2018)
Conditions - RIRO
EB
WB
NB
1 TH-RT
1 LT-TH
1 LT-RT
--
A2
B1
N/A --
A2
B1
N/A
Combined (2018)
Conditions - LO
EB
WB
NB
1 TH-RT
1 LT-TH
1 LT-RT
--
A2
B1
N/A --
A2
B1
N/A
1. Level of service for minor-street approach.
2. Level of service for major-street left-turn movement.
Improvements shown in bold.
Analysis indicates all approaches for the unsignalized intersection are expected to operate at
LOS B or better for all analysis scenarios.
Amberleigh Shores Phase II – Traffic Impact Analysis
24
7.3. Market Street and Site Drive #2
The intersection of Market Street and Site Drive #2 (constructed as part of Amberleigh Shores
Phase 1) was analyzed under existing traffic conditions with existing lane configurations and
traffic control. For background and combined traffic conditions, the intersection was analyzed
with TIP improvements. Refer to Tables 6 for a summary of the analysis results. Refer to
Appendix G for the Synchro capacity analysis reports.
Table 5: Analysis Summary of Market Street and Site Drive #2
ANALYSIS SCENARIO
A
P
P
R
O
A
C
H
LANE
CONFIGURATIONS
WEEKDAY
AM PEAK HOUR
LEVEL OF
SERVICE
WEEKDAY
PM PEAK HOUR
LEVEL OF
SERVICE
Approach Overall
(sec) Approach Overall
(sec)
Existing (2016)
Conditions
WB
NB
SB
1 RT
2 TH, 1 RT
2 TH
C1
--
--
N/A
C1
--
--
N/A
Background (2018)
Conditions
WB
NB
SB
1 RT
2 TH, 1 RT
2 TH
C1
--
-- N/A
C1
--
--
N/A
Combined (2018)
Conditions - RIRO
WB
NB
SB
1 RT
1 UT*, 2 TH, 1 RT
2 TH
C1
C2
-- N/A C1
C2
--
N/A
Combined (2018)
Conditions - LO
WB
NB
SB
1 RT
1 UT*, 2 TH, 1 RT
2 TH
C1
C2
-- N/A C1
C2
-- N/A
1. Level of service for minor-street approach.
2. Level of service for major-street U-turn movement.
Improvements shown in bold.
* U-turn modeled as a left turn for analysis purposes.
Analysis indicates site drive 2 (constructed as part of Phase 1 of the Amberleigh Shores
development) currently operates at LOS C during both the AM and PM peak hours for all
analysis scenarios.
Amberleigh Shores Phase II – Traffic Impact Analysis
25
For the combined analysis, a u-turn lane and bulb out are proposed south of the existing site
drive 2. This would provide a location for site traffic to perform the u-turn while not
impacting the signal operations. It is worth noting this movement was analyzed as a left turn.
This u-turn is expected to operate at LOS C during both the AM and PM peak hour for both
the RIRO and LO analysis scenarios. This location would also benefit from breaks in the
traffic flow provided by the signal operations at the intersection of Market Street and
Mendenhall Drive and Marsh Oaks Drive.
Amberleigh Shores Phase II – Traffic Impact Analysis
26
7.4. Market Street and Alexander Road / Site Drive #3
The intersection of Market Street and Alexander Road / Site Drive #3 was analyzed under
existing traffic conditions with existing lane configurations and traffic control. For background
and combined traffic conditions, the intersection was analyzed with TIP improvements, which
limit Alexander Road to LO access. In the combined traffic conditions, the proposed Site
Drive #3 was added as a westbound approach. Refer to Table 6 for a summary of the analysis
results. Refer to Appendix H for the Synchro capacity analysis reports.
Table 6: Analysis Summary of Market Street and Alexander Road / Site
Drive #3
ANALYSIS SCENARIO
A
P
P
R
O
A
C
H
LANE
CONFIGURATIONS
WEEKDAY
AM PEAK HOUR
LEVEL OF
SERVICE
WEEKDAY
PM PEAK HOUR
LEVEL OF
SERVICE
Approach Overall
(sec) Approach Overall
(sec)
Existing (2016)
Conditions
EB
NB
SB
1 LT-RT
1 LT, 2 TH
1 TH, 1 TH-RT
D1
C2
--
N/A
D1
C2
--
N/A
Background (2018)
Conditions
EB
NB
SB
1 RT
1 LT, 2 TH
1 TH, 1 TH-RT
C1
C2
--
N/A
D1
C2
--
N/A
Combined (2018)
Conditions - RIRO
EB
WB
NB
SB
1 RT
1 RT
1 LT, 2 TH, 1 RT
1 TH, 1 TH-RT
D1
C1
C2
--
N/A
D1
C1
C2
--
N/A
Combined (2018)
Conditions - LO
EB
WB
NB
SB
1 RT
1 RT
1 LT, 2 TH, 1 RT
1 LT, 1 TH, 1 TH-RT
D1
C1
C2
B2
N/A
D1
C1
C2
C2
N/A
1. Level of service for minor-street approach.
2. Level of service for major-street left-turn lane movement.
TIP improvements underlined.
Proposed improvements shown in bold.
Analysis indicates the minor street approach currently operates at LOS D during both the AM
and PM peak hours. The main street left turns are expected to operate at LOS C during both
the AM and PM peak hours. With the improvements associated with the TIP project, the
eastbound approach is expected to improve slightly.
Should site drive 3 be limited to right-in / right-out access, it is expected to operate at LOS C
Amberleigh Shores Phase II – Traffic Impact Analysis
27
during both the AM and PM peak hours.
Should site drive 3 be limited to left-in / right-in / right-out access, the minor street approach is
expected to operate at LOS C during both the AM and PM peak hours. The left turn in the site
is expected to operate at LOS B during the AM peak hour and LOS C during the PM peak
hour.
