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Prefabricated Bridge Elements and Systems

ABC/PBES Costs

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Slide 1. ABC/PBES Costs

by Mary Lou Ralls, P.E., Principal
Ralls Newman, LLC (formerly Texas State Bridge Engineer)

 

Slide 2. Learning Outcomes

  • Identify examples of ABC/PBES replacement projects that achieved onsite construction time and cost savings, and locate project contacts
  • Describe combinations of PBES and contracting strategies that achieved accelerated onsite construction timelines at lower costs
  • Explain why comparison of ABC costs and conventional construction costs may not be appropriate
  • Explain why moving to ABC/PBES as a standard practice will achieve cost savings

Speaker Notes:

Upon completion of this module, participants will be able to:

  • Identify examples of replacement projects that used prefabricated bridge elements for accelerated bridge construction and achieved onsite construction time and cost savings; you’ll also know where to go for the project contacts
  • Describe combinations of prefabricated bridge elements and contracting strategies that achieved accelerated onsite construction timelines at lower costs
  • Explain why ABC cost and conventional construction cost comparisons may not be appropriate, and
  • Explain why moving to prefabricated bridges as a standard practice will achieve cost savings
 

Slide 3. Cost-Competitive Projects

  • Reduced onsite construction time
  • Construction cost less than engineer’s estimate
  • Project details
  • Project owner contacts
  • Other contacts, e.g.:
    • Contractor
    • Design Engineer
    • Prefabricator

http://www.fhwa.dot.gov/bridge/prefab/successstories/091104/index.cfm

Publication Cover of PBES Cost Study: Accelerated Bridge Construction Success Stories - 2006

Speaker Notes:

I will be presenting five of the nine projects described in the 2006 FHWA-sponsored PBES Cost Study that is available from the FHWA prefabricated bridges website.

All projects are replacement projects, so reducing the impact of onsite construction to motorists was a priority. You can download this study from the website shown at the bottom of the screen. It also contains a listing of the contacts for all nine projects.

 

Slide 4. ABC/PBES Projects

  • ABC/PBES Deck Elements: full-depth precast deck panels
    • WA – Washington State Department of Transportation’s SR 433 Lewis & Clark Bridge over Columbia River – 2004
  • ABC/PBES Pier Elements: precast caps on cast-in-place columns
    • TX – Texas Department of Transportation’s State Highway 66 Bridge over Lake Ray Hubbard – 2003

Speaker Notes:

The first project to be discussed includes ABC/PBES Deck Elements, specifically full-depth precast concrete deck panels. The second includes ABC/PBES Pier Elements, specifically precast concrete caps on cast-in-place concrete columns.

 

Slide 5. ABC/PBES Projects, cont’d.

  • ABC/PBES Beam Elements: modular beams with decks
    • NJ – New Jersey Department of Transportation’s Route 1 Bridges over Olden Avenue & Mulberry Street – 2005
  • ABC/PBES Beam Elements (modular beams with decks) + Abutment Elements (precast backwalls, precast wingwalls)
    • CO – Colorado Department of Transportation’s State Highway 86 Bridge over Mitchell Gulch – 2002

Speaker Notes:

The third project includes ABC/PBES Beam Elements, modular beams with decks, while the fourth project includes ABC/PBES Beam Elements plus Abutment Elements, modular beams with decks plus precast backwalls and wingwalls. The first of these two projects is in an urban setting, while the second is a rural project.

 

Slide 6. ABC/PBES Projects, cont’d.

  • ABC/PBES Beam Elements (modular beams with decks) + Pier Elements (precast pile caps) + Miscellaneous Elements (precast approach slabs, precast parapets
    • NY – New York City Department of Transportation’s Belt Parkway Bridge over Ocean Parkway – 2004

Speaker Notes:

The last project discussed in this presentation uses a variety of ABC/PBES elements. The Beam Elements are modular beams with decks, the Pier Elements are precast pile caps, and the Miscellaneous Elements are precast approach slabs and precast parapets.

 

Slide 7. ABC/PBES Deck Elements (full-depth precast deck panels)

Speaker Notes:

A number of full-depth precast decks have been installed across the country using various construction methods.

 

Slide 8. State Route 433 Lewis and Clark Bridge over Columbia River, WA/OR – 2004

Replaced 3900 ft of deck using SPMTs during 124 nights plus 3 weekend closures...

