Riverchase-1/PP-SY 940113TRAFFIC ACCESS STUDY ADDENDUM FOR
RIVERCHASE CLUB APARTMENTS
IN COPPELL, TEXAS
Prepared For:
C.E.D. Construction
Prepared By:
DeShazo, Tang & Associates, Inc.
330 Union Station
Dallas, Texas 75202
(214) 748-6740
January 13, 1994
DT&A Job #94004
DT&A
DeShazo, Tang & A~c~tcx, Inc.
Eagi~e= o Planner~
TECHNICAL MEMORANDUM
TO:
FROM:
DATE:
SUBJECT:
Mr. David W. Brown
C.E.D. Construction
DeShazo, Tang & Associates, Inc.
January 13, 1994
Traffic Access Study Addendum for Riverchase Club Apartments, Coppell, Texas; J94004
PURPOSE
The purpose of this memorandum is to analyze traffic access for Riverchase Club Apartments, a proposed multi-
family development, in Coppell, Texas, as well as address additional concerns expressed by city staff. After an
original submittal of the Traffic Access Study on December 21, 1993, DT&A and C.E.D. Construction met with
city staff to discuss additional concerns not addressed in the initial study. The access issues of this analysis are
limited to examining the impact of the proposed development on the intersections of MacArthur Boulevard and
Belt Line Road, and MacArthur Boulevard and Riverchase Drive. The analysis will also study the need for a
southbound deceleration lane and the appropriateness of a second site access point on MacArthur Boulevard.
SITE DESCRIPTION
The proposed site consists of land located north of Belt Line Road on Mac. Arthur Boulevard in Coppell, Texas.
The site is bounded by MacArthur Boulevard to the north and east. Vacant land borders to the west while the
St. Louis & Southwestern Railroad borders to the south. Exhibit 1 illustrates the site in relation to the
surrounding thoroughfares. The development is planned to consist of 280 multi-family dwelling units. The site
provides for one driveway at the intersection of MacArthur Boulevard and Riverchase Drive. The proposed site
layout is shown in Exhibit 2.
EXISTING CONDITIONS
Accessibility
Accessibility is an important consideration in the study and design of transportation systems serving any
development. Access to the proposed site will be provided via the following roadways:
MacArthur BouleVard - is a north/south four-lane divided arterial adjacent to the site. South
of Belt Line Road it becomes a six-lane divided roadway which serves as the major spine road
for Valley Ranch. According to data collected in January 1994, MacArthur Boulevard carries
approximately 14,000 vehicles per day north of Belt Line Road. The posted speed limit is 35
mph, and the 85th percentile speed is 43 mph north of Belt Line Road. The Coppell
330 Union Station
Dallas, Texas 75202--4802
214/748-6740 Metro 214/263-5428
Fax 214f748-71B7
thoroughfare plan calls for MacArthur Boulevard to be expanded to a six-lane divided roadway
north of Belt Line Road, but the improvements have not been funded or scheduled.
Riverchase Drive - is a four-lane undivided roadway that connects MacArthur Boulevard to
Sandy Lake Road.
Belt Line Road - is an east-west arterial located south of the proposed development. East of
MacArthur Boulevard, Belt Line Road is a six-lane divided roadway providing access to IH35.
West of MacArthur Boulevard, Belt Line Road is a two-lane undivided road.
Exhibit 3 illustrates the existing lane assi~enments at the following intersections:
MacArthur Boulevard and Riverchase Drive
MacArthur Boulevard and Belt Line Road
Traffic Volumes
Twenty-four hour traffic counts were performed in January 1994 on Mac. Arthur Boulevard, Belt Line Road and
Riverchase Drive. Counts were conducted on a Thursday and a Friday, and on a Tuesday. Normally, traffic
counts are conducted on Tuesday, Wednesday or Thursday to count "normal" traffic volumes. Fridays and
Mondays are erratic at times due to vacations and other factors. Because of time constraints, the Thursday-
Friday count was used in the analysis. Exhibit 4 illustrates both of the counts taken. As shown, both days were
very similar with respect to traffic volumes. Therefore, the analysis performed on the Thursday-Friday data
should be accurate for a "normal" day. As shown in Exhibit 4, MacArthur Boulevard carries approximately
14,000 vehicles per day north of Belt Line Road and 16,800 vehicles per day south of Belt Line Road. Belt Line
Road carries about 16,600 vehicles per day east of MacArthur Boulevard and 10,800 vehicles per day west of
MacArthur Boulevard. Riverchase Drive carries approximately 1,100 vehicles per day east of MacArthur
Boulevard.
