SEISMIC BRIDGES (EUGENE) PROJECT

GOODPASTURE ISLAND ROAD OVER DELTA

HIGHWAY – BRIDGE NO. 09359

TYPE, SIZE, & LOCATION REPORT

Contract No. 900036

Prepared for:

City of Eugene Public Works

1820 Roosevelt Blvd Eugene, OR 97440

Prepared by:

4275 Commercial St SE, Suite 100 Salem, OR 97302

June 2020

0089-0126

TABLE OF CONTENTS

Project: Seismic Bridges (Eugene) Structure: Goodpasture Island Road over Delta Highway (Br. #09359)

Prepared By: Keava Campbell, EI Review By: Mike McNulty, PE Nick Robertson, PE, SE

1.0 INTRODUCTION

2.0 EXISTING STRUCTURE

3.0 DESIGN STANDARDS AND CRITERIA

4.0 BASELINE SEISMIC DEMAND AND EXISTING CAPACITY

ANALYSES

5.0 OBSERVATIONS AND CONCLUSIONS ON THE BASELINE

ANALYSES

6.0 PROPOSED SEISMIC RETROFIT STRATEGIES

7.0 TYPICAL SECTIONS

8.0 TRAFFIC STAGING AND TEMPORARY TRAFFIC CONTROL

9.0 RIGHT-OF-WAY AND EASEMENTS

10.0 UTILITIES

11.0 DRAINAGE AND STORMWATER

12.0 FOUNDATION INVESTIGATION

13.0 ENVIRONAMENTAL INVESTIGATION AND PERMITS

14.0 CONSTRUCTABILITY

15.0 CONSTRUCTION COST

16.0 CONCLUSION

FIGURES

Figure 1: Location Map and Photo for Bridge #09359 (Goodpasture Island Road)

Figure 2: Typical Bridge Elevation for Bridge #09359 (Goodpasture Island Road)

Figure 3: Isometric view of Baseline Model for Bridge #09359 (Goodpasture Island Road)

Figure 4: Stage I Construction Diagram

Figure 5: Stage II Construction Diagram

APPENDICES

Appendix 1: TS&L Plan Set

Appendix 2: Retrofit and Replacement Cost Estimates

Appendix 3: C/D Ratio Summary

Appendix 4: As-Built Plans

MGMcNulty Text Box

1.0 INTRODUCTION

In the 1980s, scientists first recognized that the Cascadia Subduction Zone (CSZ) is an active fault that poses a major geological hazard to the state of Oregon. Based on current research, the scientific community now believes that the CSZ is a fault capable of producing earthquakes that range from 8.3 to 9.3 in magnitude with a recurrence interval of approximately 250 years. In 2013, Oregon issued The Oregon Resilience Plan, which determined the likely large-scale impacts and disaster recovery times of a magnitude 9.0 CSZ earthquake. As a result of this plan, many communities, including the City of Eugene (City), have begun to implement programs to address seismic deficiencies and create more resilient infrastructure.

The national codes for bridge design have followed a similar timeline of evolution. The first modern force-based seismic design criteria were established when the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications were adopted in 1994. After additional lessons were learned in the 1994 Northridge and 1995 Kobe earthquakes, displacement-based design began to take hold and was officially adopted by AASHTO in 2009 in the form of the Guide Specifications for LRFD Seismic Bridge Design. Based on structural detailing practices at the time of their construction, bridges constructed before 2009, and especially before 1994, are particularly vulnerable in a seismic event.

This Type, Size, and Location (TS&L) report addresses seismic analyses, deficiencies, and proposed retrofits for the Goodpasture Island Road Bridge over Delta Highway (#09359) that is part of the Seismic Bridges (Eugene) project. The purpose of the project is to evaluate and address seismic deficiencies at 10 key bridge locations identified by the City and to develop cost-effective Phase I and/or II seismic retrofit concepts to a 30% design level.

Figure 1 Location Map and Photo for Bridge #09359 (Goodpasture Island Road)

The recommendations contained in this report are based upon preliminary engineering studies conducted by DOWL, LLC, (DOWL); HDR; Foundation Engineering, Inc.; and discussions with the City of Eugene. This work is a continuation of the 2016 Vulnerability Assessment and Recommendation Report that DOWL (formerly OBEC) completed for the City. In the 2016 report, DOWL conducted an initial seismic screening to evaluate 31 of Eugene’s bridges and created a prioritized list that included a total of 15 seismically deficient bridges, 10 of which are included in the current project.

The original bridge prioritization was based upon multiple weighted criterion that included the overall seismic vulnerability of the structure, the proximity of the bridge to emergency services, the in-service functionality of the bridge, and a priority ranking based on the City’s preliminary ranking of each structure’s importance.

Additionally, adjacent to the bridge is a twin structure carrying traffic in the other direction. This twin structure was not analyzed as part of this report, as the horizontal clearance between the structures is enough that they will not interact in a seismic event. The twin structure was constructed in 2014 and designed to more current seismic standards, making it less of a hazard during a seismic event.

As part of this project, in September of 2019, following a presentation to the City, DOWL prepared a project technical memorandum to outline our analysis methodology and proposed design approach. The retrofit analysis follows Oregon Department of Transportation (ODOT) and Federal Highway Administration (FHWA) design methodology, which includes evaluation for both the CSZ earthquake (lower level) and a 1,000-year return period seismic event (upper level). The design methodology is included in Section 3.0 of this report.

This TS&L report builds upon DOWL’s previous study by conducting additional geotechnical exploration, completing a detailed seismic evaluation of the existing structure, developing a seismic retrofit strategy, preparing TS&L-level drawings, and preparing cost estimates for both the proposed seismic retrofit and for replacing the existing bridge with a modern seismically resilient structure.

The work contained in this report brings the City one step closer to their overall goal of creating a seismically resilient transportation network as part of their overall hazards mitigation plan, by providing preliminary design and cost estimates that will allow the City to implement construction projects quickly when funding becomes available.

