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CHAPTER 2
National Bridge Maintenance Database
The National Bridge Maintenance Database (NBMD) is a 1. Structure,
collection of self-contained sets of data on bridge inventory, 2. Operation,
conditions, and maintenance work. Each dataset is established 3. Dates,
for one state DOT and for a fixed reporting period, usually one 4. Resources, and
year. Data are collected from records of the U.S. NBI, from 5. Outcomes.
Pontis bridge databases of state DOTs, from DOT mainte-
nance management systems, from maintenance work report- The Structure. NBMD stores selected fields from NBI
ing systems and from contract reporting systems. NBMD offers records and Pontis bridge databases. These include NBI and
a uniform, consistent format and structure for data on bridge Pontis condition data together with data on structure type,
maintenance work, on the context of bridge maintenance work, route, milepost, custodian, structural size, age, construction
and on the outcomes of bridge maintenance work. materials, and administrative authority.
The NBMD data system is a set of standard data tables, stan-
dard headings for data fields, standard keywords for indexing The Operation. Maintenance work is identified using
fields, and standard methods for the creation of unique identi- NBMD standard keywords for components and operations.
fiers for bridges, bridge elements, maintenance actions and
maintenance resources. NBMD is instantiated as a set of plain The Dates. The date(s) of completion of the maintenance
text data files, and a set of XML documents each supported by event are recorded.
an XML schema.
Three concepts are applied to NBMD design. First, bridge The Resources. Resources include usage of labor, materi-
maintenance data are collected into self-contained datasets als, and equipment for DOT work, or pay items and quanti-
that bundle all related maintenance, condition, and inventory ties for contract maintenance. Specific repair products and
data. Second, data are presented in plain language keywords manufacturers can be stored. Resource data are used to com-
so that information is easily understood without recourse to pute total costs and unit costs for actions.
coding guides or lookup tables. Data headings, too, are pre-
sented in plain language. Third, NBMD datasets are stackable. The Outcomes. Outcomes include maintenance produc-
Unique IDs for bridges, elements, actions, and resources are tion and changes to conditions. Production may be expressed
established for each dataset and remain unique when datasets in units for the maintenance action and as the quantity of
are merged. Merging allows for aggregations of large num- bridge element that is improved. Conditions are new values of
bers of data records when data analysis and statistical evalua- bridge condition ratings achieved as a result of this mainte-
tions require it. nance event.
A Database for Bridge Maintenance Standard Data for Highway
NBMD is an archive of maintenance events. An event is the Bridge Maintenance
execution of one maintenance operation at one bridge at one Standard Bridge Components
time. Each record in the database is a single event, and each
record contains complete information on the work performed. NBMD uses 14 standard bridge components (Table 9). Five
The data include the following: components are named in the NBIS (Deck, Superstructure,
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Table 9. Standard bridge components.
Component Description
Approaches/ Approach slab and pavement, slopes, slope protection (other than channel
Embankments banks), embankments.
Bearings Bearing devices, both fixed and expansion.
All bridges on the state's list, also a catch-all component for maintenance work
Bridge
not reported under other components.
Channel Watercourse, flow restrictors/deflectors, banks, and bank protection.
Culvert All types and sizes of culverts maintained by structures maintenance program.
Deck The structural deck, wearing surface, waterproofing membrane, if any.
Drains Scuppers, grates, pipes, outlets, features for over-the-edge drainage.
All joints in the deck, all maintainable (sealable) joints in superstructure and
Joints
substructure components.
Mechanical Electrical or mechanical systems on bridges, includes all mechanical and electrical
/Electrical equipment for movable spans, all gates, lights and delineators for traffic.
Movable The operable parts and systems of a movable bridge. Includes deck and
span superstructure of movable span.
nonBridge Other structural assets.
All deck accessories for directing/restricting vehicles and pedestrians. All
Rails/Walks
sidewalks and medians.
Substructure Piers, abutments, and their foundations. Wing walls.
Superstructure Stringers, floorbeams, girders, truss members, arch members, etc.
