5.1-i

Table of Contents

Section 5 ..................................................................................................................................................

Inspection and 

Evaluation of Decks 

 5.1 Timber Decks......................................................................................... 5.1.1 

 

 5.1.1 Introduction............................................................................. 5.1.1 

 5.1.2 Design Characteristics............................................................. 5.1.1 

 Plank Decks ...................................................................... 5.1.1 

 Nailed Laminated Decks................................................... 5.1.2 

 Glued-laminated Deck Panels........................................... 5.1.2 

 Stressed-laminated Decks................................................. 5.1.3 

 Structural Composite Lumber Decks................................ 5.1.4 

 

 5.1.3 Wearing Surfaces.................................................................... 5.1.5 

 Timber............................................................................... 5.1.5 

 Bituminous........................................................................ 5.1.6 

 Concrete............................................................................ 5.1.6 

 

 5.1.4 Protective Systems .................................................................. 5.1.6 

 Water Repellents............................................................... 5.1.6 

 Preservatives..................................................................... 5.1.6 

 Fumigants ......................................................................... 5.1.7 

 Fire Retardants.................................................................. 5.1.7 

 Paint .................................................................................. 5.1.7 

 

 5.1.5 Overview of Common Defects ............................................... 5.1.7 

 5.1.6 Inspection Procedures and Locations...................................... 5.1.8 

 Procedures......................................................................... 5.1.8 

 Visual ......................................................................... 5.1.8 

 Physical ...................................................................... 5.1.8 

 Advanced Inspection Techniques............................... 5.1.8 

 Locations........................................................................... 5.1.9 

 Areas Exposed to Traffic................................................. 5.1.9 

 Bearing and Shear Areas................................................. 5.1.9 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1-ii

 Tension Areas............................................................. 5.1.9 

 Areas Exposed to Drainage ........................................ 5.1.9 

 Outside Edges of Deck............................................... 5.1.9 

 Connections................................................................ 5.1.9 

 Nail Laminated Areas................................................. 5.1.9 

 Prestressing Anchorages ............................................ 5.1.9 

 Fire Damage ............................................................... 5.1.9 

 

 5.1.7 Evaluation ............................................................................. 5.1.11 

 NBI Rating Guidelines.................................................... 5.1.11 

 Element Level Condition State Assessment ................... 5.1.11 
5.1.1

Section 5 

Inspection and Evaluation of Decks 

Topic 5.1 Timber Decks 

5.1.1 

Introduction Timber bridges make up approximately 7% of the bridges listed in the National 

Bridge Inventory (NBI). Furthermore, approximately 7% of the steel bridges, 

which are categorized as steel bridges in the NBI also have timber decks. Timber 

can be desirable for use as a bridge decking material because it is resistant to 

deicing agents, which typically harm concrete and steel, and it is a renewable 

source of material. Timber can also withstand relatively larger loads over a short 

period of time when compared to other bridge materials. Finally, timber is easy to 

fabricate in any weather condition and is lightweight. 

5.1.2 

Design 

Characteristics 

Timber decks are normally referred to as decking or timber flooring, and the term 

is generally limited to the roadway portion which receives vehicular loads. 

Timber decks are usually considered non-composite because of the inefficient 

shear transfer through the attachment devices between the deck and superstructure. 

The basic types of timber decks are: 

3⁄4 Plank decks 

3⁄4 Nailed laminated decks 

3⁄4 Glued-laminated deck panels 

3⁄4 Stressed-laminated decks 

3⁄4 Structural composite lumber decks 

Plank Decks Plank decks consist of timber planks laid transversely across the bridge (see Figure 

5.1.1). The planks are individually attached to the bridge beams using spikes or 

bolt clamps, depending on the beam material. It is common for plank decks to 

have 50 mm (2-inch) depth timbers nailed longitudinally on top of the planks to 

distribute load and retain the bituminous wearing surface. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.2 

Figure 5.1.1 Plank Deck 

Nailed Laminated Decks Nailed laminated decks consist of timber planks with the wide dimensions of the 

planks in the vertical position and laminated by through-nailing to the adjacent 

planks (see Figure 5.1.2). On timber beams, each lamination is toenailed to the 

beam. On steel beams, clamp bolts are used as required. In either case, laminates 

are generally perpendicular to the roadway centerline. 

Figure 5.1.2 Section of a Nailed Laminated Deck 

Glued-laminated Deck 

Panels 

Glulam is an engineered wood product in which pieces of sawn lumber are glued 

together with waterproof adhesives. Glued laminated deck panels come in sizes 

usually 1.2 m (4 feet) wide. The panels are laid transverse to the traffic and are 

attached to the superstructure. In some applications, the panels are interconnected 

with dowels. There are several techniques used to attach glued-laminated decks to 

the superstructure or a floor system, including nailing, bolting, reverse bolting, clip 

angles and bolts, and nailers (see Figure 5.1.3). 

The nailing method is generally not preferred due to the possibility of the nails 

being pried loose by the vehicle traffic. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.3 

Bolting the deck to the superstructure or floor system provides a greater resistance 

to uplift than nailing, but bolts may still be pried loose. 

Reverse bolting involves fastening the bolts to the underside of the deck on either 

side of the superstructure members, thereby preventing the lateral movement of the 

deck. This is a rare type of connection. 

Clip angles and bolts involve attaching clip angles to the beams or stringers and 

then using bolts to attach the clip angles to the deck. 

Nailers are planks that run along the top of steel superstructure flanges. This 

technique involves the bolting of the nailers to the flanges and nailing the timber 

planks to the nailers. This prevents the costly bolting of all planks to the steel 

superstructure. 

Figure 5.1.3 Glued-laminated Deck Panels 

Stressed-laminated 

Decks 

Stressed-laminated decks are constructed of sawn lumber glulam wood posttensioned transversely utilizing high strength steel bars. Stressed timber decks 

consist of thick, laminated timber planks which usually run longitudinally in the 

direction of the bridge span. The timber planks vary in length and size. The 

laminations are squeezed together by prestressing (post-tensioning) high strength 

steel bars, spaced approximately 600 mm (24 inches) on center. With a hydraulic 

jacking system tensioning the bars, they are passed through predrilled holes in the 

laminations. Steel channel bulkheads or anchorage plates are then used to anchor 

the prestressing bars. This prestressing operation creates friction connections 

between the laminations, thereby enabling the laminated planks to span longer 

distances (see Figure 5.1.4). 

Prestressed laminated decks are used on a variety of bridge superstructures, such 

as trusses and multi-beam bridges, and they can be used as the superstructure itself 

for shorter span bridges. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.4 

Figure 5.1.4 Stressed-laminated Deck 

Structural Composite 

Lumber Decks 

Structural composite lumber (SCL) decks include laminated veneer lumber (LVL) 

and parallel strand lumber (PSL). Laminated veneer lumber is fabricated by 

gluing together thin sheets of rotary-peeled wood veneer with a waterproof 

adhesive. Parallel strand lumber is fabricated by taking narrow strips of veneer 

and compressing and gluing them together with the wood grain parallel. SCL 

bridge decks are gaining popularity and are comprised of a parallel series of fully 

laminated LVL or PSL T-beams or a parallel series of fully laminated LVL or PSL 

box beams. The T-beams and box sections run parallel with the direction of traffic 

and are cambered to meet the needs of the specific bridge site. The box sections or 

T-beams are stress laminated together by either placing steel bars or prestressing 

strands through the top flanges (timber deck area) and/or through the outside edges 

of the box section top flanges. Steel channels or bearing plates are then placed on 

the bars or strands with double nuts. Standard strand chucks are placed on the 

opposite end to initiate the prestressing process. The prestressing bars or strands 

are generally epoxy coated to resist corrosion (see Figure 5.1.5). 

Structural composite lumber decks are capable of full preservative penetration, and 

asphalt overlays are typical. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.5 

Figure 5.1.5 Structural Composite Lumber Deck Using Box Sections 

5.1.3 

Wearing Surfaces The wearing surface of a timber deck is constructed of timber, bituminous 

materials, or concrete. Timber wearing surfaces usually run parallel with traffic 

and are used with transverse plank decks. Bituminous wearing surfaces can either 

be hot mix asphalt or a chip and seal method. Concrete wearing surfaces for 

timber decks are less common than timber or bituminous wearing surfaces, 

although some exist. 

Timber A timber wearing surface may consist of longitudinal timbers placed over the 

transverse decking. Runner planks or "running boards" are planks placed 

longitudinally only in the wheel paths where the vehicles ride (see 

Figure 5.1. 6). 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.6 

Figure 5.1.6 Timber Wearing Surface on a Timber Deck 

Bituminous Bituminous or asphalt wearing surfaces generally utilize a coarse aggregate mix. 

The aggregate is mixed with a binder substance that holds the aggregate together 

and bonds the surfacing to the deck. Asphalt is a popular bituminous wearing 

surface for timber decks. However, it is not commonly used on plank decks 

because deflection of the planks will cause the asphalt to break apart. 

Concrete While concrete may be used as a wearing surface on timber decks, it is not 

frequently used for this purpose. However, new composite studies between 

concrete overlays and timber decks are being performed. These studies generally 

involve a timber deck with steel shear studs doweled into the timber deck with a 

concrete overlay completing the composite action. 

5.1.4 

Protective Systems Protective systems are necessary to resist decay in timber bridge decks. Water 

repellents, preservatives, fumigants, fire retardants, and paints are some of the 

common timber protective materials. In order for the protective material to serve 

its purpose, the surface of the timber must be properly prepared. 

Water Repellents Water repellents help to prevent water absorption in timber decks, which slows 

decay by molds and weathering. The amount of water in wood directly affects the 

amount of expansion and contraction due to temperature. Water repellents are 

used to lower the water content of timber deck members and must be reapplied 

periodically. Because it needs to be applied rather frequently, it is not the best 

means of protecting timber structures. 

Preservatives Timber preservatives are usually applied by pressure, which forces the 

preservative into the timber deck member. The deeper the preservative 

penetration, the greater the protection from decay by fungi. Preservatives are the 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.7 

best way to protect against decay. 

Preservatives are either oil-based or water-based. Some common oil-based 

preservatives are coal-tar creosote and pentachlorophenol. Chromated copper 

arsenate (CCA) is a very common water-based preservative. 

Fumigants Fumigants are applied to timber members in a liquid form through drilled holes. 

Once in the hole, the hole is plugged and the fumigant volatilizes and moves 

through the member as a gas, thus preserving the internal heartwood. Two 

common types of fumigants are chloropicrin and metham. These two fumigants 

are very hazardous and should only be applied by a professional. Also, the 

locations in which these fumigants can be applied are limited. 

Fire Retardants Fire retardants slow the spread of fire and prolong the time required to ignite the 

wood. The two main types of fire retardants are pressure impregnated salts and 

intumescent paints. These retardants insulate the wood, but adversely affect the 

material properties of wood. 

Paint Paints for timber decks can either be oil-based, oil-alkyd or latex-based. Oil-based 

paints provide the best barrier from moisture but is not very durable. Oil-alkyd 

paints have more durability than oil-based paints but contain lead pigments which 

cause various health hazards. Latex-based paints, on the other hand, are very 

flexible and resistant to chemicals. 

5.1.5 

Overview of 

Common Defects 

A prepared bridge inspector should know what to look for prior to the inspection. 

The following is a list of common defects that may be encountered when 

inspecting timber bridge decks. Refer to Topic 2.1 for a detailed description of 

these common defects: 

3⁄4 Fungus decay 

3⁄4 Damage by parasites 

3⁄4 Deflection 

3⁄4 Checks 

3⁄4 Splits 

3⁄4 Shakes 

3⁄4 Loose connections 

3⁄4 Surface depressions 

3⁄4 Chemical attack 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.8 

5.1.6 

Inspection 

Procedures and 

Locations 

Procedures Visual 

The inspection of timber decks for deterioration and decay is primarily a visual 

activity. All surfaces of the deck planks should receive a close visual inspection. 

Physical 

However, physical examinations must also be used for suspect areas. The most 

common physical inspection techniques for timber include sounding, probing, 

drilling, core sampling, and electrical testing. An inspection hammer should be 

used initially to evaluate the subsurface condition of the planks and the tightness of 

the fasteners. In suspect areas, probing can be used to reveal decayed planks using 

a pick test or penetration test (see Figure 5.1.7). A pick test involves lifting a small 

sliver of wood with a pick or pocketknife and observing whether or not it splinters 

or breaks abruptly. Sound wood splinters, while decayed wood breaks abruptly. 

Figure 5.1.7 Inspector Probing Timber with a Pick at Reflective Cracks in the 

Asphalt Wearing Surface 

 Advanced Inspection Techniques 

Several advanced techniques are available for timber inspection. Nondestructive 

methods, described in Topic 13.1.2, include: 

3⁄4 Pol-Tek 

3⁄4 Spectral analysis 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.9 

3⁄4 Ultrasonic testing 

3⁄4 Vibration 

Other methods, described in Topic 13.1.3, include: 

3⁄4 Boring or drilling 

3⁄4 Moisture content 

3⁄4 Probing 

3⁄4 Shigometer

If the deck planks are over 50 mm (2 inches) thick, suspect planks should be 

drilled to determine the extent of decay. If decks are drilled, a protectant should be 

applied and the hole should be plugged with a wooden dowel.

Locations Timber deck inspection generally includes visually interpreting the degree of 

decay on the top and, if visible, the bottom and sides of the deck. Also, all visible 

fastening devices and bearing areas should be inspected. In all instances, it is 

helpful if the inspector has the previous inspection report so that the progression of 

any deterioration can be noted. This provides a more meaningful inspection. 

The primary locations for timber deck inspection include: 

3⁄4 Areas exposed to traffic – examine for wear, weathering, and impact 

damage (see Figure 5.1.8) 

3⁄4 Bearing and shear areas where the timber deck contacts the supporting 

superstructure – inspect for crushing, decay, and fastener deficiencies (see 

Figure 5.1.9) 

3⁄4 Tension areas between the support points – investigate for flexure 

damage, such as splitting, sagging, and cracks 

3⁄4 Areas exposed to drainage – check for decay, particularly in areas 

exposed to drainage (see Figure 5.1.10) 

3⁄4 Outside edges of deck – inspect for decay 

3⁄4 Connections – note any looseness that may have developed from 

inadequate nailing or bolting, or where the spikes have worked loose. 

Observation under passing traffic will reveal looseness or excessive 

deflection in the members 

3⁄4 Nailed laminated areas – swelling and shrinking from wetting and drying 

cause a gradual loosening of the nails, displacing the laminations; this 

permits moisture to penetrate the deck and superstructure, eventually 

leading to decay and deterioration of the deck. Check for loose, corroded 

or damaged nails 

3⁄4 Prestressing anchorages – check for tightness, corrosion, crushing, and 

decay 

3⁄4 Fire damage – check for any section loss or member damage caused by 

fire
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.10 

Figure 5.1.8 Wear and Weathering on a Timber Deck 

Figure 5.1.9 Bearing and Shear Area on a Timber Deck 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.11 

Figure 5.1.10 Edge of Deck Exposed to Drainage, Resulting in Plant Growth

5.1.7 

Evaluation State and federal rating guideline systems have been developed to aid in the 

inspection of all bridge members, including timber decks. The two major rating 

guideline systems currently in use are the FHWA's Recording and Coding Guide 

for the Structural Inventory and Appraisal of the Nation's Bridges used for the 

National Bridge Inventory (NBI) component rating method and the AASHTO 

Guide for Commonly Recognized (CoRe) Structural Elements used for element 

level condition state assessment. 

NBI Rating Guidelines Using NBI rating guidelines, a 1-digit code on the Federal Structure Inventory and

Appraisal (SI&A) sheet indicates the condition of the deck. Rating codes range 

from 9 to 0, where 9 is the best rating possible. See Topic 4.2 (Item 58) for 

additional details about the NBI rating guidelines. The previous inspection data 

should be used along with current inspection findings to determine the correct 

rating. 