2.0 EXISTING STRUCTURE

The existing structure was built in 1964. It is a 228-foot-long, 4-span bridge. The span arrangement is 50 feet, 64 feet, 64 feet, and 50 feet. The out-to-out deck width is approximately 39 feet, 8½ inches, normal to traffic. The lane configurations and rails were changed in 2014 when the twin structure was built next to it. The deck section carries two eastbound lanes of Goodpasture Island Road over Delta Highway, one of which is a left-turn lane. The horizontal clearance between the existing structure and the twin bridge structure is approximately 5 feet.

Each span is supported on five 3-foot-deep American Association of State Highway and Transportation Officials (AASHTO) Type II prestressed concrete girders. All the bents are skewed at 28.1 degrees. The end bents are supported on 5-foot, 6-inch-wide spread footing abutments with backwalls and an existing beam seat width of 2 feet. The overall abutment height varies with a minimum of 6 feet, 6½ inches and a maximum of 7 feet, 7½ inches at Bent 1, and a minimum of 7 feet, ¼ inch and a maximum of 7 foot, 9¼ inches at Bent 5.

The girders at the interior bents are supported on 3-foot-wide drop cross beams, which are each supported by two 3-foot-diameter reinforced concrete columns. The columns are lightly reinforced with 13 #8 longitudinal bars. The transverse reinforcement consists of #4 hoops at 12 inches. The original column reinforcement is Grade 40.

The columns are supported on 9-foot, 6-inch square spread footings that are 2 feet thick. The columns are located 7-feet, 9-inches in from the end of the crossbeams, thus forming tee joints in the crossbeam. Columns for Bents 2 and 4 are located adjacent to the existing shoulders of Delta Highway, while Bent 3 is in the median. Embedment depths to the bottom of the spread footings vary across the bents but range from approximately 4 feet, 6 inches to 6 feet, 6 inches across the bents.

There are no deck joints on the bridge, but there are 1-inch gap expansion joints at Bents 1 and

5. The girders are pinned at Bents 2 through 4 by a doweled connection. There are no end panels on the bridge. Seven utilites run along the bridge using the diaphragms and steel brackes as supports. These utilities vary in size from approximately 2-inch- to 8-inch-diameter and are all steel pipes.

Also of note is that several girders on this bridge experienced an overheight load impact in 2018.

Damage occurred in Span 3, and affected girders 1, 3, and 5. In particular, Girder 5 sustained significant damage, including damage to rebar and a compromised prestressing strand. In 2018, DOWL, then OBEC Consulting Engineers, performed an inspection and in 2019, a load rating analysis. On April 3rd, 2019, a letter was sent to the City of Eugene concluding our finding that no load restrictions are required, but that strengthening is recommended to restore the serviceability level of the bridge prior to it being impacted. This seismic retrofit analysis operated under the assumption that said strengthening has been or will be performed per the previously sent recommendations.

Figure 2 Typical Bridge Elevation for Bridge #09359 (Goodpasture Island Road)

See Appendix 4 for the as-built plans.

3.0 DESIGN STANDARDS AND CRITERIA

The seismic response of the bridge was analyzed according to the following standards:

• ODOT Bridge Design Manual (BDM)

• ODOT Geotechnical Design Manual (GDM)

• FHWA (Federal Highway Administration) Seismic Retrofitting Manual for Highway

Structures: Part 1 – Bridges, 2006

• AASHTO LRFD (Load and Resistance Factor Design) Bridge Design Specifications, 8th

Edition

• AASHTO Guide Specifications for LRFD Seismic Bridge Design (Seismic Guide Spec.), 2nd Edition with Interim Revisions.

The above standards were applied using the following assumptions:

• Bridge importance classification as “Standard”

• Anticipated Service Life of 16-50 Years (ASL2)

• Ignore vehicle and pedestrian live load effects during a seismic event

• Use a 2-level earthquake ground motion performance criterion o Lower Level (LL) Ground Motion Earthquake: Deterministic M9.0 CSZ earthquake event Performance Level 2 (PL2) – “Operational” o Upper Level (UL) Ground Motion Earthquake: Probabilistic 1,000-year return period event Performance Level 1 (PL1) – “Life Safety”

• Apply FHWA Method C to analyze LL event

• Apply FHWA Method D2 to analyze UL event

The current bridge seismic design requirements in Oregon require the design of both new bridges and existing retrofitted bridges to meet a 2-level, LL and UL, performance criteria. The 2-level performance criteria set parameters for the magnitude of the design earthquake event and the desired performance, or acceptable level of damage, for the event. The benefit to specifying 2-level performance criteria is the ability to pair the design event loading with an appropriate level of expected damage. In general, the LL event criteria specifies a smaller design earthquake event paired with a higher level of performance, and the UL event specifies a larger design earthquake event paired with a lower level of performance.

Although an official state bridge standard is not yet available, ODOT has adopted a standard set of performance requirements. The LL ground motions are provided by a deterministic model that was developed for a full rupture of the CSZ. The UL ground motions are based on a uniform hazard response spectrum for an earthquake with a 1,000-year return period. The ground motions are quantified by developing a Response Spectrum Acceleration (RSA) curve. The RSA curves are used in structural modeling to determine the seismic demands on the structure. The application of the RSA curves and seismic structural modeling parameters will be discussed in more detail in Section 4.0 of this report. The procedures to develop RSA curves for the LL and UL design earthquake events are outlined in the BDM and GDM and were followed as part of this study.

The desired level of performance for the LL and UL events set by ODOT are “Operational” and “Life Safety”, respectively. An “Operational” level of performance requires the bridge to remain serviceable and available to traffic shortly after the design earthquake event. The damage sustained to the bridge is expected to be minimal, and full service for emergency vehicles should be available immediately after inspection and clearing of debris. Minimal damage may include minor inelastic response and narrow flexural and shear cracking in the concrete. No permanent displacements of the bridge would be expected.

