Difference between revisions of "751.12 Barriers, Railings, Curbs and Fences"

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m (Smithk moved page 751.12 Protective Barriers to 751.12 Barriers, Curbs and Fences: Per BR, EPG 751.12 Protective Barriers renamed EPG 751.12 Barriers, Curbs and Fences. Replaced most of EPG 751.12 with guidance for new Type H. Type D is now the standard barrier for most bridges.)
m (Per BR, EPG 751.12 Protective Barriers renamed EPG 751.12 Barriers, Curbs and Fences. Replaced most of EPG 751.12 with guidance for new Type H. Type D is now the standard barrier for most bridges.)
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== 751.12.1 Standard Safety Barrier Bridge Curbs ==
+
To be found eligible for Federal-aid funding, new roadside safety devices should meet the crash test and evaluation criteria contained in the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH).  Since neither FHWA nor AASHTO has a system in place to approve roadside devices, the responsibility is left with the States.  In response, MoDOT has developed a MASH Implementation process. All roadside devices that are submitted after November 1, 2019, will be reviewed by the MASH Team for approval to use on Missouri roadways. Prior to November 1, 2019 roadside devices were considered using the criterion set forth in NCHRP Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway Features”.  While MASH requirements are only applicable to the NHS, the following guidelines are recommended for all bridges.
  
 +
==751.12.1 Concrete Barriers==
  
−
=== 751.12.1.1 Standard Safety Barrier Curbs used in Missouri ===
+
Type D barrier replaced Type B barrier (previously safety barrier curb) as the standard railing for bridges awarded after December 31, 2019. Similarly, Type C barrier replaced Type A barrier (previously median barrier curb).  Types H and G shall be used respectively for situations where Types D and C is considered impractical.
 +
[[image:751.12.1.jpg|center|600px]]
 +
Single sloped barriers have been shown to reduce vehicle climb and increase vehicle stability during redirections when compared to New Jersey shaped barriers.  See the following sections for more details on standard barriers. Details for Type G have not been developed, but that does not prevent its use if need dictates.
  
−
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:center"
+
Concrete barriers were approved for TL-3 or TL-4 test levels in accordance with the MASH 2016 standards.  The required MASH 2016 test level for bridges on the National Highway System (NHS) is TL-3, but the expectation is that the TL-4 requirement will be mandated in the next publication.
 +
 
 +
Test level TL-3 is defined by AASHTO as being “generally acceptable for a wide range of high-speed arterial highways with very low mixtures of heavy vehicles and with favorable site conditions.”
 +
 
 +
Test level 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”.
 +
 
 +
===751.12.1.1 Material Properties===
 +
{| style="margin: 1em auto 1em auto"
 
|-
 
|-
−
|colspan="2"|[[Image:751.12 barrier curb - NJ Shape.gif]]
+
!Class B-1 Concrete!! !! Epoxy Coated Reinforcing Steel
 
|-
 
|-
−
|Type A<br/>Test Level TL-4
+
|Unit weight (reinforced), wc = 0.150 kcf||width="15px| ||Yield strength, fy = 60.0 ksi
−
|Type B<br/>Test Level TL-4
 
 
|-
 
|-
−
!colspan="2"|NJ Shape
+
|Compressive strength, f’c = 4.0 ksi|| ||Modulus of elasticity, Es = 29,000 ksi
 
|-
 
|-
−
|colspan="2"| &nbsp;
+
|Modular ratio, n = 8|| ||
 
|-
 
|-
−
|colspan="2"|[[Image:751.12 barrier curb - type c & d.gif]]
+
|Modulus of elasticity, Ec = 3644 ksi || ||
−
|-
 
−
|Type C<br/>Test Level TL-5
 
−
|Type D<br/>Test Level TL-4 (NCHRP 350)
 
 
|}
 
|}
  
 +
===751.12.1.2 General Details===
 +
Regardless of type of barrier shown the following sections are applicable for all concrete barrier types.
 +
 +
Top of barrier shall be built parallel to grade with barrier joints (except at end bents) normal to grade.
  
−
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:left"
+
All exposed edges of barrier shall have either a 1/2-inch radius or a 3/8-inch bevel, unless otherwise noted.  
−
|-
 
−
!Note:
 
−
|For Type F (Temporary Barrier Curb), refer to Missouri Standard Plans 617.20.
 
−
|-
 
−
| &nbsp;
 
−
|For Thrie Beam Rails, see Widening & Repair information.
 
−
|-
 
−
| &nbsp;
 
−
|See Structural Project Manager before using Type C or D barriers.
 
−
|}
 
  
−
== 751.12.2 Safety Barrier Bridge Curbs (NJ Shape) ==
+
====751.12.1.2.1 Slip Forming====
 +
Conventional or slip forming may be used except for situations where slip forming is considered impractical.
  
 +
See barrier elevation sheets of the [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier standard drawings] for the required details.
  
−
=== 751.12.2.1 General Design ===
+
Slip forming is impractical for prestressed double-tee bridges.
  
