Townshend_Lake_Spillway_Bridge_Inspection_2016.pdf

ROUTINE INSPECTION REPORT

SPILLWAY BRIDGE

TOWNSHEND LAKE

CEPNEDVT5010002

TOWNSHEND, VT

OCTOBER 2016 NEW ENGLAND DISTRICT

TOWNSHEND LAKE

SPILLWAY BRIDGE

TOWNSHEND, VERMONT

FISCAL YEAR 2016

ROUTINE INSPECTION REPORT

DATE OF ROUTINE INSPECTION 24 August 2016

TEAM MEMBERS John Kedzierski, P.E., Team Leader Joe Gonglik P.E.

DATES OF PREVIOUS INSPECTIONS Routine Inspection, 6 Aug 14

Routine Inspection, 7 Aug 12 Routine Inspection, 10 Aug 10 Routine Inspection, 7 Aug 08

Routine Inspection, 22 Jun 06 Routine Inspection, 23 Jun 04 Routine Inspection, 28 Jun 02 Routine Inspection, 30 Jun 00 Routine Inspection, 27 Jun 98 Routine Inspection, 10 Sep 96

Routine Inspection, 22 Aug 94 Routine Inspection, 23 Aug 92 Routine Inspection, 24 Jul 90 Inventory Inspection, 18 May 84

BRIDGE DESCRIPTION AND HISTORY

The spillway bridge at Townshend, Vermont is a single span, steel deck-type Pratt truss constructed in 1961. The span length center to center of bearings is 160'-0". The roadway width is 12'-4" between steel curbs, with a 1'-6" wide safety walk on both sides.

On each side of the deck, there are 1'-0" wide by 10" high curbs. There are 3'-0" high steel guardrails on either side of the bridge. The deck consists of 5" deep open steel grating.

Supporting the deck is 12" deep rolled beams spaced transversely at 4'-0" on center.

The rolled beams span 13'-4" between the upper chords of the north and south trusses which are 20'-0" deep between centerlines of top and bottom chords. The upper and lower chords and the end diagonals are built-up members. The trusses consist of 8 panels, each 20'-0" long. All connections are high strength bolts.

The east approach consists of a 900 turn from Vermont Route 30, while the west approach is straight extending across the crest of the dam. The substructure consists of L-type reinforced concrete abutments founded on rock shelves on both sides of the spillway channel.

The approach slabs and guardrails were replaced in 2013. Various bolts at the horizontal gusset plate at L0 and L8 were also replaced and the bearings were painted with an active calcium sulfonate system.

The bridge is typically inspected using an underbridge inspection vehicle (Paxton- Mitchell Mark V Snooper).

This bridge is a fracture critical bridge and fracture critical members are the bottom chord, diagonals and verticals, main truss gusset plates, and floorbeams.

RATING (T = TONS)

Type Inventory Operating Comments

H 19T 26T

HS-20 34T 47T

3 29T 40T 3S2 48T 67T 3-3 46T 64T

The current load rating is consistent with existing conditions and no further evaluation is required at this time.

INSPECTION RECORD

ITEM # 72: APPROACH FEATURES

Rating Guidelines

CODE DESCRIPTION

8 Speed reduction is NOT required.

6 A VERY MINOR speed reduction is required.

3 A SUBSTANTIAL speed reduction is required.

Components Rating

Rating Component Remarks

3 1. Horizontal Alignment Alignment at east approach is a ninety degree angle with adjacent state route. West approach is good.

8 2. Vertical Alignment Alignment is good at both approaches (see Photos 1 and 2).

3 General Rating Condition (NBI Item #72)

ITEM # 72: APPROACH FEATURES (CONTINUED)

Approach Structural Rating Guidelines Code Description

N NOT APPLICABLE

9 EXCELLENT CONDITION

8 VERY GOOD CONDITION: No problems noted.

7 GOOD CONDITION: Some minor problems.

6 SATISFACTORY CONDITION: Structural elements show some minor deterioration.

5 FAIR CONDITION: All primary structural elements are sound but may have minor section loss, cracking, spalling or scour.

4 POOR CONDITION: Advanced section loss, deterioration, spalling or scour.

SERIOUS CONDITION: Loss of section, deterioration, spalling or scour has seriously affected primary structural components. Local failures are possible. Fatigue cracks in steel or shear cracks in concrete may be present.