Element Level Condition 

State Assessment 

In an element level condition state assessment of a timber deck, the AASHTO 

CoRe element is one of the following, depending on the riding surface: 

Core Element No. Description

031 Timber Deck 

032 Timber Deck – with AC Overlay 

054 Timber Slab 

055 Timber Slab – with AC Overlay 

The unit quantity for these elements is “each”, and the entire element must be 

placed in one of the four available condition states based on the condition of the 

deck. Condition state 1 is the best possible rating. Some states have elected to use 

the total area (m2 or ft2). When a total area is used, the total area must be assigned 

to one of the four available condition states depending on the extent and severity 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.1: Timber Decks 

5.1.12 

of deterioration. See the AASHTO Guide for Commonly Recognized (CoRe) 

Structural Elements for condition state descriptions. 

For the purposes of this manual, a deck is supported by a superstructure and a slab 

is supported by substructure units. 
5.2-i

Table of Contents

Section 5 ..................................................................................................................................................

Inspection and 

Evaluation of Decks 

 5.2 Concrete Decks ...................................................................................... 5.2.1 

 5.2.1 Introduction............................................................................... 5.2.1 

 5.2.2 Design Characteristics............................................................... 5.2.1 

 Reinforced Cast-in-Place ................................................... 5.2.1 

 Precast ................................................................................ 5.2.2 

 Precast Prestressed.............................................................. 5.2.2 

 Precast Prestressed Deck Panels with 

 Cast-in-Place Topping........................................................ 5.2.2 

 Fiber Reinforced Polymer .................................................. 5.2.3 

 Fiber Reinforced Concrete ................................................. 5.2.4 

 Composite Action............................................................... 5.2.5 

 Non-Composite Action....................................................... 5.2.5 

 Steel Reinforcement ........................................................... 5.2.6 

 

 5.2.3 Wearing Surfaces ..................................................................... 5.2.8 

 Concrete.............................................................................. 5.2.8 

 Asphalt................................................................................ 5.2.9 

 5.2.4 Protective Systems .................................................................... 5.2.9 

 Sealants............................................................................... 5.2.9 

 Epoxy Coated Reinforcement Bars .................................. 5.2.10 

 Galvanized Reinforcement Bars....................................... 5.2.10 

 Stainless Steel Reinforcement Bars.................................. 5.2.10 

 Fiberglass Reinforcement Bars......................................... 5.2.10 

 Cathodic Protection of Reinforcement Bars..................... 5.2.10 

 Waterproofing Membrane ................................................ 5.2.11 

 5.2.5 Overview of Common Defects ............................................... 5.2.11 

5.2.6 Inspection Procedures and Locations...................................... 5.2.12 

 Procedures ........................................................................ 5.2.12 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2-ii

 Visual......................................................................... 5.2.12 

 Physical...................................................................... 5.2.12 

 Advanced Inspection Techniques .............................. 5.2.13 

 Locations .......................................................................... 5.2.14 

 Areas Exposed to Traffic ........................................... 5.2.14 

 Areas Exposed to Drainage....................................... 5.2. 14 

 Bearing and Shear Areas............................................ 5.2.14 

 Shear Key Joints ........................................................ 5.2.14 

 Anchorage Zones ....................................................... 5.2.14 

 Top of the Deck ......................................................... 5.2.14 

 Bottom of the Deck.................................................... 5.2.14 

 Asphalt Overlays........................................................ 5.2.14 

 Stay-in-Place (SIP) Forms ......................................... 5.2.14 

 Cathodic Protection.................................................... 5.2.14 

 

 5.2.7 Evaluation ............................................................................... 5.2.16 

 NBI Rating Guidelines ..................................................... 5.2.16 

Element Level Condition State Assessment..................... 5.2.16 

 
5.2.1

Topic 5.2 Concrete Decks 

5.2.1 

Introduction The most common bridge deck material is concrete. The physical properties of 

concrete permit placing in various shapes and sizes, providing the bridge designer 

and the bridge builder with a variety of construction methods. This topic discusses 

various aspects of concrete bridge decks and related bridge inspection issues. 

5.2.2 

Design

Characteristics

The role of a concrete bridge deck is to provide a smooth riding surface for 

motorists, divert runoff water, distribute traffic and deck weight loads to the 

superstructure, and act compositely or non-compositely with the superstructure. 

Increased research and technology are providing the bridge deck designer with a 

variety of concrete mix designs, from lightweight concrete to fiber reinforced 

concrete to high performance concrete, as well as different reinforcement options, 

to help concrete bridge decks better perform their role. 

There are four common types of concrete decks: 

3⁄4 Reinforced cast-in-place (CIP) 

3⁄4 Precast 

3⁄4 Precast prestressed 

3⁄4 Precast prestressed deck panels with CIP topping 

Reinforced Cast-in-Place Concrete decks that are cast in place on the bridge are referred to as “cast-inplace” (CIP). Forms are used to contain reinforcing bars and wet concrete so that 

after curing, the deck components will be in the correct position and shape. “Bar 

chairs” are used to support reinforcement in the proper location during 

construction. There are two types of forms used when placing cast-in-place 

concrete: removable and stay-in-place. 

Removable forms are usually wood planking or plywood but can also be fiberglass 

reinforced plastic. These forms are taken away from the deck after the concrete has 

cured. 

Stay-in-place (SIP) forms are corrugated metal sheets permanently installed 

between the supporting superstructure members. After the concrete has cured, 

these forms, as the name indicates, remain in place as permanent, nonworking 

members of the bridge (see Figure 5.2.1). 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.2

Figure 5.2.1 Stay-in-Place Forms 

Precast Precast deck panels are reinforced concrete panels that are cast and cured 

somewhere other than on the bridge. Precast decks are typically reinforced with 

conventional mild reinforcement. The deck panels are transported to the bridge 

site, then placed on the bridge, leveled, and attached to the superstructure/floor 

system. Proper deck elevations are generally accomplished using leveling bolts 

and a grouting system. 

The precast deck panels fit together using match cast keyed construction. After 

leveling, precast deck panels are attached to the superstructure/floor system. 

Mechanical clips can be used to connect the deck panels to the superstructure. An 

alternate method involves leaving block-out holes in the precast panels as an 

opening for shear connectors. The deck panels are positioned over the shear 

connectors, and the block-out holes are then filled with concrete or grout. 

Precast Prestressed Precast prestressed decks are also reinforced concrete decks cast and cured away 

from the bridge site. However, they are reinforced with prestressing steel in 

addition to some mild reinforcement. The prestressing tendons or bars are 

tensioned prior to placing the deck (pretensioned) or after the deck is cured (posttensioned). The tendons are held in position until the deck has sufficiently cured. 

This creates compressive forces in the deck, which reduce the amount of tension 

cracking in the cured concrete. 

Precast Prestressed Deck 

Panels with Cast-in-Place 

Topping 

Precast prestressed deck panels can also be used in conjunction with a cast-inplace concrete overlay. Partial depth reinforced precast panels are placed across 

the beams or stringers and act as forms (see Figure 5.2.2). A cast-in-place layer, 

which may be reinforced, is then placed which engages both the supporting

superstructure members and the precast deck units. After the cast-in-place layer 

has cured, composite action is achieved with the shear connectors and 

superstructure. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.3

Figure 5.2.2 Precast Deck Panels (with Lifting Lugs Evident and Top Beam 

Flange Exposed) 

In addition to the four common concrete decks, there are two new types of decks 

that may become more common in the future: 

3⁄4 Fiber reinforced polymer (FRP) 

3⁄4 Fiber reinforced concrete (FRC) 

Fiber Reinforced 

Polymer 

New and innovative research is being performed in the area of fiber reinforced 

polymer (FRP) bridge decks. Most of the FRP composite deck systems use glass 

reinforcing fibers set in a polyester or vinyl ester resin matrix. The two most 

common FRP deck systems use prefabricated panels comprised of pultruded tubes 

that are glued together with adhesive and honeycomb or sandwich core systems 

that are hand-laid up or utilize vacuum assisted resin transfer molding techniques. 

These deck systems are factory built to the specified deck panel dimension and are 

then shipped to the erection site. Once at the site, the individual deck panels are 

bonded together with high performance adhesives. If beams support this type of 

deck system, a grouted haunch or fillet is required to take into account the 

imperfections of the beams. Composite action can be developed with FRP deck 

systems by cutting pockets in the deck to access welded shear studs on the beams 

and then grouting the pockets. The effectiveness of composite action in FRP deck 

systems is still being researched. 

FRP decks require an overlay due to the low skid resistance of the materials. 

Latex concrete, micro-silica concrete, or dense concrete are not very compatible 

with FRP deck systems in the areas of stiffness, tensile strength, or compressive 

strength. Thin epoxy or polymer modified concrete overlays are better suited for 

use with FRP deck systems. Hot asphalt has been used as an overlay and has 

worked well over several years on some decks. 

An 200 mm (8 inch) deep FRP deck weighs only 98 kg/m2 (20 pounds per square 

foot (puff)) compared to 488 kg/m2

 (100 (puff)) for a conventional 200 mm (8 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.4

inch) concrete bridge deck (see Figure 5.2.3). 

Figure 5.2.3 Fiber Reinforced Polymer (FRP) Deck 

Fiber Reinforced 

Concrete 

Another new bridge deck material is fiber reinforced concrete (FRC). This type of 

bridge deck uses common Portland cement concrete mixes with 0.2 to 0.8 percent 

fiber by volume (see Figure 5.2.4). The most common type of fiber reinforcement 

is polypropylene. The purpose of the fiber is to minimize shrinkage cracking of 

fresh concrete and increase the impact strength of cured concrete. 

Figure 5.2.4 Fiber Reinforced Concrete (FRC) 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.5

An FRC bridge deck can either be reinforced with conventional rebar or have no 

conventional steel reinforcement included in the deck. Initial research testing the 

ability of polypropylene fibers to block the corrosion of steel reinforcement in 

concrete bridge decks proved that the fibers did not significantly retard the 

corrosion process. Therefore, some FRC bridge decks have been designed and 

constructed without steel reinforcement. FRC decks without steel reinforcement 

have transverse steel straps welded to the top flange of steel girders and are made 

composite with the superstructure via shear studs welded to the top flange (see 

Figure 5.2.5). The steel straps run the entire width of the deck and provide lateral 

restraint of the supporting girders. Since no steel reinforcement is included in the 

deck itself, the deck does not deteriorate due to steel reinforcement corrosion. 

Therefore, steel-free bridge decks give designers a viable alternative in areas 

where deicing salts are used. 

Figure 5.2.5 Fiber Reinforced Concrete (FRC) Bridge Deck Cross-Section 

Composite Action A concrete deck is generally required when composite action is desired in the 

superstructure (refer to Topic P.2.10). Composite action is defined as dissimilar 

materials joined together so they behave as one structural unit. A composite 

bridge deck structure is one in which the deck acts together structurally with the 

beams to resist the applied loads. An example of composite action is a cast-inplace concrete deck joined to steel or prestressed concrete beams or a steel floor 

system using shear connectors (see Figures 5.2.6 and 5.2.7). A precast deck can 

also develop composite action through grout pockets, which engage shear 

connectors. Some examples of shear connectors are studs, spirals, channels, or 

stirrups. Shear connectors are generally welded to steel beams. In concrete beams, 

shear connectors are simply extended portions of shear stirrups which protrude 

beyond the top of the beam. Composite action does not occur until the CIP deck is 

placed and cured or the precast deck grout pockets have been filled and cured. 

 

Non-Composite Action A non-composite concrete deck is not mechanically attached to the superstructure 

and does not contribute to the capacity of the superstructure. A non-composite 

concrete deck only carries vehicular loads. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.6

Figure 5.2.6 Shear Connectors Welded to the Top Flange of a Steel Girder 

Figure 5.2.7 Prestressed Concrete Beams with Shear Connectors Protruding 

Steel Reinforcement Because concrete has relatively little tensile strength, steel reinforcement is used to 

resist the tensile stresses in the deck. When reinforcement was first used for 

bridge decks, it was either round or square steel rods with a smooth finish and had 

a tendency to debond with the surrounding concrete when a tension force was 

applied. Today, the most common reinforcement is steel deformed reinforcing 

bars, commonly referred to as "rebars." These bars are basically round in cross 

section with lugs or deformations rolled into the surface to create a mechanical 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.7

bond between the reinforcement and the concrete. Lap splices and bar 

development are dependent on that mechanical bond. A lap splice is the amount of 

overlap that is needed between two rebars to successfully have the two bars act as 

one. A typical lap splice length is approximately 30 bar diameters. Mechanical 

end anchorages or lock devices can also be used to splice rebar. Bar development 

is the length of embedded rebar needed to develop the design stress and varies 

based on material properties and bar diameter. For large bars, this length is 

significant. When space is limited, a mechanical hook (90° or 180° bend) is 

placed at the end of a bar to achieve full development. 

Although concrete decks could not function efficiently without reinforcement, the 

corrosion of the reinforcing steel is the primary cause of deck deterioration. Since 

about 1970, epoxy coatings have been a common method of protecting steel rebars 

against corrosion. Less common methods of protection include galvanizing and 

use of stainless steel. 

Primary reinforcement carries the tensile stress in a concrete deck and is located on 

both the top and bottom of the deck. Secondary reinforcement is temperature and 

shrinkage steel and is placed perpendicular to the primary reinforcement. 

Additional longitudinal deck reinforcement is generally placed over piers to help 

resist the negative moments in the composite superstructure. 

The inspector must be able to identify the direction of the primary reinforcement to 

properly evaluate any cracks in the deck. Primary reinforcement is placed 

perpendicular to the deck's support points. For example, the support points on a 

multi-beam bridge and a stringer type floor system are parallel with the direction 

of traffic. Therefore, the primary deck reinforcement on these deck types is 

perpendicular to the direction of traffic (see Figure 5.2.8). The support points on a 

floorbeam-only type floor system are perpendicular with the traffic flow, and the 

primary deck reinforcement is therefore parallel with the traffic flow. In all cases, 

the primary reinforcement is closer to the top and bottom concrete surface. 

Figure 5.2.8 Spall Showing Deck Reinforcing Steel Perpendicular to Traffic 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.8

Primary reinforcement is generally a larger bar size than temperature and 

shrinkage steel. However, to improve design and construction efficiencies, 

concrete decks may be reinforced with the same size bar in both the top and 

bottom rebar mats. Reinforcement cover is generally 50 to 64 mm (2 to 2-1/2 

inches) minimum for cast-in-place decks without a wearing surface, and 25 mm (1 

inch) minimum for precast decks with a separate wearing surface. 

5.2.3 

Wearing Surfaces Wearing surfaces are placed on top of the deck and protects the deck and provides 

a smooth riding surface. The wearing surface materials most commonly used on 

concrete decks are generally either special concrete mixes or asphalt concrete. 

Wearing surfaces are incorporated in many new deck designs and are also a 

common repair procedure for decks. 

Concrete There are two categories of concrete wearing surfaces: integral and overlays. An 

integral concrete wearing surface is cast with the deck, typically adding an extra 

13 to 25 mm (1/2 to 1 inch) of thickness to the deck. When the wearing surface has 

deteriorated to the extent that readability is affected, it is milled, leveled and 

replaced with an overlay. 

 

A concrete overlay wearing surface is cast separately over the previously cast 

concrete deck. Some concrete wearing surfaces may have transverse grooves cut 

into them as a means of improving traction and preventing hydroplaning. The 

grooves can be tined while the concrete is still plastic or they can be diamondsawed after the concrete has cured. There are various types of concrete overlays in 

use or being researched at the present time. These include: 

3⁄4 Low slump dense concrete (LSDC) 

3⁄4 Polymer/latex modified concrete (LMC) 

3⁄4 Internally sealed concrete 

3⁄4 Lightweight concrete (LWC) 

3⁄4 Fiber reinforced concrete (FRC) 

Low slump dense concrete (LSDC) uses a dense concrete with a very low watercement ratio (approximately 0.32). LSDC overlays were first used in the early 

1960's for patches and overlays on bridges in Iowa and Kansas (hence the common 

term "Iowa Method"). The original overlays were 31 mm (11⁄4 inches) thick, but 

now a 50 mm (2-inch) minimum is specified. This type of overlay is generally 

used because it cures rapidly and has a low permeability. The low permeability 

resists chloride penetration, while the fast curing decreases the closure period. 

