# 751.12 Protective Barriers

## 751.12.1 Standard Safety Barrier Bridge Curbs

### 751.12.1.1 Standard Safety Barrier Curbs used in Missouri

 NJ Shape Type ATest Level TL-4 Type BTest Level TL-4 Type CTest Level TL-5 Type DTest Level TL-5

 Note: For Type F (Temporary Barrier Curb), refer to Missouri Standard Plans 617.20. For Thrie Beam Rails, see Widening & Repair information. See Structural Project Manager before using Type C or D barriers.

## 751.12.2 Safety Barrier Bridge Curbs (NJ Shape)

### 751.12.2.1 General Design

New safety barrier curbs "shall be shown to be structurally and geometrically crashworthy". Therefore, the shape of the safety barrier curb is selected based on crash-tested, or equivalent crash-tested geometry.

The safety barrier curb used on new bridges shall be the 16” New Jersey (MO) safety shape barrier curb which has been crash-tested and FHWA approved as meeting test level TL-4.

Test level TL-4 shall be used for safety barrier curb design. TL-4 is defined by AASHTO as being “generally acceptable for the majority of applications on high-speed highways, freeways, expressways, and interstate highways with a mixture of trucks and heavy vehicles”.

* Use Rustication on Highway Grade Seperations only
Safety Barrier Curb Dimensions

Concrete Safety Barrier Curbs Unit weight of reinforced concrete, $\, \gamma_c$ = 150 $\,lb/ft^3$ for modulus of elasticity, $\, \gamma_c$ = 145 $\,lb/ft^3$ Safety Barrier Curbs shall consist of: Class B-1 Concrete $\, f'_c$ = 4.0 ksi $\, n$ = 8 Median Barrier Curbs shall consist of: Class B-1 Concrete $\, f'_c$ = 4.0 ksi $\, n$ = 8 Minimum yield strength, $\, f_y$ = 60.0 ksi Steel modulus of elasticity $\, E_s$ = 29000 ksi

### 751.12.2.2 Standard Reinforcement Details

(*) The single R bar adds to the rigidity of the reinforcement during construction and it is believed to help prevent cracking. The single bar also appears to assist maintaining uniform reinforcement cover.

Reinforcement (No Wearing Surface)
#5-R3
Shape 19
#5-R4
Shape 27 (*)
R-Bar 16" Safety Barrier Curb R-Bar Permissible
Alternate Shape (**)

Reinforcement (1 3/4" Wearing Surface)
#5-R3
Shape 19
#5-R4
Shape 27
R-Bar 16" Safety Barrier Curb R-Bar Permissible
Alternate Shape (**)

Reinforcement (2 1/4" Wearing Surface)
#5-R3
Shape 19
#5-R4
Shape 27
R-Bar 16" Safety Barrier Curb R-Bar Permissible
Alternate Shape (**)
(*) Increase leg for latex or low slump concrete wearing surface.
(**) The R3 bar and #5 bottom transverse slab bar in cantilever (P/S panels only) combination may be
furnished as one bar as shown, at the contractor's option.
 Note: Use same grade reinforcing steel in Barrier Curb as in slab. Splice length for #5 bars in Barrier Curb = 35". Dimensions shown are also typical for structures with latex or low slump concrete (except as indicated).

### 751.12.2.3 End Bent Reinforcement

End Elevation Elevation of Barrier Curb * Spaced with #5-K4 bars. ** Fit bar to follow transition face of curb.

#5-K1Shape 19 #5-K2Shape 14 All bars are epoxy coated. All bars are stirrup bends except for K4, K9, K10 & K11. (*) Increase leg for slabthickness greater than8 1/2".

End Elevation Elevation of Barrier Curb * Spaced with #5-K4 bars. ** Fit bar to follow transition face of curb. *** On skewed structures, if end K3 bar does not meet the Min. 1 1/2" clearancefrom front face of diaphragm, a K12 bar may be substituted.