CRITICAL CONDITION: Advanced deterioration of primary structural elements. Fatigue cracks in steel or shear cracks in concrete may be present or scour may have removed substructure support. Unless closely monitored it may be necessary to close the bridge until corrective action is taken.

IMMINENT FAILURE CONDITION: Major deterioration or section loss present in critical structural components or obvious vertical or horizontal movement affecting structure stability. Bridge is closed to traffic but corrective action may put back in light service.

0 FAILED CONDITION: Out of service – beyond corrective action.

Approach Structural Components Rating

N 1. Relief Joints

7 2. Approach:

a) Guardrail

West Appr.: New guardrails installed in 2013. North side guardrail at bridge end has minor collision damage – post intact (see Photo 3). There is no guardrail transition to the bridge on the west approach.

East Appr.: New guardrails installed in 2013. North side: ~16’ section of W-beam on north side and two posts out of vertical alignment (see Photo 5).

South side: ~3’ section of W-beam is scraped and 25’ section of guardrail is damaged. 2nd post from bridge is damaged. The guardrail transition attachment to the bridge is damaged on both sides (see Photo 4).

7 b) Pavement

West Appr.: Slab replaced in 2013. Transverse and longitudinal cracks (.015-.05” wide). See Photo 6 and West Approach Detail Figure. The west approach slab has isolated areas (<.25 sf each) that are unsound and will likely become popouts. There are more cracks than in 2014, but overall the slab is still sound.

East Appr.: Slab replaced in 2013. Transverse and longitudinal cracks (.015-.05” wide). See Photo 7 and East Approach Detail Figure. There are more cracks than in 2014, but overall the slab is still sound.

8 c) Embankment

N 3. Load Posting Sign

N 4. Hazard Markers

ITEM #36: TRAFFIC SAFETY FEATURES

CODE DESCRIPTION

1 Inspected feature MEETS currently acceptable standards.

0 Inspected feature DOES NOT currently meet acceptable standards or a safety feature is required and NONE

IS PROVIDED.

N NOT APPLICABLE

0 1. Bridge Rails Good condition.

0 2. Transition There is no transition from the west approach to the bridge rail. The guardrail connection to the bridge was replaced on both sides of the east approach in 2013.

1 3. Approach Rails Collision damage at both approaches.

1 4. End Treatments

ITEM #58, #59 & #60:

Code Description

N NOT APPLICABLE

9 EXCELLENT CONDITION

8 VERY GOOD CONDITION: No problems noted.

7 GOOD CONDITION: Some minor problems.

6 SATISFACTORY CONDITION: Structural elements show some minor deterioration.

5 FAIR CONDITION: All primary structural elements are sound but may have minor section loss, cracking, spalling or scour.

4 POOR CONDITION: Advanced section loss, deterioration, spalling or scour.

3 SERIOUS CONDITION: Loss of section, deterioration, spalling or scour has seriously affected primary structural components. Local failures are possible. Fatigue cracks in steel or shear cracks in concrete may be present.

CRITICAL CONDITION: Advanced deterioration of primary structural elements. Fatigue cracks in steel or shear cracks in concrete may be present or scour may have removed substructure support. Unless closely monitored it may be necessary to close the bridge until corrective action is taken.

IMMINENT FAILURE CONDITION: Major deterioration or section loss present in critical structural components or obvious vertical or horizontal movement affecting structure stability. Bridge is closed to traffic but corrective action may put back in light service.

0 FAILED CONDITION: Out of service – beyond corrective action.

ITEM #58: DECK FEATURES

N 1. Wearing Surface Integral with deck. See description below.

6 2. Deck Structural Condition

The open grating steel deck remains in overall good structural condition.

It was painted in 1999 and the paint has worn off throughout most of the deck, particularly in the tire traffic areas (see Photo 8). A close visual inspection of the grating revealed isolated bent bars mostly within 20’ of the west approach and other isolated areas (see Photo 9) and the following broken bars:

1 broken bar over 3rd flbm. from east 1 broken bar btwn. 5th and 6th flbm. from east 2 broken bars btwn. 2nd and 3rd flbm. from west

In addition, there is one broken bar about 7” from east end of bridge and another directly adjacent to the west end about 15” from the north side (see Photo 10).