Conversely, a “Life Safety” level of performance would require the bridge to remain standing, but not available to traffic. Significant damage is expected during an earthquake, including concrete cracking, major spalling, and permanent displacements of the structure. Replacement of the bridge may be necessary; however, the performance goal is to avoid any loss of life. The ODOT BDM outlines these performance objectives and how to achieve them for new bridge design;

however, for bridge seismic retrofit design, the BDM leans heavily on the FHWA manual. Two methods of analysis provided by the FHWA manual will be used to achieve desired LL and UL event level of performance: Method C and Method D2, respectively.

The FHWA Method C essentially requires the seismic analysis and performance of the structure to remain in the elastic range of the materials. This analysis and design methodology will limit nonlinear permanent deformations observed to the structure when materials exceed their elastic performance during an earthquake event. Typically, this design methodology results in larger seismic design forces and requires larger seismic retrofits. The result is a retrofitted structure that remains in the elastic range and remains serviceable after the seismic event.

The FHWA Method D2 allows for inelastic behavior, or plastic hinging, to occur in the system.

Structural systems that allow plastic hinging to occur are significantly more flexible and will see smaller seismic demands as a result of their ability to more efficiently dissipate energy. However, this inelastic behavior is likely to result in permanent deformations and damage. FHWA and ODOT have established allowable Earthquake Resisting Systems (ERS) and Earthquake Resisting Elements (ERE) that define where the inelastic behavior can occur to confirm that the structure remains standing and that damage following the earthquake can be readily inspected.

The ERS and ERE selection process will be discussed in more detail in Section 6.0 of this report.

The ability of the structure to perform inelastically and remain stable is evaluated by conducting a push-over analysis. Push-over analyses are nonlinear structural models that account for the plastic behavior the system to determine how much lateral load or lateral displacement the system can accommodate before becoming instable.

4.0 BASELINE SEISMIC DEMAND AND EXISTING CAPACITY

ANALYSES

The seismic demand based on the LL CSZ earthquake event was analyzed first to determine the existing structural deficiencies. The LL event was selected over the UL 1,000-year earthquake event because its peak seismic coefficient (0.408) is 65% of the UL’s (0.619). The UL event demands would be evaluated if no structural deficiencies were identified during LL analysis. All proposed retrofits were checked against the both the LL and UL event design criteria.

The existing bridge was modeled in GTStrudl with a 3-dimensional grillage model that included iterated elastic spread footing foundation springs and passive abutment springs, when engaged, with expansion joints at the abutments. Spread footing foundation springs were calculated following guidance from the BDM, section 1.10.4.2(2), and modified to consider the longitudinal translational springs as passive springs, when friction was overcome. This was done to capture the most accurate spring response from the spread footing abutment, as the spread footing spring passive contribution in the longitudinal direction is the abutment passive soil spring. Passive soil springs were developed according to section 1.10.4.2(1) of the BDM. Passive soil spring skew correction factors were not applied to the existing bridge baseline analysis. Skew correction factors were applied to the seismic retrofit analyses and will be discussed in further detail in Section 6.0. The available passive soil resistance was capped at 50% and 70% of the ultimate value for the LL and UL events, respectively.

The retrofit model also employed driven piles. Driven pile foundation springs were developed according to section 1.10.4.2(3) of the BDM using both Group Pile and LPile software developed by Ensoft Inc. Design material properties (i.e. modulus of elasticities) were employed. The concrete elements were modeled as uncracked sections for the LL event.

Figure 3 Isometric view of Baseline Model for Bridge #09359 (Goodpasture Island Road)

The response spectra and foundation modeling data were provided by Foundation Engineering and can be found in the Preliminary Geotechnical Report.

Multiple foundation restraint configurations were developed and iterated to envelope the seismic response of the bridge. The primary load cases analyzed were longitudinal and transverse loading cases, using 1.0L+0.4T and 0.4L+1.0T load combinations per the FHWA Seismic Retrofitting Manual.

Expected material properties (i.e. modulus of elasticities and compression strengths) were employed following guidance in the FHWA Seismic Retrofitting Manual. The concrete elements were modeled as uncracked sections, leading to a stiffer model than a cracked section model in order to meet the expected level of damage associated with the LL event. Ultimate effective bearing pressures were provided by Foundation Engineering.

5.0 OBSERVATIONS AND CONCLUSIONS ON THE BASELINE

ANALYSES

Results indicate that the bridge will not remain serviceable during the LL event. Capacity-to-demand (C/D) ratios for the spread footings indicated failure in eccentricity, flexure, and shear at both the abutments and all interior bents. Additionally, interior bent columns all failed in flexure and shear.

A summary of the as-constructed models’ global seismic behavior is presented in the below table.

Fundamental Period (sec) Global Displacement (in)

Design Event Longitudinal Transverse Longitudinal Transverse

Lower Level 0.69 0.45 1.33 0.70 Upper Level 1.08 0.60 3.63 2.02

The summary of controlling C/D ratios for the LL event is in Appendix 3.

6.0 PROPOSED SEISMIC RETROFIT STRATEGIES

Based on preliminary analyses, a retrofit strategy was developed to obtain the required seismic performance for both the LL and UL events.

Differing performances are allowed from the bridge under the LL event and UL event. For the LL event, the structural elements of the retrofitted bridge are to behave essentially elastically so that the bridge remains serviceable. For the UL event, the Type 1 Global Seismic Design Strategy (ductile substructure and elastic superstructure) can be employed for this bridge per BDM Article

1.17.3.2. However, the low ductility of the existing bridge foundation limited the amount of elastic and inelastic displacement capacity, and the necessary retrofit measures to achieve the desired LL and UL event performances resulted in an elastic behavior for both LL and UL events.