Exhibit 4
Existing Daily Traffic Volumes
Vehicles per Day
Count Percent
Location Thursday-Friday Tuesday Difference
(January 6-7, 1994) (January 11, 1994)
Mac. Arthur Blvd.
North of Belt Line Road 14,010 14,029 0.1%
Mac. Arthur Blvd.
South of Belt Line Road 16,903 16,641 1.6%
Belt Line Road
East of MacArthur Blvd. 16,617 16,692 0.4%
Belt Line Road
West of MacArthur Blvd. 10,996 10,725 2.5%
Riverchase Drive
East of MacArthur Blvd. 1,133 1,096 3.4%
Manual peak hour traffic movement counts were obtained from 4:00 to 6:00 p.m. on Thursday, January 6, 1994
and from 6:30 to 8:30 a.m. on Friday, January 7, 1994 at the intersections of Mac. Arthur Boulevard and Belt Line
Road, and MacArthur Boulevard and Riverchase Drive. Exhibits 5 and 6 illustrate the existing morning and
evening peak hour traffic movements.
FUTURE CONDITIONS
Area Development
To determine the appropriate design year in which to examine the impact of the proposed development on the
adjacent street system, the year in which the construction of the site will be completed must be estimated. For
this proposed development, a completion date of 1996 is anticipated. Other developments that are expected to
affect the traffic conditions in the vicinity of the proposed development in 1996 include a retail center planned
for the southeast quadrant of MacArthur Boulevard and Riverchase Drive. Although additional apartments are
planned on Riverchase Drive east of MacArthur Boulevard, they are not expected to be completed until after
1996. Additional single-family homes are also planned in the vicinity of Riverchase Drive. The trips generated
by these homes were assumed to be taken into account in the growth rate applied to existing traffic volumes.
Traffic Volumes
In order to accurately assess the impact of the proposed development on the adjacent roadway system, future
traffic volumes must be estimated. Because the proposed development is projected to be completed by early
1996, a design year of 1996 was used to analyze the effect of the development on the adjacent streets. Traffic
projections for the study area were obtained by applying a growth factor to existing traffic and adding the
planned retail center traffic to the projected volumes. The retail center is not anticipated to affect the traffic
volumes during the morning peak hour; however, in the evening peak hour, the retail center is estimated to
produce 365 trips into the development and 354 trips out of the development. No passby trips were assumed
for this retail center in order to examine the worst case scenario. The growth rate was determined using historic
traffic count data near the proposed site.
In 1986, DT&A performed 24-hour traffic volume counts at the intersection of MacArthur Boulevard and Belt
Line Road. Comparing these volumes to the April 1993 daily traffic counts conducted for the retail center
planned in the southeast quadrant of Mac. Arthur Boulevard/Riverchase Drive, a growth rate of 6.5% per year
was calculated. This growth rate was applied to the existing turning movements collected by DT&A on January
6 and 7, 1994, at the intersections of MacArthur Boulevard and Belt Line Road, and MacArthur Boulevard and
Riverchase Drive. Exhibits 7 and 8 depict the projected 1996 morning and evening peak hour turning movements
without the proposed development. These turning movements include the trips generated by the retail center
located on the southeast quadrant of MacArthur Boulevard and Riverchase Drive.
Trip Generation
The fifth edition of the Institute of Transportation Engineers (ITE) Trip Generation Manual was used to
determine the number of trips generated by the proposed development. The manual provides rates developed
by ITE for various land uses. The trip generation rates for low-rise multi-family dwelling units were used to
calculate the trips anticipated to be generated by the proposed development. The results are shown in Exhibit
9.