State Route 433 Lewis and Clark Bridge over Columbia River, WA/OR – 2004 – After deck replacement...Replaced 3900 ft of deck using SPMTs during 124 nights plus 3 weekend closures.
State Route 433 Lewis and Clark Bridge over Columbia River, WA/OR – 2004. SPMTs with frame carrying panel..with no impact to rush-hour traffic
...with no impact to rush-hour traffic

Speaker Notes:

The full-depth deck project discussed today used self-propelled modular transporters (SPMTs) combined with a gantry framing system to install the deck panels. Other projects have installed panels with cranes. Local construction capabilities and site requirements determine the most appropriate construction method.

The Lewis and Clark Bridge over the Columbia River spans the state line between Longview, Washington and Rainier, Oregon and is jointly owned by the Washington State DOT and the Oregon DOT. The 1929 steel through-truss bridge provides access across state lines for over 18,000 vehicles each day.

In early 2000 its deck was severely deteriorated and required replacement. Accelerated onsite construction was needed to limit the impact to emergency services and to avoid extended use of a 40-mile detour west that included a ferry ride or an 80-mile detour south.

In 2004 WSDOT completed replacement of the bridge deck on this mile-long bridge with no impact to rush-hour traffic. A total of 3,900 ft of deck were replaced during 124 night closures plus 3 weekend closures. Construction using conventional cast-in-place methods would have required 4 years.

The deck replacement extended the life of the bridge another 25 years.

 

Slide 9. State Route 433 Lewis and Clark Bridge over Columbia River, WA/OR – 2004

103 full-width, 6-inch full-depth precast lightweight concrete panels, each 36 ft wide & 20 ft to 45 ft long State Route 433 Lewis and Clark Bridge over Columbia River, WA/OR – 2004. 103 full-width, 6-inch full-depth precast lightweight concrete panels, each 36 ft wide & 20 ft to 45 ft long

State Route 433 Lewis and Clark Bridge over Columbia River, WA/OR – 2004. 103 full-width, Removal of old deck section & installation of new panel in avg. 6.5 hours overnight
Removal of old deck section & installation of new panel in avg. 6.5 hours overnight

A total of 103 prefabricated deck panels were installed. They were 36 ft wide and 20 ft to 45 ft long. The lightweight concrete panels were 6-in. thick plus 1-in. thick overlay. Each panel was supported on two longitudinal steel beams. The panel units had a maximum weight of 96 tons.

The bridge was closed on Sunday through Thursday nights from 9:30 p.m. to 5:30 a.m. The SPMTs with truss frame moved a new panel to the bridge, lifted the old panel out, and then lowered the new panel into place before taking the old panel off the bridge. Each panel movement took an average 6.5 hours.

 

Slide 10. SR 433 Lewis and Clark Bridge over Columbia River Contract Requirements

  • "A" + "B" + "C" Bidding Method to determine lowest responsible bidder
    • "A" = bid items
    • "B" = bridge closures @ $8,000
    • "C" = single lane closures @ $2,000

Speaker Notes:

WSDOT utilized an "A" + "B" + "C" bidding method to determine the lowest responsible bidder, where "A" equals the bid items, "B" equals the total number of bridge closures established by the bidder to complete the work times the Total Bridge Rental Closure Cost, and "C" equals the total number of single lane closures established by the bidder to complete the work times the Bridge Single Lane Rental Cost. The "B" and "C" parts of the bid were only used to determine the lowest responsible bidder, not to determine final payment to the contractor.

 

Slide 11. SR 433 Lewis and Clark Bridge over Columbia River Incentives for Early Completion

  • $100,000 for completion by April 2004
  • $55,000 per Weekend Bridge Closure less than 4
  • $4,000 per Total Bridge Closure less than number bid
  • $1,000 per Single Lane Closure less than number bid

Speaker Notes:

The contract included several incentives for early completion. If the contractor finished all work requiring Weekend or Total Bridge Closures by April 30, 2004, he would receive $100,000. This was put in the contract as a neutral cost to the owner because a $100,000 extension was due then for a helicopter with landing pad on the south side of the river for emergency crossings during the closures.

Other incentives were also included as shown on the slide.

 

Slide 12. SR 433 Lewis and Clark Bridge over Columbia River Liquidated Damages

  • $16,000 per Total Bridge Closure more than number bid
  • $4,000 per Single Lane Closure (SLC) more than number bid
  • $1,700 per 15-min period beyond times specified for Weekend or Total Closure
  • $900 per 15-min period beyond SLC

Speaker Notes:

The contract also included liquidated damages for not meeting the time constraints for accelerated construction at the amounts shown on the slide.