Section 3.3 of the Guide Spec. provides common examples of ERSs and EREs and highlights the importance of identifying the ERSs and EREs of the structure early in the design to achieve the proper LL and UL event performance. As defined by the Guide Spec., ERSs are the structural systems that provide a reliable and uninterrupted load path for transmitting seismically induced forces through the structure, and the EREs are the individual components, such as columns, connections, bearings, joints, foundation, and abutments, that together constitute the ERS. The Guide Spec. subdivides ERSs and EREs into three categories:

• Permissible

• Permissible that requires Owner’s approval

• Not recommended

The BDM further refines the Guide Spec. list of permissible and permissible that requires an Owner’s approval, reducing the number of available permissible ERSs and EREs without an Owner’s approval and even excluding some of them from an ODOT project outright. During the concept review meeting with the City, the BDM revisions to the Guide Spec. were discussed, and it was the City’s desire to follow ODOT BDM guidance when possible. The following identified ERSs and EREs for the proposed seismic retrofit follow the ODOT BDM requirements.

The following ERSs, as described in the Guide Spec. Fig. 3.3-1a and modified for this bridge site, will include:

Type 2 – Bearings at interior bents to accommodate full displacement; however, abutment is required as part of ERS

Type 5 – Elastic design at abutment for longitudinal and transverse response.

The following EREs, as described in the Guide Spec. Fig. 3.3-1b and modified for this bridge site, will include:

Type 3 – Isolate substructure from superstructure longitudinal demand load path at all interior bents; additionally, isolate substructure from superstructure transverse demand load path at Bent 3

Type 9 – pier walls without piles for longitudinal and transverse response at interior Bents 2 and 4

Type 10 – spread footings that do not allow rocking at all interior bents

Type 11 – passive abutment resistance required for longitudinal response o 50% of passive soil strength for LL o 70% of passive soil strength for UL

Type 14 – seat abutments whose backwall is designed to resist the expected impact force in an essentially elastic manner

As stated previously, the available retrofitted passive restraining force to the longitudinal seismic demands was adjusted for skewed abutment effects. Current research efforts by the academic community has identified and started to quantify the negative effects to the available passive resistance at skewed bridge abutments. While the engineering community has yet to develop a standardized method to apply these initial findings, the design team felt this needed to be considered and accounted for in the bridge seismic retrofit analysis. DOWL and Foundation Engineering collaborated to interpret the available data and to develop a project-specific application to account for skewed abutment effects. DOWL presented the design team’s recommended skewed abutment analysis approach to the City for their review and obtained the City’s approval prior to use. See Foundation Engineering’s Preliminary Geotechnical Report for further detail.

Based on observation of the structural behavior, preliminary analysis results, and construction constraints, a preferred alternative has been developed. The team initially considered widening the abutment spread footing to accommodate longitudinal displacements of the superstructure and buckling-restrained braces (BRBs) at interior bents for transverse capacity. However, the necessary width of abutment spread footing to accommodate movement was quickly deemed unreasonable and not cost-effective. Also, as the interior bents needed to resist significant longitudinal responses, even when isolated from the superstructure in this direction, BRBs were found to be ineffective. Consideration was also given to a micropile-supported spread footing beneath the pier walls to increase transverse capacity at interior bents; however, a wider spread footing without piles was found to be constructible, provide enough capacity, and be more cost-effective. The effort to avoid work at the base of Bent 3, due to construction constraints, guided the retrofit scheme to its current preferred design.

Phase I Retrofits:

• Provide reinforced concrete shear lugs between each girder at the abutments o Improves transverse connection capacity between the superstructure and substructure at the abutments, as they are currently reliant on deficient wingwalls running towards the interior bents

• Provide reinforced concrete shear lugs between each girder at interior Bents 2 and 4 o Addresses the loss in transverse restraint from the pile foundation when the substructure is isolated from the superstructure at these bents

• Widen the top of the existing cross beams at interior bents by a minimum of 4 inches on each side o Addresses deficient beam seat length o Beam seat extension could be constructed using cast-in-place concrete methods or bolting steel brackets to the side of the existing beam seat

• Widen the beam seat at the abutments by a minimum of 6 inches o Addresses deficient beam seat length o Beam seat extension could be constructed using cast-in-place concrete methods or bolting steel brackets to the side of the existing beam seat

Phase II Retrofits:

• Isolate the bridge substructure from the superstructure longitudinal and transverse seismic load path by cutting the existing dowel-pinned connections o The revised load path minimizes the bridge longitudinal seismic demands on all interior bents, as well as transverse seismic demands at Bent 3 o The installation of shear lugs at Bents 2 and 4 will provide missing transverse restraint after the dowels are cut

• Replace existing elastomeric bearing pads at Bent 3 with low-friction Polytetrafluorethylene (PTFE, also known as Teflon) dimpled and lubricated sliding pads o Addresses existing spread footing stability issues by decreasing the load contribution from the superstructure before overcoming friction

• Cast 3-foot-thick concrete infill walls between existing columns and cast an 18-foot-wide continuous spread footing that encompasses the existing spread footings at interior Bents 2 and 4 o Provides the primary bridge superstructure and substructure transverse restraint as Bent 3 is removed from the transverse seismic load path o Also attracts some transverse seismic load away from the abutments, decreasing the need for robust transverse retrofit at Bents 1 and 5 o Addresses stability issues of existing interior bent spread footings

• Cast 4.8-foot wide by 4-foot-deep pile caps at the abutment with a single row of five 20-inch pipe piles filled with concrete o Provides superstructure and abutment longitudinal restraint o Addresses stability issues of abutment spread footings

• Strengthen closure pour to provide adequate positive moment capacity by a means such as closure ties or steel anchors o Increases the capacity of the closure pour to adequately resist the magnitude of positive moment being applied within this region

• Increase Bent 3 crossbeam positive moment capacity by a means such as fiber-reinforced polymer (FRP) wrapping or near surface-mounted reinforcement o Increases the capacity of the crossbeam such that it is enough for the positive moment demands on the beam near the top of columns

Preliminary analysis of the above retrofit strategy produced acceptable C/D ratios (i.e. greater than 1.0) for all piles and superstructure displacements. See Appendix 3 for a complete summary of post-retrofit and retrofitted bridge C/D ratios.