Exhibit 9
Trip Generation
Proposed Multi-Family Development
Number Weekday AM Peak Hour PM Peak Hour
Use of Trips Trips Trips
Units Total [ I
In Out In Out
Multi-Family 280 - 1,852 26 103 108 56
Note: Trip generation for multi-family low-rise apartments is based on ITE Land Use Code 221
The site is projected to generate 1,852 trip ends during a twenty-four hour period. During the A.M. peak hour,
approximately 26 inbound trips will be generated while 108 inbound trips will be generated during the P.M. peak
hour. Outbound site trips for the A.M. and P.M. peak hours were calculated to be 103 and 56, respectively. The
total projected trip ends during the A.M. and P.M. peak hour are 129 and 164, respectively.
In December 1993, DT&A conducted a study of two existing apartments to provide a comparison of actual trips
for apartments in the Dallas area to the projected ITE rates shown in the Trip Generation Manual. Exhibit 10
summarizes the results. As shown, the actual trips generated in the morning peak hour were almost identical
to the ITE rates for low-rise multi-family (ITE Code 221). In the evening peak hour, the actual trips were
approximately 80% of the calculated rates. Therefore, the low-rise multi-family rates provide an accurate
estimate for the morning peak hour; however, they overestimate the evening peak hour by about 20%. For the
purposes of this study, the low-rise multi-family ITE rates were used to calculate the trips antidpated to be
generated by the proposed development.
Exhibit 10
Comparison of ITE Low-Rise Multi-Family Trip Generation Rates to
Actual Trips Generated
Location # of Occu- Volumes AM Peak Hour PM Peak Hour
Units pancy I
In Out Total In Out Total
Jefferson 300 97% Projected 27 106 133 112 58 170
Creek Actual 15 127 142 86 42 128
Apartments Act/Proj 0.56 1.20 1.07 0.77 0.72 0.75
Villas of 124 98% Projected 13 52 65 52 27 79
Valley Ranch Actual 4 56 60 48 16 64
Act/Proj 0.31 1.08 0.92 0.92 0.59 0.81
Average [ Act/Proj I I 1.00 I 0.78
Traffic Orientation and Assignment
At the request of city staff, trip orientations of site-generated traffic were based on the adjacent roadway network
traffic during the morning and evening peak hours. Using this method, two sets of orientations were developed,
one for the morning peak hour and one for the evening peak hour. These orientations represent the direction
that the trips from the proposed development wish to travel during the particular peak hour. According to the
adjacent roadway network morning peak hour traffic volumes, the following orientations were developed:
AM Peak Hour
PM Peak Hour
To/From the North 12% 20%
To/From the South 37% 45%
To/From the East 49% 32%
To/From the West 2% 3%
Trip assignment consisted of modeling the site trips to take the most direct approach possible to the intended
desire line. Exhibits 11 and 12 illustrate the trip orientations used in distributing site generated traffic to the
surrounding thoroughfare network during the morning and evening peak hour, respectively. The morning and
evening peak hour trips generated by the proposed development are depicted in Exhibits 13 and 14.
Exhibits 15 and 16 show the A.M. and P.M. 1996 projected peak hour background traffic with the projected site
generated traffic volumes. Background traffic includes the retail development located on the southeast corner
of MacArthur Boulevard and RiverChase Drive.
5
ANALYSIS/OBSERVATIONS
Intersection Analysis
Unsignalized capacity analyses have been conducted utilizing the Hi~,hway Capacity_ Manual methodology for the
intersection of MacArthur Boulevard and Riverchase Drive. Using this methodology, the worst turning
movement level of service represents the intersection level of service, where level of service reflects the expected
operation of the intersection. Level of service ranges from "A~ to "F~', where a level of service A is very good
and a level of service F reflects a situation that is considered undesirable. Exhibit 17 depicts the results. For
existing conditions, the westbound left turns from Riverchase Drive to Mac. Arthur Boulevard experience a level
of service E during the A.M. and P.M. peak hours. In the 1996 design year, this intersection is expected to
operate at a level of service E in the morning peak hour and level of service F in the evening peak hour due to
the westbound left turns. The level of service will remain "E" in the morning peak hour and "F' in the evening
peak hour with the addition of the proposed development trips. The proposed multi-family development is
expected to increase the number of trips traveling through the intersection by only 6% during the A.M. peak
hour and 7% during the P.M. peak hour.
