Pittsburgh bridge collapse 32

Is one trillion enough?

Here is the location:


This is not a small, forgotten bridge on a back road somewhere.

Bradley Wilder, P.E.
Construction P.E. (KY), MBA
Bridge Rehab, Coatings, Structural Repair

Name: FORBES AVENUE over 9 MILE RUN & FERN HOLLOW
Structure number: 000000000002410
Old structure number: 027301000030330 (from 1992 edition)
Location: 301033 NEAR S BRADDOCK AV

Latest Available Inspection: September 2017
Good/Fair/Poor Condition: Poor
Status: Posted for load [P]
Average daily traffic: 14,500 [as of 2005]
Truck traffic: 7% of total traffic
Deck condition: Fair [5 out of 9]
Superstructure condition: Poor [4 out of 9]
Substructure condition: Satisfactory [6 out of 9]
Structural appraisal: Meets minimum tolerable limits to be left in place as is [4]
Deck geometry appraisal: Basically intolerable requiring high priority of corrrective action [3]
Water adequacy appraisal: Superior to present desirable criteria [9]
Roadway alignment appraisal: Better than present minimum criteria [7]
Channel protection: There are no noticeable or noteworthy deficiencies which affect the condition of the channel. [9]
Scour condition: Bridge foundations (including piles) on dry land well above flood water elevations. [9]
Sufficiency rating: 18.7
Recommended work: Bridge rehabilitation because of general structure deterioration or inadequate strength. [35]
Estimated cost of work: $1,522,000

Bradley Wilder, P.E.
Construction P.E. (KY), MBA
Bridge Rehab, Coatings, Structural Repair

Hard to see on Google, but it looks like a rigid K-frame.



Bradley Wilder, P.E.
Construction P.E. (KY), MBA
Bridge Rehab, Coatings, Structural Repair

Condition rated as poor since 2011.

[/sarc] Nothing to see here. [/end sarc]

Gathering some data...

Story says there was an articulated city bus on the bridge and at least 4 vehicles.

There was at least some snow on the bridge.

As of the May 2019 street view photo, the bridge was posted at 26 TONS.

From Wikipedia, PAAC has New Flyer D60LFR buses, which have a 41,500-43,700 curb weight and New Flyer XD60 Xcelsiors which have a curb weight of 39,000-45,500 lb.



Bradley Wilder, P.E.
Construction P.E. (KY), MBA
Bridge Rehab, Coatings, Structural Repair

I grew up 5 or six miles from that bridge. I remember its predecessor, but I had to search to refresh my memory of the current structure, which agrees with the picture above.

Google street view shows it posted with a 26 ton weight limit.

Also, for what it's worth, from Wednesday night into yesterday morning it was awfully cold here. Minus 12 at 7:30 a.m. where I was.

Pic from December 2018 from Twitter @gpk320



Bradley Wilder, P.E.
Construction P.E. (KY), MBA
Bridge Rehab, Coatings, Structural Repair

It looks like they tried a band aid fix for that. But not a large enough band aid if that member goes into compression.

With a few inches of snow and the bus, that was well over the posted weight limit. Interesting to see how this might affect public transportation policy if our vehicles are too large for our aging infrastructure.

It looks like the east bent is missing the lower cross bracing compared to the west end. It's a bit blurry from the google street view but its still clearly missing. The resolution is too poor to see if the cables are still there. The images are from 2020, 2 years after the pic of the cables was posted.

bradw1128

Thanks for the inspection report, I was just watching a video of Mayor Ed Gainy (sp) speaking to reporters as he was given false information on that inspection date, he was told September of 2021. First he said he thought it was about 2 yrs ago.

- time stamp at around 15:00 in.

It's amazing timing that 3 days ago Biden planned this visit to Pittsburgh today.

There was a snow event on Jan 16-17 that put down about 7" in that area, but this morning's snow was an inch, or less.

Looks like maybe the city was considering repairs as of 2019:

From the 2019 capital budget

Page 172:
Legislative & Contractual Committments [OMB] Maintenance and Improvements to Forbes Ave Bridge $ 3,000,000.00 $ - 4

I can't tell if it was ever actually funded.