A summary of the seismic retrofitted models’ global seismic behavior is presented in the below table.

Fundamental Period (sec) Global Displacement (in)

Design Event Longitudinal Transverse Longitudinal Transverse

Lower Level 0.46 0.28 0.70 0.39 Upper Level 0.48 0.30 1.10 0.69

The proposed retrofits are illustrated in the TS&L plan set in Appendix 1.

Other Work:

Replacement of the concrete slope paving or fencing under the end spans will be required. Slope paving has been included in the cost estimates.

No aesthetic requirements for the bridge have been identified.

7.0 TYPICAL SECTIONS

The deck section carries two 12-foot eastbound lanes of Goodpasture Island Road over Delta Highway, one of which is a left-turn lane. The traffic lanes are bordered by a 3-foot, 6¼-inch shoulder on the left, and a 6-foot bike lane and 3-foot, 8¾-inch sidewalk on the right. ODOT Standard Concrete F-Rail bridge rail is mounted on the left side of the bridge and concrete barrier with tube rails is mounted on the right.

Delta Highway runs underneath the bridge, comprised of two northbound and two southbound lanes, all 12 feet wide. There is a 16-foot median between the two directions of traffic, in which Bent 3 of the bridge is positioned. There is approximately 14 feet from the centerline of Bent 2 to the existing fog line of the southbound lanes, and approximately 25 feet from the centerline of Bent 4 to the existing fog line of the northbound lanes.

Goodpasture Island Road Bridge crosses over Delta Highway with a minimum vertical clearance, as noted by the 1964 as-built plans, of 17 feet.

No changes are planned to the roadway configuration. Horizontal and vertical alignments will be maintained.

8.0 TRAFFIC STAGING AND TEMPORARY TRAFFIC CONTROL

Goodpasture Island Road is a heavily trafficked commuter street over Delta Highway. This bridge is one of only two access points across Delta Highway connecting the community west of the highway and east of the Willamette River to the rest of the City of Eugene. The 2010 Average Daily Traffic (ADT) and Average Daily Truck Traffic (ADTT) on Goodpasture Island Road was observed to be 16,368 and 1,637, respectively, per the latest Bridge Inspection Report.

Construction will also need to occur underneath the bridge on Delta Highway, which is also a heavily trafficked main arterial running north and south. The 2010 Average Daily Traffic (ADT) and Average Daily Truck Traffic (ADTT) on Delta Highway was observed to be 41,091 and 2,055, respectively, per the latest Bridge Inspection Report.

During the concept design meeting with the City, the City expressed a strong desire to avoid and/or limit the need for full road closures to retrofit the bridge on both Goodpasture Island Road and Delta Highway. The above proposed retrofit was developed with this in mind. As previously mentioned, there is also a need to avoid significant work at Bent 3 due to construction constraints on Delta Highway. Staged construction is needed on Goodpasture Island Road for the abutment retrofit; whereas, the interior bent retrofits can be done in one stage underneath the bridge on Delta Highway.

Further temporary traffic control and staged construction analysis and details will need to be developed during final design. However, one possible approach could be as described below.

For the substructure construction at the interior bents:

• At Bent 2:

o Push Delta Highway traffic east towards the median, maintaining two 12-foot traffic lanes o Remove and replace the existing guard rail, and implement a temporary barrier during construction o Confirm access is maintained to the Delta Highway off-ramp just past the bridge

• At Bent 3:

o Shift Delta Highway traffic east towards northbound shoulder, but maintain two 12-foot lanes

• At Bent 4:

o Close the Delta Highway northbound left shoulder o Maintain two 12-foot northbound lanes o Remove and replace the existing guard rail, and implement a temporary barrier during construction

For superstructure construction at the abutments, staged construction may look like:

• Stage I Construction – South sides of the abutments under construction o Close the south lane of Goodpasture Island Road across the bridge and provide the following layout:

2-foot-wide shoulder One 12-foot eastbound lane on the north side of the bridge 2-foot-wide shoulder from the barrier 3-foot-wide buffer from the face of the barrier to construction limits o Potential left-turn lane closure at the east side intersection, to be determined during final design o Perform construction on closed south halves of the abutments

Figure 4 Stage I Construction Diagram

• Stage II Construction – North sides of the abutments under construction o Close the north lane of Goodpasture Island Road across the bridge and provide the following layout:

3-foot-wide buffer from construction limits to the face of the barrier One 10-foot eastbound lane on the south side of the bridge Minimal buffers on either side of the lane, as possible o Potential left-turn lane closure at east side intersection, to be determined during final design o Perform construction on closed north halves of the abutments

Figure 5 Stage II Construction Diagram

Staged construction will require temporary shoring at the abutments to maintain necessary lane widths. During staged construction on top of the bridge, pedestrians and cyclists will be detoured onto the adjacent bridge, which has both a sidewalk and bike lane. Signalized intersections with protected crossings are on either side of the bridge at Goodpasture Island Road and the Delta Highway Northbound ramps, and Goodpasture Island Road and the Delta Highway Southbound ramps.

9.0 RIGHT-OF-WAY AND EASEMENTS

A detailed survey of the City’s existing right-of-way and private property boundaries was not conducted as part of this study. All proposed seismic retrofit work is located either within the current footprint of the bridge or beneath the roadway immediately adjacent to the ends of the bridge and is not anticipated to require the purchase of additional right-of-way for construction.

Temporary easements are not anticipated at this time. A complete assessment of the project right-of-way and temporary easement will be completed during final design.

