ST9401-CS 98101111 "'38 0:3:51Pr.1 WIER
ASSOCIATES
F'.2
VIII
MEMORANDUM
TO: Ken Griffin
FROM: Ulys Lane
DATE: 10-11-98
PROJECT: Denton Tap Road; Coppell, Texas
W&A #: 94093
We looked at removing the inside bridge rails and connecting the two bridges. As you
know, much of the west bridge up to the deck is completed. We believe the best
solution at this time will be to move the east bridge to the west approximately five feet
and re-aligning the pavement to match. The span between beams will not allow leaving
the east briclge in the current location since the span length will be too long.
We are very busy with ongoing project commitments and our staff has not been able to
devote enough time to address the issues fully. We have contacted the contractor to get
his input on options. We note issues to the solution discussed above as follows:
1. The water line air valve extends above the bridge deck in the current plans. I am
sure we can work out a solution to this issue but we have not attempted to determine a
detailed solution.
2. The storm drainage pipe at the northeast corner of the east bridge will be in conflict
with the north approach wingwall pier. I know we can work out a solution without
relaying the pipe An offset pier with special spread footings will work and we will have
to detail a solution.
3. The hick and bike trails and plan details along the east side of the east bridge will
need to be revised. All these items will work with the change it will just take time to re-
design plans and re-compute quantities.
4, The horizontal alignment of the roadway can be adjusted to match the relocated
bridge and there does not appear to be any issues such as inlets already constructed.
The tangent length in the roadway section south of the bridge between reversing curves
will need to be reduced to about 145' or the minimum roadway radius reduced below
1400'. There is no specific criteria for tangent distance in reverse curves in the AASHTO
manual but it is recommend that a tangent be provLded. We typically use 200' as a
desirable minimum and 145' will be acceptable. We might prefer a combination of
reducing the radius to 1200' to get the tangent length closer to 200'.
5. On the west bridge once traffic is temporarily routed over this bridge while the east
bridge is constructed a temporary guard rail will be needed. We believe placement of
the standard sotid concrete road rail could be used
6. I don't know if any change will effect any ongoing effort by private utilities in line
relocations. You may want to advise them immediately. Several have obtained digital
copies of plans from us wlnicn will be changing.
4300 Beltway Place, Suite 130 Arlington, Texas 76010
metro (817) 467-7700
!r
i".tC:~'v' 11 "'gL=', l~3: 5ZF'M NTEFE'. S: ~SSOCT~TES *-, P. 3
Memorandum
W&A #
November 11, 1998
Page 2 of z
Perhaps we should schedule a work meeting with your staff the contractor, our structural
engineer and myself to go over options and to try and make the best decisions for the
City.
END OF MEMO
4300 Beltway Place, Suite 130 Arlington, Texas 76018 metro (817) 467-7700