Item 4G AudioHonorable Mayor and members of the City Council, Item 4G on tonight’s agenda is
Approve
to
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NDM prepared and submitted conceptual design to the city for review of a conventional
four-lane divided roadway using the existing centerline and taking right of way equally from
both sides of the proposed roadway. It was later determined that the straight roadway
alignment of White Chapel Boulevard should be shifted at the intersection of Highland
Street so that no additional right of way will be required from the Southlake Church, due to
the proximity of the existing building to the right of way. Since the property at the northwest
corner of the intersection belongs to the City, there would also be a cost savings in the right
of way acquisition by shifting the horizontal alignment of the roadway to the west.
Supplemental Agreement No. 1, in the amount of $12,285 was approved by
the City Manager in January, 2010 to revise the horizontal alignment of White Chapel
Boulevard at the intersection of Highland Street to the west and add 2 feet of pavement on
both sides of the road for bike lanes. The design fee for the revision also included revising
the new typical sections of the roadway to include the additional 2’ on each side of the road
to accommodate bike traffic.
NDM coordinated with design engineers for the White Chapel Countryside Office Park and
made alignment recommendations for the city’s waterline construction project along
Highland Street, which is now complete. NDM had also revised the schematic layout at the
intersection and submitted it to staff for review. Design had progressed to nearly 30% when
the city suspended work on the roadway design.Whenand Why?
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Traffic circulation issues at Carroll High School caused the staff to reconsider
operation of the Highland Street intersection. Several different types of intersection
control methods were evaluated to determine the most advantageous approach. A
traffic engineering consultant looked at the costs and level of service (LOS) for two
way stop control, four way stop control, traffic signal control, a single lane
roundabout, and a dual lane roundabout. Staff has presented these options to
members of the City Council and Planning and Zoning Commissioners at two
Southlake 2030 work sessions. Summarizing those discussions, the two way and
four way stop control intersection and the single lane roundabout will not efficiently
handle the projected 2019 volume of traffic without excessive delay. Signal control
would be useful during the morning and afternoon peak periods, but would not
operate efficiently during the remainder of the day and would impose continuing
maintenance and operation costs. The dual lane roundabout, does improve
capacity at the intersection and creates the least delay for drivers of the options
considered. Council and Planning and Zoning members of the 2030 committee
directed Staff to move forward with the design of a dual lane roundabout at the
intersection of North White Chapel Boulevard and Highland Street.
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Supplemental Agreement No. 2, in the amount of $173,827 is for the completion of
design of White Chapel Boulevard along the revised alignment and will include a
dual lane roundabout at the intersection of Highland Street.
The revised scope as outlined in Supplemental Agreement No. 2
includes additional survey of up to 350’ beyond the original limits of Highland Street
and up to 500’ north of Highland Street along White Chapel to accommodate the
dual lane roundabout and the revised alignment of the intersection. The agreement
also includes landscaping and irrigation design of the proposed roundabout and the
center medians along White Chapel Boulevard. Subsurface utility engineering work
will be performed in order to verify the location of existing water and sanitary sewer
lines and any other private utilities within the corridor that will need to be relocated
prior to beginning construction. The utility design includes the relocation of existing
sanitary sewer mains which will be in conflict with the new pavement. The drainage
design will need to be updated to incorporate the drainage from the new
Countryside White Chapel Office Park development that has been constructed
since the original drainage study was performed by NDM. Finally, the revised scope
includes final engineering plans, traffic control and sequencing for construction,
contract documents, bidding of the construction project and construction
administration.
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This is a breakdown of the costs for amendment No.2 for a total of $173,827
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Funding for the design contract is available in the previously approved capital
improvement program project budget
60% plans –Summer 2012
ROW june 2012 –spring 2013
Utility relocation –end of 2012 –Fall of 2013
Construction –late 2013
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