10.0 UTILITIES

Seven utilities run along the bridge, supported by blockouts in the bridge diaphragms and steel brackets, on both the left and right sides. Utilities are metal conduits. All utilities will be protected in place.

The seismic vulnerability of the existing utility crossings was not considered at this time. The anticipated longitudinal and transverse seismic displacement of the retrofitted structure is 1.10-inch and 0.08-inch, respectively. The existing utility crossings’ ability to accommodate these anticipated seismic displacements needs to be considered during final design.

No consideration for future utilities will be made during the final design phase. Though the utility supports were not included in seismic analysis, by inspection there is minimal or no lateral bracing for these supports. A suggested minimum future retrofit would be laterally bracing existing utility supports.

11.0 DRAINAGE AND STORMWATER

The drain system of surface flow off the end of the bridge will not be modified as a result of the seismic retrofit work.

12.0 FOUNDATION INVESTIGATION

Foundation Engineering performed review of soil information shown on the as-built plans and performed new geotechnical explorations at this site. Results showed that the subsurface profiles at the bridge bents were similar throughout: dense to very dense gravel with silt, sand, and cobbles, followed by weathered bedrock. Backfill at the footings and approach embankments were noted as likely similar to the foundation soils with some more variability in the relative compaction. Based on anticipated ground water depths, saturated conditions were assumed below the interior footings for bearing capacity.

Nominal bearing resistances at the abutments and interior bents on the dense gravel soil are 11.0ksf and 35.2ksf, respectively.

These soils are classified as Site Class C. The site appears to have a low risk of experiencing liquefaction and deep-seated soil instability during a seismic event.

See the Preliminary Geotechnical Report for further details.

13.0 ENVIRONAMENTAL INVESTIGATION AND PERMITS

A wetland and waters reconnaissance and determination memo will be required. The National Wetland Inventory (NWI) and Local Wetland Inventory (LWI) both map wetlands in the project vicinity. There is a mapped Category B wetland site northeast of the bridge that requires a 25-foot conservation setback per the Eugene Goal 5 Water Resources Conservation Plan and the Eugene Land Use Code Section 9.4920. The project will likely be subject to the Water Resources Conservation Overlay development standards and review. Additionally, the project area is mapped in the Willamette Greenway boundary. A Willamette Greenway Permit may be required.

The project will be required to provide stormwater treatment pursuant to ODOT's Stormwater Management Program policies and guidelines if there is any increase in traffic bearing impervious surface. The proposed seismic retrofit will not increase traffic bearing impervious surfaces and the existing stormwater drainage facilities with either be maintained and protected in place or reconstructed. Therefore, no additional stormwater treatment facilities are anticipated to be necessary. A 1200-C permit is required if ground disturbance is one acre or greater and the project isn’t covered by ODOT’s 1200-CA (disturbance of five acres or more).

The USFWS Information for Planning and Consultation (IPaC) tool maps eleven listed species as having the potential to occur within the project area. Given the intensity of land use and disturbance in the surrounding area, it is unlikely that these species or their habitat are present in the project area. A no effect memo will be required.

According to the State Historical Preservation Office (SHPO), there are no historic resources eligible for the National Register within the study area or in the immediate vicinity. To investigate any potential archaeological resources within the project area, and to comply with Section 106 of the National Historic Preservation Act of 1966 (as amended) and Oregon state laws requiring identification and protection of archaeological resources, an Archaeological Baseline Report may be required.

14.0 CONSTRUCTABILITY

Both Goodpasture Island Road and Delta Highway are heavily utilized main arterial roads in the City of Eugene. Construction of seismic retrofits at the abutments will need to be stage-constructed to minimize impacts to traffic on Goodpasture Island Road. Temporary shoring will be used to allow one lane to stay open on the bridge during both phases. Temporary impacts to the bike lane on the bridge during construction will need to be considered during final design. The load rating performed by DOWL last year showed that, though no posting was required for legal trucks, low rating factors were found for emergency vehicles and permit trucks. As Goodpasture Island Road Bridge is near a fire station, and with staged construction shifting traffic out onto damaged Girder 5, it is important that the recommended strengthening of the girder is performed prior to the construction of the abutment retrofits. A construction bid item has been added to the seismic retrofit construction cost estimate for the recommended additional work.

Construction at the interior bents can be achieved without any lane closures but will require some lane shifting on Delta Highway, particularly at Bents 2 and 3. Excavation has been avoided at Bent 3; however, the cutting of the pinned connection and replacement of the bearing pads will need to be done from underneath the bridge. Bent 3 will be accessed from the east side, necessitating a shift of the northbound lanes east into the shoulder, and the girders will need to be jacked for bearing pad replacement. Existing lane widths can be maintained for the northbound travel lanes. Temporary shoring will be used at Bents 2 and 4 to avoid lane closures on Delta Highway and to avoid undermining the existing slope towards the abutments. Coordination between the City and utility agencies occupying the bridge will be necessary during final design to coordinate the design and construction of the retrofit.

15.0 CONSTRUCTION COST

Cost estimates for the seismic bridge retrofit and for a bridge replacement alternative were developed to capture professional engineering services (PE), construction engineering services (CE), and construction costs. PE project costs typically include environmental, survey, permitting, ROW, traffic control, roadway, structural, and other project-specific engineering services to develop a Plans, Specifications, and Estimate (PS&E) package ready for construction. CE project costs typically include construction contract administration, construction inspection, and engineering support during construction of the project. For the seismic retrofit, the remaining PE costs were estimated at 15% of the total construction bid item costs. For the bridge replacement alternative, PE costs were estimated at 20% of the total construction bid item costs.

CE costs were estimated to be 20% of the total construction bid item costs for both alternatives.

All costs are based on 2020 equivalent construction dollars.