 

Slide 13. SR 433 Lewis and Clark Bridge over Columbia River – 2004 Construction Costs

  • Engineer’s Estimate: $28.8 M
  • Number of bidders: 6
  • 2nd lowest bid: $29.2 M
  • Low Bid: $18.0 M
  • Savings: -38% = $10.8 M

Closures: Only 124 nights & 3 weekends

Speaker Notes:

The engineer’s estimate for this project was $ 28.8M. The low bid of $18.0M was 38% or $10.8M less than the engineer’s estimate. There were 6 bidders on this project.

The contractor completed all work requiring closures by the end of April 2004 and, therefore, received the $100,000 incentive. He also received an incentive of $55,000 for using 3 instead of 4 Weekend Bridge Closures, and an additional $30,000 for having 30 fewer Single Lane Closures than the 173 allowed. The contractor received a total incentive of $185,000. No liquidated damages were assessed.

3900 linear feet of deck were replaced during only 124 nights plus 3 weekend closures. The Washington State DOT obtained the new deck ahead of time and significantly under budget.

 

Slide 14. ABC/PBES Pier Elements: precast caps on cast-in-place columns

Speaker Notes:

The second element to be discussed is caps. The terms pier cap and bent cap are used interchangeably to describe this prefabricated substructure element. Prefabricated caps are increasingly being specified to speed substructure construction.

 

Slide 15. State Highway 66 Bridge over Lake Ray Hubbard, Texas – 2003

State Highway 66 Bridge over Lake Ray Hubbard, Texas – 2003 – Precast bent caps saved 215 days of onsite construction
Precast bent caps saved 215 days of onsite construction


Speaker Notes:

In 2000 the Texas DOT’s State Highway 66 over Lake Ray Hubbard near Dallas was a narrow, congested, 40-year-old 2-lane bridge. It was replaced with a pair of bridges in 2003. The new 4,360-ft long, 40-ft wide eastbound bridge has two traffic lanes and shoulders, and precast bent caps as part of its substructure due to a contractor-initiated field change.

Precasting 43 identical caps resulted in a time savings of 5 to 7 days per cap, at least 215 days of effort. Forming, concrete placement, and curing for conventional bent caps would have required 7 days of critical path activity per cap. This represented a total potential delay of 9 months for the 43 bent caps.

 

Slide 16. State Highway 66 Bridge over Lake Ray Hubbard, Texas – 2003


State Highway 66 Bridge over Lake Ray Hubbard, Texas – 2003. 43 identical precast concrete bent caps...
43 identical precast concrete bent caps...
State Highway 66 Bridge over Lake Ray Hubbard, Texas – 2003...proposed by the Contractor
...proposed by the Contractor

Speaker Notes:

First the new westbound bridge was built adjacent to the existing bridge using conventional construction. Traffic was then moved to the new bridge, the old bridge was demolished, and the eastbound bridge was built approximately on the bridge’s original alignment.

The contractor fabricated the caps adjacent to one end of the bridge. Each cap is supported by three cast-in-place columns, and provides the bearing for the five beams per span. TxDOT designed grouted-duct connections between the precast caps and the cast-in-place columns based on previous research at the University of Texas at Austin. Seismic design was not required.

In addition to speeding onsite construction, fabricating the caps off the critical path allowed the use of a normal-strength high performance concrete mix design that results in greater durability but with a slower strength gain due to the 35 percent replacement of cement with ground-granulated blast-furnace slag.

 

Slide 17. State Highway 66 Bridge over Lake Ray Hubbard Contract Requirements

  • Contract specified cast-in-place concrete bent caps
  • Contractor proposed field change to precast concrete bent caps for eastbound bridge
  • TxDOT accepted proposed field change, with no change in funding

Speaker Notes:

The contract specified conventional cast-in-place construction for the substructures. Early in the project the contractor proposed a field change to precast reinforced concrete bent caps as a way to speed construction, to avoid the difficulties in handling formwork and materials over water, and to minimize the construction workers’ exposure to high-voltage transmission lines running adjacent to the eastbound bridge.TxDOT approved the contractor’s proposal with no change in funding.

The contract did not include incentives or disincentives.