And from a draft STIP project page, a longer term replacement plan:

Page 45:

Allegheny Forbes Ave Bridge over Fern Hollow* $6,892,000 7301 Long‐Term (2033‐2045)
Bridge restoration/replacement on Forbes Avenue
Bridge over Fern Hollow in the City of Pittsburgh,
Allegheny County; Project sponsor is City of
Pittsburgh
Bridge Reconstruction 20192023

Bradley Wilder, P.E.
Construction P.E. (KY), MBA
Bridge Rehab, Coatings, Structural Repair

A more interesting question, "How much more of that stuff is out there?" I'm glad there were no fatalities.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

dik, as I drive around Ohio and surrounding states, I would have to say that it is extensive. The levels of corrosion and failing concrete is spooky. 90% of this issues in this area are a direct result of the application of de-icing materials, be it salt, calcium chloride, brine, etc. At some point, we need to wake up and stop the direct application of these chemicals to our bridge decks. Galvanizing and epoxy paint can only do so much. My state DOT uses and average of 600,000 tons of salt per year. This does not include all of the cities, counties, townships, etc. that also clear roads.

I was thinking of that condo unit in Florida that collapsed, killing nearly 100. I suspect a lot of the problem was poor design and lack of maintenance. Things will not get better without 'fixing' things.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

The link to inventory data above is outdated. I downloaded the 2021 inventory data below.

This represents the 2019 routine inspection and 2020 fracture critical and special inspection. All seemed to be on a September schedule. There likely was a +/- September 2021 inspection after this data was uploaded.

There were fracture critical and special inspections on a 12 month frequency.


