ST9302-CS 950110 (2)Leftwich & Associates
Urban Transportation Planners 8. Engineers
909 Shiloh, DeSoto, TX 7~110
Phone (214) 230-0865 · Fax (2~4) 230-8183
January 10, 1995
Mr. Ken Griffin
Assistant City Manager
City of Coppell
P.O. Box 478
Coppell, Texas 75019
RE: SUMMARY OF FINDINGS - SANDY LAKE ROAD
Dear Ken,
As requested I have made two TranPlan runs testing Sandy Lake as a 4-lane and as a 6-
lane during the planning year 2010. I have used the North Central Texas Council of
Governments (NCTCOG) projections of employment and population for 2010. These
projections were based on the 1990 Census Data and approved by the region during 1994.
The roadway network included the completion of S.H. 121 Bypass, the S.H. 190 and 161
Connector and the upgrading of I.H. 35 as an 6-8 lane freeway with High Occupancy
Vehicle lanes. This network was furnished by NCTCOG as part of the City of Coppell
Roadway Impact Fee Study.
Scenario 1 modelled Sandy Lake as a 6-lane divided roadway from Mac, Arthur to the
City's east city limits and a 4-lane divided roadway from Mac, Arthur to the west city limits.
The volumes projected along Sandy Lake between Denton Tap Road and the east city
limits were between 8,000 and 12,000 daily. These volumes are easily handled by a 4-
lane divided roadway which carry between 21,000 to 28,000 vehicles per day (vpd).
The segment of Sandy Lake between Denton Tap and S.H. 121 generated higher volumes
due to traffic accessing Denton Tap Road and Freeport Parkway which serve as major
regional thoroughfares connecting a large concentration of industrial uses (Coppell) to
residential to the north. Volumes ran from 18,000 to 28,000 vehicles daily. Sandy Lake
between S.H. 121 and Freeport Parkway was at Level of Service E for a four-lane divided
roadway, it is recommended that this segment be constructed as six-lane divided
(capacity of 42,000 vpd) roadway to accommodate traffic generated by S.H. 121, Freeport
and Denton Tap.
Scenario 2 of the analysis looked at Sandy Lake as a 6-lane divided roadway throughout
the city limits of Coppell. Volumes increased from 3 to 16 percent on Sandy Lake while
adjacent roadways (Parkway Blvd. and Bethel School Road) decreased 12 to 23%. S.H.
121 Bypass also decreased in volume by 1 to 3%. With traffic volumes running between
8,500 to 14,000 between Denton Tap and the east city limit line and 23,000 in the Coppell
Road area Sandy Lake does not justify a six-lane divided roadway. However, the volume
of traffic on Sandy Lake between Freeport Parkway and S.H. 121 Bypass exceeded the
capacity of a 4-lane divided and should be constructed as a 6-lane to better serve the
area. It should be noted that when Sandy Lake was modelled as a six-lane divided
roadway, the increased capacity served to pull trips off the adjacent collectors and major
freeways. The increased trips may not be critical if they are local traffic shifting from a
collector to a major arterial. It is not advantageous to encourage long distant cut thorough
trips along Sandy Lake since these drivers put stress on the signal system and contribute
little to the funding of improvements.
The comparison of Scenario I and 2 showed little change in the pattern of traffic accessing
this area. Volumes did not increase dramatically to justify a six-lane roadway throughout
the City of Coppell. It is recommended that Sandy Lake be designated and built as a 4-
lane divided roadway from Coppell Road to the east city limits of Coppell. It is further
recommended that this roadway's designation stay es a 6-lane divided from Coppell Road
to the west city limits.
If you should have any questions conceming this analysis please contact me at 230-0865.
I will be happy to assist you.
Sincerely,
Barbra L. Leftwich
Principal
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