 

Slide 18. State Highway 66 Bridge over Lake Ray Hubbard – 2003 Construction Costs

  • Engineer’s Estimate: $48.2 M
  • Number of bidders: 8
  • 2nd lowest bid: $43.1
  • Low Bid: $40.9 M
  • Savings: -15% = $7.3 M

Onsite Time Savings: 215 Days

Speaker Notes

The engineer’s estimate for this project was $48.2M. The low bid of $40.9M was 15% less than the engineer’s estimate. There were 8 bidders on this project.

Using the 43 precast bent caps reduced onsite construction time by 215 days. TxDOT obtained the bridge ahead of schedule and under budget.

 

Slide 19. ABC/PBES Beam Elements (modular beams with decks)

Speaker Notes:

The next project to be discussed in this presentation has ABC/PBES Beam Elements. Many superstructures consisting of modular beams with decks have been installed across the country. The project presented here was installed with conventional construction equipment including cranes, and many superstructures across the country have been installed with similar methods.

 

Slide 20. Route 1 Bridges over Olden Avenue & Mulberry Street, New Jersey – 2005

Map of Route 1 Bridges over Olden Avenue & Mulberry Street, New Jersey – 2005. NJDOT’s 1st Hyperbuild Project
NJDOT’s 1st Hyperbuild Project


Speaker Notes

Each day the New Jersey DOT’s Route 1 carries more than 50,000 vehicles through the city of Trenton. Three bridge decks on Route 1, one at the Olden Avenue Connector and two adjacent bridges at Mulberry Street, were deteriorated and in need of constant maintenance. In 2005 the replacement of these three bridges was the NJDOT’s first Hyperbuild project.

Each of the three bridges was replaced over a weekend during three consecutive months, with no impact to rush-hour traffic. Design and construction would have taken 22 months using conventional methods.

 

Slide 21. Route 1 Bridges over Olden Avenue & Mulberry Street, New Jersey – 2005

Route 1 Bridges over Olden Avenue & Mulberry Street, New Jersey – 2005. Left to Right: Deteriorated Route 1 decks over Mulberry Street and Olden Avenue, New Route 1 decks over Mulberry Street, Elevation of new Route 1 Bridges over Mulberry Street.


Speaker Notes

These bridges are relatively small. The 2-lane 87-ft long, 35-ft wide single-span Route 1 bridge over the Olden Avenue Connector is a highly-skewed steel girder bridge with concrete deck. The 4-lane 60-ft long, 82-ft wide single-span Route 1 bridge over Mulberry Street consists of two bridges with a median barrier separating each direction of traffic.

 

Slide 22. Route 1 Bridge Construction

Route 1 Bridge Construction over Olden Avenue Route 1 Bridge Construction over Mulberry Street

Speaker Notes:

Construction photos are shown here. Each bridge was closed at 7 p.m. on a Friday and traffic was rerouted. The bridge was demolished in place using conventional methods. The existing abutments were repaired and new bearing seats constructed (see upper right photo). The prefabricated superstructure was then erected. Parapets and median barriers were cast-in-place concrete.

Each superstructure span consists of 5 full-length segments of varying width, each with two steel girders and a 9-inch thick composite concrete deck (Inverset) system (see lower left photo). The segments were required to be onsite 24 hours prior to the start of demolition of the existing bridge. The contract specified high performance concrete for all concrete on the job.

Each bridge is expected to see a 75-100 year service life due to the quality of its prefabricated superstructure, the use of high performance concrete, and the attention given to connection details. Conventionally constructed bridges have an average minimum 50-year life in New Jersey.

 

Slide 23. Route 1 Bridges over Olden Avenue & Mulberry Street Contract Requirements

  • For each bridge, maximum 57 hours from complete closure to 2 lanes open
  • Lane Occupancy Charge up to $10K/da
  • Substantial Completion by November 16, 2005
  • All work completed by January 13, 2006

Speaker Notes:

Each of the 3 bridges was allowed a 57-hour window from complete closure to re-opening of both lanes. If this window was exceeded, a Lane Occupancy Charge would be assessed. In addition, Substantial Completion of all 3 bridges was required by a specified date, and all work was to be completed four months later.

 

Slide 24. Route 1 Bridges over Olden Avenue & Mulberry Street Incentives

  • If less than 57 hours:
    • Bridge over Olden Avenue
      • $1,500 per hour
      • Cap of $27,000
    • Each bridge over Mulberry Street
      • $2,000 per hour
      • Cap of $36,000

Speaker Notes:

Incentives were also included as shown here.