Low slump dense concrete overlays are placed mainly in locations where deicing 

salts are used. Surface cracking is a problem in areas where the freeze/thaw cycle 

exists. The number of applications of deicing salts also plays a role in the 

deterioration of LSDC overlays. Higher strength dense concrete has been used in 

the recent past, and results have shown that LSDC overlaid bridge decks will 

require resurfacing after about 25 years of service, regardless of the concrete deck 

deterioration caused by steel reinforcement corrosion. 

Polymer/latex modified concrete overlay involves the incorporation of polymer 

emulsions into the fresh concrete. The polymer emulsions have been polymerized 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.9

prior to being added to the mixture. This is commonly known as latex-modified 

concrete (LMC). LMC is conventional Portland cement concrete with the addition 

of approximately 15 percent latex solids by weight of the cement. The typical 

thickness of 31 mm (11⁄4 inches) is used for LMC. 

The primary difference between the LSDC and the LMC overlays is that low 

slump concrete uses inexpensive materials but is difficult to place and requires 

special finishing equipment. Conversely, latex-modified concrete utilizes 

expensive materials but requires less manpower and is placed by conventional 

equipment. The performance of LMC has generally been satisfactory, although in 

some cases, extensive map cracking and debonding have been reported. The 

causes for this are likely the improper application of the curing method, 

application under high temperature, or shrinkage due to high slump. 

Lightweight concrete (LWC) overlays use concrete with lightweight aggregates 

and a higher entrained air content. This produces an overlay of approximately 

1280 to 1600 kg/m3

 (80 to 100 pcf) compared to 2240 to 2400 kg/m3 (140 to 150 

pcf) for conventional concrete. This type of overlay has a reduced dead load 

compared to a traditional concrete overlay. Lightweight concrete is also used for 

cast-in-place and precast decks. 

Fiber reinforced concrete (FRC) overlays using Portland cement and metallic, 

glass, plastic, or natural fibers are becoming a popular solution to bridge deck 

surface problems. This type of reinforcement strengthens the tension properties in 

the concrete, and tests have shown that FRC overlays can stop a deck crack from 

reflecting through the overlay. This type of overlay is gaining acceptance but is 

still in the research stage. 

Asphalt The most common overlay material for concrete decks is asphalt. Asphalt 

overlays generally range from 25 mm (1 inch) up to 63 mm (21⁄2 inches), 

depending on the severity of the repair and the load capacity of the superstructure. 

When asphalt is placed on concrete, a waterproof membrane may be applied first 

to protect the reinforced concrete from the adverse effects of water borne deicing 

chemicals, which pass through the permeable asphalt concrete layer. Not all 

attempts at providing a waterproof membrane are successful. 

5.2.4 

Protective Systems 

Sealants 

With increasing research, the uses of protective systems are increasing the life of 

reinforced concrete bridge decks. Most reinforced concrete bridge decks need 

repair years before the other components of the bridge structure. Therefore 

protecting the bridge deck from contamination and deterioration is gaining 

importance. 

Reinforced concrete deck sealants are used to stop chlorides from contaminating 

the steel reinforcement. These sealants are generally pore sealers or hydrophobing 

agents, and their performance is affected by environmental conditions, traffic 

wear, penetration depth of the sealer, and ultraviolet light. 

Boiled linseed oil is a popular sealant that is used to cure or seal a concrete deck. 

It is applied after the concrete gains the appropriate amount of strength. This 

material resists water and the effects of deicing agents. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.10

Epoxy Coated 

Reinforcement Bars 

Galvanized 

Reinforcement Bars 

Stainless Steel 

Reinforcement Bars 

Fiberglass Reinforced 

Polymer (FRP) bars 

Cathodic Protection of 

Reinforcement Bars 

Elastomeric membranes are another approach when sealing a concrete bridge 

deck. This type of sealant is mixed on site and cures to a seamless viscous 

waterproof membrane. It is generally applied prior to placing an asphalt overlay. 

Steel reinforcement corrosion causes detrimental effects on concrete decks. An 

epoxy coating is often used on all steel deck reinforcement to prevent corrosion. 

The epoxy coating is resistant to chemicals, water, and atmospheric moisture. 

Epoxies utilize an epoxy polymer binder that forms a tough, resilient film upon 

drying and curing. Drying is by solvent evaporation, while curing entails a 

chemical reaction between the coating components. 

Another method of protecting steel reinforcement is by galvanizing the steel. 

Galvanizing slows down the corrosion process and lengthens the life of the 

reinforced concrete deck. Galvanizing is achieved by coating the bare steel 

reinforcement with zinc. The two unlike metals form an electrical current between 

them, and one metal virtually stops its corrosion process while the other’s 

accelerates due to the electrical current. In this situation, the steel stops corroding 

while the zinc has accelerated corrosion. 

The corrosion process is negligible when stainless steel reinforcement is used. 

Fiberglass Reinforced Polymer (FRP) bars for concrete reinforcement have the 

advantage of resistance to corrosion. They are also lightweight, weighing about 

one-quarter the weight of an equivalent size steel bar. 

 

Cathodic Protection is sometimes used on decks with black bare steel 

reinforcement (not epoxy coated). Steel reinforcement corrosion can also be 

slowed down by cathodic protection. Corrosion of steel reinforcing bars in 

concrete occurs by an electrical process in a moist environment at the steel surface. 

During corrosion, a voltage difference (less than 1 volt) develops between rebars 

or between different areas on the same rebar. Electrons from the iron in the rebar 

are repelled by the negative anode area of the rebar and attracted to the positive 

cathode area. This electron flow constitutes an electrical current that is necessary 

for the corrosion process. Corrosion occurs only at the anode, where the electrons 

from the iron are given up. 

By cathodic protection, this electrical current is reversed, slowing or stopping 

corrosion. By the impressed current method, an electrical DC rectifier supplies 

electrical current from local electrical power lines to a separate anode embedded in 

the concrete. The anode is usually a wire mesh embedded just under the concrete 

surface. Another type of anode consists of an electrically conductive coating 

applied to the concrete surface. The wires from the rectifier are embedded in the 

coating at regular intervals (see Figure 5.2.9). 

When the impressed current enters the mesh or coating anode, the voltage on the 

rebars is reversed, turning the entire rebar network into a giant cathode. Since 

natural corrosion occurs only at the anode, the rebars are protected. 

The natural corrosion process is allowed to proceed by electrons leaving the iron 

atoms in the anode. With impressed current cathodic protection, however, the 

electrons are supplied from an external source, the DC rectifier (see figure 5.2.9). 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.11

Thus, the artificial anode mesh or coating is also spared from corrosion. 

Figure 5.2.9 Cathodic Protection 

Waterproofing 

Membrane 

There are two types of bridge deck waterproofing membrane systems. 

3⁄4 Self-adhering membrane – is a high strength polyester reinforced 

membrane with a rubber/bitumen compound, which is cold applied. A 

layer of bituminous base and wearing course is then applied over the 

membrane. 

3⁄4 Liquid waterproofing membrane – is a two-component compound, which 

is simply mixed on site to produce a viscous seamless rubber/bitumen 

liquid that cures to an elastomeric waterproof membrane. 

These systems are used to retard reflective cracking and provide waterproofing. 

5.2.5 

Overview of 

Common Defects 

Common concrete deck defects are listed below. Refer to Topic 2.2 for a detailed 

description of these defects: 

3⁄4 Cracking 

3⁄4 Scaling 

3⁄4 Delamination 

3⁄4 Spalling 

3⁄4 Chloride Contamination 

3⁄4 Efflorescence 

3⁄4 Ettringite formation 

3⁄4 Honeycombs 

3⁄4 Pop-outs 

3⁄4 Wear 

3⁄4 Collision damage 

3⁄4 Abrasion 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.12

3⁄4 Overload damage 

3⁄4 Reinforcing steel corrosion 

3⁄4 Prestressed concrete deterioration 

5.2.6 

Inspection 

Procedures and 

Locations 

Procedures Visual 

The inspection of concrete decks for cracks, spalls, and other defects is primarily a 

visual activity. All surfaces of the concrete deck should receive a close visual 

inspection. 

Physical 

Hammers can be used to detect areas of delamination. A delaminated area will 

have a distinctive hollow “clacking” sound when tapped with a hammer or 

revealed with a chain drag. A hammer hitting sound concrete will result in a solid 

"pinging" type sound. 

The physical examination of a deck with a hammer can be a tedious operation. In 

most cases, a chain drag is used. A chain drag is made of several sections of chain 

attached to pipe that has a handle attached to it. The inspector drags this across a 

deck and makes note of the resonating sounds. A chain drag can usually cover 

about a 915 mm (3-feet) wide section of deck at a time (see Figure 5.2.10). 

Figure 5.2.10 Sounding for Delaminated Areas of Concrete
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.13

Many of the problems associated with concrete bridge decks are caused by 

corrosion of the rebar. When the deterioration of a concrete deck progresses to the 

point of needing rehabilitation, an in-depth inspection of the deck is required to 

determine the extent, cause, and possible solution to the problem. Several 

techniques and methods are available. 

Advanced Inspection Techniques 

Several advanced techniques are available for concrete inspection. Nondestructive 

methods, described in Topic 13.2.2, include: 

3⁄4 Acoustic wave sonic/ultrasonic velocity measurements 

3⁄4 Delamination detection machinery 

3⁄4 Electrical methods 

3⁄4 Electro magnetic methods 

3⁄4 Pulse Velocity 

3⁄4 Flat jack testing 

3⁄4 Ground-penetrating radar 

3⁄4 Impact-echo testing 

3⁄4 Infrared thermography 

3⁄4 Laser ultrasonic testing 

3⁄4 Magnetic field disturbance 

3⁄4 Neutron probe for detection of chlorides 

3⁄4 Nuclear methods 

3⁄4 Pachometer 

3⁄4 Rebound and penetration methods 

3⁄4 Ultrasonic testing 

3⁄4 Smart concrete 

Other methods, described in Topic 13.2.3, include: 

3⁄4 Core Sampling 

3⁄4 Carbonation 

3⁄4 Concrete permeability 

3⁄4 Concrete strength 

3⁄4 Endoscopes and video scopes 

3⁄4 Moisture content 

3⁄4 Petrographic examination 

3⁄4 Reinforcing steel strength 

3⁄4 Chloride test 

3⁄4 Matrix analysis 

3⁄4 ASR evaluation 

If the inspector deems it necessary, core samples can be taken from the deck and 

sent to a laboratory to determine the extent of any chloride contamination. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.14

Locations Both the top and bottom surfaces of concrete decks should be inspected for 

cracking, scaling, spalling, corroding reinforcement, chloride contamination, 

delamination, and full or partial depth failures. In all instances, it is helpful if the 

inspector has available the previous inspection report so that the progression of 

any deterioration can be noted. This provides a more meaningful inspection. 

Refer to Topic 2.2 for a detailed description of concrete defects. 

For concrete deck inspections, special attention should be given to the following 

locations: 

3⁄4 Areas exposed to traffic – examine for surface texture and wheel ruts due 

to wear. Check cross-slopes for uniformity. Verify that repairs are acting 

as intended. 

3⁄4 Areas exposed to drainage – investigate for ponding water, scaling, 

delamination, and spalls. 

3⁄4 Bearing and shear areas where the concrete deck is supported – check 

for cracks, spalls and crushing near supports. 

3⁄4 Shear key joints between precast deck panels – inspect for leaking joints, 

cracks, and other signs of independent action. 

3⁄4 Anchorage zones of precast deck tie rods – check for deteriorating grout 

pockets or loose lock-off devices. If a previous inspection report is 

available, this should be used by the inspector so that the progression of 

any deterioration can be noted.

3⁄4 Top of the deck over the supports – examine for flexure cracks which 

would be perpendicular to the primary reinforcement. 

3⁄4 Bottom of the deck between the supports – check for flexure cracks (see 

Figure 5.2.11). 

3⁄4 Asphalt overlays – if present, they should be inspected. Cracks, 

delaminations, and spalls are to be noted. Often water penetrates overlays 

and then penetrates into the structural deck. Asphalt overlays prevent 

visual inspection of the top surface of the deck. The wearing surface does 

not affect the evaluation of the structural deck. 

3⁄4 Stay-in-place forms – investigate for deterioration and corrosion of the 

forms, often indicating contamination of the concrete deck; these forms 

can retain moisture and chlorides which have penetrated full depth cracks 

in the deck (see Figure 5.2.12). 

3⁄4 Cathodic protection – during the bridge inspection, check that all visible 

electrical connections and wiring from the rectifier to the concrete 

structure are intact. If cathodic protection appears not to be working, 

notify maintenance personnel. Some agencies that use cathodic protection 

have specialized inspection/maintenance crews for these types of bridge 

decks. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.15

Figure 5.2.11 Underside View of Longitudinal Deck Crack 

Figure 5.2.12 Deteriorated Stay-in-Place Form 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.2: Concrete Decks 

5.2.16

5.2.7 

Evaluation State and federal rating guideline systems have been developed to aid in the 

inspection of concrete decks. The two major rating guideline systems currently in 

use are the FHWA's Recording and Coding Guide for the Structural Inventory and 

Appraisal of the Nation's Bridges used for the National Bridge Inventory (NBI) 

component rating method and the AASHTO Guide for Commonly Recognized 

(CoRe) Structural Elements used for element level condition state assessment. 

NBI Rating Guidelines Using NBI rating guidelines, a 1-digit code on the Federal Structure Inventory and 

Appraisal (SI&A) sheet indicates the condition of the deck. Rating codes range 

from 9 to 0, where 9 is the best rating possible. See Topic 4.2 (Item 58) for 

additional details about the NBI rating guidelines. The previous inspection data 

should be used along with current inspection findings to determine the correct 

rating. 

Element Level Condition 

State Assessment 

In an element level condition state assessment of a concrete deck, the AASHTO 

CoRe element is one of the following, depending on the riding surface: 

Element No. Description

012 Concrete Deck – Bare 

013 Concrete Deck – Unprotected with AC Overlay 

014 Concrete Deck – Protected with AC Overlay 

018 Concrete Deck – Protected with Thin Overlay 

022 Concrete Deck – Protected with Rigid Overlay 

026 Concrete Deck – Protected with Coated Bars 

027 Concrete Deck – Protected with Cathodic System 

For the purpose of this manual, a deck is supported by a superstructure, and a slab 

is supported by substructure units. 

The unit quantity for the CoRe elements is “each”, and the entire element must be 

placed in one of the five available condition states based solely on the top surface 

condition. Condition state 1 is the best possible rating. The inspector must know 

the total deck surface area in order to calculate a percent deterioration and fit into a 

given condition state description. Some states have elected to use the total area (m2 

or ft2). When a total area is used, the total area must be assigned to one of the five 

available condition states depending on the extent and severity of deterioration. 

See the AASHTO Guide for Commonly Recognized (CoRe) Structural Elements for 

condition state descriptions. 

A Smart Flag is used when a specific condition exists, which is not described in 

the CoRe element condition state. The severity of the damage is captured by 

coding the appropriate Smart Flag condition state. The Smart Flag quantities are 

measured as each, with only one each of any given Smart Flag per bridge. 

For structural cracks in the top surface of bare decks, the “Deck Cracking” Smart 

Flag, Element No. 358, can be used and one of four condition states assigned. Do 

not use Smart Flag, Element No. 358, if the bridge deck/slab has any overlay 

because the top surface of the structural deck is not visible. For concrete defects 

on the underside of a deck element, the “Soffit” Smart Flag, Element No. 359, can 

be used and one of five condition states assigned. 
5.3-i

Table of Contents

Section 5 ..................................................................................................................................................