All welds from grate to top of floor beams were intact.

7 3. Curbs Both north and south curbs have areas of scraped paint from traffic impacts (see Photo 6).

N 4. Median

7 5. Sidewalk (Safety Walks) Minor paint scraping from vehicles (see Photo 6).

N 6. Parapet

6 7. Railing The bridge railings are in fair condition (see Photo 6) with minor damage on the south top rail near the west end of the bridge (see Photo 8).

N 8. Utilities

5 9. Deck Joints

The east expansion dam plate is rusted and there is minor to moderate rusting of the grating/transverse beam interface. The underside of the plates are corroded with apparent minor section loss.

The west joint plate is loose and makes a loud banging noise when traffic goes over it. There is a cracked tack weld which has caused this.

6 10. Approach Settlement

The east approach pavement is about ½” to ¾” lower than the deck joint plate.

6 General Rating Condition (NBI Item # 58)

Deck Joint Measurements

@ Centerline 2010 2012 2014 2016 of Roadway @65o @75o @75o @60o

East Appr. 2 3/8” 2 ¼” 2-7/16” 2 ¼” West Appr. 1” 1 ¼” 1-1/16” 1”

ITEM # 59: SUPERSTRUCTURE FEATURES – TRUSSES

5 1. Bearing Devices

All bearings and the first 4 feet of the horizontal and diagonal members including gusset plates for each bearing have been painted in 2013 (see Photo 11). Isolated areas of the newly painted bearing have already failed and chipped and the paint is soft and easily scraped (see Photo 12).

East Brgs.: Typical at each bearing are that the nuts have section loss, the bolts are corroded, and many of the sole plate nuts and anchor bolts have severe corrosion. The south rocker bearing has remained tilted slightly inward (see Photo 13).

West Brgs.: The bearings at the west abutment are fixed and are in similar condition to the east abutment (see Photo 14). The southwest bearing has corroded nuts and the northwest bearing has 100% section loss on one nut attaching the bottom chord to the sole plate. The masonry grout pad at the north truss is spalled and there are two areas of loss of grout under the bearing. The holes are 4” deep under the bearings on both the north and south sides of the bearing (see Photos 15 and 16).

N 2. Floor System A. Stringers

6 B. Floor beams

Overall satisfactory condition. Previous minor section loss at top chord interface and surface rust, especially near both approach ends of the bridge (see Photo 17). There are areas of minor pack rust between the floorbeams and the top of the top chord member (see Photo 18).

7 C. Bracing Overall good condition. Surface rust throughout.

N 3. End Posts

6 4. Verticals Satisfactory condition. See Photos 21-24, Figure 1, Field Notes Sketch.

6 5. Diagonals Satisfactory condition. See Photos 21-24, Figure 1 Field Notes Sketch.

6 6. Chord A. Upper

Isolated areas of pack/crevice rust or minor deterioration or deformation (i.e., small dent, see Photo 12 of 2010 inspection – no change). Satisfactory condition. See Photo 19 & Figure 1, Field Notes Sketch.

6 B. Lower Isolated areas of pack/crevice rust or minor deterioration or deformation (i.e., small dent). See Photo 20 & Figure 1, Field Notes Sketch. Clearances between the top and bottom chords and the backwalls are typically between 9"-11".

7 7. Gusset Plates

All gusset plates were in good condition with no significant corrosion or deformations. The bolts at the panel point connections typically have surface rust and some have minor to severe corrosion, particularly those on the horizontal connection plates. The lower chord gusset plates over the bearings have been repainted; however some nuts have significant section loss. See Photos 25 and 26 & Figure 1, Field Notes Sketch.

8. Secondary members, connection plates

There were also isolated areas where the secondary members (batten plates, lacing bars) exhibited minor deformations (e.g., bent lacing bar on L8U7 of south truss) and section loss. These conditions have not changed since the last inspection. There is minor accumulation of debris on the upper chord connections to the sway bracing. See Photos 21-24.

