Memorandum
City of Lawrence
Public Works
|
TO: |
David L. Corliss, City Manager
|
|
FROM: |
David P. Cronin, P.E., City Engineer
|
|
CC: |
Charles Soules, P.E., Director of Public Works Mark Thiel, Assistant Public Works Director
|
|
Date: |
May 16, 2013
|
|
RE: |
Project PW1135 - 6th & Iowa Geometric Improvements Approve Supplemental Service Agreement for Engineering Design
|
Project Description
The primary scope of the 6th & Iowa project has been to include a dedicated left turn lane for west bound traffic. The proposed left turn lane will reduce the average intersection delay, reduce accidents and improve traffic flow in a significant way.
The dedicated left turn lane can be established by widening the roadway to the north and reducing the width of the existing lanes from 12 feet to 11 feet. Sidewalk on the north side will be reconstructed and the existing guard rails on both north and south side of 6th street will be replaced with a combination of concrete safety barrier and new guard rails. Additional improvements include an eastbound right turn lane, new sidewalk on the south side of 6th Street and new traffic signal equipment. Pavement in the intersection will be milled and overlaid as the base is generally in good condition.
The attached general layout sheet shows a plan view of the proposed improvements and traffic lane configuration.
Project Status
The project was designed to KDOT field check review with the intentions of extending the existing headwalls of the box bridges vertically a couple feet to hold the additional fill required to widen the roadway. A preliminary structural review of this design and the concern of modifying the existing boxes yielded KDOT's recommendation to seek an alternate design. The new design would include steepening the slopes with permanent erosion control and possibly using soil ties/anchors on the slope/wing walls for boxes. The new design is outside the original scope of work as it will include some geotechnical investigation and structural analysis. It should be noted the boxes were built in the late 50's and have a life expectancy of 75 years; approximately 18 more years.
Project Funding
Original Engineering Design Services: $72,000
Additional Engineering Design Services: $38,900
Original Construction Cost Estimate: $850,000
Additional Construction Cost Estimate: $150,000
Total Cost: $1,110,900
The total project cost including Engineering Design Services is $1,110,900 and will be financed by issuing General Obligation (GO) bonds.
Project Schedule
Completion of plans: early July 2013
Advertise and bidding: July 2013
Construction: late summer/fall 2013
Action Item
Authorize City Manager to sign purchase order for supplemental agreement with Landplan Engineering for professional services in the amount of $38,900, Project Number PW1135, 6th and Iowa Street Intersection, Geometric Improvements, Westbound Turn Lane.