Construction costs for the retrofit were developed using ODOT 2018 bridge unit cost data and adjusted for inflation and constructability considerations. Temporary traffic control and mobilization construction costs were both included on a percentage basis and were each estimated to be 10% of the total bridge construction costs. Bridge replacement costs were estimated on a per-square-foot replacement cost basis. See Appendix 2 for detailed cost estimate breakdowns and quantity calculations for both the seismic bridge retrofit and bridge replacement alternatives.

Cost estimates are based on the Association for the Advancement of Cost Engineering (AACE) Cost Estimate Classification System to provide a total project cost range to account for project cost uncertainty at this stage of design development. AACE divides project construction cost estimating into five classes. Each class considers the level of confidence in the cost estimate at the time of development, and other secondary items, such as end usage, estimating methodology, expected accuracy range, and preparation effort. For the seismic retrofit alternative, based on a 30% design level, a preliminary cost estimate (AACE Class 3) was developed with a -10% to +20% expected accuracy range. For the replacement alternative, a feasibility cost estimate was developed (AACE Class 4) with a -20% to +30% expected accuracy range.

The estimated cost range for the proposed retrofit approach is $1.43 million to $1.91 million. For comparison purposes, when the adjacent bridge was constructed in 2015, the bridge costs were approximately $2.7 million. Based on square foot costs for a typical replacement, the replacement cost of the bridge is $3.2 million to $5.2 million.

16.0 CONCLUSION

The seismic response of Bridge #09359 was evaluated in accordance with FHWA-HRT-06-032 – Seismic Retrofitting Manual for Highway Structures. The investigation found that the bridge is deficient for both the upper and lower level seismic events and should be either retrofitted or replaced to meet the desired performance criteria. We believe the bridge can be reasonably retrofitted by rebuilding the interior bents to be pier walls on widened continuous spread footing foundations, constructing a pile cap integral to the existing spread footings at the abutments, and modifying the girder bearings. This retrofit design is preliminary in nature; if the City chooses to proceed with retrofit rather than replacement or no action, the detailed design of the retrofit components would take place during the final design phase of the project. Additional considerations beyond the seismic performance described in this report, which would need to be considered at that point, include: a complete traffic control design and incorporating results from a final geotechnical report.

Based on the preliminary design, a cost estimate for the seismic retrofit is provided. For comparison purposes, a planning-level estimate of bridge replacement costs was also developed.

The estimated construction cost (including design and construction engineering) to retrofit the structure is estimated to be 37%-45% of a full bridge replacement. Typically, seismic retrofit alternatives become less favorable when the cost to retrofit starts to approach 50% of the bridge replacement cost. However, the decision to retrofit versus replace also relies on a number of variables that were not explicitly evaluated as part of this report including: the remaining life of the bridge, the load carrying capacity of the structure, additional repairs and maintenance to the existing structure that may be required in the future, and the future operational capacity of the roadway.

The results and findings of this report indicate the Goodpasture Island Road bridge is a viable candidate for seismic retrofit. Based on this preliminary design effort, final design of the retrofit could begin as soon as the City is able to secure funding for the final design and construction phases.

APPENDIX 1: TS&L PLAN SET

61°52'30"

TYP.

EL

EV

AT

IO

N

IN

F

EE

T

430 C BENT 1L C BENT 2L C BENT 3L C BENT 4L C BENT 5L

SL. NOR.EXISTING

SLOPE

PAVING

SL. NOR.

EXISTING 36" DIA. CONC.

COLUMN, TYP.

EXISTING CONC. CROSS BEAM

EXISTING

PRESTRESSED

CONC BEAM, TYP.

SB DELTA HWY NB DELTA HWY

EXISTING

SLOPE

PAVING

EXISTING CONC.

SPREAD FOOTING

EXISTING EXIT SIGN

NOTE:

ELEVATIONS SHOWN ARE BASED ON THE

NATIONAL GEODETIC VERTICAL DATUM, 1929.

0" M

IN

CL

EA

RA

N

CE

EL.

LT. 387.2

RT. 386.7 EL.

LT. 386.7

RT. 386.7

EL.

LT. 386.7

RT. 386.2380

EXISTING

SPREAD

FOOTING

ABUTMENT

4 5 4 5

EXISTING 2-TUBE PARAPET HANDRAIL (RIGHT). STD. TYPE "F" CONCRETE RAIL (LEFT)

6PRELIMINARY

TIP EL. 375

PRELIMINARY

TIP EL. 375

2 2 4 5

7" O

UT

-O

UT

D

EC

K

6' -0

BI

KE

LA

N E

0"

LA

N E

0"

LA

N E

3' -6

4"

SH

O

UL

D

ER

1' -4

RA

IL

1' -0

RA

IL

3' -8

4"

SI

D

EW

AL

K

64'-0"

SPAN 3

BENT 3 BENT 4

228'-0" CTR.-CTR. END BENTS

EXTG. TYPE II PRESTRESSED CONC. BEAM SPANS

50'-0"

SPAN 1

64'-0"

SPAN 2

BENT 1 BENT 2 BENT 5

EDGE OF PAVEM

ENT

EDGE OF PAVEM

ENT

EDGE OF PAVEM

ENT

EDGE OF PAVEM

ENT

24'-0" 24'-0"

16'-0"

S42°18'30"E

5' -0

ST

RU

CT

UR

E

CL

EA

RA

N

CE

50'-0"

SPAN 4

5 6

EXISTING

ADJACENT

BRIDGE

EL. 413.63 EL. 415.12

EL. 415.74

EL. 414.92 EL. 413.29

EL. 413.86EL. 415.17EL. 412.69

5 6

1 1

EXTG. (4) UTILITIES,

VARYING IN SIZE 2"

TO 6" DIA.

EXTG. (2) UTILITIES,

VARYING IN SIZE 6"

TO 8" DIA.

ST

A.

.8

ST

A.