5 9. Rivets or Bolts

All bolts and nuts appear to be intact. No loose or missing nuts or bolts were noted. In 1999, approximately 60 bolts and/or nuts were replaced. In 2013, 34 bolts were replaced at L8 and 40 bolts replaced at lower L0 just above the bearings. See Photos 21-24

N 10. Welds

4 11. Paint/Year Painted

Painted in 1999. There is scattered surface corrosion and areas of flaking paint throughout, especially on the floorbeams at the ends (see Photo 17).

Bearings painted in 2013. Used Watson Coatings – Armor Shield, but the coating is soft and easily scraped off (see Photo 12).

6 General Rating Condition (NBI ITEM # 59)

ITEM #60: SUBSTRUCTURE FEATURES

7 1. Abutments

a) Wings

The top of the northwest abutment was repaired at the same time as the approach slab repairs in 2013. No further deterioration has occurred.

7 b) Backwall The previously sealed cracks in the backwalls are in good condition (see Photos 27 and 28).

5 c) Bearing Seats There is minor debris and vegetation on both abutment bridge seats. The north fixed bearing masonry plate has spalling under the grout bed (see Photos 15 and 16).

N d) Breast Wall / Bulkhead

N e) Footing

N f) Piles

8 h) Scour / Erosion

8 i) Settlement

7 General Rating Condition (NBI Item # 60)

CONDITION RATING Routine, 2016 6 Routine, 2014 7 Routine, 2012 6 Routine, 2010 6 Routine, 2008 6 Routine, 2006 6 Routine, 2004 6 Routine, 2002 7 Routine, 2000 7 Routine, 1998 6 Routine, 1996 7 Routine, 1994 7 Routine, 1992 7 Routine, 1990 7 Routine, 1988 7 Inventory, 1984 7/8

CONCLUSIONS & RECOMMENDATIONS

This bridge is in satisfactory condition.

A. Status of Previous Recommendations

1. Engineering-Planning should prepare Plans and Specifications for the complete maintenance painting of the bridge. (Awaiting O&M funding, possibly in FY18).

2. Monitor the sealant applied to the hairline cracks in the newly repaired approach slabs. Notify Engineering of deteriorated conditions. (ONGOING).

B. Revised Recommendations

1. Engineering-Planning should prepare Plans and Specifications for the complete maintenance painting of the bridge.

Estimated Cost = $560,000 (incl. construction, design & S&A)

2. Reapply sealant applied to the cracks in the approach slabs. Estimated Cost = $5,000

3. Repair grout pads under fixed bearings. Estimated Cost = $5,000

4. Subsequent inspections should allow time to remove all vegetation and silt from around bearings.

5. Repair guardrails at east approach.

Estimated Cost = $75,000 (incl. construction, design & S&A)

PHOTOS & SKETCHES

Photo 1 – East approach.

Photo 2 – West approach.

Photo 3 – Minor damage guardrail west approach.

Photo 4 – Damaged guardrail east approach, south side.

Photo 5 – Minor damage of guardrail east approach, north side.

Photo 6 – Hairline cracking of west approach slab.

Photo 7 – Hairline cracking of east approach slab.

Photo 8 – Surface rust on entire open grating steel deck; scrapes along curbs and top dented rail (see circle).

Photo 9 – Typical bent or broken bars in open grating steel deck.

Photo 10 – Missing bars in open grating at west end of deck.

Photo 11 – View of painted members framing into the west fixed bearing.

Photo 12 – View of painted member and easily removed paint coating.

Photo 13 – South truss movable bearing.

Photo 14 – North truss fixed bearing.

Photo 15 – North truss fixed bearing hole in grout pad.

Photo 16 – North truss fixed bearing hole in grout pad.

Photo 17 – Floorbeam near east approach. Note advanced corrosion from road salts.

Photo 18 – Typical pack rust under floorbeams.

Photo 19 – Typical upper chord, north truss.

Photo 20 – Typical lower chord, south truss.

Photo 21 – Typical truss members, South truss.

Photo 22 – Typical truss members, South truss.

Photo 23 – Typical interior truss panel point, North truss.

Photo 24 – Typical lower chord splice plate, South truss.

Photo 25 – Typical gusset plate, South truss.

Photo 26 – Typical horizontal gusset plate at bearing with debris.

Photo 27 – East abutment backwall. Note sealed cracks towards the top.