Exhibit 17
Unsignalized Intersection Analysis
MacArthur Boulevard at Riverchase Drive
Turning AM Peak Hour PM Peak Hour
Year Movement
Reserve Level of Reserve Level of
Capacity Service Capacity Service
Existing Westbound Left 74 E 4 E
Southbound Left 774 A 196 D
Intersection -- E -- E
Year 1996 Base Westbound Left 62 E -108 F
Southbound Left 769 A 9__.~2 E
Intersection -- E -- F
Year 1996 Base Westbound Left 7 E -114 F
+ Development Southbound Left 759 A 82 E
Eastbound Left 21 E 33 E
Northbound Left 88 E 517 A
Westbound Thru 41 E 28 E
Eastbound Thru 40 _.E 30 E
Intersection -- E -- F
The unsignalized location of Mac. Arthur Boulevard at Riverchase Drive is expected to analytically operate at level
of service F in the P.M. peak hour by the year 1996. The westbound left-mm maneuver from Riverchase Drive
controls the intersection level of service. However, the unsignalized analysis used to determine the level of
service for uusignalized intersections assumes a random arrival rate. Because of the proximity of Belt Line Road
to the unsignalized intersection of Riverchase Drive, the vehicles on Mac. Arthur Boulevard are grouped in
platoons. The platooning of vehicles creates larger gaps ia the traffic on the major roadway, which allows the
vehicles turning left from the minor roadway to operate more efficiently than analytically predicted.
Although the intersection of Mac. Arthur Boulevard and Riverchase Drive is expected to operate at a level of
service E ia the morning peak hour and level of service F in the evening peak hour in the year 1996, the
intersection will probably not meet traffic signal warrants by 1996 because of the relatively low traffic volumes
on Riverchase Drive. Future signalization of this intersection may be warranted, but should be examined closely.
A signal at this intersection could promote additional traffic on Riverchase Drive from Sandy Lake Road to
Mac. Arthur Boulevard. The possibility of additional access from Riverchase Drive to Belt Line Road east of
MacArthur Boulevard may also be provided ia the future. This connection would decrease the number of trips
from Riverchase Drive to MacArthur Boulevard, improving the projected level of service of this intersection.
The intersection of MacArthur Boulevard and Belt Line Road was also examined to determine thc impact of
the proposed development on the operations of the intersection. The Highway Capacity Manual methodology
was used to analyze the intersection. For signalized intersection, the total intersection delay is used to determine
the intersection level of service. Exhibit 18 summarizes the results of the analysis. As shown ia Exhibit 18, the
intersection currently operates at a level of service D ia the morning peak hour. In examining the turning
movement volumes at this intersection, the southbound left turns were very high, with over 800 vehicles turning
left from MacArthur Boulevard to Belt Line Road. To improve traffic operations at this intersection, the
following modification to the existing southbound lane configuration is recommended:
Existing Lane Configuration:
Proposed Lane Configuration:
Lane 1 Lane 2 Lane 3
Right/Through Shared Through Left
Right/Through Shared
Through/Left Shared Left
By implementing this improvement, the intersection level of service is expected to be improved to a level of
service C during the morning peak hour through the year 1996 with the proposed development. In the evening
peak hour, the intersection of MacArthur Boulevard and Belt Line Road currently operates at a level of service
C. By the year 1996, this level of service is expected be "D". The proposed development will increase
intersection delay approximately 7%, but the intersection will remain at a level of service D.
7
Exhibit 18
Signalized Intersection Analysis
MacArthur Boulevard at Belt Line Road
AM Peak Hour PM Peak Hour
Year
Intersection Delay Level of Intersection Delay Level of
(seconds/vehicle) Service (seconds/vehicle) Service
Existing 37.2 D 21.7 C
Existing w/Improvement 20.0 C 21.7 C
Year 1996 Base 22.6 C 32.8 D
Year 1996 Base + 23.5 C 35.0 D
Development
Queue Analysis
One factor in this analysis is to determine if the left-turn storage lanes on MacArthur Boulevard at Riverchase
Drive are adequate to accommodate the vehicles expected to stack in these lanes. This was done by conducting
a queuing analysis. The queuing theory utilized is documented in the Transportation and Traffic En~neerin~
Handbook, 2nd Edition, published by the Institute of Transportation Engineers, 1982 (page 461). The theory
utilizes a random (i.e., Poisson) arrival rate. Four analysis "years" were examined. Exhibits 19 and 20 illustrate
the existing morning and evening peak hours. Exhibits 21 and 22 illustrate the existing morning and evening peak
hours with the recommended modification at the intersection of Mac. Arthur Boulevard and Belt Line Road.
