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MEHAFFEY BRIDGE CONSTRUCTIONMehaffey Bridge Road Structure G-32-1 over the Iowa River at Coralville LakeProject #LFM-MEH BR--7X-52
PRESENTATION OUTLINE
• Introductions• Project Background• Structural Highlights• Construction Challenges• Questions
APWA Spring Conference March 27, 2015
YOUBrilliant, engaged professional
Your job today:◦ Actively engage in the discussion◦ Learn a little something◦ Ask questions
APWA Spring Conference March 27, 2015
ORIGINAL RESERVOIR BRIDGE
49 years old (started 1964, completed 1966) Cost to Johnson County - $100,000
($6.55/SF) Structurally deficient (posted 10%), SR=33.3 28’ Width not suitable for current/expected
traffic levels Subject to closure during 1993/2008 level
flood events
APWA Spring Conference March 27, 2015
NEW MEHAFFEY BRIDGE DESIGNDesign Constraints/ Project Goals
Design for better flood resistance Capable of handling 4-lane traffic Include a multi-purpose trail Maintain traffic during construction (Current: 3700,
Design 5500 AADT) Open waterway by minimizing number of piers to
allow for better recreation traffic Do it all for $3M
APWA Spring Conference March 27, 2015
NEW MEHAFFEY BRIDGE DESIGNAlternatives Considered
Do nothing/repair Conventional IDOT bridge (PPCB) Hump-Back Steel Cantilevered Pre-Stressed Concrete 2-Pier
Design Cable-stay bridge (End or Center
Support) Something else???
APWA Spring Conference March 27, 2015
NEW MEHAFFEY BRIDGE DESIGN
Flood resistant at 1993/2008 Levels (Elev. 717.00)
565’ x 55’ = 31075 SF 2 traffic lanes (40’ Roadway), 12’ Multi-Use Path Long span = 112’ (BTC) Traffic maintained on the old bridge throughout
sub-structure construction Only 2 piers in the water Distance from pier to pier = 224’ Contract amount = $8.9M ($286/SF)
APWA Spring Conference March 27, 2015
REDUNDANCYWhen Might Sometimes Makes Right
HAMILTON COUNTY, OH — On the night of Tuesday, May 20, 2008, a flatbed trailer carrying an old 80-ton locomotive broke free from its truck hitch. The trailer drifted forward along the southbound lane of I-275 and crashed into a pier supporting the eastbound I-74 overpass.The 32-year-old steel bridge sagged, but didn’t collapse. Eastbound traffic on I-74 traveled over the damaged bridge for about 10 minutes before officials arrived to close the bridge and reroute traffic.
APWA Spring Conference March 27, 2015
REDUNDANCY MET
Multiple stringers Diagonals and floor beams have multiple
rebar and two systems for reinforcing. Prestressed beams will be continuous for
extreme event and will carry in the event of loss of a diagonal or floor beam.
APWA Spring Conference March 27, 2015
TRAFFIC/THE PUBLIC
A recent count showed almost 5k AADT◦ They are not patient◦ They will not go around
The expectation is increasingly - zero delays Accelerated Bridge Construction
◦ 90 day critical closure incentive/disincentive◦ We build the new bridge, from a traffic impact
perspective, in approximately 3 months◦ Tier 5 ABC - Definitely◦ Tier 4 ABC - Most likely
How do we manage expectations???
APWA Spring Conference March 27, 2015
COMMUNICATIONSQR Code Road Signs
Website
Dynamic Message
Signs
APWA Spring Conference March 27, 2015
COMMUNICATIONSDynamic Speed Signs
QR Code
Public Informational Meetings
Press ReleasesRadio Spots
APWA Spring Conference March 27, 2015
PROJECT STAGING
◦ Stage 1 - Construct the towers◦ Stage 2 - Construct Diagonals, Floor Beams,
Compression Struts and Knuckles◦ Stage 3 - Construct Trail portion of the deck◦ Stage 4 - Switch traffic, demo old bridge,
complete deck and paving
APWA Spring Conference March 27, 2015
THANK YOU!
A special thank you to:◦ Johnson County Board of Supervisors◦ VJ Engineering◦ Steve Jacobsen, SE◦ Iowa Bridge & Culvert, LC◦ The US Army Corps of Engineers◦ The Iowa Department of Natural Resources
APWA Spring Conference March 27, 2015
CONTACT
Greg S. Parker, PE◦ Johnson County Engineer◦ 4810 Melrose Avenue West◦ Iowa City, Iowa 52246◦ 319.356.6046◦ [email protected]