Inspection and 

Evaluation of Decks 

 5.3 Steel Decks ............................................................................................ 5.3.1 

 5.3.1 Introduction............................................................................... 5.3.1 

5.3.2 Design Characteristics............................................................... 5.3.1 

 Orthotropic Decks .............................................................. 5.3.1 

 Buckle Plate Decks............................................................. 5.3.2 

 Corrugated Steel Flooring .................................................. 5.3.2 

 Grid Decks.......................................................................... 5.3.3 

 Welded Grid Decks...................................................... 5.3.5 

 Riveted Grate Decks..................................................... 5.3.6 

 Exodermic Decks.......................................................... 5.3.6 

 5.3.3 Wearing Surfaces...................................................................... 5.3.8 

 Serrated Steel...................................................................... 5.3.8 

 Concrete.............................................................................. 5.3.8 

 Asphalt................................................................................ 5.3.8 

 

 5.3.4 Protective Systems .................................................................... 5.3.9 

 Paints .................................................................................. 5.3.9 

 Galvanizing ........................................................................ 5.3.9 

 Overlay ............................................................................... 5.3.9 

 Epoxy Coating.................................................................... 5.3.9 

 

 5.3.5 Overview of Common Defects ................................................. 5.3.9 

 5.3.6 Inspection Procedures and Locations........................................ 5.3.9 

 Procedures .......................................................................... 5.3.9 

 Visual........................................................................... 5.3.9 

 Physical...................................................................... 5.3.10 

 Advanced Inspection Techniques .............................. 5.3.10 

 Locations .......................................................................... 5.3.10 

 Bearing and Shear Areas............................................ 5.3.10 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3-ii

 Areas Exposed to Traffic ........................................... 5.3.11 

 Tension Areas ............................................................ 5.3.11 

 Areas Exposed to Drainage........................................ 5.3.11 

 Corrugated flooring.................................................... 5.3.11 

 Orthotropic Decks...................................................... 5.3.11 

 Check for Slipperiness ............................................... 5.3.11 

 Section Loss............................................................... 5.3.11 

 Connections................................................................ 5.3.11 

 Filled Grid Decks....................................................... 5.3.11 

 Areas Previously Repaired......................................... 5.3.11 

 

 5.3.7 Evaluation ............................................................................... 5.3.12 

 NBI Rating Guidelines ..................................................... 5.3.12 

Element Level Condition State Assessment..................... 5.3.12
5.3.1

Topic 5.3 Steel Decks 

5.3.1 

Introduction Steel decks are found on many older bridges and moveable bridges. Their 

popularity grew until concrete decks were introduced. Today, steel bridge decks 

have various advantages and disadvantages, depending on the application, and are 

mainly used for bridge deck rehabilitation or for very long spans. 

5.3.2 

Design 

Characteristics 

Steel bridge decks are mainly used when weight is a major factor. The weight of a 

steel deck per unit area is less than that of concrete. This weight reduction of the 

deck means the superstructure and substructure can carry more live load. The 

trade-off for this weight savings is that water is permitted to pass through, which 

corrodes the superstructure. Steel decks are sometimes filled with concrete to 

prevent the water from passing through. The four basic types of steel decks are: 

3⁄4 Orthotropic decks 

3⁄4 Buckle plate decks 

3⁄4 Corrugated steel flooring 

3⁄4 Grid decks 

Orthotropic Decks An orthotropic deck consists of a flat, thin steel plate stiffened by a series of 

closely spaced longitudinal ribs at right angles to the floor beams. The deck acts 

integrally with the steel superstructure. An orthotropic deck becomes the top 

flange of the entire floor system (see Figure 5.3.1). 

Steel Plate Deck

Types of Closed

Ribs

Epoxy Asphalt

Wearing Surface 3⁄4"

to 2" Thick

Figure 5.3.1 Orthotropic Bridge Deck 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.2

Buckle Plate Decks Buckle plate decks are found on older bridges. They consist of steel plates 

attached to the floor system which support a layer of reinforced concrete (see 

Figure 5.3.2). The plates are concave or "dished" with drain holes in the center. 

All four sides are typically riveted to the floor system. Buckle plate decks serve as 

part of the structural deck and as the deck form. They are obsolete, however, and 

are no longer used today. 

Figure 5.3.2 Underside View of Buckle Plate Deck 

Corrugated Steel 

Flooring 

Corrugated steel flooring is popular because of its light weight and high strength. 

This deck consists of corrugated steel planks covered by a layer of asphalt (see 

Figure 5.3.3). The planks are set upon the superstructure so that the corrugations 

run perpendicular to the length of the bridge. Corrugations are smaller than stayin-place (SIP) forms, but the steel is thicker, ranging from 3 mm (0.1 inch) to 5 

mm (0.18 inch). The steel planks are welded in place to steel superstructure. In 

the case of timber beams, the planks are attached by lag bolts. The corrugations 

are filled with bituminous pavement, and then a wearing surface is applied. This 

deck is used primarily for the rehabilitation of small bridge decks. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.3

Corrugated Steel Floor

2" - 2 1⁄2"

bituminous wearing course

(2" at C of roadway)

(1" at edge of roadway)

24"

6"

Figure 5.3.3 Sectional View of Corrugated Steel Floor 

Grid Decks Grid decks are probably the most common type of steel deck because of their light 

weight and high strength. They are commonly welded units, which may be open 

or filled with concrete. 

Open decks are lighter than concrete-filled decks, but they are vulnerable to 

corrosion since they are continually exposed to weather, debris, and traffic. 

Another disadvantage of open decks is that they allow dirt and debris to fall onto 

the supporting members. 

Concrete-filled grid decks offer protection for the floor system against water, dirt, 

debris, and deicing chemicals that usually pass directly through open grid decks. 

They can be partially-filled or fully-filled. 

Partially-filled decks are grid decks which have been partially filled with concrete. 

This provides a reduction in the dead load and the protection of a concrete-filled 

floor system. Grid decks are often found on rehabilitated bridges. Their low 

weight reduces the dead load on a rehabilitated bridge, and their easy installation 

reduces the time that the bridge must be closed for repairs. 

Fully-filled decks are grid decks that have been completely filled with concrete 

(see Figure 5.3.4). These decks provide the maximum load carrying capacity. 

Form pans are welded within the grid to hold the concrete. Filled decks often 

contain rebars for extra strength. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.4

Distribution Bars Bearing Bars

Figure 5.3.4 Concrete Filled Grid Deck 

Figure 5.3.5 Filled and Un-filled Steel Grid Deck 

Distribution Bars Bearing Bars
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.5

The three types of grid decks include: 

3⁄4 Welded grid decks 

3⁄4 Riveted grate decks 

3⁄4 Exodermic decks 

 Welded Grid Decks 

Welded grid decks have their components welded together. These components 

consist of bearing bars, cross bars, and supplementary bars (see Figure 5.3.6). 

Figure 5.3.6 Various Patterns of Welded Steel Grid Decks 

The bearing bars support the grating. Bearing bars are laid on top of the beams or 

stringers perpendicularly and are then field-welded or bolted to the superstructure. 

These bars are also referred to as the primary or main bars (see Figure 5.3.4). 

The distribution bars are grating bars that are laid perpendicular on top of the 

bearing bars. They may be either shop- or field-welded to the grating system. 

Cross bars, also referred to as secondary bars or distribution bars, are generally 

serrated for improved traction (see Figure 5.3.4). 

The supplementary bars are grating bars parallel to the bearing bars. They are also 

shop- or field-welded to the cross bars. Not all grating systems have 

supplementary bars. These supplementary bars are also referred to as tertiary bars.
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.6

 Riveted Grid Decks 

A riveted grid deck consists of bearing bars, crimp bars, and intermediate bars and 

can either be fully or partially filled with concrete (see Figure 5.3.7). 

Figure 5.3.7 Riveted Grid Deck

Bearing bars run perpendicular to the superstructure and are attached to the beams 

or stringers by either welds or bolts. They are similar to the bearing bars in welded 

grates. 

Crimp bars are riveted to the bearing bars to form the grating. 

Intermediate bars are parallel to the bearing bars but, in order to reduce the weight 

of the deck, are not as long. The crimp bars are riveted to intermediate bars. 

Intermediate bars may not be present on all riveted grate decks. 

Welds and rivets used to construct steel grid decks have long been be a source of 

cracking. In recent years, steel grid decks have been fabricated to eliminate the 

use of welds or rivets. The bearing bars are fabricated with slotted holes. 

Transverse distribution bars are inserted into the slots rotated into position and 

locked into place without the use of any welds or rivets (see Figure 5.3.8). 

Exodermic Decks 

Exodermic decks are a newer type of bridge deck. Reinforced concrete is 

composite with the steel grid (see Figure 5.3.9). Composite action is achieved by 

studs that extend into the reinforced concrete deck and are welded to the grid deck 

below. Galvanized sheeting is used as a bottom form to keep the concrete from 

falling through the grid holes. Exodermic decks generally weigh 50% to 65% 

lighter than precast reinforced concrete decks. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.7

Figure 5.3.8 Steel Grid Deck with Slotted Holes (to eliminate welding and 

riveting) 

Figure 5.3.9 Schematic of Exodermic Composite Profile 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.8

5.3.3 

Wearing Surfaces Wearing surfaces protect the steel deck, provide an even riding surface, and may 

reduce the water on the deck and superstructure. Wearing surfaces for steel decks 

can consist of: 

3⁄4 Serrated steel 

3⁄4 Concrete 

3⁄4 Asphalt 

Studs can be welded to steel decks for skid resistance. 

Serrated Steel Open grid decks usually have serrated edges on the grating (see Figure 5.3.5). 

Designed not to wear, these serrations are the riding surface of an open grid deck. 

Concrete Concrete flush with the top of the grids, acts as the wearing surface for filled grid 

decks. This concrete wearing surface and the concrete used to fill the grids are 

generally placed at the same time. Different types of concrete wearing surfaces 

are listed and described in Topic 5.2.3. In the case of an exodermic bridge deck, 

the wearing surface is part of a reinforced deck. 

Asphalt Steel plate decks, such as orthotropic decks, typically have a layer of asphalt as the 

wearing surface. Asphalt overlays generally range from 25 mm (1 inch) up to 63 

mm (21⁄2 inches), depending on the severity of the repair and the load capacity of 

the superstructure. Corrugated steel plank decks also have asphalt wearing 

surfaces. 

An epoxy asphalt polymer concrete also is used for orthotropic bridge deck 

wearing surfaces. Unlike conventional asphalt mixes, epoxy asphalt polymer 

concrete will not melt after it has cured because of the thermoset polymer in the 

mix. This polymer is different than thermoplastic polymer used in conventional 

asphalt mixes. Epoxy asphalt polymer concrete is used when high strength and 

elastic composition are important. 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.9

5.3.4 

Protective Systems 

Paints Paints provide protection from moisture, oxygen, and chlorides. Usually three 

coats of paint are applied. The first coat is the primer, the next is the intermediate 

coat, and the final coat is the topcoat. Various types of paint are used, such as 

oil/alkyd, vinyl, epoxy, urethane, zinc-rich primer, and latex paints. 

Galvanizing Galvanizing is used to protect steel decks. The galvanized coating retards the 

corrosion process and lengthens the life of the steel deck. This occurs by coating

the bare steel with zinc. The two dissimilar metals form an electrical current 

between them and one metal virtually stops its corrosion process while the other’s 

accelerates due to the electrical current. In this situation, the steel stops corroding, 

while the zinc has accelerated corrosion. 

There are two methods of galvanizing steel decks (shop applied and field applied). 

Hot-dipping the steel deck member usually takes place at a fabrication shop prior 

to the initial placement of the steel deck. When sections of the deck are too large 

or when maintenance painting is to take place, the zinc-rich-primers can be applied 

in the field. The zinc paint must be mixed properly, and the surface must be 

prepared correctly. 

Overlay Another protective system for steel decks is the overlay material itself. The 

overlay covers the steel deck to create a barrier from corrosive agents. Overlays 

slow down the deterioration process for steel decks. 

Epoxy Coating Epoxy coating steel grates is another means of protecting the steel decking. This 

protective coating is rare. However, there are a limited number of steel decks with 

epoxy coating still in service. 

5.3.5 

Overview of 

Common Defects 

Some of the common steel deck defects are listed below. Refer to Topic 2.3 to 

review steel defects in detail. 

3⁄4 Bent, damaged, or missing members 

3⁄4 Corrosion 

3⁄4 Fatigue cracks 

3⁄4 Other stress-related cracks 

5.3.6 

Inspection 

Procedures and 

Locations 

Procedures Visual 

The inspection of steel decks for corrosion, section loss, buckling, and cracking is 

primarily a visual activity. All surfaces of the steel deck should receive a close 

visual inspection. See Topic 2.3 for a more detailed explanation of visual 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.10

inspection procedures for steel bridge members. 

Physical 

Once the defects are identified visually, physical procedures must be used to verify 

the extent of the defect. Use an inspection hammer or wire brush to remove loose 

corrosion. This partial loss of cross section due to corrosion is known as section 

loss. Section loss should be measured using a straight edge and a tape measure. 

However, a more exact method of measurement, such as calipers or a D-meter, 

should be used to measure the remaining section of steel. The inspector must 

remove all corrosion products (rust scale) prior to making measurements. 

The inspector should also measure the non-corroded bridge members to verify that 

the sizes recorded in the plans or inspection report are accurate. If incorrect 

member sizes are used, the load rating analysis for safe load capacity of the bridge 

is not accurate. 

Broken or cracked welds and rivets can be found by listening to the bridge deck. 

As vehicles drive across the steel deck, list for any unusual or clanking noises. 

 Advanced Inspection Techniques

In addition, several advanced techniques are available for steel inspection. 

Nondestructive methods, described in Topic 13.3.2, include: 

3⁄4 Acoustic emissions testing 

3⁄4 Computer programs 

3⁄4 Computer tomography 

3⁄4 Corrosion sensors 

3⁄4 Smart paint 1 

3⁄4 Smart paint 2 

3⁄4 Dye penetrant 

3⁄4 Magnetic particle 

3⁄4 Radiographic testing 

3⁄4 Robotic inspection 

3⁄4 Ultrasonic testing 

3⁄4 Eddy current 

Other methods, described in Topic 13.3.3, include: 

3⁄4 Brinell hardness test 

3⁄4 Charpy impact test 

3⁄4 Chemical analysis 

3⁄4 Tensile strength test 

Locations The primary locations for steel deck inspection include: 

3⁄4 Bearing and shear areas – check the primary bearing bars for cracked 

welds or broken fasteners, or missing bars which connect the steel deck to 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.11

the supporting floor system. 

3⁄4 Areas exposed to traffic – examine the top surface for wheel ruts or wear. 

Verify that the deteriorated deck will not damage tires. 

3⁄4 Tension areas – on steel grid decks, check positive and negative moment 

regions of the primary bearing bars. Look for damage such as broken, 

bent, fatigue cracks or other stress related cracks, or missing bars. 

3⁄4 Areas exposed to drainage – check areas where drainage can lead to 

corrosion. Look at areas along the curb lines that collect dirt and debris. 

3⁄4 Corrugated flooring – check between the support points for section loss 

due to corrosion. Vertical movement of the deck under live load may 

indicate weld failure. 

3⁄4 Orthotropic decks – check orthotropic steel plate decks for debonding of 

the overlay, rust-through or cracks in the steel plate, and for the 

development of fatigue cracks in the web elements or connecting welds. 

The connection between the orthotropic plate deck and supporting 

members should be checked. 

3⁄4 Check for slipperiness – on steel grid decks caused by excessive wear. 

3⁄4 Section loss – in areas where corrosion is evident, all scale should be 

removed with an inspection hammer in order to evaluate the amount of 

remaining material. 

3⁄4 Connections – examine for broken connections, and listen for rattles as 

traffic passes over the deck. 

3⁄4 Filled grid decks – inspect for grid expansion at joints and bridge ends, 

often caused by corrosion. Check the condition of the concrete. 

3⁄4 Areas previously repaired – document the location and condition of any 

repair plates and their connections to the deck. 

