2019_USAFs_Pedestrian_Bridge_Inspection_Report.pdf

STATEMENT OF INSPECTION REVIEW AND APPROVAL

Part 1: TO BE COMPLETED BY THE DISTRICT OR OPERATING MSC

UPON COMPLETION OF INSPECTION AND EVALUATION

A qualified inspection team, according to the NBIS and USACE Policy, has completed the inspection and evaluation of the CEXMVPMN-00USAF / USAF Pedestrian Bridge.The inspection report received an independent technical review by a qualified bridge engineer and all substantive issues arising during the review have been resolved to meet the provisions of PL 100-17 and existing USACE policy.

/s/ Jacob Fall 06-NOV-2019 Bridge Inspection Team Leader (Final Report Signature Date)

Technical Review Team Leader (Date)

Chief, Engineering Division (Date)

Part 2: TO BE COMPLETED BY MSC

The inspection, evaluation and review of the USAF Pedestrian Bridge has been completed in accordance with the approved Quality Control Plan, and this report is approved as sufficient in accordance with ER 1110-2-111 for updating the data in the CEBIS, and for proceeding to budget, schedule and design all maintenance and rehabilitation work necessary to correct deficiencies which jeopardize the structural safety and integrity of the USAF Pedestrian Bridge.

Chief, Engineering Division (Date)

Page 1 of 13Reports

11/6/2019https://cebis.usace.army.mil/brgtest/cebis_2.rpts_dtl_utl.rpt_open?p_url=entire_rpt

USAF Pedestrian Bridge

CEXMVPMN-00USAF

USAF

Hennepin County, Minnesota

MISSISSIPPI VALLEY DIVISION

ST. PAUL DISTRICT

INSPECTED MARCH 2020

Page 2 of 13Reports

1. Summary of Inspection:

This combined routine and fracture critical inspection of the Upper Saint Anthony Falls (USAFs) Pedestrian Bridge was conducted on 15 OCT 2019 by Jake Fall, P.E. (Bridge Program Manager and Team Leader) of the Saint Paul District, and Scott Hibbs, P.E., Mike Coleman, and Dakota Keller of Extreme Access, Inc. The previous inspection was conducted in March 2015. The weather conditions during the inspection were mostly cloudy skies, with a light NW wind at approximately 5 mph, and 51°F +/- 2°F.

Fracture critical and routine inspection plans were prepared prior to the inspection. The inspection team leader ensured all required pre-inspection planning was conducted and also made sure the inspection plans were followed during the inspection execution phase.

The quality control process for the pre-inspection planning and inspection execution phases are documented in checklists which are contained in the bridge file rather than attached to this report.

The bridge deck and hand railing was inspected from the top of the deck. Meanwhile, the superstructure, substructure, and bearings were inspected, via rope access, by rappelling from the bridge’s handrail base.

Located in downtown Minneapolis, Minnesota, just upstream of the stone arch bridge on the Mississippi River. The bridge is used as the downstream lock chamber crossing that conveys pedestrian traffic from the land wall to the river wall.

Constructed in 1956, and approximately 57’ 10” in length, the pedestrian bridge is a single simple span. The substructure consists of a two welded steel trusses. The deck is aluminum grating, and the bridge bearings rest on the lock walls.

After being placed into service the following repairs have been conducted:

1. The bridge was last sandblasted and painted in 2002.

2. Weld repairs were conducted prior to being painted in 2002.

2. Summary of Findings:

The primary focus of this combined routine and fracture critical inspection was to conduct a close up (within arm’s length) visual inspection of all FCMs and fatigue sensitive details (FSDs). This bridge consists of an aluminum open grating deck supported by two welded steel trusses. The trusses bear on the lock wall. Careful attention was given to all truss member connections, and the bottom (tension) chord. All members were inspected for section loss, distortion, bends, buckling, and cracks with no major defects noted. Only minor changes were noted from the previous inspection.

The deck is in good condition. No significant defects were observed.

The superstructure is in overall satisfactory condition. The paint system is mostly intact.

Light surface rust is present in those areas where the paint system has failed. Section loss is not significant at this time. Welding quality may be characterized as fair. Several poor quality welds were repaired in 2002 in conjunction with the painting project. All members were found to be generally straight and true. No cracks were observed in the truss members or their welded connections.

The substructure is in satisfactory condition. Minor cracking with efflorescence was

Page 3 of 13Reports observed under the bearing areas. A few small spalls are present on the horizontal surfaces. The horizontal bearing seat area in the lock wall is not sloped well and tends to hold water. The bearings all have moderate corrosion present.

The bridge was observed under a normal pedestrian load near mid span, and no visually perceptible deflection was observed.

The load rating is deemed to be in agreement with the general condition of the bridge.