Substructure, Channel, Culvert). Seven more components are Standard Maintenance Operations
used by many DOTs as objects of maintenance actions (Joints,
Drains, Railings, Bearings, Approaches, Movable Bridge, Elec- NBMD uses eight standard maintenance operations:
trical & Mechanical Systems). A twelfth component, Bridge, Clean, Reset, Coat, Repair, Replace, Modify, Emergency, and
is used when actions are applied to an entire structure, or a nonMaintenance (Table 10). Note that a Replace operation
specific component is not reported. The thirteenth compo- refers to the replacement of a part or portion of the bridge.
nent, nonBridge, is used for other assets. Complete replacement of a bridge is not maintenance. In a
Table 10. Standard maintenance operations.
Operation Description
Sweeping, washing, debris removal, graffiti removal, clearing scuppers, clean-out
Clean/clear
drain lines.
Renew consumable elements such as lights, removable joint seals; Tighten bolts or
Reset rods, Lubricate bearings or other moving parts; Minor re-alignment of railings,
repositioning of bearings.
All surface applications of paint, waterproofing, galvanic coatings, chemical
Coat
preservatives, crack sealing materials.
Repair Restoring damaged or deteriorated elements. Patching, welding, reinforcing, etc.
Replace In-kind replacement of damaged or deteriorated elements.
Repair or replacement actions that yield changes to elements. These may be
improvements to function as when drains are extended, changes in function as when
relief joints are installed in rigid pavements, changes to vulnerability as by seismic
Modify
retrofit, changes to strength by post-tensioning, jacketing, installation of scab plates,
changes to clearances as by re-positioning of bracing in truss portals, or installation
of a system for corrosion protection when none was present before.
All repairs, replacements, and modifications completed as an immediate response to
Emergency
a sudden condition or event.
nonMaintenance Operations, inspections.
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similar way, Modify operations include minor modifications, Improvements may include: greater clearances, greater resis-
and exclude larger projects such as bridge rehabilitation. tance to fatigue, greater safety for traffic, greater resistance to
Maintenance activities are generic methods for maintenance high water flow, etc. Modify operations may be in response to
operations. Activities are modifiers to operations, providing obsolete features, as when railings are upgraded, or in response
more specific reports of maintenance work. Each operation has to damage or deterioration.
its own set of activities. Actions are reported in a hierarchy of
fields such as the following:
Maintenance Activities
Component Operation Activity Mode Activities are descriptive keywords for NBMD bridge main-
tenance operations. Examples of Activities for maintenance
NBMD employs standard keywords for components and operations are presented in the following sections.
operations and allows descriptive keywords for activities and
modes. Actions must be reported by component, should be Activities for Clean/Clear Operations. The Clean/Clear
reported by operation, may be reported by activity, and might operation includes washing of structures, and removal of detri-
be reported by mode. This hierarchy admits both general tus, drift, and vegetation. Activities for Clean/Clear operations
are described in Table 11.
(component only) and detailed (all four descriptors) report-
ing of maintenance actions. Activities for Reset Operations. The Reset operation
provides expected maintenance for consumable parts or parts
Notes on Maintenance Operations needing periodic lubrication or adjustment. Activities for reset
operations are described in Table 12.
Reset versus Repair/Replace. The replacement of con-
sumable parts is a Reset operation. Parts such as light bulbs, Activities for Coat/Paint Operations. The Coat/Paint
fan belts, gaskets, and rubber joint elements are replaced as operation includes all application, maintenance and renewal
needed or on a set schedule. Repairs are made in response to of surface-applied sealers, paints and chemical treatments.
deterioration or damage and entail parts that are not con- Activities for Coat/Paint operations are described in Table 13.
sumable. The designation of these activities as Repair or
Replace correctly identifies the significance of the operation Activities for Repair Operations. The Repair operation
within the maintenance program, and correlates with costs restores original condition or functionality of bridge compo-
since consumable elements are designed for replacement and nents after deterioration or damage. Repair does not include
other parts might not be. substantial replacement of components and does not include
improvements to components beyond their original capacity
Modify versus Repair/Replace. Modify operations are or function. Activities for repair operations are described in
repairs or replacements that change (usually improve) bridges. Table 14.
Table 11. Activities for clean/clear operations.
Activity Description
Wash The use of water at moderate pressure to clean bridge components.