A left-in location is not currently included as part of the TIP project. However, it appears that
a median break in order to construct the left turn would be possible while also maintaining the
planned median break to serve Alexander Road.
Amberleigh Shores Phase II – Traffic Impact Analysis
28
8. CONCLUSIONS
The contents of this report present the findings of the Traffic Impact Analysis conducted for
the proposed Amberleigh Shores Phase II, to be located east of Market Street at its intersection
with Alexander Road and south of Marsh Oaks Drive in Wilmington, North Carolina. The
proposed development is expected to consist of 288 apartment units and will have a future
analysis year of 2018. The study analyzes traffic conditions during the weekday AM and PM
peak hours for the following scenarios:
Existing (2016) Traffic Conditions
Background (2018) Traffic Conditions
Combined (2018) Traffic Conditions
Two access scenarios are considered as a part of this study. The first is limiting the proposed
site drive to a right-in / right-out driveway, and the second is considering the same driveway as
an unsignalized left-over.
It is estimated that the proposed development will generate 1,900 total site trips on the
roadway network during a typical 24-hour weekday period. Of the daily traffic volume, it is
anticipated that 145 trips (29 entering and 116 exiting) will occur during the AM peak hour
and 176 (114 entering and 62 exiting) will occur during the PM peak hour.
Capacity analysis indicates all intersections are expected to operate at an acceptable level of
service for all analysis scenarios during both the AM and PM peak hour.
A u-turn location was considered in order to accommodate vehicles exiting site drive 3 with
the goal of ultimately heading south of the study area. This will prevent a large number of u-
turns at the existing signal at the intersection of Market Street and Mendenhall Drive / Marsh
Oaks Drive. The other alternative is for these vehicles to travel through the adjacent
residential development in order to make a left turn at this signal.
The existing signal would provide breaks in the southbound traffic on Market Street,
facilitating the u-turn movement.
Amberleigh Shores Phase II – Traffic Impact Analysis
29
The two alternatives for site access function similarly, with all movements operating at an
acceptable level of service. The left-in to the sight, provided as a part of the left-over scenario,
would prevent traffic from turning left at the signalized intersection and traveling through the
adjacent residential properties.
While the current STIP project U-4902 plans show a median break to allow left turns onto
Alexander Road, one is not currently provided for the location of the proposed site drive.
However, it does appear possible to construct a median break for the site access without
compromising the left turn onto Alexander Road.
Amberleigh Shores Phase II – Traffic Impact Analysis
30
9. RECOMMENDATIONS
Based on the findings of this study, geometric roadway improvements will only be needed at
the Site Driveways. See a more detailed description of the recommended improvements below.
Refer to Figure 9 for an illustration of the recommended lane configuration for the proposed
development.
Improvements by TIP Project
Market Street and Marsh Oaks Drive / Mendenhall Drive
Extend the northbound left turn lane to 500 feet of full width storage and adequate
taper.
Extend the northbound right turn lane to Site Drive 2.
Market Street and Alexander Road
Construct a northbound left turn lane with 375 feet of full width storage and
appropriate taper.
Construct a northbound right turn lane with 200 feet of full width storage and
appropriate taper.
Amberleigh Shores Phase II – Traffic Impact Analysis
31
Improvements Recommended by Developer – Left-over
Market Street and Site Drive 2
Construct a northbound u-turn lane with 300 feet of full storage and adequate taper.
Construct a bulb out to accommodate vehicles.
Market Street and Alexander Road / Site Drive #3
Construct a southbound left turn lane with 300 feet of full storage and adequate
taper.
Extend the northbound right turn lane for the adjacent property to serve the site
drive.
Construct the site access with one ingress and one egress lane, allowing only right
turns exiting the site.
Provide stop control for the site drive.
Improvements Recommended by Developer – Right-in / Right-out
Market Street and Site Drive 2
Construct a northbound u-turn lane with 300 feet of full storage and adequate taper.
Construct a bulb out to accommodate vehicles.
Market Street and Alexander Road / Site Drive #3
Extend the northbound right turn lane for the adjacent property to serve the site
drive.
Construct the site access with one ingress and one egress lane, allowing only right
turns exiting the site.
Provide stop control for the site drive.
Ma
r
k
e
t
S
t
r
e
e
t
Alexander Road
Mendenhall Drive Marsh Oaks Drive
Si
t
e
D
r
i
v
e
#
1
Site Drive #3
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 9a
Recommended
Lane Configurations
Alternative 1
N
LEGEND
Signalized Intersection
Unsignalized Intersection
Existing Lane
X'Storage (In Feet)
Improvement by Developer
32
TIP U4902 Improvement
Right-In/Right-Out Intersection
TWLTL Two Way Left Turn Lane
50
0
'
TW
L
T
L
37
5
'
20
0
'
30
0
'
17
5
'
75'
Left-Over Intersection
Site
Ma
r
k
e
t
S
t
r
e
e
t
Alexander Road
Mendenhall Drive Marsh Oaks Drive
Si
t
e
D
r
i
v
e
#
1
Site Drive #3
Site Drive #2
Scale: Not to Scale
Amberleigh Shores
Wilmington, NC
Figure 9b
Recommended
Lane Configurations
Alternative 2
N
LEGEND
Signalized Intersection
Unsignalized Intersection
Existing Lane
X'Storage (In Feet)
Improvement by Developer
33
TIP U4902 Improvement
Right-In/Right-Out Intersection
TWLTL Two Way Left Turn Lane
50
0
'
TW
L
T
L
37
5
'
20
0
'
30
0
'
17
5
'
75'
Left-Over Intersection
Site
30
0
'