STATE_CODE_001 PA
STRUCTURE_NUMBER_008 000000000002410
RECORD_TYPE_005A on
ROUTE_PREFIX_005B city street
SERVICE_LEVEL_005C mainline
ROUTE_NUMBER_005D n/a
DIRECTION_005E n/a
HIGHWAY_DISTRICT_002 11
COUNTY_CODE_003 Allegheny
PLACE_CODE_004 61000
FEATURES_DESC_006A
CRITICAL_FACILITY_006B
FACILITY_CARRIED_007 'FORBES AVENUE'
LOCATION_009 '301033 NEAR S BRADDOCK AV'
MIN_VERT_CLR_010 99.99
KILOPOINT_011 0
BASE_HWY_NETWORK_012 1
LRS_INV_ROUTE_013A
SUBROUTE_NO_013B
LAT_016 40262229
LONG_017 79540120
DETOUR_KILOS_019 5
TOLL_020
[highlight #FCE94F]MAINTENANCE_021 City or Municipal Highway Agency
OWNER_022 City or Municipal Highway Agency[/highlight]
FUNCTIONAL_CLASS_026 other principal arterial
YEAR_BUILT_027 1970
TRAFFIC_LANES_ON_028A 4
TRAFFIC_LANES_UND_028B 0
ADT_029 14500
YEAR_ADT_030 2005
DESIGN_LOAD_031 H 20
APPR_WIDTH_MT_032 15.2
MEDIAN_CODE_033 0
DEGREES_SKEW_034 0
STRUCTURE_FLARED_035 0
RAILINGS_036A 0
TRANSITIONS_036B 0
APPR_RAIL_036C 0
APPR_RAIL_END_036D 0
HISTORY_037 Bridge is not eligible for the National Register of Historic Places
NAVIGATION_038 0
NAV_VERT_CLR_MT_039 0
NAV_HORR_CLR_MT_040 0
OPEN_CLOSED_POSTED_041 posted for load
SERVICE_ON_042A highway-pedestrian
SERVICE_UND_042B waterway
STRUCTURE_KIND_043A steel continuous
STRUCTURE_TYPE_043B frame
APPR_KIND_044A n/a
APPR_TYPE_044B n/a
MAIN_UNIT_SPANS_045 3
APPR_SPANS_046 0
HORR_CLR_MT_047 15.2
MAX_SPAN_LEN_MT_048 50.6
STRUCTURE_LEN_MT_049 136.2
LEFT_CURB_MT_050A 2.1
RIGHT_CURB_MT_050B 2.1
ROADWAY_WIDTH_MT_051 15.2
DECK_WIDTH_MT_052 19.5
VERT_CLR_OVER_MT_053 99.99
VERT_CLR_UND_REF_054A N
VERT_CLR_UND_054B 0
LAT_UND_REF_055A N
LAT_UND_MT_055B 0
LEFT_LAT_UND_MT_056 0
DECK_COND_058 poor
[highlight #FCE94F]SUPERSTRUCTURE_COND_059 poor[/highlight]
SUBSTRUCTURE_COND_060 satisfactory
CHANNEL_COND_061 There are no noticeable or noteworthy deficiencies which affect the condition of the channel
CULVERT_COND_062 n/a
OPR_RATING_METH_063 load factor (LF)
[highlight #FCE94F]OPERATING_RATING_064 29.9 metric tons[/highlight]
INV_RATING_METH_065 load factor (LF)
[highlight #FCE94F]INVENTORY_RATING_066 17.2 metric tons[/highlight]
STRUCTURAL_EVAL_067 Meets minimum tolerable limits to be left in place as is
DECK_GEOMETRY_EVAL_068 Basically intolerable requiring high priority of corrective action
UNDCLRENCE_EVAL_069 n/a
POSTING_EVAL_070 10.0 - 19.9% below (relationship of operating rating to maximum legal load)
WATERWAY_EVAL_071 Superior to present desirable criteria
APPR_ROAD_EVAL_072 Meets minimum tolerable limits to be left in place as is
[highlight #FCE94F]WORK_PROPOSED_075A Bridge rehabilitation because of general structure deterioration or inadequate strength.[/highlight]
WORK_DONE_BY_075B Work to be done by owner's forces
IMP_LEN_MT_076 136
DATE_OF_INSPECT_090 Sep-19
INSPECT_FREQ_MONTHS_091 24
[highlight #FCE94F]FRACTURE_092A Yes - 12 months[/highlight]
UNDWATER_LOOK_SEE_092B N
[highlight #FCE94F]SPEC_INSPECT_092C Yes - 12 months[/highlight]
[highlight #FCE94F]FRACTURE_LAST_DATE_093A Sep-20[/highlight]
UNDWATER_LAST_DATE_093B
[highlight #FCE94F]SPEC_LAST_DATE_093C Sep-20[/highlight]
BRIDGE_IMP_COST_094 113,000
ROADWAY_IMP_COST_095 332,000
TOTAL_IMP_COST_096 1,522,000
YEAR_OF_IMP_097
OTHER_STATE_CODE_098A
OTHER_STATE_PCNT_098B 0
OTHR_STATE_STRUC_NO_099
STRAHNET_HIGHWAY_100 0
PARALLEL_STRUCTURE_101 N
TRAFFIC_DIRECTION_102 2
TEMP_STRUCTURE_103
HIGHWAY_SYSTEM_104 Inventory Route is on the NHS
FEDERAL_LANDS_105 n/a
YEAR_RECONSTRUCTED_106 0
DECK_STRUCTURE_TYPE_107 Concrete Cast-in-Place
SURFACE_TYPE_108A Bituminous
MEMBRANE_TYPE_108B none
DECK_PROTECTION_108C none
PERCENT_ADT_TRUCK_109 7
NATIONAL_NETWORK_110 The inventory route is not part of the national network for trucks
PIER_PROTECTION_111
BRIDGE_LEN_IND_112 yes
SCOUR_CRITICAL_113 Bridge foundations determined to be stable for calculated scour conditions; scour within limits of footing or piles
FUTURE_ADT_114 18000
YEAR_OF_FUTURE_ADT_115 2030
MIN_NAV_CLR_MT_116 0
FED_AGENCY N
SUBMITTED_BY 42
BRIDGE_CONDITION P
LOWEST_RATING 4
DECK_AREA 2655.9


Bradley Wilder, P.E.
Construction P.E. (KY), MBA
Bridge Rehab, Coatings, Structural Repair

While salt/chlorine is bad for bridges, I do think a part of the issue here is lack of maintenance over the year. Relatively speaking the bridge being 50 years old should not be in such a poor condition for so long (since 2011?). We use probably just as much salt here in Toronto and of all the road bridges I inspected past few year I do not recall seeing one with an entire bracing member corroded through.

Dik - I'd wager every major city in a snowy climate has at least 1 similar situation. when i lived in pittsburgh, there was an old (80 years old) concrete bridge i remember that had such bad spalling problems they ended up building a deck over the road below to catch the falling debris. they finally replaced the concrete bridge a few years back but that catch deck was up for 10 or 15 years.

In our small town in Maine the DOT has been trying to replace an 80 year old truss bridge since 2017 but has been stymied by court efforts from historic preservation groups that want it preserved and rehabbed rather than replaced. a beautiful bridge for sure, but the prolonged court proceedings has meant that neither replacement nor repairs have been made at all and the bridge was posted to 10 tons a couple months ago.


I'll be reconsidering my driving routes the rest of winter.