Riverchase-1/PP-SY 931221I
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C.E.D. Construction
TRAFFIC ACCESS STUDY FOR
R1VERCHASE CLUB APARTMENTS
IN COPPELL, TEXAS
DeShazo, Tang & Associates, Inc.
330 Union Station
Dallas, Texas 75202
December 21, 1993
DT&A
TRAFFIC ACCESS STUDY 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
December 21, 1993
DT&A Job #93170
DT&A 'r g
TO:
FROM:
DATE:
SUBJECT:
TECHNICAL MEMORANDUM
Mr. David W. Brown
C.E.D. Construction
DeShazo, Tang & Associates, Inc.
December 21, 1993
Traffic Access Study for Riverchase Club Apartments, Coppell, Texas; J93170
PURPOSE
The purpose of thi~ memorandum is to analyze traffic access for Riverchase Club Apartments, a proposed multi-
family development, in Coppell, Texas. The access issues of this analysis are limited to projecting the site
generated traffic at Belt Line Road and to assess possible congestion at the main driveway at MacArthur
Boulevard and Riverchase Drive. The analysis will also study the need for a southbound deceleration lane and
the appropriateness of a second access point for the site off of 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 Mac. Arthur 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 consists 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 the summer of 1993, MacArthur Boulevard
carries approximately 17,900 vehicles per day south of Belt Line Road. With a posted speed
limit is 35 mph, the average speed is 40 mph north of Belt Line Road. The Coppell
thoroughfare plan calls for MacArthur Boulevard to be expanded to a six-lane divided roadway,
but the improvements have not been scheduled as of now.
Riverchase Drive - is a four-lane undivided roadway that connects MacArthur Boulevard to
Sandy Lake Road.
330 Union Station
Dallaa, Teaas 75202-4802
214/748-6740 Mel~o 214/263-5428
Fax 214/748-7(137
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 currently a two-lane undivided road.
Exhibit 3 illustrates the existing lane assignments at the following intersections:
MacArthur Boulevard and Riverchase Drive
MacArthur Boulevard and Belt Line Road
A major retail center is planned for the southeast comer of MacArthur Boulevard and Riverchase Drive. A new
f'tre station is also planned for the land south of the proposed site, between the railroad and the property line.
Traffic Volumes
Twenty-four hour traffic counts were performed in April, 1993 at the intersection of MacArthur Boulevard and
Belt Line Road. As shown in Exhibit 4, MacArthur Boulevard carries approximately 6,800 vehicles southbound
and 10,300 vehicles northbound during a twenty-four hour period. Belt Line Road carries about 6,600 vehicles
eastbound and 8,000 vehicles westbound during this same time period.
Manual peak hour traffic movement counts were obtained from 4:30 to 6:30 p.m. on Friday, December 17, 1993
and from 6:30 to 8:30 a.m. on Monday, December 20, 1993 at the intersection of 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 opening date of 1995 is anticipated. Other developments that are expected to
affect the traffic conditions in the vicinity of the proposed development in 1995 include a retail center planned
for the southeast comer 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
1995. 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 and leased
out by mid-1995, a design year of 1995 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 retail center traffic to the projected volumes. 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 MacArthur 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
December 17 and 20, 1993, at MacArthur Boulevard/Riverchase Drive. Exhibits 7 and 8 depict the projected
1995 morning and evening peak hour turning movements without the proposed development. These turning
movements include the trips generated by the retail center location the southeast quadrant of MacArthur
Boulevard and Riverchase Drive.
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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 multi-family low-rise 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
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.
Traffic Orientation and Assignment
Trip orientations of site-generated traffic are based on city staff projections. The orientations used resulted in
a 35% attraction to the north, 20% to the south, 20% to the east and 25% to the west.
Trip assignment consisted of modeling the site with trip ends taking the most direct approach possible to the
intended desire line. Exhibit 10 illustrates the trip orientations used in distributing site generated traffic to the
surrounding thoroughfare network. The morning and evening peak hour trips generated by the proposed
development are depicted in Exhibits 11 and 12, respectfully.
Exhibits 13 and 14 show the A.M. and P.M. 1995 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.
ANALYSIS/OBSERVATIONS
Intersection Analysis
Unsigva!iTed capacity analyses have been conducted for the intersection of MacArthur Boulevard and Riverchase
Drive. For existing conditions, the westbound left turns from Riverchase Drive to MacArthur Boulevard
experience a level of service E in the A.M. peak hour and level of service F in the P.M. peak hour due to the
westbound left from Riverchase Drive, even though only 1 vehicle every two minutes make this left turn
movement in the morning peak hour and 1 vehicle per minute in the evening peak hour. In the 1995 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 proposed multi-family development is expected
to increase the number of trips traveling through the intersection by only 7% during the A.M. peak hour and
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7% during the P.M. peak hour.
The unsignalized location of MacArthur Boulevard at Riverchase Drive currently analytically operate at level of
service F in the P.M. peak hour. The left-turn maneuver from the east 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 uusignalized intersection of Riverchase
Drive, the vehicles on MacArthur Boulevard are grouped in platoons. The platooning of vehicles creates larger
gaps in the traffic on the major roadway, which allows the vehicles turning left from the minor roadway to
operate more efficiently than analytically predicted. The vehicles will queue on the minor roadway and will not
effect the flow of traffic on the major roadways.