−
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. 
+
'''Cross Bracing C Bars'''
  
−
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.
+
Slip forming requires two No. 5 cross bracing C bars located each side of all joints and at barrier ends.
  
−
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”.
+
List C bars in the Bill of Reinforcing Steel and note that bars are for the slip-formed option only.
  
 +
For barrier segments on top of the bridge deck, use 12-foot C1 bars.
  
−
[[Image:751.12.2.1.jpg|center|400px]]
+
For barrier segments on top of the end bent wings:
−
All exposed edges shall have either a 1/2-inch radius or a 3/8-inch bevel, unless otherwise noted.
+
:For segments < 14'-4", use C2 bars ending no closer than 29.5" from end of barrier.
 +
:For segments ≥ 14'-4" and ≤ 18'-0", use the 12-foot C1 bars.
 +
:For segments > 18'-0", use two sets of C2 bars with first set ending no closer than 29.5" from end of barrier.
  
−
The values shown above are only applicable for the standard normal crown of two percent. See [[#751.12.2.10 Superelevation Details |EPG 751.12.2.10 Superelevation Details]] for adjustment of values for different cross slopes.
+
'''Textured Fiberglass Bars'''
  
 +
Slip forming requires three four-feet long No. 4 textured fiberglass bars centered at each joint.
  
 +
====751.12.1.2.2 Joints====
 +
See barrier elevation sheets of the [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier standard drawings] for the required details.
  
−
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:center"
+
One-fourth-inch joints are located in the barrier at locations of negative moments to prevent cracking in the barrier. Barrier joints may be formed using ¼-inch joint filler in accordance with Sec 1057 or saw cut and seal with silicone joint sealant in accordance with Sec 717. Saw cuts joints may be used with the conventional forming option.
−
|+'''Material Properties'''
 
−
!align="left"|Concrete
 
−
| &nbsp;
 
−
|-
 
−
|align="right"|Unit weight of reinforced concrete,
 
−
|<math>\, \gamma_c</math> = 150 <math>\,lb/ft^3</math>
 
−
|-
 
−
|align="right"|for modulus of elasticity,
 
−
|<math>\, \gamma_c</math> = 145 <math>\,lb/ft^3</math>
 
−
|-
 
−
!align="left"|Safety Barrier Curbs
 
−
| &nbsp;
 
−
|-
 
−
|align="left"|Safety Barrier Curbs shall consist of:
 
−
| &nbsp;
 
−
|-
 
−
|align="right"|Class B-1 Concrete
 
−
| <math>\, f'_c</math> = 4.0 ksi
 
−
|-
 
−
| &nbsp;
 
−
|<math>\, n</math> = 8
 
−
|-
 
−
!align="left"|Median Barrier Curbs
 
−
| &nbsp;
 
−
|-
 
−
|align="left"|Median Barrier Curbs shall consist of:
 
−
| &nbsp;
 
−
|-
 
−
|align="right"|Class B-1 Concrete
 
−
| <math>\, f'_c</math> = 4.0 ksi
 
−
|-
 
−
| &nbsp;
 
−
|<math>\, n</math> = 8
 
−
|-
 
−
!align="left"|Reinforcing steel
 
−
| &nbsp;
 
−
|-
 
−
|align="right"|Minimum yield strength,
 
−
|<math>\, f_y</math> = 60.0 ksi
 
−
|-
 
−
|align="right"|Steel modulus of elasticity
 
−
|<math>\, E_s</math> = 29000 ksi
 
−
|}
 
  
−
=== 751.12.2.2 Standard Reinforcement Details ===
+
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 placement of barrier joints at integral end bents see integral end bent details.
 +
[[image:751.12.1.2.2.1.jpg|center|550px]]
  
−
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.
+
Additional joints at 12-foot spacing from joint at intermediate bents may be required based on span lengths. The following details provide guidance on locating flexural joints near intermediate bents. This spacing will allow the full yield-line failure pattern to develop for Type D barrier. For simplicity, the 12-foot spacing shall also be used for all other concrete barrier types.
 +
[[image:751.12.1.2.2.2.jpg|center|600px]]
  
−
Use same grade reinforcing steel in barrier curb as in slab.
+
====751.12.1.2.3 Plastic Waterstops====
 +
See barrier elevation sheets of the [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier standard drawings] for the required details.  
  
−
Splice length for #5 bars in barrier curb shall be 3’-1” except splice length of #5-K9 bars with #4 K-bars above wing walls shall be 2’-7” (embedment of #5 bars controls over splice length of #4 bars).  
+
Plastic waterstops are typically located inside formed joints to eliminate water seepage problems on grade separations. They shall be excluded over railroads and county roads and are only required on the lower side of superelevated decks.
  