Washing of selected portions of components, usually those portions exposed to salt
Zone
water, salt spray, or standing water. These can include parapets facing traffic, gutters
Wash
in decks, and areas below open joints. Any selective washing of portions of structures.
Sweep Dry removal of sand, grit, or other minor detritus on bridge components.
The use of water at higher flow rate and/or pressure to clear more substantial size or
Flush
amounts of detritus on bridge components.
Unclog Maintenance of scuppers, troughs, pipes, and other drainage elements. Methods
and entail opening grates and cleanouts, removal of waste material, flushing as needed and
Cleanouts reassembly of parts.
Graffiti Removal or covering (masking) of unauthorized markings on bridges.
Trimming and/or removal of brush, trees, etc., on slopes, approach embankments,
Vegetation
channel banks and within channels.
Debris & Removal of (loose) material on substructures, at foundations, on channel banks and
Drift within channels. This activity does not include channel dredging.
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Table 12. Activities for reset operations.
Activity Description
Consumables Replacing light bulbs, rubber joint elements, pavement reflectors, etc.
Checking and tightening of bolts, anchors, rods and other threaded parts. Tighten also
Tighten
includes replacement of missing fasteners in otherwise complete connections.
Caulk Removal and replacement of caulk in railings, fixed joints and construction joints.
Inspection and lubrication of bearings, expansion joints, railing joints and other moving
Lubricate
or sliding parts.
Inspection and re-centering or re-alignment of bearings, joints, and other parts needing
Reposition
periodic adjustment.
Gates and
Inspection and servicing of traffic control systems, especially for movable bridges.
Signals
Inspection and servicing of mechanical parts of motion equipment for movable spans.
Mechanical
Mechanical Equipment includes consumables (filters, belts, etc), lubrication, and
Equipment
adjustment of machinery.
Inspection and servicing of electrical parts of motion equipment for movable spans.
Electrical
Electrical Equipment includes consumables (fuses, switches), and adjustment of
Equipment
equipment.
Table 13. Activities for coat/paint operations.
Activity Description
Paint Application of paint on bridge components, usually to an entire component.
Application of paint on selected areas of components that may include: areas of
Spot
deteriorated paint, areas of special exposure (splash zones), damaged areas (as by
Paint
collision), etc.
Seal Application of water-repelling or other surface treatments, usually to concrete or
Surface asphalt surfaces.
Use of epoxy, high-weight methyl-methacrylate or other pourable materials to fill
Seal
existing cracks. Usually applied to concrete surfaces, but can be crack sealing in
Cracks
asphalt surfaces and crack sealing in timber elements.
Chemical Surface application of preservatives for timber components. Surface application of
Treatments herbicides or pesticides on slopes as part of bridge maintenance.
Surface Preparation of surfaces for coating or painting if separate tracking of preparation cost
Preparation is desired. Otherwise, surface preparation is part of a coating or painting action.
Table 14. Activities for repair operations.
Activity Description
Repairs to concrete components, concrete surfaces, or asphalt surfaces by filling
Patch
with cementitious or bituminous material
Work to restore lost or weakened anchors for railings, joints, bearings, or other
Re-attach/ Re-anchor
components.
Straighten For metal components, the use of bending or heat to restore proper shape.
For pavements or substructures, the use of jacking and filling to mitigate tilting
Jack/Align
or settlement.
Application of welds, scab plates, concrete jackets, cables, post-tensioning, etc.,
Reinforce/Strengthen
to restore strength to weakened structural components.
Earth moving activities to repair shifted or scoured slopes and banks, or to re-
Dredge/Grade
establish channel depth and profile.
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Table 15. Activities for replace operations.
Activity Description
Replacement of an individual unit of a component made up of a collection of units,
Individual such as replacement of individual bearings, individual joints, individual beams,
individual piers.
Replacement of a portion of a continuous component, such as a bridge deck, that is not
Section
a collection of similar units.
Replacement of an entire component. Complete replacement of a collection of
Complete
elements. Complete replacement of a continuous component.
Span Complete replacement of a component within one span of a multispan bridge.