#5-K1Shape 19 All bars are epoxy coated. All bars are stirrup bends except for K4, K9, K10 & K11.

Elevation of Barrier Curb End Elevation Section A-A Section B-B * Spaced with #5-K4 bars. ** Fit bar to follow transition face of curb.

#5-K1Shape 19 All bars are epoxy coated. All bars are stirrup bends except for K4, K9, K10 & K11.

End Elevation Elevation of Barrier Curb * Spaced with #5-K4 bars. ** Fit bar to follow transition face of curb.

#5-K1Shape 19 #5-K2Shape 14 All bars are epoxy coated. All bars are stirrup bends except for K4, K9, K10 & K11. * According to the development length allowed with the slab depth used, bar may or may not be hooked. Development length starts at slab/barrier interface, basic development length for a straight, #5 epoxy coated bar is 18". ** Length varies depending on slab depth. Extend bar to within 1" of construction joint at bottom of slab. *** Use Shape 11 or create shape as necessary when development length requires hook.

### 751.12.2.4 Slip-Form Reinforcement Details

Section at End Bent (Optional Slip-Form Barrier) (*) Each side of Joint Location.

NOTE TO DETAILER:

Optional Slip-Form Safety Barrier Curb details shall be placed on all jobs (except Prestressed Double-Tee Structures) where applicable.

Add #5 cross bracing bars for Slip-Form option. Base the length of these bars on the shortest distance between joints throughout the structure. Show the C-Bars in the Bar List and note that these bars are for the Slip-Form option only.

### 751.12.2.5 SBC for Wing with Detached Wing Wall

SBC on Non-Integral End Bent (*) SBC on Integral End Bent (*) (*) Detached Wing Wall shown is for illustration purpose only. If the detached wing wall has more than one section, see the Structural Project Managerfor possible additional joints in the safety barrier curb (between sections).

### 751.12.2.7 Joint & Rustication Details

Curb Expansion Joints. Openings required for expansion shall be provided in the barrier curb in conjunction with deck joints. For details of expansion joints in barrier curb see expansion device details.

Curb Joints. 1/4 in. joints are located in the barrier curb at locations of negative moments to prevent cracking in the barrier curb. These joints are required when decks are continuous over intermediate bents for both continuous and simple span structures. These joints are also required at the front face of integral end bents. For details of 1/4 in. curb joints at integral end bents see integral end bent details.

Rustication. Rustication shall be used on grade separations only. Rustication shall be terminated four feet from the end of the barrier curb.

Cast-In-Place Barrier Curbs
Note: Sawcut between spans shall be offset from centerline of intermediate bent to match any existing offset.
Continuous Structures Part Plan    Continuous Re-Deck of Simple Span Structures Part Plan

Part Section Showing Placement of Joints
 * One space = 1/4 Span to nearest 1 in. increment (Span < 40 ft.) One space = 10 ft. (Span = 40 ft. to 125 ft.) Two spaces = 10 ft. (Span > 125 ft.)

Optional Slip-Form Barrier Curbs
Section A-A Section Thru Joint
Part Section Showing Placement of Joints

Continuous Structures Part Plan Note: Sawcut between spans shall be offset from centerline of intermediate bent to match any existing offset. Note: Rustication shall be used on grade separations only. Terminate rustication 4 ft. 0 in. from end of wing.

Part Section Showing Rustication Details Note: Rustication to be used onhighway grade separation only.End rustication 4'-0" from endof wing.

### 751.12.2.8 Plastic Waterstop

To eliminate water seepage problems, use a plastic waterstop, as specified, and in accordance with details shown below.

Use a plastic waterstop at all safety barrier curb joints on grade separations, except over railroads and county roads.

Use a plastic waterstop on lower safety barrier curb joint only, for structures with superelevation on grade separations.