This is a pedestrian bridge, therefore, no speed limit signage is required, however, the load limit sign that is posted is incorrect and needs to be replaced.

3. Previous Inspection Findings and Recommendations:

Recommendations from the previous inspection (and their status) include:

Sandblast and spot paint all areas of active corrosion as budget and schedule allow (Not Done) The current load limit sign is incorrect. It needs to be replaced with a load posting sign that indicated

3.5 tons is the safe load limit. (Not Done) Perform the next routine and FCM inspection in March 2020. (Done. Oct 2019) The current hand rail has wide gaps that present a safety risk to the public. Place cyclone fence or other appropriate barrier on the handrail to reduce the maximum opening size to less than four inches in diameter. estimated cost: $1,500. (Done. OCT 2019)

The downstream hand railing has a loose connection on the third post from the left end. This connection needs to be tightened. estimated cost: $150. (Done. OCT 2019)

4. Recommendations:

Recommendations from this inspection are:

Perform the next routine and FCM inspection in October 2024. estimated cost: $5,000.

Sandblast and spot all areas of active corrosion. estimated cost: $5,000.

The load rating needs a QC check. estimated cost: $2,000.

There are three sections of deck grating that are loose. Their connections need to be replaced.

estimated cost: $250.

The old load posting sign which indicated a safe load of 11.6 tons is incorrect. This sign should be removed and replaced a new sign indicating a safe load limit of 3.5 tons. estimated cost: $200.

Condition Classification Component Subcomponent

A General Comment

Condition Classification Component Subcomponent

A General Comment

Condition Classification Component Subcomponent A General Comment

Condition Classification Component Subcomponent

A Deck Steel Deck-Open Grid

Condition Classification Component Subcomponent A General Comment

5. Evaluation Summary:

No evaluations were conducted in conjunction with this inspection.

Page 4 of 13Reports

PUBLIC HIGHWAY/ROADWAY BRIDGES INVENTORY AND APPRAISAL (SI&A) SHEETS Printed: 06-NOV-2019

202. Structure Number: CEXMVPMN-00USAF 8 NBI Structure Number: CEXMVPMN-00USAF

Geographical and Route Data

1. State Code Minnesota

2. District 00

3. County Hennepin County

4. Place Code 04300

6. Features Intersected Upper St Anthony Lock

7. Facility Carried by Structure Public Pedest

9. Location USAF

16. Latitude 445850.96

17. Longitude 0931523.39

General Data

21. Maintenance Responsibility 70

22. Owner 70

34. Skew 00

35. Structure Flared 0

42. Type of Service 35

43. Structure Type Main 309

44. Structure Type Approach 000

45. No. of Spans Main 001

46. No. of Approach Spans 0000

27. Year Built 1956

106. Year Reconstructed

107. Deck Structure Type 3

108. Wear/SurfProt Sys 000

Inspection Data

90. Inspection Date 03-2020

91. Designated Inspection Frequency 60

92. Critical Feature Inspection Frac Crit Insp: Y60

Underwater Insp: N Other Spec Insp: N

93. Critical Feature Inspection Date Frac Crit Insp: 10-2019 Underwater Insp: - Other Spec Insp: -

Dimensional Data

48. Length of Maximum Span 58.0 feet

49. Structure Length 58.0 feet

51. Bridge Roadway Width, Curb-to-Curb 4.0 feet

52. Deck Width, Out-to-Out 4.0 feet

Proposed Improvements

75. Type of Work 382

94. Bridge Improvement Cost 50

95. Roadway Improvement Cost 5

96. Total Project Cost 75

97. Year of Improvment Cost Estimate 2019

Condition Rating

58. Deck 7

59. Superstructure 6

60. Substructure 6

61. Channel and Channel Protection N

62. Culverts N

Appraisal Rating

71. Waterway Adequacy N

72. Approach Roadway Alignment N

36. Traffic Safety Features NNNN

113. Scour Critical Bridges 9

Load Rate and Post

41. Structure Open, Posted or Closed to Traffic P

220. Pedestrian (kilopascal) 1.5

221. Vehicle 0

Over 200 Items

200. COE Division CEMVD

201. COE District CEMVP

202. Number CEXMVPMN-00USAF

203. Inspection Office CEMVP

204. Inspector Jake Fall

205. Inspections Cost 4000

216. Seismic Category A

217. Acceleration Coefficient 0.09

218. Soil Site Coefficient 1.00

Page 5 of 13Reports

Structure Number Name NBI Structure Number CEXMVPMN-00USAF USAF Pedestrian Bridge CEXMVPMN-00USAF

Operational Condition and Relative Risk Assessment System: Public Pedestrian 231) Life Safety: Low Impact (10)

235) Subsystem: Lock 232) USACE Mission: Minor Impact (10)