Exhibits 23 and 24 show the queues expected in 1996 without the proposed development during the morning and
evening peak hours. Exhibits 25 and 26 depict the queues in 1996 with the proposed development during the
morning and evening peak hours.
With a confidence level of 95%, the results reveal that a queue of one vehicle or less can be expected during the
morning and evening peak hours for the northbound left turn into the development in 1996 (Exhibits 24 and 25).
The southbound left turn from Mac. Arthur Boulevard to Riverchase Drive can expect a queue of approximately
two vehicles or less during the peak hours in 1996. Therefore, the existing left-turn storage lanes on Mac. Arthur
Boulevard at Riverchase Drive are adequate to accommodate the left-mm demand and not disrupt the through
vehicles on Mac. Arthur Boulevard.
A queuing analysis was also performed to examine the intersection of MacArthur Boulevard at Belt Line Road.
Currently, traffic occasionally queues past Riverchase Drive on southbound Mac. Arthur Boulevard during the
morning peak hour. The service rate necessary for the queuing analysis was obtained through the utilization of
Greenshields theory. This theory is documented in the Transportation and Traffic Engineering Handbook, 2nd
Edition (page 465). As shown is Exhibit 18, it was determined a queue of over 1,500 feet per lane can be
expected during the morning peak hour if no changes are made to the intersection of Mac. Arthur Boulevard and
Belt Line Road. The distance between Belt Line Road and Riverchase Drive is approximately 800 feet.
The recommended improvement of restriping the southbound lanes on Mac. Arthur Boulevard at Belt Line Road
and retiming the traffic signal is expected to reduce this queue length. In 1996, the queue is expected to be
approximately 360 feet with the development, or a decrease of almost 1,150 feet from existing queues.
Secondary Driveway
A second driveway located at the median opening on MacArthur Boulevard immediately north of Riverchase
Drive was also examined. A driveway at this location should improve the traffic conditions at the intersection
of MacArthur Boulevard and Riverchase Drive by decreasing the turning movements in and out of the
development at Riverchase Drive. It should be noted that this driveway was not included in the previous analysis.
Because this driveway would be located on the inside of a curve, intersection sight distances were examined to
ensure the safety of implementing a driveway at this location. Based on the actual 85th percentile speed of 43
miles per hour, a minimum sight distance of 320 feet (desirable of 450 feet) is required by the City of Coppell
Ordinance number 90496 to provide safe access to and from the site. Currently, sight distances exceed 350 feet.
If a sight distance of 320 feet or more cannot be maintained due to fencing or landscaping, the median opening
can be modified to allow northbound left turns into the site, but prohibit eastbound left turns out of the site (see
Exhibit 27).
Deceleration Lane
Another factor in this analysis was the examination of the need for a deceleration lane on southbound MacArthur
Boulevard at the main driveway. The City of Arlington has developed guidelines for the implementation of
deceleration lanes that they feel provide additional capacity at driveways when necessary. The Arlington criteria
states that a deceleration lane is required if:
1)
2)
over 50 vehicles turn right into the development during the peak hour, or
over 40 vehicles turn right into the development during the peak hour and the speed limit exceeds 40
mph.
The main driveway is expected to have approximately 22 vehicles turning right into the development during the
peak hour (without the secondary driveway). Therefore, a deceleration lane should not be required at this
location.
CONCLUSION
The proposed 280-unit multi-family development, located on MacArthur Boulevard north of Belt Line Road, is
expected to increase the traffic at the intersection of MacArthur Boulevard and Riverchase Drive by 6% in the
morning peak hour and 7% in the evening peak hour in the design year 1996. This represents an average
increase in the morning traffic on MacArthur Boulevard of two additional vehicles per minute, and three vehicles
per minute in the evening peak hour. The increase in traffic on MacArthur Boulevard is not expected to affect
the level of service at the intersections of MacArthur Boulevard and Riverchase Drive or Mae. Arthur Boulevard
and Belt Line Road. Therefore, the proposed development will not adversely affect the roadway system.