* Rustication to be used on highway grade separations only.
Filled Joint Detail

### 751.12.2.9 Details of Mounting Light Poles on Safety Barrier Curbs

Part Plan Anchor bolts and nuts shall be in accordance with ASTM F1554 Grade 55. Anchor bolts, nuts and washers shall be fully galvanized. Note to Detailer: Extend slab transverse steel to edge of slab in blister region. Note: Conduit not shown for clarity.

### 751.12.2.10 Superelevation Details

Section Thru Superelevated Slab

Section Thru Superelevated Approach Slab at Integral End Bent

Section Thru Superelevated Approach Slab at Non-Integral End Bent
 "A" = 2'-8" + (Superelev. Slope x 16") "B" = 2'-8" - (Superelev. Slope x 16") "C" = 8 1/2" + (Superelev. Slope x 16") "D" = 8 1/2" - (Superelev. Slope x 16")

## 751.12.3 Medians

### 751.12.3.1 Double Faced Median Barrier Curb (NJ Shape)

 Note: Use same grade reinforcing steel in barrier curb as in slab. Splice length for #5-R bars in barrier curb = 35". Do not use this barrier curb over precast prestressed panels.

 Note to detailer: Provide slip-form option for double faced median safety barrier curb. For slip-form option additional #5 cross bracing bars shall be placed on both sides of all joints and R2 bars shall be one bar.

### 751.12.3.2 Concrete Median Curbs

Open Joint (Twin Bridges Typ.) Note: All reinforcement shown shall be epoxy coated. Details shown are very general. Consult Design Layout for specific details for each individual structure.

Open Joint (Twin Bridges Typ.) Barrier Class (No Joint) Bent Bar: Add note to plans: No additional payment will be allowed for the usage ofeither alternate anchoring systems. Resin Anchor: Note: All reinforcement shown shall be epoxy coated.

Superstructure Near Steps Design Crieria:Fence fabric weight = 10#/lin. ft.Eff. wind area = 0.11 area/sq.ft.

Landing (**) May conflict with any proposed expansion device sidewalk, consult Structural Project Manager. Note: 8'-0" max. post spacing for superstructure. (*) Locate at about 30'-0" centers with at least one splice gap between pull posts. (Add the following notes to the plans.)The maximum spacing allowed between pull posts and end posts is 100 ft. Post brace and 1/2”Ø truss rod are required for panels adjacent to pull posts and end posts only. Connect the lower end of the 1/2"Ø truss rod to the bottom of the pull posts and end posts to which the stretcher bar is attached.

Section A-A (Optional fence detail when requested by district or railroad personnel) NOTE: 8'-0" Max. post spacing for superstructure. (*) Locate at about 30'-0" centers with at least one splice gap between pull posts. The maximum spacing allowed between pull posts and end posts is 100 feet. Post brace and 1/2"Ø truss rod are required for panels adjacent to pull posts and end posts only. Connect the lower end of the 1/2"Ø truss rod to the bottom of the pull posts and end posts to which the stretcher bar is attached. (**) May conflict with any proposed expansion device sidewalk, consult Structural Project Manager. Note: 8'-0" max. post spacing for superstructure. (*) Locate at about 30'-0" centers with at least one splice gap between pull possts and end posts.

## 751.12.5 Two Tube Rail (Top Mounted) TL-4 (NCHRP 350)

Guidance

• Meets TL-4 (NCHRP 350)
• Typically used on spread box beam bridges.
• May be used on adjacent box beam bridges where reinforcement is embedded in the beam.
• Use only in certain applications because of cost.
• Acceptable for use when roadway width or site distance is a concern.
• Curb is intrinsic to TL rating and shall be used. Curb shall be used to prevent drainage over deck.
Bridge Standard Drawings - Two Tube Rail (Top Mounted)
(DGN and PDF)
Standard Drawing Guidance may not be available on
Bridge Standard Drawings (PDF) due to formatting.
All Bridge Standard
Drawings (DGN and PDF)
(PDF)
Two Tube Rail Plan and Elevation Details – TTR1
Two Tube Rail Transition Details – TTR2
Two Tube Rail Details – TTR3