Activities for Replace Operations. The Replace operation Activities for Emergency Operations. Emergency activi-
provides in-kind replacement of bridge components in whole ties are performed in response to extreme events and/or sudden
or in part. Activities for Replace operations are described in damage to structures. Activities for Emergency operations are
Table 15. described in Table 17.
Activities for Modify Operations. The Modify operation
provides improvements to components. Improvements may Operations, Activities, and Bridge Components
mitigate observed problems in performance of components, Activities, more so than operations, may target specific com-
may reduce vulnerability of components, or may deliver com- ponents or construction materials. Frequent combinations of
pliance with higher or newer standards, especially where stan- activities with bridge components are discussed in this section.
dards can be met within a maintenance project rather than a
rehabilitation project. Activities for Modify operations are Clean/Clear Operations. Among the activities for Clean/
described in Table 16. Clear operations: Wash applies to structural elements, but not
Table 16. Activities for modify operations.
Activity Description
Modifications to clearances including internal clearances of thru-trusses and thru-
Geometry
arches.
Addition of protection system that is new to the component, including corrosion
Protection
protection, fenders, channel modifications.
Modifications that reduce vulnerability to fatigue, seismic loads, sudden fracture,
Vulnerability
etc.
Modifications that increase load rating of bridges, flood/flow capacity of channels,
Strength/Capacity
flow capacity of drains, motion capacity of expansion joints or bearings, etc.
Modifications that alter load paths or expansion regimes. These may be: helper
Function
bents, conversion to integral abutments, relief joints in approach pavements, etc.
Modifications that provide a newer device, such as a joint, bearing, or railing in
Assembly
place of an older, obsolete device.
Table 17. Activities for emergency operations.
Activity Description
Post Investigations and repairs leading to load restrictions on structures.
Installation of temporary supports for decks or superstructures. Construction of
Shore
"diapers" to catch loose materials.
Closure, Activities to exclude traffic from some portion of a structure, such as closures at
Partial weakened or blocked traffic lanes.
Closure, Full Complete closure of a structure.
Activities needed to establish alternate routes around restricted or closed
Detour
structures.
Temporary
Deployment and maintenance of temporary bridges.
Bridge
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Table 18. Clean/clear--frequent uses of activities.
Clean/Clear Bridge Components
Wash All except earth slopes and banks.
Zone wash All except earth slopes and banks.
Sweep Decks, Joints, Approach pavement, Substructures.
Flush All except earth slopes and banks.
Unclog /cleanouts Drains.
Graffiti Superstructure, Substructure, Parapets/Sidewalks, Culverts.
Vegetation /trees Earth slopes and banks.
Debris /Drift Substructures, Channels, Culverts.
earth slopes and banks; Sweep applies to horizontal surfaces, equipment for movable bridges, but not other equipment. A
but not vertical ones; Unclog applies to drains but not to open list of likely applications of reset activities with bridge com-
surfaces; Vegetation control applies to earth slopes and banks, ponents is shown in Table 19.
but not to structural components. A list of likely applications
of Clean/Clear activities to bridge components is shown in Coat/Paint Operations. Among the activities for Coat/
Table 18. Paint operations: Paint applies to structural components, but
not earth slopes and banks; Sealing applies to concrete and
Reset Operations. Among the activities for Reset opera- bituminous surfaces usually; Chemical Treatments apply to
tions: Consumables maintenance applies to light bulbs, rub- timber elements, and to control of vegetation. A list of likely
ber parts of joints, but not other bridge components; Tighten applications of coat/paint actions with bridge components is
applies to threaded parts; Caulk applies to fixed, closed joints shown in Table 20.
in components, but not other joints; Lubricate applies to
moving joints, bearings and rails, but not other parts; Gates/ Repair Operations. Among the activities for Repair oper-
Signals applies to traffic control on movable bridges, but not ations: Patch applies to concrete structural components and
other traffic control; Equipment maintenance applies to motion bituminous wearing surfaces; Re-attach applies to anchors for
Table 19. Reset--frequent uses of activities.
Reset Bridge Components
Consumables Bridge (lights), Joint seals.
Tighten All components having bolts or rods.
Caulk All except Embankment, Channel.
Lubricate Bearings, Railings (at joints).
Reposition Bearings, Railings, Channel (protection), Movable Span.
Gates and signals Movable span.