Figure 5.3.10 Broken Members of an Open Steel Grid Deck 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.3: Steel Decks 

5.3.12

5.3.7 

Evaluation State and federal rating guideline systems have been developed to aid in the 

inspection of steel decks. The two major rating guideline systems currently in use 

are the FHWA's Recording and Coding Guide for the Structural Inventory and 

Appraisal of the Nation's Bridges used for the National Bridge Inventory (NBI) 

component rating method and the AASHTO Guide for Commonly Recognized 

(CoRe) Structural Elements used for element level condition state assessment. 

NBI Rating Guidelines Using NBI rating guidelines, a 1-digit code on the Federal Structure Inventory and 

Appraisal (SI&A) sheet indicates the condition of the deck. Rating codes range 

from 9 to 0, where 9 is the best rating possible. See Topic 4.2 (Item 58) for 

additional details about the NBI rating guidelines. The previous inspection data 

should be used along with current inspection findings to determine the correct 

rating. 

Element Level Condition 

State Assessment 

In an element level condition state assessment of a steel deck, the AASHTO CoRe 

element is one of the following, depending on the riding surface: 

Element No. Description

028 Steel Deck – Open Grid 

029 Steel Deck – Concrete Filled Grid 

030 Steel Deck – Corrugated/ Orthotropic 

The unit quantity for the CoRe elements is “each”, and the entire element must be 

placed in one of the five available condition states based solely on the top surface 

condition. Condition state 1 is the best possible rating. The inspector must know 

the total deck surface area in order to calculate a percent deterioration and fit into a 

given condition state description. Some states have elected to use the total area (m2 

or ft2). When a total area is used, the total area must be assigned to one of the five 

available condition states depending on the extent and severity of deterioration. 

See the AASHTO Guide for Commonly Recognized (CoRe) Structural Elements for 

condition state descriptions. 

A Smart Flag is used when a specific condition exists, which is not described in 

the CoRe element condition state. The severity of the damage is captured by 

coding the appropriate Smart Flag condition state. The Smart Flag quantities are 

measured as each, with only one each of any given Smart Flag per bridge. 

For connections of steel decks showing rust packing between steel plates, the 

“Pack Rust” Smart Flag, Element No. 357, can be used and one of four condition 

states assigned. The unit quantity for Element Level Smart Flags is “each” and the 

entire element must be placed into one condition state. 
5.4-i

Table of Contents

Section 5 ..................................................................................................................................................

Inspection and 

Evaluation of Decks 

 5.4 Deck Joints, Drainage Systems, Lighting and Signs.............................. 5.4.1 

 

5.4.1 Function of Deck Joints, Drainage Systems, Lighting 

 and Signs................................................................................... 5.4.1 

 Deck Joints ......................................................................... 5.4.1 

 Drainage Systems ............................................................... 5.4.1 

 Lighting and Signs.............................................................. 5.4.1 

 

5.4.2 Components of Deck Joints, Drainage Systems, Lighting 

 and Signs................................................................................... 5.4.1 

 Deck Joints ......................................................................... 5.4.1 

 Open Joints................................................................... 5.4.2 

 Formed Joints ........................................................ 5.4.2 

 Finger Plate Joints ................................................. 5.4.3 

 Closed Joints................................................................ 5.4.5 

 Poured Joint Seal................................................... 5.4.5 

 Compression Seal.................................................. 5.4.6 

 Cellular Seal .......................................................... 5.4.6 

 Sliding Plate Joint.................................................. 5.4.6 

 Prefabricated Elastomeric Seals ............................ 5.4.7 

 Modular Elastomeric Seal ..................................... 5.4.9 

 Asphaltic Expansion Joint ..................................... 5.4.9 

 Drainage Systems ............................................................. 5.4.10 

 Runoff ........................................................................ 5.4.10 

 Bridge Deck Cross Slope and Profile ........................ 5.4.10 

 Deck Drains ............................................................... 5.4.10 

 Outlet Pipes................................................................ 5.4.11 

 Downspout Pipes ....................................................... 5.4.11 

 Cleanout Plugs ........................................................... 5.4.11 

 Drainage Troughs....................................................... 5.4.11 

 Lighting ............................................................................ 5.4.12 

 Highway Lighting ...................................................... 5.4.12 

 Traffic Control Lighting ............................................ 5.4.12 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4-ii

 Aerial Obstruction Lighting....................................... 5.4.13 

 Navigational Lighting ................................................ 5.4.13 

 Signs ................................................................................. 5.4.13 

 Warning Signs............................................................ 5.4.13 

 Vertical Clearance ............................................... 5.4.13 

 Lateral Clearance................................................. 5.4.13 

 Narrow Underpass............................................... 5.4.13 

 Traffic Regulatory Signs............................................ 5.4.14 

 Weight Limit ....................................................... 5.4.14 

 Guide Signs................................................................ 5.4.14 

 5.4.3 Common Problems of Deck Joints, Drainage Systems, 

 Lighting and Signs .................................................................. 5.4.14 

 Deck Joints ....................................................................... 5.4.14 

 Drainage Systems ............................................................. 5.4.14 

 Lighting and Signs............................................................ 5.4.15 

 

 5.4.4 Inspection Locations and Procedures for Deck Joints, Drainage 

Systems, Lighting and Signs................................................... 5.4.15 

 Deck Joints ....................................................................... 5.4.15 

 Dirt and Debris Accumulation ................................... 5.4.16 

 Proper Alignment....................................................... 5.4.17 

 Damage to Seals and Armored Plates........................ 5.4.18 

 Indiscriminate Overlays............................................. 5.4.19 

 Joint Supports............................................................. 5.4.20 

 Joint Anchorage Devices ........................................... 5.4.21 

 Drainage Systems ............................................................. 5.4.21 

 Bridge Deck Cross Slope and Profile ........................ 5.4.22 

 Grates......................................................................... 5.4.22 

 Deck Drains and Inlets............................................... 5.4.22 

 Drainage Troughs....................................................... 5.4.22 

 Outlet Pipes................................................................ 5.4.23 

 Lighting ............................................................................ 5.4.23 

 Signs ................................................................................. 5.4.23 

 

 5.4.5 Evaluation ............................................................................. 5.4.24 

 NBI Rating Guidelines ..................................................... 5.4.24 

 Element Level Condition State Assessment..................... 5.4.24 
5.4.1 

Topic 5.4 Deck Joints, Drainage Systems, 

Lighting and Signs 

5.4.1 

Function of Deck 

Joints, Drainage 

Systems, Lighting 

and Signs 

Deck Joints The deck joint is a very important part of a bridge. The primary function of deck 

joints is to accommodate the expansion, contraction and rotation of the deck and 

superstructure. In most bridges, the deck joints must accommodate this movement 

and prevent runoff from reaching bridge elements below the surface of the deck. 

In addition, the deck joint provides a smooth transition from the approach roadway 

to the bridge deck. The deck joint must be able to withstand all possible weather 

extremes in a given area. It must do all of this without compromising the ride 

quality of vehicles crossing the bridge. 

Drainage Systems The purpose of a drainage system is to remove water and all hazards associated 

with it from the structure. The purpose is also to protect the superstructure, 

bearings and substructure. The drainage system should also require as little 

maintenance as possible and be located so that it does not cause safety hazards. 

Lighting and Signs Lighting serves various functions on bridge structures. Highway lighting is used 

to increase visibility on a bridge structure. Traffic signal lighting controls traffic 

on a structure. Aerial obstruction lighting warns aircrafts of a hazard around and 

below the lights. Navigational lighting is used for the safe control of waterway 

traffic under a bridge structure. Finally, sign lighting ensures proper visibility for 

traffic signs. 

Typical signs that are present on or near bridges provide regulatory (e.g., speed 

limits) information and advisory (e.g., clearance warnings) information. Such 

signs serve to inform the motorist about bridge or roadway conditions that may be 

hazardous. 

5.4.2 

Components of 

Deck Joints, 

Drainage Systems, 

Lighting and Signs 

Deck Joints Deck joints should not be confused with construction joints. While deck joints are 

used primarily to facilitate expansion and contraction of the deck and 

superstructure, construction joints mark the beginning or end of concrete 

placement sections during the construction of the bridge deck. The two major 

categories of deck joints are open joints and closed joints. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.2 

 Open Joints

Open joints allow water and debris to pass through the joint. The two types of 

open joints are as follows: 

3⁄4 Formed joints 

3⁄4 Finger plate joints 

Formed Joints 

Formed joints are little more than a gap between the bridge deck and the abutment 

backwall or, in the case of a multiple span structure, between adjacent deck 

sections. They are usually found on very short span bridges where expansion is 

minimal. The formed joint is usually unprotected, but the deck and backwall can 

be armored with steel angles. Formed joints are common on short span bridges 

with concrete decks (see Figures 5.4.1 and 5.4.2). 

Figure 5.4.1 Formed Joint 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.3 

Figure 5.4.2 Cross Section of a Formed Joint 

Finger Plate Joints 

A finger plate joint, also known as a tooth plate joint or a tooth dam, consists of 

two steel plates with interlocking fingers. These joints are usually found on longer 

span bridges where greater expansion is required. The two types of finger plate 

joints are cantilever finger plate joints and supported finger plate joints. 

The cantilever finger plate joint is used when relatively little expansion is required. 

The fingers on this joint cantilever out from the deck side plate and the abutment 

side plate. The supported finger plate joint is used on longer spans requiring 

greater expansion. The fingers on this joint have their own support system in the 

form of transverse beams under the joint. Some types of finger plate joints are 

segmental, allowing for maintenance and replacement if necessary. Finger plate 

joints are used to accommodate movement from 100 to over 600 mm (4 to over 24 

inches) (see Figures 5.4.3 through 5.4.5). 

Troughs are sometimes placed under open finger plate joints. Their purpose is to 

direct water that passes through the joint away from the superstructure, bearings 

and substructure. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.4 

Figure 5.4.3 Finger Plate Joint 

Figure 5.4.4 Cross Section of a Cantilever Finger Plate Joint 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.5 

Figure 5.4.5 Supported Finger Plate Joint 

 Closed Joints 

Closed joints are designed so that water and debris do not pass through them. The 

superstructure and substructure members directly below the joint are protected 

from the effects of water and debris buildup. There are several types of closed 

joints, including the following: 

3⁄4 Poured joint seal 

3⁄4 Compression seal 

3⁄4 Cellular seal 

3⁄4 Sliding plate joint 

3⁄4 Prefabricated elastomeric seal 

3⁄4 Modular elastomeric seal 

3⁄4 Asphaltic expansion joint 

Poured Joint Seal 

A poured joint seal is made up of two materials: a base and a poured sealant. The 

base consists of a preformed expansion joint filler. The top of this material is 25 to 

50 mm (1 to 2 inches) from the top of the deck. The remaining joint space consists 

of the poured sealant that is separated from the base by a backer rod or a bond 

breaker. Since the poured joint seal can only accommodate a movement of about 6 

mm (1/4 inch), it is usually found on short span structures. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.6 

Compression Seal 

A compression seal consists of neoprene formed in a rectangular shape with a 

honeycomb cross section (see Figure 5.4.6). The honeycomb design allows the 

compression seal to fully recover after being distorted during bridge expansion and 

contraction. It is called a compression seal because it functions in a partially 

compressed state at all times. Compression seals can have steel angle armoring on 

the deck and backwall. In some cases, the deck joint is saw cut to accept the 

installation of the compression seal. In such cases, no armoring is provided. 

These seals come in a variety of sizes and are often classified by their maximum 

movement capacity. A large compression seal can accommodate a maximum 

movement of approximately 50 mm (2 inches). 

Figure 5.4.6 Cross Section of a Compression Seal with Steel Angle Armoring 

Cellular Seal 

The cellular seal is similar to the compression seal, and its armoring is almost 

identical. However, they differ in the type of material used to seal the joint. 

Unlike the compression seal, the cellular seal is made of a closed-cell foam that 

allows the joint to move in different directions without losing the seal. This foam 

allows for expansion and contraction both parallel and perpendicular to the joint. 

The parallel movement is referred to as racking and occurs during normal 

expansion and contraction of a curved structure or a bridge on a skew. 

Sliding Plate Joint 

A sliding plate joint is composed of two plates. The top plate slides across the 

bottom plate. Although classified as a closed joint, the sliding plate joint is usually 

not watertight. In an attempt to seal the joint, an elastomeric sheet is sometimes 

used. This sheet is attached between the plates and the joint armoring. The 

resulting trough serves to carry water away to the sides of the deck (see Figure 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.7 

5.4.7). The sliding plate joint can accommodate a maximum movement of 

approximately 100 mm (4 inches). 

Figure 5.4.7 Cross Section of a Sliding Plate Joint 

Prefabricated Elastomeric Seal 

Prefabricated elastomeric seals are frequently proprietary products and include 

three basic types: 

3⁄4 Plank seal 

3⁄4 Sheet seal 

3⁄4 Strip seal 

A plank seal consists of steel reinforced neoprene that supports vehicular wheel 

loads over the joint. This type of seal is bolted to the deck and is capable of 

accommodating movement ranges from 50 to 330 mm (2 to 13 inches) (see Figure 

5.4.8). 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.8 

Figure 5.4.8 Plank Seal 

A sheet seal consists of two blocks of steel reinforced neoprene. A thin sheet of 

neoprene spans the joint and connects the two blocks. This joint can accommodate 

a maximum movement of approximately 100 mm (4 inches) (see Figure 5.4.9). 

Figure 5.4.9 Sheet Seal 

A strip seal consists of two slotted steel anchorages cast into the deck or backwall. 

A neoprene seal fits into the grooves to span the joint extrusion. This joint can 

accommodate a maximum movement of approximately 100 mm (4 inches) (see 

Figure 5.4.10). 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.9 

Figure 5.4.10 Strip Seal (Drawing Courtesy of the D.S. Brown Co.) 

Modular Elastomeric Seal 

The modular elastomeric seal is another neoprene type seal which can support 

vehicular wheel loads. It consists of hollow, rectangular neoprene block seals, 

interconnected with steel and supported by its own stringer system (see Figure 

5.4.11). The normal range of operation for movement is between 100 and 600 mm 

(4 and 24 inches). It can, however, be fabricated to accommodate movements up 

to 1200 mm (48 inches). 

Figure 5.4.11 Schematic Cross Section of a Modular Elastomeric Seal 

Asphaltic Expansion Joint 

An asphaltic expansion joint is typically used on short bridges that are to be 

overlaid with asphalt. The joint expansion must be 50 mm (2 inches) or less. The 

original joint is usually a formed open joint that has deteriorated. Once the bridge 

joint is overlaid, the overlay material on the joint and a set distance in both 

directions of the joint is removed down to the original deck. A backer rod is then 

placed in the open joint and a sealant material is placed in the joint. Next, an 

aluminum or steel plate is centered over the joint to bridge the opening, and pins 

are put through the plate into the joint to hold it in place. A heated binder material 

is then poured on the plate to create a watertight seal. Layers of aggregate 

saturated with hot binder are then placed to the depth needed. The filled joint is 

then compacted. This type of joint allows for bridge decks to be overlaid without 

damaging existing expansion joints and is gaining popularity (see Figure 5.4.12). 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.10

Figure 5.4.12 Asphaltic Expansion Joint 

Drainage Systems In order to perform an inspection of a deck drainage system, it is necessary to 

become familiar with its various elements: 

3⁄4 Runoff 

3⁄4 Bridge deck cross slope and profile 

3⁄4 Deck drains 

3⁄4 Outlet pipes 

3⁄4 Downspout pipes 

3⁄4 Cleanout plugs 

Runoff 

Runoff is the water and any contents from the surface of the bridge deck. 

Bridge Deck Cross Slope and Profile 

The cross slope of the bridge deck is the first component of the drainage system 

that the runoff encounters. The proper cross slope and profile directs the runoff to 

the deck drains and eliminates or reduces ponding. 