The operation of the intersection of MacArthur Boulevard and Belt Line Road can be improved by implementing
an alternative lane configuration. By allowing the southbound middle lane (currently a through lane only) to
serve both through and left turn traffic, the delay currently experienCed at the intersection can be improved by
almost 90%.
The left-turn storage on Mac. Arthur Boulevard at Riverchase Drive was also examined to determine if the
existing storage lengths were sufficient to accommodate the future traffic volumes. The northbound left-turn into
the development is not expected to have more than one vehicle in the lane at a time during the peak hour. The
southbound left-turn lane is expected to have between one and two vehicles stored in the left-turn lane at
Riverchase Drive during the peak hour. Sufficient storage currently exists to accommodate the expected left-turn
vehicle queues on Mac. Arthur Boulevard at Riverchase Drive.
In order to improve traffic flow from Riverchase Drive to MacArthur Boulevard, a second driveway located at
the median opening north of Riverchase Drive may be considered. The sight distance for this driveway should
be maintained at a minimum of 320 feet as per City of Coppell ordinance requirements. If this sight distance
cannot be obtained, and the second driveway is desired, the median opening should be channelized to allow
northbound left-turns into the proposed development, but prohibit eastbound left-turns from the development
(see Exhibit 27).
The option of constructing a deceleration lane on southbound MacArthur Boulevard at the main entrance was
also examined. The deceleration lane had originally been recommended due to the controlled access point
(gates) at the main entrance. These gates have since been removed from the site plan. Because only 22 vehicles
are expected to execute this southbound right-turn movement, a deceleration lane should not be required.
10
· .Riverchase Dr.
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St.Louis & Southwestern
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Railroad
Belt. Line Rd.
Exhibit 1
Site Location
I
I
Exhibit 2
Site Plan for Riverchase Club Apartments
J
Exhibit 3
Lane Assignments
Exhibit 5
Existing AM Peak Hour Traffic Volumes
(7:15-8:15 am)
Belt Une Rd.
Exhibit 6
Existing PM Peak Hour Traffic Volumes
(5-6 pm)
Belt Line Rd.
Exhibit 7
AM Peak Hour Traffic Volumes
1996 Base (+ Retail)
Belt Une Rd.
SSi IqO
Exhibit 8
PM Peak Hour Traffic Volumes
1996 Base (+ Retail)
Belt Une Rd.
Exhibit 11
AM Peak Hour Trip Orientations
Belt Line Rd.
Exhibit 12
PM Peak Hour Trip Orientations
Belt Line Rd.
Exhibit 13
AM Peak Hour Site Generated Trips
Belt Une Rd.
Exhibit 14
PM Peak Hour Site Generated Trips
Belt Line Rd.
Exhibit 15
AM Peak Hour Traffic Volumes
1996 Base + Site
Belt Une Rd.
Exhibit 16
PM Peak Hour Traffic Volumes
1996 Base + Site
Belt Une Rd.
1=
18
Exhibit 19
AM Peak Hour Queue Lengths
with Existing Geometry
Belt Line Rd.
Belt Une Rd.
Exhibit 20
PM Peak Hour Queue Lengths
with Existing Geometry
13111
Exhibit 21
AM Peak Hour Queue Lengths
with Improved Geometry
Belt Une Rd.
Exhibit 22
PM Peak Hour Queue Lengths
with Improved Geometry
10
Belt Line Rd.
,0
AM Peak Hour Queue Lengths / I I t/
1996 Base /Htl
13
Belt Une Rd.
Exhibit 24
PM Peak Hour Queue Lengths
1996 Base
,f
AM Peak Hour Queue Lengths
1996 Base + Site
13
Belt Line Rd.
Exhibit 26
PM Peak Hour Queue Lengths
1996 Base + Site
Belt Line Rd.
Exhibit 27
Potential Channelization of 2nd Driveway