 

Slide 25. Route 1 Bridges over Olden Avenue & Mulberry Street Liquidated Damages

  • If more than 57 hours:
    • Bridge over Olden Avenue
      • $1,500 per hour
    • Each bridge over Mulberry Street
      • $2,000 per hour
  • If after Nov. 16 – $4,200 per day
  • If all work not completed by Jan. 13 – additional $900 per day

Speaker Notes:

Liquidated damages were also specified.

 

Slide 26. Route 1 Bridges over Olden Avenue & Mulberry Street – 2005 Construction Costs

  • Engineer’s Estimate: $3.8 M
  • Number of bidders: 5
  • 2nd Lowest Bid: $3.8 M
  • Low Bid: $3.5 M
  • Savings: -8% = $0.3 M

3 bridges replaced in 3 weekends

Speaker Notes:

The engineer’s estimate for this project was $ 3.8M. The low bid was 8% less than the engineer’s estimate. There were 5 bidders on this project.

All three bridges were opened in less than the required 57 hours. The replacements were completed  in 6 days over 3 consecutive months, in significantly less than the 22 months required for conventional design and construction, and they were completed under budget. The design and construction savings, including delay-related user costs, are in excess of $2M.

 

Slide 27. ABC/PBES Beam Elements (modular beams with decks) + Abutment Elements (precast backwalls, precast wingwalls)

Speaker Notes:

The next project has Beam Elements and also Abutment Elements. Replacing both the superstructure and substructure with prefabricated elements and systems is being done more frequently as owners become comfortable with prefabrication and as the performance of more connection details are confirmed. Unlike the previous project, this project is in a rural setting.

 

Slide 28. State Highway 86 Bridge over Mitchell Gulch, Colorado – 2002

State Highway 86 Bridge over Mitchell Gulch, Colorado – 2002. No impact to rush-hour traffic
No impact to rush-hour traffic

46-hour weekend construction of 40-ft long, 43-ft wide single span
State Highway 86 Bridge over Mitchell Gulch, Colorado – 2002. 46-hour weekend construction of 40-ft long, 43-ft wide single span.

Speaker Notes:

The State Highway 86 Bridge over Mitchell Gulch southeast of Denver was a timber bridge built in 1953 and rated in 2002 as one of Colorado’s worst 10 bridges. It was replaced with a totally prefabricated bridge over a weekend in 2002. During construction the bridge was closed and the 12,000 vehicles per day were diverted to a short detour around the bridge.

The existing 40-ft long, 26-ft wide 2-span bridge was replaced with a 40-ft long, 43-ft wide single-span bridge .

The new prefabricated bridge was opened just 46 hours after closure. Construction occurred over a weekend, with no impact to rush-hour traffic. Construction would have taken 2 to 3 months using conventional methods.

 

Slide 29. State Highway 86 Bridge over Mitchell Gulch, Colorado – 2002

State Highway 86 Bridge over Mitchell Gulch, Colorado – 2002. Early Saturday morning, Saturday afternoon, Saturday afternoon. Precast concrete abutments, wingwalls, superstructure units with railing, & steel H piles
Early Saturday morning Saturday afternoonSaturday afternoon

Precast concrete abutments, wingwalls, superstructure units with railing, & steel H piles.

Speaker Notes:

Prior to the bridge closure, the contractor drove steel H piles at the abutments in the stream banks just outside the existing roadway width. The precast concrete abutments, wingwalls, and superstructure units were shipped to the site just before being installed.

At 7 p.m. on a Friday the bridge was closed and traffic detoured. The existing timber bridge was demolished. Early Saturday morning, 44-ft wide precast abutments and 23-ft long precast wingwalls with embedded steel plates were erected with a crane and welded to the steel H piles and to each other prior to placing flowable fill behind the abutments. On Saturday afternoon, the eight precast superstructure units were erected, including the edge units complete with precast railing. The units were then transversely post-tensioned and grouted. On Sunday the earthwork and asphalt overlay were completed.

The bridge was reopened to traffic at 5 p.m. on Sunday, 46 hours after closure of the bridge. Only 38 hours of construction work were required for the replacement. They expect to see a 75-year service life due to the quality of prefabricated components and attention given to connection details.