Deck Drains 

The deck drain is the second component of the drainage system that runoff 

encounters. A deck drain is a receptacle to receive water. Deck drains may be 

nothing more than openings in a filled grid deck, holes in a concrete deck, or slots 

in the base of a parapet. Inlet boxes and scuppers are also examples of deck 

drains (see Figure 5.4.13). 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.11

Figure 5.4.13 Bridge Deck Drain 

Inlet boxes have a grate, which is a ribbed or perforated cover. Grates are 

fabricated from steel bars that are frequently oriented with the longitudinal 

direction of the bridge and spaced at approximately 50 mm (2 inches) on center. A 

bicycle safety grate has steel rods placed perpendicular to the grating bars, spaced 

at approximately 100 mm (4 inches) on center. 

Grates keep larger debris from entering the drainage system while allowing water 

to pass through. They also serve to support traffic and other live loads. 

Outlet Pipes 

If present, the outlet pipe leads water away from the drain. For bridges over 

roadways, the outlet pipe connects to other pipes. When the bridge is not over a 

roadway, the outlet pipe may simply extend just below the superstructure so that 

drainage water is not windblown onto the superstructure. 

Downspout Pipes 

When a bridge is located over a roadway, the deck drainage must be directed from 

the outlet pipe to a nearby storm sewer system or another appropriate release point. 

This is accomplished with a downspout pipe network (see Figure 5.4.14). 

Cleanout Plugs 

The cleanout plug is a removable plug in the piping system that allows access for 

cleaning. 

Drainage Troughs

Drainage troughs may be located under open joints to divert runoff away from 

underlying superstructure, bearings and substructure members. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.12

Figure 5.4.14 Downspout Pipes and Cleanout Plugs 

Lighting The four basic types of lighting which may be encountered on a bridge are: 

3⁄4 Highway lighting 

3⁄4 Traffic control lighting 

3⁄4 Aerial obstruction lighting 

3⁄4 Navigation lighting 

Highway Lighting 

The typical highway lighting standard consists of a lamp or luminary attached to a 

bracket arm. Both the luminary and bracket arm are usually made of aluminum. 

The bracket arm is attached to a shaft or pole made of concrete, steel, cast iron, 

aluminum, or, in some cases, timber. It is generally tapered toward the top of the 

pole. 

The shaft is attached at the bottom to an anchor base. Steel and aluminum shafts 

are fitted inside and welded to the base. In the case of concrete, the shaft is 

normally cast as an integral part of the base. Sometimes the thickness of the 

parapet or median barrier is increased to accommodate the anchor base. This area 

of the barrier or parapet is called a “blister”. Where the standard is exposed to 

vehicular traffic, a breakaway type base or guardrail may be used. Anchor bolts 

hold the light standard in place. These L-shaped or U-shaped bolts are normally 

embedded in a concrete foundation, parapet, or median barrier. 

Traffic Control Lighting 

Traffic control lights are used to direct traffic on a structure. Lights can serve a 

similar purpose to those found at intersections, but they can also indicate which 

lanes vehicular traffic is to use. These are referred to as lane control signals. Red 

and green overhead lights indicate the appropriate travel lanes. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.13

Aerial Obstruction Lighting 

Aerial obstruction lights are used to alert aircraft pilots that a hazard exists below 

and around the lights. They are red and should be visible all around and above the 

structure. Aerial obstruction lights are located on the topmost portion of any 

bridge considered by the Federal Aviation Administration (FAA) to present a 

hazard to aircraft. Depending on the bridge size, more than one light may be 

required. 

Navigation Lighting 

Navigation lights are used for the safe control of waterway traffic. The United 

States Coast Guard determines the requirements for the type, number, and 

placement of navigation lights on bridges. The lights are either green, red, or 

white and the specific application for each bridge site is unique. 

Green lights usually indicate the center of a channel. These lights are placed at the 

bottom midspan of the superstructure. Red lights indicate the existence of an 

obstacle. When placed on the bottom of the superstructure, a red light indicates 

the limit of the channel. Lights placed to indicate a pier are placed on the pier near 

the waterline. Three white lights in a vertical fashion placed on the superstructure 

indicate the main channel. 

Signs Among the various types of signs to be encountered are signs indicating: 

3⁄4 Warning signs 

3⁄4 Traffic regulatory signs 

3⁄4 Guide signs 

Warning Signs 

Warning signs alert drivers to existing or potentially hazardous conditions. 

Vertical Clearance 

Vertical clearance signs indicate the minimum vertical clearance for the structure. 

This clearance is measured at the most restrictive location within the traveling 

lanes. 

Lateral Clearance 

Lateral clearance signs indicate that the bridge width is less than the approach 

roadway width. Lateral clearance restrictions may be called out with a "Narrow 

Bridge" sign or with reflective stripe boards at the bridge. 

Narrow Underpass 

Narrow underpass signs indicate where the roadway narrows at an underpass or 

where there is a pier in the middle of the roadway. Striped hazard markings and 

reflective hazard markers should be placed on these abutment walls and pier edges. 

The approaching pavement should be appropriately marked to warn motorists of 

the hazard. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.14

Traffic Regulatory Signs 

Regulatory signs instruct drivers to do or not do something. Traffic regulatory 

signs indicate speed restrictions which are consistent with the bridge and roadway 

design. Additional traffic markers may be present to facilitate the safe and 

continuous flow of traffic. 

Weight Limit 

Weight limit signs are very important since they indicate the maximum vehicle 

load that can safely use the bridge. 

Guide Signs

Guide signs come in a variety of shapes and colors and have information to help 

drivers arrive safely at their destination. 

5.4.3 

Common Problems 

of Deck Joints, 

Drainage Systems, 

Lighting and Signs 

Deck Joints Common problems encountered when inspecting deck joints include the following:

3⁄4 Debris and accumulation of dirt in deck joints and troughs under finger 

joints 

3⁄4 Corrosion on joints and their supports 

3⁄4 Damaged, torn, or missing joint seals due to snow plows, traffic, or debris 

buildup 

3⁄4 Spalled edges on joints without armor 

3⁄4 Spalled edges on joints due to misalignment of both sides of the joint 

3⁄4 Broken or misaligned fingers 

3⁄4 Leaking closed joint systems (or evidence of leaking) 

Drainage Systems Common problems encountered when inspecting drainage systems include the 

following: 

3⁄4 Debris buildup at inlet grate where water from the deck enters the drainage 

system 

3⁄4 Clogged or partially clogged deck drains and/or inlets 

3⁄4 Disconnected/clogged downspout piping 

3⁄4 Cracked or split pipes 

3⁄4 Loose or missing connections (from drain pipe below the deck to outlet 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.15

pipe) 

3⁄4 Corrosion or section loss in metal pipes 

Lighting and Signs Common problems encountered when inspecting lighting and signs include the 

following: 

3⁄4 Lighting and signs obstructed from view due to tree growth or other signs 

3⁄4 Lighting and signs not present at bridge site 

3⁄4 Signs presented unacceptably or incorrectly 

3⁄4 Signs defaced or covered with graffiti 

3⁄4 Corrosion or section loss on lighting or sign supports 

3⁄4 Loose or missing anchorages at supports 

3⁄4 Missing signs 

3⁄4 Lighting outages 

5.4.4 

Inspection 

Locations and 

Procedures for 

Deck Joints, 

Drainage Systems, 

Lighting and Signs 

Deck Joints The deck joints must allow for the expansion and contraction of the bridge deck 

and superstructure. The inspector must be aware of and record conditions that 

keep the deck joint from functioning properly. 

Using the NBIS guidelines, there is not a separate item on the Structure Inventory 

and Appraisal (SI&A) sheet to code the serviceability of deck joints. Deck joint 

conditions are not considered in the rating of the deck. However, it is important 

for the inspector to note their condition since leaking deck joint problems are the 

root cause of the majority of the deterioration of superstructure and substructure 

elements beneath the joints. 

The Element Level Inspection system, however, does rate deck joints. For a 

detailed description of deck joint condition states, see the AASHTO Guide for 

Commonly Recognized (CoRe) Structural Elements and the evaluation section of 

this topic. 

Deck joints should be inspected for: 

3⁄4 Dirt and debris accumulation 

3⁄4 Proper alignment (horizontal/vertical) 

3⁄4 Damage to seals and armored plates 

3⁄4 Indiscriminate overlays 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.16

3⁄4 Joint supports 

3⁄4 Joint anchorage devices 

Dirt and Debris Accumulation 

Dirt and debris lodged in the joint may prevent normal expansion and contraction, 

causing cracking in the deck and backwall, and overstress in the bearings. In 

addition, as dirt and debris is continually driven into a joint, the joint material can 

eventually fail (see Figures 5.4.15 and 5.4.16). 

Figure 5.4.15 Debris Lodged in a Sliding Plate Joint 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.17

Figure 5.4.16 Dirt in a Compression Seal Joint 

 Proper Alignment 

Both sides of the joint should be at the same level with no vertical displacement 

between the two. On straight bridges, the joint opening should be parallel across 

the deck. 

In a finger plate joint, the individual fingers should mesh together properly, and 

they should be in the same plane as the deck surface (see Figure 5.4.17). 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.18

Figure 5.4.17 Improper Vertical Alignment at a Finger Plate Joint 

It is important that the relative movements of the joint are consistent with the 

temperature. During the coldest and the warmest times of the day, the air 

temperature and the superstructure temperature should be recorded, and the joint 

opening should be documented. Measurements should be taken at each curb line 

and the centerline of the roadway. Since heat causes expansion, the joint opening 

should be smallest when the temperature is greatest. The superstructure 

temperature can be taken by placing a surface temperature thermometer or the bulb 

of a standard thermometer against the superstructure member itself. The 

superstructure temperature is generally about 1.7 to 2.8 °C (3 to 5 oF) lower than 

the air temperature. 

Damage to Seals and Armored Plates 

Damage from snow plows, traffic, and debris can cause the joint seals to be torn, 

pulled out of the anchorage, or removed altogether (see Figure 5.4.18). It can also 

cause damage to armored plates. Any of these conditions should be noted by the 

inspector. Also look for evidence of leakage through closed joints. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.19

Figure 5.4.18 Failed Compression Seal 

 Indiscriminate Overlays 

When new pavement or wearing surface is applied to a bridge, it is frequently 

placed over the deck joints with little or no regard for their ability to function 

properly. This occurs most frequently on small, local bridges. Transverse cracks 

in the pavement may be evidence that a joint has been covered by the 

indiscriminate application of new overlay, and the joint function may be severely 

impaired (see Figure 5.4.19). 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.20

Figure 5.4.19 Asphalt Wearing Surface over an Expansion Joint 

 Joint Supports 

Where larger expansions and contractions must be accommodated, the joint may 

be fully or partially supported from beneath by transverse beams. These joint 

supports should be carefully inspected for proper function and for corrosion and 

section loss (see Figure 5.4.20). 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.21

Figure 5.4.20 Support System under a Finger Plate Joint 

 Joint Anchorage Devices 

Deficiencies in joint anchorage devices are a common source of deck joint 

problems. Therefore, joint anchorage devices should be carefully inspected for 

proper function and for corrosion. The concrete area in which the joint anchorage 

device is cast should also be inspected for signs of deterioration. This area 

adjacent to the joint is known as the joint header. 

Drainage Systems A properly functioning drainage system removes water, and all hazards associated 

with it, from a structure. There is not a separate item on the NBIS SI&A Sheet to 

code the serviceability of drainage systems, and drainage system conditions are not 

considered in the rating of the bridge. However, it is important for the inspector to 

note their condition, since drainage system problems can eventually lead to 

structural problems. 

The following drainage system elements should be inspected: 

3⁄4 Bridge deck cross slope and profile 

3⁄4 Grates 

3⁄4 Deck drains and inlets 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.22

3⁄4 Drainage troughs 

3⁄4 Outlet pipes 

Bridge Deck Cross Slope and Profile 

The cross slope and profile should not prevent runoff from entering the deck drains 

and inlets. Adequate cross slope should be provided so that water runs off the 

bridge deck at a sufficient rate. Ponding is an indication of insufficient cross slope 

or profile. 

Grates 

Grates should be clear of debris (e.g., plants and grass) and free to allow deck 

runoff to enter. Grates that are deteriorated, broken, or missing should be reported.

Deck Drains and Inlets 

Deck drains and inlets must be of sufficient size and spacing to carry the runoff 

away from the structure effectively. Since runoff conditions can change due to 

development, these drainage elements should be carefully examined with each 

bridge inspection. Clogged deck drains lead to accelerated deck deterioration and 

the undesirable condition of standing water in the traffic lanes (see Figure 5.4.21).

Standing water on the deck is a safety hazard. 

Figure 5.4.21 Clogged Drainage Inlet 

 Drainage Troughs 

Drainage troughs located under the joint should be carefully examined. A buildup 

of debris can accelerate the deterioration of the trough and allow water to drain 

onto structural members (see Figure 5.4.22). If possible, use a shovel to clean as 

much debris as practical; report the remaining condition for appropriate 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.23

maintenance work. Once cleaned, any holes found in the trough should be noted. 

Any evidence that indicates the trough is overflowing should also be recorded. 

Figure 5.4.22 Drainage Trough with Debris Accumulation 

 Outlet Pipes 

Outlet pipes carry runoff away from the structure. The outlet pipe may be a 

straight extension of the deck drain, in which case it should be long enough so that 

runoff is not discharged onto the structure. The outlet pipe may also be a series of 

pipes, called downspouting. This type of outlet pipe should be examined for split 

or disconnected pipes that may allow runoff to accelerate deterioration of the 

structure. Check the connections between the outlet pipes and substructure. If a 

pipe is embedded inside of a substructure unit such as a concrete pier wall, check 

for cracking, delamination, or other freeze-thaw damage to the substructure. Open 

clean out plugs to verify pipes are not clogged and functioning properly. 

Lighting All lights should be clearly visible. Verify that all lights are functioning and that 

they are not obstructed from view. Check for corrosion and collision damage to 

light supports. Verify that appropriate lighting is provided. Exercise caution 

against electrical shock. The inspector should contact the maintenance department 

to de-energize the lighting. 

Signs Signs should be located sufficiently in advance of the structure to permit the driver 

adequate time to react. All signs should be clearly legible. Verify that signs have 

not been defaced and are not obstructed from view. Inspect for corrosion and 

collision damage to sign supports. Verify that appropriate signing is provided. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.4: Deck Joints, Drainage Systems, Lighting and Signs 

5.4.24

5.4.5 

Evaluation State and federal rating guideline systems have been developed to aid in the 

inspection of deck joints, drainage systems, lighting, and signs. The two major 

rating guideline systems currently in use are the FHWA's Recording and Coding 

Guide for the Structural Inventory and Appraisal of the Nation's Bridges used for 

the National Bridge Inventory (NBI) component rating method and the AASHTO 

Guide for Commonly Recognized (CoRe) Structural Elements used for element 

level condition state assessment. 

NBI Rating Guidelines Deck joints, drainage systems, lighting, and signs should not impact the deck 

rating, but their condition should be described on the inspection form. 

Deficiencies in deck joints, drainage systems, lighting, and signs should be placed 

on the maintenance sheet showing estimated quantities. 

Element Level Condition 

State Assessment 

In an element level condition state assessment of expansion joints, the AASHTO 

CoRe element is one of the following, depending on the type of joint: 

Element No. Description

300 Strip seal expansion joint 

301 Pourable joint seal 

302 Compression joint seal 

303 Assembly joint seal (modular) 

304 Open expansion joint 

Individual states have the option to change or add element numbers. In the case of 

expansion joints, some states have added a miscellaneous expansion joint element 

number. 

The unit quantity for these elements is in meters or feet, and the total length must 

be distributed among the three available condition states depending on the extent 

and severity of deterioration. The sum of all condition states must equal the total 

quantity of the CoRe element. Condition state 1 is the best possible rating. See 

the AASHTO Guide for Commonly Recognized (CoRe) Structural Elements for 

condition state descriptions. 

Drainage systems, lighting, and signs have no separate element numbers. The 

condition of the drainage systems, lighting, and signs should, however, be noted 

on the inspection form. 
5.5-i

Table of Contents

Section 5 ..................................................................................................................................................