Photo 28 – West abutment backwall. Note sealed cracks.

NORTH (UPSTREAM) ELEVATION

SOUTH (DOWNSTREAM) ELEVATION

L8 L7 L6 L5 L4 L3 L2 L1 L0

U8 U7 U6 U5 U4 U3 U2 U1 U0

EAST ABUT

EXPANSION

END

WEST ABUT

FIXED END

L0 L1 L2 L3 L4 L5 L6 L7 L8

U0 U1 U2 U3 U4 U5 U6 U7 U8

WEST ABUT

FIXED END

EAST ABUT

EXPANSION

END

GENERAL NOTES:

1. WORST CORROSION OF NUTS IS UNDER EACH FLOOR BEAM AT

UPPER CHORD; PACK RUST UNDER MOST FLOORBEAMS.

2. MINOR PACK RUST AT EACH UPPER PANEL POINT AT FLOOR BEAM

SUPPORT ANGLE.

1 BOLT 50% SL

1 BOLT 100% SL

DELAM & PACK RUST & 1

NUT WITH 1/3 SL UNDER

FLBM.; SPLICE PLATE

NO ISSUES

CREVICE RUST BTWN.

BOTTOM PLATE & CHORD

1 NUT 80% SL

1 NUT 100% SL

1 NUT > 50% SL &

PACK RUST AT

SWAY BRACE

DEFORMED HORIZ.

PLATE NEAR L7

SURFACE RUST SPLICE

PLATE

2” DIAM. X 3/4” CUT OUT

ON VERT. SEE PHOTO 8

FROM 2004 INSP.

REPAINTED BEARINGS & FIRST 4FT

OF DIAG., HORIZ., VERT., & CROSS

MEMBERS.

100% SL ON ONE NUT OF SOLE PLATE

BOTTOM CHORD WITH 25% SL AT

LOWER HORIZ. CONNECTION PLATE.

7 NUTS WITH 25% SL.

REPAINTED BEARINGS & FIRST

4FT OF DIAG., HORIZ., VERT., &

CROSS MEMBERS.

ANCHOR BOLT NUTS AND

RODS CORRODED; ~50% SL

REPAINTED BEARINGS & FIRST

4FT OF DIAG., HORIZ., VERT., &

CROSS MEMBERS.

ANCHOR BOLTS AND NUTS

CORRODED

REPAINTED BEARINGS & FIRST 4FT

OF DIAG., HORIZ., VERT., & CROSS

MEMBERS.

3 NUTS WITH 25-50% SL.

2 NUTS WITH 100% SL

OTHER NUTS HAVE HEAVY

CORROSION.

10% SL ON TOP PLATE

OF TOP CHORD

ONE NUT 50% SL AT

INTERIOR HORIZONTAL

GUSSET PLATE.

BENT LACING BAR

ONE NUT 50% SL

7 NUTS RUSTED

PACK RUST BETWEEN BOTTOM

PLATE AND CORSS BRACING. ONE

NUT SEVERE CORROSION ON

INTERIOR OF HORIZ. PLATE.

ONE NUT WITH 50% SL & SIGNIFICANT

PACK RUST ON INTERIOR LOWER

GUSSET PLATE. RUST BETWEEN

BOTTOM PLATE.

ONE BENT BAR 8FT

FROM U7

DENT ON BOTTOM

CHORD

ONE BENT

LACING BAR. SEE

PHOTO 7 2004

INSP.

WARPED WEB AT

BASE FOR 12”

LENGTH

ONE BENT LACING

BAR

VERT. MEMBER WEB IS

DEFORMED AT LOWER

6” OF MEMBER.

MINOR RUST ON TWO NUTS

SURFACE RUST ON

PLATES & BOLTS OF

LOWER LATERAL

BRACING GUSSETS.

MINOR RUST

BETWEEN CHANNELS

& BATTEN PLATE.

PACK RUST UNDER

FLBM.

RUSTED LACING

BARS ON UPPER

PART OF

MEMBER

SPLICE PLATE OK

SPLICE PLATE OK

SOUTH TRUSS - ALL SPLICE PLATES OK

INTERIOR GUSSET

PLATE SURF. RUST,

PEELING PAINT; MINOR

PACK RUST.