233) Business Line: Navigation 234) Regional Commerce: Minor Impact (10)

236) Project (P2) number: 000000 Consequence Score/Category : 10 / IV

Bridge Subcomponent Condition Classification

Component Subcomponent Condition

Classification Bearings Fixed Bearing B

Moveable Bearing (roller, sliding, etc.) B

Bridge Rail Metal Bridge Railing B Deck Steel Deck-Open Grid A

Substructure Reinforced Concrete-Pier Wall A

Superstructure Steel-Truss B

Page 6 of 13Reports

Bridge Number: CEXMVPMN-00USAF Bridge Name: USAF Pedestrian Bridge Inspection Date: 03-2020

NBI No. CEXMVPMN-00USAF Condition Ratings Appraisal Ratings

1. State: Minnesota 58.Deck: 7 67.Structural Evaluation: N

2. District: 00 59. Superstructure: 6 68. Deck Geometry: N

9. Location: USAF 60. Substructure: 6 71. Waterway Adequacy: N

6. Features Intersected: Upper St Anthony Lock 61. Channel: N 72. Approach roadway Alignment: N

203. Inspection Office: CEMVP 36. Traffic Safety Features: NNNN

204. Inspector: Jake Fall 113. Scour Critical: 9

Element Cond Cond Cond Cond No. Name QTY ENV 1 2 3 4

Decks/Slabs Span Range: 1 to 001 60 Other Deck 217 2 152 65 0 0

Quantities are in square feet. Deck is in good condition. Galvanized steel grating panels with serrated bars. All panels are in good condition. Three sections of grating are loose. See photographs 3, 4 and 11.

Superstructure Span Range: 1 to 001 120 Steel Truss 116 2 99 17 0 0

Quantities are in linear feet. Superstructure is in satisfactory condition. There is light corrosion and isolated pitting along the top of the bottom tension chord, which tends to hold water. Section loss is not yet a concern. There are some welds with poor quality including pin holes, weld spatter, undercut and non uniform weld profile. Overall there was little to no change noted from the previous inspection. See photographs 1, 2, 7, 8, and 12.

Substructure Span Range: 1 to 001 215 Reinforced Concrete Abutment 8 2 0 6 2 0

Quantities are in linear feet. The abutments were inspected in the vicinity of the bearings and were found to be in satisfactory condition. The horizontal bearing seat areas hold water and have poor drainage. There are a few spalls less than one square foot in area located between the bearings on the horizontal surfaces.

Minor vertical cracking with efflorescence was observed spaced about three feet apart on both lock walls. See photographs 7 and 9.

Bearings Span Range: 1 to 001 311 Movable Bearing 4 2 0 4 0 0

Quantities are each. Bearing plates are anchored to bearing seats with bolts welded to the anchor plates. New bolts were welded to the bearing plates in 2002.

Holes at bridge bearings are slotted at each end. Bearings are in fair condition. Light to moderate corrosion is present due to the poor drainage of the bearing seat areas formed into the lock walls. See photographs 9 and 10.

Bridge Railings Span Range: 1 to 001 330 Metal Bridge Railing 116 2 93 23 0 0

Quantities are in linear feet. Steel handrail is in overall good condition. There are poor quality welds at the post connection brackets including pin holes, uneven weld profile, undercut, incomplete fusion, and overlap. Cyclone fencing has been installed on the handrail to reduce the maximum opening size to less than four inches in diameter. See photographs 1, 3, and 4.

Protective Coatings and Concrete Reinforcing Steel Protective Systems Span Range: 1 to 001 515 Steel Protective Coating 350 1 263 87 0 0

Quantities are in square feet. The steel protective coating appears to be in fair condition, with minor localized failures. See photographs: 7, 8, 10, 11, and 12.

Page 7 of 13Reports

Photograph 1: Downstream elevation view of bridge.

Photograph 2: Upstream elevation view of bridge.

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Photograph 3: West approach looking east.

Photograph 4: East approach looking west.

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Photograph 5: View of the upstream channel from mid span.

Photograph 6: View of the downstream channel from mid span.

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Photograph 7: General view of the upstream truss top of the bottom chord flange. Minor corrosion and localized paint failures are present.

Photograph 8: General view of the interior cross bracing between the trusses. Minor corrosion is present.

Page 11 of 13Reports

Photograph 9: General concrete condition of the lock wall under the bearings. Minor spalling and cracks with efflorescene is present.

Photograph 10: The moveable bearings appear to be in fair condition.

Page 12 of 13Reports

Photograph 11: General view of underneath the deck. The deck grating clips are not properly attached.

Photograph 12: Illustrates intersecting welds, a fatigue sensitive detail (FSD) within the truss bottom chord connection.

Page 13 of 13Reports