Inspection and 

Evaluation of Decks 

 5.5 Safety Features....................................................................................... 5.5.1 

 

 5.5.1 Introduction............................................................................. 5.5.1 

 Purpose ............................................................................. 5.5.1 

 Four Basic Components.................................................... 5.5.2 

 Bridge Railings......................................................... 5.5.2 

 Transitions ................................................................ 5.5.2 

 Approach Guardrail .................................................. 5.5.2 

 Approach Guardrail Ends ......................................... 5.5.2 

 5.5.2 Evaluation ............................................................................... 5.5.3 

 Design Criteria.................................................................. 5.5.3 

 History of Crash Testing................................................... 5.5.4 

 Crash Test Criteria............................................................ 5.5.5 

 Current FHWA Policy ...................................................... 5.5.5 

 Railing Evaluation Results/Resources .............................. 5.5.6 

 Available Courses............................................................. 5.5.7 

 

 5.5.3 Identification and Appraisal.................................................... 5.5.8 

 Appraisal Coding .............................................................. 5.5.8 

 36A Bridge Railings ......................................................... 5.5.9 

 36B Transitions............................................................... 5.5.10 

 36C Approach Guardrail................................................. 5.5.10 

 36D Approach Guardrail Ends........................................ 5.5.11 

 

 5.5.4 Median Barriers .................................................................... 5.5.13 

 Inspection of Median Barriers ................................ 5.5.13 

 5.5.5 Safety Feature Inspection...................................................... 5.5.14 

 Inspection........................................................................ 5.5.14 

 Bridge Railing......................................................... 5.5.14 

 Approach Guardrail ................................................ 5.5.15 
SECTION 5: Inspection and Evaluation of Decks 

Topic 5.5: Safety Features 

5.5-ii

 Transition................................................................ 5.5.16 

 End Treatment ........................................................ 5.5.17 

 Inspection for Non-NHS Bridges ................................... 5.5.18 
5.5.1

Topic 5.5 Safety Features 

5.5.1 

Introduction Highway design includes a special emphasis on providing safe roadsides for 

errant vehicles that may leave the roadway. Obstacles or fixed object hazards 

have typically been removed from within a specified roadside recovery area. 

Whenever this has not been feasible (for example, at bridge waterway crossings), 

then safety features such as highway or bridge barrier systems have been provided 

to screen motorists from the hazards present (see Figure 5.5.1). Such barriers 

sometimes constitute fixed object hazards themselves, though hopefully of less 

severity than the hazard they screen. 

Figure 5.5.1 Bridge Safety Feature 

Purpose The barriers on bridges and their approaches are typically intended to provide 

vehicular containment and prevent motorist penetration into the hazard being 

over-passed, such as a stream or under-passing roadway or railroad. Containment 

of an errant vehicle is a primary consideration, but survival of vehicle occupants 

is of equal concern. Thus the design of bridge railing systems and bridge 

approach guardrail systems is intended to first provide vehicular containment and 

redirection, but then to also prevent rollover, to minimize snagging and the 

possibility of vehicle spinout, and to provide smooth vehicular redirection parallel 

with the barrier system. In addition, the bridge railing and bridge approach 

guardrail systems must do all of this within tolerable deceleration limits for seatbelted occupants. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.2

Four Basic Components Barrier systems at bridges are composed of four basic components: 

3⁄4 Bridge railings 

3⁄4 Transitions 

3⁄4 Approach guardrail 

3⁄4 Approach guardrail ends 

Bridge Railings 

The function of bridge railing is to contain and redirect errant vehicles on the 

bridge (see Figured 5.5.2 and 5.5.3). Many rails could conceivably do this, but the 

safety of the driver and redirection of the vehicle must be taken into account. 

Transitions 

A transition occurs between the approach guardrail system and bridge railing (see 

Figures 5.5.2 and 5.5.3). Its purpose is to provide both a structurally secure 

connection to the bridge end post and also a zone of gradual stiffening and 

strengthening of the more flexible approach guardrail system where it is connected 

with the rigid bridge railing. Stiffening is essential to prevent “pocketing” or 

“snagging” of a colliding vehicle just before the rigid bridge railing end. 

If, on impact, a redirective device undergoes relatively large lateral displacements 

within a relatively short longitudinal distance, pocketing is said to have occurred. 

Depending on the degree, pocketing can cause large and unacceptable vehicular 

decelerations. When a portion of the test vehicle, such as a wheel, engages a 

vertical element in the redirective device, such as a post, snagging is said to have 

occurred. The degree of snagging depends on the degree of engagement. 

Snagging may cause large and unacceptable vehicular decelerations. 

Approach Guardrail 

The approach guardrail system is intended to screen motorists from the hazardous 

feature beneath the bridge as they are approaching the bridge (see Figures 5.5.2 

and 5.5.3). This approach guardrail screening is often extended in advance of the 

bridge so as to also screen motorists from any hazardous roadside features on the 

approach to the bridge. 

Approach guardrail must have adequate length and structural qualities to safely 

contain and redirect an impacting vehicle within tolerable deceleration limits. 

Redirection should be smooth, without snagging, and should minimize any 

tendency for vehicle rollover or subsequent secondary collision with other 

vehicles. Similar to bridge railing, approach guardrail systems must satisfy agency 

standards, which specify acceptable heights, materials, strengths, and geometric 

features. 

Approach Guardrail Ends 

The approach guardrail end treatment is the special traffic friendly anchorage of 

the approach guardrail system (see Figures 5.5.2 and 5.5.3). It is located at the end 

at which vehicles are approaching the bridge. Ground anchorage is essential for 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.3

adequate performance of the guardrail system. Special end treatment is necessary 

in order to minimize its threat to motorists as another fixed object hazard within 

the roadside recovery area. 

Figure 5.5.2 Traffic Safety Features 

Figure 5.5.3 Bridge Railing, Transition, Approach Guardrail and End Treatment

(Turn down end treatment no longer acceptable for this roadway

type) 

5.5.2 

Evaluation Each of the various elements of traffic safety features are designed to meet a 

specific function. Based on items from an inspection checklist, the inspector can 

make a determination of whether or not these elements function as intended. The 

elements for bridge railings and guardrail systems including transitions and end 

treatments must pass the minimum standard criteria established by AASHTO and 

FHWA and NCHRP minimum standards for structures on the NHS. 

Design Criteria Until the mid 1980’s, bridge railings were designed consistent with earlier 

precedent, the guidance provided in the AASHTO Standard Specifications for 

Highway Bridges, and professional judgment. The AASHTO Standard 

Specifications called for application of a 10-kip horizontally applied static load at 

key locations, and certain dimensional requirements were also specified. Fullscale crash testing was not required, although a design that “passed” such testing 

was also considered acceptable for use. Subsequent crash testing of several 

commonly used, statically designed bridge railings revealed unexpected failures of 

the systems. It was soon concluded that static design loadings were not sufficient 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.4

to ensure adequate railing performance. As a result of these findings, the FHWA 

issued guidance in 1986 requiring that bridge railing systems must be successfully

crash tested and approved to be considered acceptable for use on Federal-aid 

projects. 

Longitudinal roadside barriers, such as guardrail systems, had also been designed 

consistent with earlier precedent and judgment. Subsequent crash testing of these 

systems again revealed some unacceptable designs and prompted development of 

several new guardrail systems and details that were then identified as acceptable 

for new highway construction on Federal-aid projects. 

History of Crash Testing Full scale crash testing began in 1962. “Highway Research Correlation Circular 

482” listed procedures including specified vehicle mass, impact speed and 

approach angle. 

National Cooperative Highway Research Program (NCHRP) Project 22-2 in 1973 

addressed questions not covered in “Circular 482”. The final report is “NCHRP 

Report 183” which gives more complete set of testing procedures. Several parts of 

the document were known to be based on inadequate information. Procedures 

gained wide acceptance after their publication in 1974, but the need for periodic 

updates was recognized. In 1976, Transportation Research Board (TRB)

committee A2A04 accepted responsibility for reviewing procedure efficiency. The

minor changes were addressed and “Transportation Research Circular 191” was 

published in 1978. 

NCHRP Project 22-2(4) initiated in 1979 was intended to address the major 

changes required in “NCHRP Report 183”. The objective was to review, revise 

and expand the scope of “Circular 191” to reflect current technology. Final report 

was published as NCHRP Report 230 “Recommended Procedures for the Safety 

Performance Evaluation of Highway Safety Appurtenances” in 1980. This report 

served as the primary reference for full scale crash testing of highway safety 

appurtenances. 

In 1987, AASHTO recognized the need to update Report 230. This was due to 

changes in vehicle fleet, emergence of many new designs, matching safety 

performance to levels of roadway utilization, new policies requiring use of safety 

belts, and advances in computer simulation and other evaluation methods. 

NCHRP Project 22-7 was initiated to update Report 230. 

Efforts began in 1989 with a series of white papers. A panel met to discuss the 

issues, debate and develop a consensus on procedures to be included in the update. 

The draft document was distributed for review, and the panel met two more times 

to discuss comments and to develop a final document. This document is NCHRP 

Report 350. This report differs from Report 230 in the following ways: 

3⁄4 Presented as all-metric document 

3⁄4 Provides wider range of test procedures to permit safety performance 

evaluations for a wider range of safety features and utility poles 

3⁄4 Uses a 2000 kg (4,409 pound) pick-up truck in place of a 2040 kg (4500 

pound) passenger car 

3⁄4 Defines other test vehicles including a mini-compact passenger car at 700 

kg (1,543 pounds), single-unit cargo trucks 8000 kg (17,637 pounds), and 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.5

tractor-trailer vehicles 36000 kg (77,366 pounds) for optional testing. 

3⁄4 Includes a broader range of tests for each category of safety feature that 

consider the levels of used of the roadway facility. Six (6) basic test levels 

are defined as well as a number of optional test levels to support more or 

less stringent performance criteria 

3⁄4 Guidelines for selection of critical impact point on redirecting type 

hardware 

3⁄4 Enhance measurement techniques related to occupant risk, and 

incorporates guidelines for device installation and test instrumentation 

3⁄4 Three basic evaluation categories remain the same: occupant risk, lateral 

occupant impact velocity, redirection criteria 

3⁄4 Critical review of methods and technologies for safety performance 

evaluation and incorporates state-of-the-art methods 

3⁄4 Provides optional criteria for side impact testing 

Crash Test Criteria Test requirements generally accepted at first were those contained in the National 

Cooperative Highway Research Program (NCHRP) Report 230 and in several 

earlier Transportation Research Board publications. In 1989, AASHTO published 

its “Guide Specifications for Bridge Railings,” wherein not only were the required 

tests specified but they were categorized into three separate performance levels. A 

warrant selection procedure was also included for determining an appropriate 

performance level for a given bridge site. As the crash test criteria differed in 

some respects from Report 230, use of the “Guide Specification” was, and 

continues to be, optional. 

In 1990, the FHWA identified a number of crash-tested railing systems that met 

the requirements of NCHRP Report 230 or one of the performance levels in the 

AASHTO Guide Specifications. At this point, the FHWA considered that any 

railing that was acceptable based on Report 230 testing could also be considered 

acceptable for use, at least as a PL-1 (performance level 1) as described by the 

AASHTO Guide Specifications. They also stated that any SL-1 (service level 1) 

railing developed and reported in NCHRP Report 239, “Multiple-Service-Level 

Highway Bridge Railing Selection Procedures,” could be considered equivalent to 

a PL-1 railing. 

In 1993, NCHRP Report 230 was superseded by NCHRP Report 350, 

“Recommended Procedures for the Safety Performance Evaluation of Highway 

Features.” Its current testing criteria include provisions for six different test levels, 

all of which differ in some ways from the previous Report 230 tests, as well as 

those in the AASHTO Guide Specifications. No selection procedures or warrants 

for the use of a specific test level are included in Report 350, although a separate 

research effort is underway to establish such warrants. Adding to the conflicting 

guidance for selection of an appropriate bridge railing system, the 1994 AASHTO 

LRFD Bridge Design Specifications were issued as an alternate to the longstanding AASHTO Standard Specifications for Highway Bridges. The 2005 

AASHTO LRFD Bridge Design Specifications now have six test levels to 

correspond to the six levels in Report 350. 

Current FHWA Policy Bridge railings to be installed on National Highway System (NHS) projects must 

meet the acceptance criteria contained in NCHRP Report 350 or a recognized 

successor to those criteria. The minimum acceptable bridge railing for high-speed 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.6

highways is a Test Level 3 (TL-3) unless supported by a rational selection 

procedure (see Table 5.5.1). For locations where the posted speed limit is less than 

72 km/hr (45 mph), a TL-2 bridge railing is considered acceptable. 

Test Level Impact Speed Vehicle Type 

TL-1 50 kph (30 mph) 820 kg car; 2000 kg pickup 

TL-2 70 kph (45 mph) 820 kg car; 2000 kg pickup 

TL-3 100 kph (62 mph) 820 kg car; 2000 kg pickup 

TL-4 100 kph (62 mph) 

80 kph (50 mph) 

820 kg car; 2000 kg pickup 

8000 kg single unit truck 

TL-5 100 kph (62 mph) 

80 kph (50 mph) 

820 kg car; 2000 kg pickup 

36000 kg tractor trailer 

TL-6 100 kph (62 mph) 

80 kph (50 mph) 

820 kg car; 2000 kg pickup 

36000 kg tanker truck 

Table 5.5.1 NCHRP Report 350 Test Level Index 

Railings that have been found acceptable under the crash testing and acceptance 

criteria of NCHRP Report 230, the AASHTO Guide Specifications for Bridge 

Railings, or the AASHTO LRFD Bridge Design Specifications will be considered 

as meeting the requirements of NCHRP Report 350, provided they are equivalent 

to appropriate Report 350 Test Levels. This comparison of equivalencies has been 

tabulated by the FHWA in their May 30, 1997 memorandum on crash testing of 

bridge railings, with an attached May 14, 1996 document on bridge railing design 

and testing. 

The FHWA continues to encourage support for development of railing test level 

selection procedures. In the interim, until AASHTO adopts a new railing test level 

selection procedure, the FHWA will accept the procedures in the AASHTO Guide 

Specifications or, as an alternate, a rational, experience-based, cost beneficial, 

consistently applied procedure proposed by an individual state. A 1996 document 

includes a listing of railings considered acceptable under the NCHRP Report 350 

guidelines or their presumed equivalent guidelines. New crash-tested railings 

continue to be approved and added, and their identity and features can be obtained 

from the FHWA roadside hardware website, 

http://safety.fhwa.dot.gov/roadway_dept/road-_hardware.htm. 

For non-NHS projects, the setting of criteria for establishing acceptability for 

bridge railings has been relegated by the FHWA to the individual states. Some 

states require conformity with the FHWA’s NHS criteria for all bridges, on any of 

the highway systems. In other states, lesser performance criteria are accepted for 

bridges on non-NHS roads, so there may be variations between states as to safety 

feature acceptability. 

Railing Evaluation 

Results/Resources 

The FHWA maintains a website, http://safety.fhwa.dot.gov/roadway_dept/road-

_hardware.htm which identifies all of the bridge and longitudinal roadside barrier 

systems, transitions, and end treatments which have been found to meet the various 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.7

crash test requirements of NCHRP Reports 350 and 230. The website includes 

acceptance letters as well as links to manufacturers’ websites for information on 

proprietary systems. Listings for several categories of safety features are 

accessible. New listings of bridge barriers more recently tested may be found on 

the longitudinal barrier list, so a thorough search of all listings is advisable to 

identify a specific feature and its test results. The May 30, 1997 memorandum and 

its attached document with test level equivalencies can also be found on the 

website. 

Longitudinal barriers specifically used as bridge barriers which meet current crash 

test performance are found at www.fhwa.dot.gov/bridge/bridgerail/ . The “2005 

Bridge Rail Guide” can be found at this web site. This document contains 

photographs, drawings, test level, contact information and cost for the currently 

accepted bridge rails. 

Additional information can also be found in the current AASHTO “Roadside

Design Guide” and in the current AASHTO-AGC-ARTBA Report, “A Guide to 

Standardized Highway Barrier Hardware.” 