 

Slide 30. State Highway 86 Bridge over Mitchell Gulch Contract Requirements

  • Contract specified 3-cell cast-in-place concrete box culvert to replace 2-span timber bridge
  • Value engineering change proposal by contractor/design team
    • Prefabricated single-span bridge
    • Completion in one weekend

Speaker Notes:

The Colorado DOT awarded the construction contract to replace the deteriorated bridge with a conventional 3-cell cast-in-place concrete box culvert. However, the contractor was concerned about the safety of his construction crews on this project because of the steep downward grade of the highway approach as well a nearby curve of the detour around the bridge site. The contractor teamed with a local design firm to submit a value engineering change proposal to build the single-span totally prefabricated bridge over a weekend to limit the onsite exposure time of his crew.

 

Slide 31. State Highway 86 Bridge over Mitchell Gulch Contract Requirements, cont’d.

  • CDOT response:
    • Accepted VE change proposal
    • Implemented lane rental fee
  • Lane Rental Specification
    • $500/hr starting 6 a.m. Monday
    • Fee based on user costs to occupy SH 86

Speaker Notes:

The Colorado DOT accepted the value engineering change proposal, with no change to the project funding. However, as part of the acceptance of the proposal, CDOT implemented a lane rental specification that imposed fees should the contractor exceed the allowed weekend closure. The lane rental was based on road user costs to occupy SH 86.

No incentives were included in the contract.

 

Slide 32. State Highway 86 Bridge over Mitchell Gulch – 2002 Construction Costs

  • Engineer’s Estimate: $394.2 K
  • Number of biddgers: 12
  • 2nd Lowest Bid: $365.8 K
  • Low Bid: $365.2 K
  • Savings: -7 % = $29.0 K

Closure: Only 46 hours

Speaker Notes:

The engineer’s estimate for this project was $ 394.2K. The low bid was 7% less than the engineer’s estimate. Twelve contractors bid on the project.

The 5 p.m. Sunday opening of the new bridge was 13 hours earlier than the required 6 a.m. Monday opening. No rush hours were impacted and, therefore, no lane rental fees were charged. The contractor said that he expects to cut the 46-hr closure time in half on similar subsequent projects due to his learning curve.

 

Slide 33. ABC/PBES Beam Elements (modular beams with decks) + Pier Elements (precast pile caps) + Miscellaneous Elements (precast approach slabs, precast parapets)

Speaker Notes:

The final project to be discussed has ABC/PBES Beam Elements, Pier Elements, and Miscellaneous Elements. The Beam Elements consist of modular beams with decks, similar to the New Jersey project previously discussed. The Pier Elements are precast pile caps. The Miscellaneous Elements are precast approach slabs and precast parapets.

 

Slide 34. Belt Parkway Bridge over Ocean Parkway, New York City (Brooklyn) – 2004

Map of Belt Parkway Bridge over Ocean Parkway, New York City (Brooklyn) – 2004 - Left to right: Existing Interchange, Reconstructed Interchange

Speaker Notes:

The New York City DOT’s Belt Parkway Bridge over Ocean Parkway in south Brooklyn was deteriorated and required complete replacement. The entire design-build project included replacing the existing bridge with a longer and wider bridge, as well as reconfiguring the existing outdated cloverleaf interchange into a modified tight diamond interchange, and other rehabilitation and upgrade work to the Parkways.

The selected design-build team specified extensive use of prefabricated bridge components to achieve an accelerated onsite construction timeline. The rapid construction was required to minimize disruption to the 166,000 average daily vehicles that used the Belt Parkway. The Belt Parkway is a major artery through Brooklyn that also had a large hospital and two schools fronting on the project limits.

Onsite installation of each half of the new bridge took only a few nights in each of two weeks. The entire design-build project was completed in 14 months, including a 3-month winter shutdown. Construction would have taken 3 to 4 years using conventional methods.

 

Slide 35. Belt Parkway Bridge over Ocean Parkway, New York City (Brooklyn) – 2004

Replaced existing 2-span, 149-ft long, 78-ft wide bridge with 3-span, 221-ft long, 134-ft wide bridge...
Belt Parkway Bridge over Ocean Parkway, New York City (Brooklyn) – 2004 . Replaced existing 2-span, 149-ft long, 78-ft wide bridge with 3-span, 221-ft long, 134-ft wide bridge...

Belt Parkway Bridge over Ocean Parkway, New York City (Brooklyn) – 2004...with no lane closures during peak traffic hours

...with no lane closures during peak traffic hours

The old bridge was lengthened and widened to add shoulders and acceleration/deceleration lanes at the entrance and exit points, in addition to the existing 3 lanes in each direction.