Although the intersection of Mac. Arthur Boulevard and Riverchase Drive 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, the intersection will probably
not meet traffic signal warrants by 1995 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 would promote additional traffic on Riverchase Drive from Sandy Lake Road to MacArthur
Boulevard. This additional traffic may be seen as undesirable to the golf coarse patrons and the residents in the
area.
Left-Turn Storage Lane Requirements
One factor in this analysis is to determine if the northbound left-turn lane on Mac. Arthur Boulevard at the main
entrance of the proposed development is adequate to accommodate the vehicles expected to stack in this lane.
This was done by conducting a queuing analysis. The queuing theory utilized is documented in the
Transportation and Traffic Engineerine Handbook. 2nd Edition, published by the Institute of Transportation
Engineers, 1982 (page 461). The theory utilizes a random (i.e., Poisson) arrival rate. 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. Therefore, the existing left-turn storage lane is adequate to accommodate the left-turn demand into
the development and not disrupt the vehicles northbound on MacArthur Boulevard.
A queuing analysis was also performed to examine southbound MacArthur Boulevard traffic at Belt Line Road.
Currently, traffic occasionally queues past Riverchase Drive during the morning peak hour. The service rate
necessary for the queuing analysis was obtained through the utilization of Greeushields theory. This theory is
documented in the Transportation and Traffic En~neering Handbook, 2nd Edition (page 465). By the year 1995
(without the proposed development), it was determined a queue of over 5,000 feet per lane could be expected
during the morning peak hour if no changes are made to the intersection of MacArthur Boulevard and Belt Line
Road. The distance between Belt Line Road and Riverchase Drive is approximately 800 feet.
In order to improve this queue length, the signal timing at MacArthur Boulevard and Belt Line Road should be
examined to determine the possibility of retiming the signal to allow more green time for southbound MacArthur
Boulevard during the A.M. peak hour. For example, if approximately five seconds of green time were added
to the southbound movements during each cycle, the queue length of over 5,000 feet could be decreased to about
620 feet. If this is not possible, the widening of MacArthur Boulevard from Riverchase Drive to Belt Line Road
from four lanes to six lanes should be examined. Not only would this improvement provide additional capacity
to the intersection of MacArthur Boulevard and Belt Line Road, it would eliminate the current situation in which
the southbound left turn-lane is in line with a through lane, causing confusion for southbound traffic.
Secondary Driveway
To allow trips to and from the proposed development improved access to MacArthur Boulevard, a second
driveway located at the median opening immediately north of Riverchase Drive should be considered. Because
this driveway would be located on the inside of a curve, sight distances were examined to ensure the safety of
implementing a driveway at this location. Based on the actual average speed of 40 mph, a minimum sight
distance of 275 feet is required to provide safe access to and from the sight (reference Transportation and Traffic
Engineering Handbook, 2nd Edition). Currently, sight distances exceed 300 feet. If a sight distance of 275 feet
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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 15). This design
would 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.
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 a maximum of 38 vehicles turning right into the development during the
peak hour. Therefore, a deceleration lane should not be required.
CONCLUSION
The proposed 280-unit multi-family development, located on Mac. Arthur Boulevard north of Belt Line Road, is
expected to increase the traffic at the intersection of Mac. Arthur Boulevard and Riverchase Drive by 7% in the
morning and evening peak hours in the design year 1995. This represents an increase in the morning traffic on
Mac. Arthur Boulevard of two 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 of the intersection of
Mac. Arthur Boulevard and Riverchase Drive. Therefore, the proposed development will not adversely affect the
roadway system.
The left-turn storage on MacArthur 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 MacArthur Boulevard at Riverchase Drive.
In order to improve traffic flow from Riverchase Drive to Mac. Arthur Boulevard, a second driveway located at
the median opening north of Riverchase Drive should be considered. The sight distance for this driveway should
be maintained at a minimum of 275 feet. If this sight distance cannot be obtained, 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 15).
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 38 vehicles
are expected to execute this southbound right-mm movement, a deceleration lane should not be required.
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.Riverchase Dr.
~ ~111111111111111111111111
Exhibit 1
Site Location
St. Louis& Southwestern Railroad
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~!
Belt, Line Rd.
c:
Exhibit 2
Site Plan for Riverchase Club Apartments
Exhibit 3
Lane Assignments
? .Riv er ch as e Dr.
St.Louis & 'Southweste Railroad
'],q~ Belt. Line Rd.
Exhibit 4
Existing 24-Hour Traffic Volumes
Exhibit 5
Existing AM Peak Hour Traffic Volumes
Exhibit 6
Existing PM Peak Hour Traffic Volumes
Exhibit 7
1995 AM Peak Hour Base Traffic Volumes
~ ~o R~ DRiVe'
Exhibit 8
1995 PM Peak Hour Base Traffic Volumes
Exhibit 10
Site Trip Distribution & Orientation
Exhibit 11
AM Peak Hour Site Traffic
Exhibit 12
PM Peak Hour Site Traffic
Exhibit 13
1995 AM Peak Hour Base Plus Site Traffic
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