Available Courses FHWA-NHI 380032 AASHTO Roadside Design Guide 

This two-day course discusses the use of the Roadside Design Guide including 

applying the clear zone concept, identifying the need for a traffic barrier, 

recognizing unsafe roadside design features and elements. 

FHWA-NHI 380034 Design, Construction, and Maintenance of Highway Safety 

Appurtenances and Features 

This one-day course allows participants to identify advantages and disadvantages 

of different types of longitudinal barriers and crash cushions, identify NCHRP 350 

tested safety appurtenances, and recognize substandard or potentially hazardous 

highway appurtenances or features. 

FHWA-NHI 380034A Design, Construction, and Maintenance of Highway Safety 

Appurtenances and Features 

This two-day course allows participants to identify advantages and disadvantages 

of different types of longitudinal barriers and crash cushions, identify NCHRP 350 

tested safety appurtenances, and recognize substandard or potentially hazardous 

highway appurtenances or features. 

FHWA-NHI 380034B Design, Construction, and Maintenance of Highway Safety 

Appurtenances and Features 

This three-day course allows participants to identify advantages and disadvantages 

of different types of longitudinal barriers and crash cushions, identify NCHRP 350 

tested safety appurtenances, and recognize substandard or potentially hazardous 

highway appurtenances or features. 

The courses listed above can be found by using the following website link 

www.nhi.fhwa.dot.gov/category.asp?category_id=16
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.8

5.5.3 

Identification and 

Appraisal 

Identification of conforming and non-conforming bridge safety features will vary 

depending upon highway classification and the jurisdiction involved. With various 

acceptance criteria to consider and with continuing crash testing and approvals of 

new barriers, it is advisable to rely on the most current specific acceptance criteria 

for the particular state or jurisdiction within which a bridge is located. A listing of 

currently conforming versus non-conforming bridge safety features should be 

obtained for each jurisdiction prior to identification and appraisal of these features 

in the course of bridge inspections within that jurisdiction. 

Appraisal Coding The FHWA Recording and Coding Guide for the Structure Inventory and 

Appraisal of the Nation’s Bridges (Coding Guide) requires an evaluation and 

reporting as to whether each of the four basic components satisfactorily conform to 

current safety design criteria for the respective component. 

The condition of the safety features is not considered in the appraisal, but should 

be well documented in the inspection report. After determining whether the safety 

features at the site are acceptable, the inspector should assign an appraisal code. 

The FHWA Coding Guide contains four entries for safety features: one each for 

the bridge railing, approach guardrail, transition, and end treatment. Some states 

have modified and set different coding standards. 

After making the determination as to whether or not safety features at the site meet 

currently acceptable standards, the inspector assigns an appraisal code of either 1 

(meets) or 0 (does not meet) or N (Not applicable or a safety feature is not 

required*) for each element of Item 36 (page 17), FHWA Coding Guide: 

36A Bridge railings 

36B Transitions 

36C Approach guardrail 

36D Approach guardrail ends 

* For structures on the NHS, national standards are set by federal regulation. For 

those not on the NHS, it shall be the responsibility of the highway agency (state, 

county, local or federal) to set standards. 

While there is only one safety features coding for each element, there are at least 

two bridge railings and up to four approach guardrail treatments. Therefore, the 

bridge inspector should code the worst condition for each element even though 

they may occur at different locations on the bridge. 

The following descriptions of Appraisal Items 36A – 36D are for bridge sites on 

the National Highway System (NHS). Local bridge owners may set different 

criteria to evaluate Items 36A – 36D. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.9

36A Bridge Railings Factors that affect the appraisal ratings of NHS bridge railings, Item 36A, include 

height, material, strength and geometric features (see Figure 5.5.4). The railing 

must be able to smoothly redirect the impacting vehicle. Bridge railings should be 

evaluated using the current AASHTO Standard Specifications for Highway Bridges 

for specific geometric criteria and static loading. The railings must be crash tested 

as per FHWA policy (see Figure 5.5.5). If the railings meet these criteria and 

loading conditions, they are considered acceptable. Other railings that have been 

crash tested but may not meet static load or geometric requirements are considered 

acceptable. 

Figure 5.5.4 Acceptable Bridge Rail 

Figure 5.5.5 Bridge Rail Guide 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.10

36B Transitions Appraisal Item 36B, transitions, requires the transition from the approach guardrail 

to the bridge railing be firmly attached to the bridge rail and gradually stiffened as 

it approaches the bridge rail (see Figure 5.5.6). Transition stiffening is usually 

accomplished through use of: 

3⁄4 Decreased post spacing 

3⁄4 Increased post size 

3⁄4 Embedment of posts in concrete bases 

3⁄4 Increased rail thickness, using a thicker gage rail element or by nesting 

two layers 

Figure 5.5.6 Acceptable Transition 

The ends of curbs or safety walks must be gradually tapered out or shielded. 

Vehicle snagging is discouraged by providing an increased rail surface projection 

with either a broader rail face (e.g., thrie beam) or a rub rail being placed beneath 

the primary rail, to minimize both guardrail post and bridge endpost exposure as 

potential snag points. 

Older transitions usually have some of the essential features but are often lacking 

in some. There may be guardrail anchorage to the bridge but insufficient 

stiffening, or perhaps some degree of stiffening but insufficient concealment of 

potential snag points such as the front corner of the bridge endpost or exposed 

guardrail posts. Cable connections to the bridge railing do not meet minimum 

criteria because they do not provide a smooth stiffened transition. Timber 

approach rail attached to the bridge rail is not an acceptable transition on the NHS. 

No transition is provided at all when the bridge railing and approach guardrail are 

not structurally connected. 

36C Approach Guardrail Because the need for a barrier generally does not stop at the end of the bridge, the 

approach guardrail, Item 36C, must also be evaluated for adequacy. The structural 

adequacy and design compatibility of the approach rail and transition must be 

evaluated. The approach guardrail must be of adequate length and strength to 

shield motorists from the hazards at the bridge site. The guardrail must be able to 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.11

safely redirect the impacting vehicle without snagging or pocketing. Acceptable 

design suggestions may be found in the AASHTO Roadside Design Guide, 

subsequent AASHTO guidelines, or the previously referenced FHWA website. 

The strong post (steel or wood) W-beam guardrails with wood or approved plastic 

blocks (see Figure 5.5.7) are examples of systems meeting the requirements of Test 

Level 3, as are the strong post thrie-beam systems. The same W-beam barriers 

used with a steel block are included for Test Level 2. 

Figure 5.5.7 Approach Guardrail System 

Post and cable systems do not meet minimum criteria for bridge approach 

guardrail systems because they allow both snagging and pocketing of a vehicle 

upon impact. Timber approach guardrail does not meet minimum criteria for 

strength, continuity, or performance. 

36D Approach Guardrail 

Ends 

Approach guiderail ends, Item 36D, must be evaluated for adequacy. A variety of 

guardrail end treatments have been approved for use by the FHWA. The specific 

installation is dependent on various roadway features and testimony procedures as 

administered by the National Cooperative Highway Research Program (NCHRP). 

Current listings of crash tested end treatments and documentation of their 

performance can be found at http://safety.fhwa.dot.gov/

roadway_dept/road_hardware/term_cush.htm. Probably the most universally 

effective is the buried-in-back-slope treatment where the longitudinal barrier is 

introduced from a buried anchorage, typically from a cut slope preceding the 

bridge approach guardrail installation (see Figure 5.5.8). Essential for these 

installations are keeping a constant rail height relative to the roadway grade and 

then provision of both a rub rail and an anchorage capable of developing the full 

strength of the W-beam rail. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.12

Figure 5.5.8 W-Shaped Guardrail End Flared and Buried into an Embankment 

Flaring the guardrail end to reduce the likelihood of a vehicular impact is only 

effective if there is enough space for a substantial flare from the edge of traveled 

way. The guardrail must be flared beyond the clear zone which is the area beyond 

the traveled way available for vehicle recovery. This area may consist of 

shoulder, recoverable or non-recoverable slope, and/or clear run-out area. The 

required width depends on traffic volume, speed, and roadside geometry. 

Burying the guardrail end has been used with and without flaring. If the guardrail 

end is turned down for burying without flaring, it has frequently produced rollover 

accidents and is not currently considered an acceptable end treatment. 

One of several breakaway treatments can be used. The guardrail end is modified 

to permit safe penetration through the system for end impacts, yet effective 

redirection of vehicles for impacts slightly after of the end treatment. 

The last method for railing end treatment is shielding of the barrier with an 

energy-absorbing or attenuating system which dissipates impact energy as an 

impacting vehicle is gradually brought to a stop before reaching a rigid bridge rail 

endpost. Though vehicle damage may be severe, deceleration is controlled within 

tolerable limits to minimize occupant injury. 

A variety of impact attenuators have been used, including expendable sand-filled 

containers, which shatter and absorb energy during impacts. There are also more 

elaborate telescoping fender systems, which redirect side impacts but also 

telescope and attenuate crash energy through crushing of replaceable foam-filled 

cartridges for direct impacts. Older versions absorbed energy through expulsion 

of water from water-filled tubes as the device collapsed. Most parts for these 

more elaborate devices are reusable, making them very suitable for approach 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.13

guardrail end locations where frequent impacts might be expected. 

In certain cases, such as at the trailing end of a one-way bridge, guardrail is not 

required at all. 

The type of end treatment, which has sometimes been called a boxing glove, is not 

an acceptable end treatment unless properly flared away from the traveled way. If 

the guardrail ends are left unprotected, this is also unacceptable (see Figure 5.5.9). 

Figure 5.5.9 Unacceptable Blunt Ends 

5.5.4 

Median Barriers Median barriers are used to separate opposing traffic lanes when the average daily 

traffic (ADT) on the road exceeds a specified amount. They are usually found on 

high speed, limited access highways. 

The most commonly used median barrier on bridges is the concrete median barrier. 

This is a double sided parapet, and it should meet the current criteria for the crash 

testing of bridge railing. The only acceptable end treatment for a concrete median 

barrier is an impact attenuator. 

Double-faced steel W-beam or thrie beam railing on standard heavy posts are also 

used for median barriers. 

Inspection of Median Barriers 

Median barriers should be firmly attached to the deck, and they should be 

functional. They should meet the requirements for Item 36A, bridge railing. 

Inspect for collision damage and attachment to any additional safety features. 

Check for deterioration and spalling on concrete median barriers, and examine for 

corrosion on steel railings and posts. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.14

5.5.5 

Safety Feature 

Inspection 

The inspection of bridge safety features involves evaluation of the condition of the 

bridge railing, the transition, the approach guardrail, and approach guardrail ends

leading from the bridge, the guardrail system leading from the approach roadway 

to the bridge end, and whether these two systems will likely function acceptably 

together to safely contain and redirect errant vehicles which may collide with 

them. 

For structures which are over roadways, the adequacy and condition of traffic 

safety features for both the upper and lower roadways should be evaluated. 

Inspection Criteria that must be considered during the inspection of the bridge railing are the 

height, material, strength, geometric features, and the likelihood of acceptable 

crash test performance. See Subtopic 5.5.3 for the appraisal coding of Items 36A – 

36D. Keep in mind that only the design of the traffic safety feature is addressed in 

Items 36 A – 36D. Deficiencies due to the condition must be recorded separately 

in the inspection notes. 

Many state agencies have developed their own acceptance guidelines for bridge 

railings. The inspector should be familiar with agency guidelines for his or her 

state. 

Bridge Railing 

Comparison of existing bridge railing systems with approved crash-tested designs 

will establish their acceptability and crash worthiness. 

Metal bridge railings should be firmly attached to the deck and should be 

functional. Check especially for corrosion and collision damage, which might 

render these railings ineffective (see Figure 5.5.10). 

Concrete bridge railing is generally cast-in-place and engages reinforcing bars to 

develop structural anchorage in the deck slab. Verify that the concrete is sound 

and that reinforcing bars are not exposed. Inspect for impact damage or rotation, 

and note areas of damage or movement. 

Check for evidence of anchorage failure in precast parapets. Sound exposed 

anchor bolts with a hammer. Check for separations between the base of the precast 

units and deck, or evidence of active water leakage between parapet and deck. 

Some states are removing all precast parapets. 

Inspect post and beam railing systems for collision damage and deterioration of the 

various elements. Post bases should be checked for loss of anchorage. The 

exposed side of the railing must be smooth and continuous. 

For a through truss or arch configuration, separate traffic from structural members, 

especially fracture critical members, with an adequate railing system to prevent 

major structural damage to the bridge and protect vehicle. 

If add-on rails are other than decorative or for pedestrians, their structural 

adequacy can again be verified by comparison with successfully crash tested 

designs. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.15

Figure 5.5.10 Damaged Steel Post Bridge Railing 

 Approach Guardrail 

For approach guardrail, the inspector should verify that agency standards are met.

Make note of rail element type, post size and post spacing for comparison with 

approved designs to verify acceptability of the guardrail system. Note any areas 

where the railing may “pocket” during impact, causing an abrupt deceleration or 

erratic rebound. 

Document any significant collision damage, which is evident (see Figure 5.5.11).

Posts which are displaced horizontally should be reported. Note any deterioration 

of guardrail elements, which could weaken the system. Check for cracks, rust or 

breakage of elements. Check wood posts for rot or insect damage, especially at the 

ground line. The connection between rails and posts should be secure and tight. 

Loose or missing bolts should also be noted. 

Check the approach rail for proper alignment. Note any area of settlement or frost 

heave. Posts embedded in the ground should not be able to be moved by hand. 

Check the slope beyond the posts for settlement or erosion which may reduce 

embedment of the posts (see Figure 5.5.12). 

Unless specifically designed for impact, timber approach guardrail does not meet 

minimum criteria for strength. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.16

Figure 5.5.11 Approach Guardrail Collision Damage 

Figure 5.5.12 Erosion Reducing Post Embedment 

Transition 

Check the approach guardrail transition to the bridge railing for adequate structural 

anchorage to the bridge railing system. Check for sufficiently reduced post 

spacing to assure stiffening of the guardrail at the approach to the rigid bridge rail 

end. Check for smooth transition details to minimize the possibility of snagging 

an impacting vehicle, causing excessive deceleration. For nested installations, be 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.17

sure that the approach rail is properly nested with the lap splice away from the 

direction of traffic. (see Figure 5.5.13). Also check railing, post and offset bracket 

condition. 

Timber should not be used for the rails in transitions on the National highway 

System. 

Figure 5.5.13 Proper Nesting of Guardrail at Transition 

End Treatment 

Note the type, condition, and suitability of any end treatment. Acceptable crashtested end treatments are identified in the AASHTO Roadside Design Guide or with 

current FHWA issuances. Check impact attenuation devices adjacent to bridge 

elements for evidence of damage due to impact and that the energy absorbing 

elements have not ruptured (see Figure 5.5.14). Ensure that any cables and 

anchorages are secure and undamaged. 

End treatments may not be required on the trailing end of a one-way bridge. 
SECTION 5: Inspection and Evaluation of Decks 

TOPIC 5.5: Safety Features 

5.5.18

Figure 5.5.14 Impact Attenuator 

Inspection for Non-NHS 

Bridges 

The requirements for inspection of traffic safety features presented in this topic are 

applicable to bridges on the National highway System (NHS). For bridges which 

are not located on the NHS, it is up to each state department of transportation to set 

its own policies. 

There are still various requirements for that should be met as a minimum for these 

installations. The bridge rail must be crashworthy. The approach guardrail must 

be adequately connected to the bridge rail. Post spacing from the approach 

guiderail to the transition should be reduced to limit deflection. It is recommended

to have nested rail at the transition, but it is not absolutely necessary. End 

treatments should be crash worthy with no blunt ends. Existing turned down ends 

and breakaway cable terminal (BCT) end treatments are acceptable if state policy 

is so stated. Crash worthy end treatments would be better, but may not be cost 

effective on low volume, low speed roads. 

Figure 5.5.15 Timber Traffic Safety Features, Rocky Mountain National Park