Throughout the project, six lanes of traffic remained open during rush hour, with limited lane closures as needed during off-peak hours. A temporary bridge was erected adjacent to the south side of the existing bridge to maintain the existing number of lanes on Belt Parkway during the bridge reconstruction. Traffic was diverted onto the temporary bridge and the south portion of the existing bridge while the north portion of the existing bridge was demolished and reconstructed. Traffic was then rerouted to the six lanes, three in each direction, on the new north portion of the bridge and the remaining existing bridge was then demolished and reconstructed.

 

Slide 36. Belt Parkway Bridge over Ocean Parkway – 2004

Prefabricated:

  • Piles
  • T-Walls
  • Cap Beams
  • Superstructure
  • Parapets & Barriers
  • Approach Slabs
Belt Parkway Bridge over  Ocean Parkway – 2004 – 51 superstructure segments in new 221-ft long x 134-ft wide bridge (49’-107’-65’)

51 superstructure segments in new
221-ft long x 134-ft
wide bridge (49’–107’–65’)

Speaker Notes

To minimize traffic disruption, prefabricated components were used extensively. Prefabricated components included concrete-filled steel pipe piles, precast T-walls, precast post-tensioned cap beams, prefabricated superstructure segments, precast bridge parapets, median barriers, and approach slabs. High performance concrete with 4000 psi compressive strength was specified for all precast components.

Stainless steel reinforcement was specified for the precast decks, parapets, and median barriers. While the stainless steel reinforcement increased the cost of the bridge by approximately one percent, the bridge is anticipated to last twice as long as the 45-year-old bridge it replaced.

The 51 span-length prefabricated superstructure segments, as well as the other precast concrete components, were fabricated in upstate New York and shipped 200 miles to the jobsite. Each (Inverset) superstructure segment consisted of two steel girders and a composite deck.

The bridge is expected to see a 75-100 year service life due to the quality of its prefabricated components and the attention given to connection details, including the loop-on-loop closure joints connecting the deck segments.

 

Slide 37. Belt Parkway Bridge over Ocean Parkway Contract Requirements

  • "A" + "B" Bidding Method to achieve reduced onsite construction timeline
    • "A" = bid items
    • "B" = "Critical Duration" x $85,000

Speaker Notes:

The NYCDOT utilized a modified "A" + "B" bidding method, where "A" equals the bid items and "B" equals a "Critical Duration" in days, with the number of days specified by the contractor. The contractor-specified number of days was multiplied by $85,000 to translate the duration into a delay-related user cost, with the $85,000 representing the delay-related user cost per day set by the NYCDOT. "Critical Duration" was defined as the period of time from when the design-build team permanently impacted the roadways for construction until the time that all new roadways were in their final completed configuration.

 

Slide 38. Belt Parkway Bridge over Ocean Parkway Incentives/Disincentives

  • Incentive for completion before "Critical Duration":
    • $85,000 per day
    • Cap of $2,000,000
  • Disincentive for completion after "Critical Duration":
    • $85,000 per day
    • No dollar limit

Incentive/disincentive and liquidated damages clauses were included in the contract as shown here.

 

Slide 39. Belt Parkway Bridge over Ocean Parkway Construction Costs

  • Engineer’s Estimate: $60.0 M
  • Number of bidders: 5
  • Low Bid: $47.9 M
  • Awarded Bid*: $55.5 M
  • Savings: -8% = $4.5 M

* Best Value: only 285 "Critical Duration" days

Speaker Notes:

The engineer’s estimate for this project was $ 60.0M. The awarded bid of $55.5M was 8% less than the engineer’s estimate. There were 5 bidders on this project. The awarded bid proposed a "Critical Duration" of only 285 days, which was 300 "Critical Duration" days shorter than the low bid. Therefore, at $85,000 per day, the awarded bid was the best value, with a delay-related user cost that was $25M lower than the low bid.

The bridge was completed 29 days ahead of the "Critical Duration" of 285 consecutive calendar days that was bid in the contract. The actual number of "Critical Duration" days was just 256 days, with no lane closures during peak traffic hours. The contractor received the maximum $2M incentive.

The bridge work on this design-build project was approximately a third of the total project cost.

 

Slide 40. Did these projects cost less than conventional construction?

Speaker Notes:

Did these ABC projects cost less than conventional construction? We know that the projects went well because they were all completed under the engineer’s estimates and within the owners’ timelines, but we don’t know what the engineer’s estimates for conventional construction, if it were possible, would have been for these projects.