.8

2 3

C GOODPASTURE ISLAND RD.L

STA. 9+80.85STA. 7+52.85 STA. 8+02.85 STA. 8+66.85 STA. 9+30.85

FREED* FREED* FREED* FREED* FREED*

*RETROFITTED LONGITUDINAL FIXITY

4 4

RETROFIT ITEMS

CAST PILE CAP INTEGRAL TO ABUTMENT SPREAD FOOTING

ISOLATE SUPERSTRUCTURE FROM SUBSTRUCTURE

CAST CONCRETE INFILL WALL AND CONTINUOUS SPREAD

FOOTING

CAST SHEAR BLOCKS BETWEEN GIRDERS AND AT GIRDER

ENDS

BEAM SEAT EXTENSION

STRENGTHEN CLOSURE POUR TO PROVIDE ADEQUATE

POSITIVE MOMENT CAPACITY

STRENGTHEN CROSSBEAM TO PROVIDE ADEQUATE POSITIVE

MOMENT CAPACITY

SEISMIC DEFICIENCIES

COLUMN FLEXURE AND SHEAR CAPACITY

SPREAD FOOTING FLEXURE AND SHEAR CAPACITY

SPREAD FOOTING SLIDING FAILURE

BEAM SEAT LENGTH

CLOSURE POUR POSITIVE FLEXURE CAPACITY

SPREAD FOOTING OVERTURNING AND BEARING FAILURE

CROSSBEAM POSITIVE FLEXURE CAPACITY

STRUCTURE

ST

A.

8+

P

IV

C

EL

. 4

.8

400' VC+7.00% -7.00%

PROFILE GRADE OF ℄ OF ROADWAY

PLAN AND ELEVATION 1 00000

SHEET

OF

DRAWING NO.CALC. BOOKSTRUCTURE NO.DATE

C:\OBEC\PWOBEC01\D0376755\OBEC_COE_BR009359 - PLAN AND ELEVATION.DWG 2020/05/18 12:29

DESIGNER:

CHECKER:

REVIEWER:

DRAFTER:

ACCOMPANIED BY DRAWINGS:DATE REVISION BY

If scale bar does not measure one inch, then drawing is not to scale

SCALE WARNING

WWW.DOWL.COM

4275 Commercial St. SE, Ste. 100 Salem, Oregon 97302

503-589-1400

WWW.DOWL.COM

GOODPASTURE ISLAND ROAD

SEISMIC BRIDGES

DELTA HIGHWAY

LANE COUNTY

KEAVA CAMPBELL, EIT

KURT SCHWEITZER, PE

MICHAEL McNULTY, PE

BRENNEN BOESE

MAY 2020 09359 0000 2

TYP

E, S

IZE

LO

CATIO

N PLA

NS

IN

FO

RMATIO

N O

NLY

LOCATION MAP

NO SCALE

SEC. 18, T.17S., R.3W., W.M.

LAT. 44.0850N, LONG. -123.1021W

R

P

E J

O

T C

PLAN

Scale: 1" = 30'-0"

ELEVATION

Scale: 1" = 30'-0"

GRADELINE DIAGRAM

No Scale

NOTE:

ELEVATIONS SHOWN ARE TOP OF DECK @ GUTTER LINES

AT CENTERLINES OF BENTS AND ARE BASED ON

AS-CONSTRUCTED BRIDGE PLANS. FIELD VERIFY.

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EXPIRES: 12/31/

0.80

0.700.60

0.500.40

0.300.20

0.100.000.00 0.50 1.00 1.50 2.00 2.50 3.00

0.800.70

0.600.50

0.400.30

0.200.10

0.00

0.90

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

34'-3"

3' -0

VA

RI

ES

3'-0" THICK CONCRETE

PIER WALL, 18'-0" WIDE

CONTINUOUS SPREAD

FOOTING

4CAST SHEAR BLOCKS

BETWEEN GIRDERS AND

AT GIRDER ENDS

3 ADD STRUCTURAL STEEL

BRACKETS TO PROVIDE

ADEQUATE BEAM SEAT

LENGTH FOR GIRDERS,

SEE TYPICAL SECTION

- BENT 3 BELOW

EXISTING CONCRETE

SPREAD FOOTING

EXISTING

CONCRETE

COLUMN

EXISTING

CONCRETE

CROSSBEAM

2" ACWS

SEVER DOWEL CONNECTION, TYP. 2

3' -6

℄ BEARING

CONCRETE FILLED

PIPE PILE, PP 20 x 0.5

EXISTING SPREAD

FOOTING ABUTMENT

CAST PILE CAP INTEGRAL WITH

EXISTING SPREAD FOOTING

ABUTMENT, DRIVE PILES AT

EACH GIRDER LINE

5 WIDEN BEAM SEAT

TO PROVIDE

ADEQUATE SEAT

LENGTH

6"

4'-8"

3' -1

1"

2' -0

9'-91 4"

4 CAST SHEAR BLOCKS BETWEEN

GIRDERS AND AT GIRDER ENDS

℄ BENT 3

3'-0"

4" MIN.

16"

EXISTING CONC.

DIAPHRAGM, BEAM E

BEAM CLOSURE

POUR

6 STRENGTHEN CLOSURE

POUR TO PROVIDE

POSITIVE MOMENT

CAPACITY, SUCH AS WITH

CLOSURE TIES OR STEEL

ANCHORS

5INSTALL STEEL SUPPORTS

TO PROVIDE ADEQUATE

BEAM SEAT LENGTH

2JACK GIRDERS, SEVER DOWEL

CONNECTION AND REPLACE

ELASTOMERIC BEARING PAD

WITH PTFE SLIDING PAD,

DIMPLED AND LUBRICATED

7 STRENGTHEN CROSSBEAM TO

PROVIDE ADEQUATE POSITIVE

MOMENT CAPACITY, SUCH AS

WITH FRP WRAPPING OR

NEAR SURFACE MOUNTED

REINFORCEMENT

GENERAL NOTES 2 00000

GENERAL NOTES:

BRIDGE SEISMIC RETROFIT IS…