Mechanical equipment Movable span.
Electrical equipment Movable span.
Table 20. Coat/paint--frequent uses of activities.
Coat/Paint Bridge Components
Paint All except Embankments, Channels.
Spot paint All except Embankments, Channels.
Concrete or Bituminous elements of Deck, Wearing surface,
Seal surface Parapets/Railings/Sidewalks, Superstructure, Substructure, Embankment (protection),
Culvert, Movable Span.
Concrete or Bituminous elements of Deck, Wearing surface,
Seal cracks Parapets/Railings/Sidewalks, Superstructure, Substructure, Embankment (protection),
Culvert, Movable Span.
Chemical Preservatives for Timber Deck, Railings, Superstructure, Substructure, Culverts and
treatment Movable Spans. Herbicides/Pesticides for earth slopes and banks.
Surface
All structural components.
prep
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Table 21. Repair--frequent uses of activities.
Repair Bridge Components
All concrete or bituminous Deck/Wearing course, Parapets/Railings/Sidewalks,
Patch Superstructure, Substructure Approach/Embankment (protection), Channel
(protection), Culvert, Movable Span.
Deck (grate), Joints (armor), Joint (seal), Drains, Parapets/Railings/Sidewalks,
Re-attach/
Superstructure, Bearings, Substructure, Channel (protection), Culvert (metal),
re-anchor
Movable Span.
Parapets/Railings (metal), Superstructure (metal members), Substructure (metal
Straighten
elements), Culvert (metal), Movable Span.
Jack/Align Approach slabs (mudjack), Substructures, Culverts.
Reinforce/ Deck (structural), Parapets/Railings/Sidewalks, Superstructure, Substructure, Culvert,
Strengthen Movable Span.
Dredge/
Approach/Embankment, Channel.
Grade
joint, bearings, railings, etc.; Straighten applies to metal ele- Table 22. Replace--frequent
ments; Jack applies to components that have tilted or settled; uses of activities.
strengthen applies to structural components; Dredge/Grade
Replace Bridge Components
applies to earth slopes, banks, and channels. A list of likely
Individual Unit, all components.
applications of Repair activities with bridge components is Section All components
shown in Table 21. Complete All components
Span All components
Replace Operations. Among the activities for Replace
operations: Individual applies to items such as joints, bear-
ings, railing sections and beams where the component is a
collection of similar elements; Section applies to decks, wear- ponents; strength applies to increases in load rating for struc-
ing surfaces, and other components that are continuous; tural components, and increases in motion or flow capacity
Complete is full in-kind replacement of a component; span is for joints, drains, bearings and channels; Function applies to
complete replacement of a component in one span of a multi- changes in load path or movement regime; Assembly applies
span bridge. A list of likely applications of Replace activities to upgrades of joints, bearings, railings and other devices. A
with bridge components is shown in Table 22. list of the frequent uses of Modify activities with bridge com-
ponents is shown in Table 23.
Modify Operations. Among the activities for Modify
operations: Geometry applies to improvements to clearances; Emergency Operations. Among the activities for Emer-
protection applies to new protection of structural components gency operations, Post applies to structural components; Shore
against corrosion, or channels against scour; Vulnerability applies to any component needing additional support; Clo-
applies to the potential for sudden failure of structural com- sure applies to bridges and culverts; Detour applies to bridges
Table 23. Modify--frequent uses of activities.
Modify Bridge Components
Geometry Bridge, Superstructure, Parapets/Railings/Sidewalks, Culvert, Movable Span.
Bridge, Deck, Parapets/Railings/Sidewalks, Superstructure, Substructure,
Protection
Approach/Embankment, Culvert, Channel, Movable Span.
Bridge, Parapets/Railings/Sidewalks, Superstructure, Substructure, Culvert, Channel,
Vulnerability
Movable Span.
Strength/ Bridge, Deck, Parapets/Railings/Sidewalks, Superstructure, Substructure, Culvert,
capacity Movable Span.
Bridge, Deck, Joints, Drains, Parapets/Railings/Sidewalks, Superstructure, Bearings,
Function
Substructure, Movable Span.
Assembly Bridge, Parapets/Railings/Sidewalks, Movable Span.