When projects have high-traffic volumes that must be maintained, conventional construction is frequently not even a possibility. Long traffic queues and long detours that would result from the use of conventional construction are increasingly considered unacceptable. Extended work zones, working over water, and working adjacent to high-voltage transmission lines or other hazards lead to safety and constructability concerns that eliminate use of conventional construction. So why are we comparing ABC and conventional costs when conventional construction is not even a possibility on a project? Obviously, doing so is not appropriate. It’s not an apples-to-apples comparison.

Slide 41. Did these projects cost less than conventional construction? (Cont’d)

Project Engineer’s Estimate Awarded Bid Cost Savings
$ %
WSDOT Lewis & Clark Bridge $ 28.8M $ 18.0M $ 10.8M 38
TxDOT SH 66 Bridge
over Lake Ray Hubbard
48.2M 40.9M 7.3M 15
NYCDOT Belt Parkway Bridge 60.0M 55.5M 4.5M 8
NJDOT Rt. 1 Bridge 3.8M 3.5M 0.3M 8
CDOT Mitchell Gulch Bridge 0.394M 0.365M 0.029M 7
Totals $ 141.2M $ 118.3M $ 22.9M 16% avg.

Speaker Notes:

For the projects presented here, the Lake Ray Hubbard project and the Mitchell Gulch project are the closest we can come to comparing ABC costs to conventional bridge construction costs. For both of these projects, the engineer’s estimate was based on conventional construction, and the contractor was required to bid the job for conventional construction. The contractor could then request a change to prefabrication, which the owner would have to approve after bid award. Because the bid came in under the engineer’s estimate for each of the two projects, we can assume the prefabricated bridge costs were less than or equal to conventional construction.

 

Slide 42. So, what is needed to ensure cost savings or, at a minimum, cost competitiveness on ABC/PBES projects?

So, what is needed to ensure cost savings or, at a minimum, cost competitiveness on ABC/PBES projects?

 

Slide 43. For Effective ABC Implementation

  • Make ABC standard practice, not just project-specific use
    • Shows owner’s commitment to future use – a program of work
    • Reduces costs with multiple use
  • Example: Utah DOT transition to ABC as standard practice for projects as appropriate

Speaker Notes:

The answer is making ABC/PBES a standard practice rather than a project-specific use. In this way the contractor can feel that spending the money to gear up his operations for ABC/PBES will be cost-effective because of the potential for future similar projects. The owner must show a commitment to the use of ABC/PBES on future projects, that is, the owner should have a program of ABC/PBES work. One of the modules in this web conference will discuss a new tool developed in a pooled-fund study led by the Oregon DOT. That tool will help owners quantify the differences between using ABC and conventional construction at the planning stage of a project, to ensure cost effectiveness. In addition, we all know that costs decrease with increasing use. The Utah DOT is one example of the lower costs that can be achieved with making ABC/PBES a standard practice. They are now seeing lower costs on their ABC/PBES projects.

 

Slide 44. Cost of implementing SPMT Bridge Moves – 19 Utah Bridges

Graph representing the cost of implementing SPMT Bridge Moves – 19 Utah Bridges. As an example, the costs of implementing SPMT bridge moves for Utah’s first 19 bridges is shown on this slide. The first project, the 4500 South Bridge in 2007, is on the left, with more recent bridges shown as you go right along the horizontal axis. While some variability in costs occurred due to site conditions, the downward trend in costs is apparent.

Speaker Notes:

As an example, the costs of implementing SPMT bridge moves for Utah’s first 19 bridges is shown on this slide. The first project, the 4500 South Bridge in 2007, is on the left, with more recent bridges shown as you go right along the horizontal axis. While some variability in costs occurred due to site conditions, the downward trend in costs is apparent.

 

Slide 45. Module Conclusion

You should now be able to:

  • Identify examples of ABC/PBES replacement projects that achieved onsite construction time and cost savings, and locate project contacts
  • Describe combinations of PBES and contracting strategies that achieved accelerated onsite construction timelines at lower costs
  • Explain why comparison of ABC costs and conventional construction costs may not be appropriate
  • Explain why moving to ABC/PBES as a standard practice will achieve cost savings
 

Slide 46. QUESTIONS?

Mary Lou Ralls, P.E.
ralls-newman@sbcglobal.net
512-422-9080

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Page last modified on August 14, 2013.
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