−
All bars are epoxy coated. All bent bars are formed using stirrup bends except for the R1, K4 and K11 bars.
+
====751.12.1.2.4 Guardrail Attachment====
 +
See barrier at end bents sheets of the [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier standard drawings] for the required details.
 +
[[image:751.12.2.6.jpg|center|325px]]
  
−
'''(No Wearing Surface)'''
+
====751.12.1.2.5 Superelevation====
 +
Superelevated slope, S.E., is in decimal format for the follow calculation, i.e. use 0.04 for 4.0%.
 +
[[image:751.12.2.5.1.jpg|center|650px]]
 +
[[image:751.12.2.5.2.jpg|center|670px]]
  
−
Dimensions shown are also typical for structures with latex or low slump concrete (except as indicated).
+
====751.12.1.2.6 Detached Wing Walls====
−
[[image:751.12.2.2 no wearing.jpg|center|750px]]
+
If the detached wing wall has more than one section, see the Structural Project Manager for possible additional joints in the barrier (between sections).  
  
 +
The following details are for illustration purposes only:
 +
[[image:751.12.2.6 end bents.jpg|center|550px]]
  
−
'''(1¾” Wearing Surface)'''
+
====751.12.1.2.7 Light Poles====
−
[[image:751.12.2.2 1 3-4 wearing.jpg|center|750px]]
+
[[image:751.12.2.7.1.jpg|center|675px]]
 +
[[image:751.12.2.7.2.jpg|center|650px]]
  
−
+
Anchor bolts and nuts shall be in accordance with ASTM A449. Anchor bolts, nuts and washers shall be fully galvanized.  
−
'''(2¼” Wearing Surface)'''
 
−
[[image:751.12.2.2 2 1-4 wearing.jpg|center|750px]]
 
  
−
=== 751.12.2.3 End Bent Reinforcement ===
+
'''Note to Detailer:''' Extend slab transverse steel to edge of slab in blister region often shown with an additional detail with the slab details.  
  
−
See [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier curb standard drawings] for the placement of the following reinforcement for barrier ending on wing walls. The dimensions shown below are for barrier ending on wing walls; see [http://www.modot.org/business/standard_drawings2/WFRedecking.htm redecking templates] for dimensions and placement of the reinforcement for barrier ending on slabs.
+
'''Note:''' Conduit not shown for clarity.
  
−
All bars are epoxy coated. All bent bars are formed using stirrup bends except for the K4 and K11 bars.
+
===751.12.1.3 Type D and H (42ʺ and 32ʺ single sloped railing)===
 +
The 42-inch single sloped Type D barrier shall be used for railing on all new or replacement bridge projects except where sight distance is a concern.  Type D meets the height requirements for both MASH TL-4 (36ʺ) and Occupational Safety and Health Administration’s OSHA (42ʺ).  Type D barrier has been reviewed by the Midwest Roadside Safety Facility (MwRSF) and is compliant with MASH 2016 TL-4.  This assessment is applicable for continuous and discontinuous sections of the barrier.  Type D barrier shall be used on all redecks and rehabs where the full length of barrier is being replaced with exceptions for the following: 1) sight distance concerns, 2) rating concerns where the weight of the barrier prohibits its use or causes impractical restrictions or costs for the project. The Type D barrier dimensions shall not be adjusted for inclusion of a wearing surface.
  
−
'''Integral End Bents and Semi-Deep Abutments'''
+
The 32-inch single sloped Type H barrier shall be used for railing, upon approval of the SPM or SLE, on all new or replacement bridge projects where sight distance concerns prohibit the use of Type D. Type H has the same front face slope as Type D. The minimum height for MASH TL-3 is 30 inches so there are minimal concerns with Type H for future overlays. The TL-3 height requirement has been updated since the release of SEG 20-001. Type H barrier has been reviewed by the Midwest Roadside Safety Facility (MwRSF) and is compliant with MASH 2016 TL-3. This assessment is applicable for continuous and discontinuous sections of the barrier. When a wearing surface is applied with the newly constructed Type H barrier, a pedestal is recommended to keep the holes for the guardrail attachment in the same location with respect to the top of the barrier.
−
[[image:751.12.2.3 Integral 1.jpg|center|700px]]
 
−
[[image:751.12.2.3 Integral 2.jpg|center|700px]]
 
  
 +
====751.12.1.3.1 Typical Section====
 +
All values may be used with both 2.0% and 3/16 inch-per-foot cross slopes.
  
−
'''*''' On skewed integral end bents, if the end K3 bars do not meet the minimum 1 1/2" clearance from the front face of the diaphragm, a K12 bar shall be substituted.
+
See [[#751.12.1.2.5 Superelevation|EPG 751.12.1.2.5 Superelevation]] for adjustment of values for different cross slopes.
 +
[[image:751.12.1.3.1.jpg|center|700px]]
  
−
'''Non-Integral End Bents'''
+
====751.12.1.3.2 Typical Section Reinforcement====
−
[[image:751.12.2.3 Non-integral 1.jpg|center|700px]]
+
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.  
−
[[image:751.12.2.3 Non-integral 2.jpg|center|700px]]
 
  
 +
Splice length for horizontal #5 bars in barrier curb shall be 37 inches.
  
−
'''Continuous Concrete Slab'''
+
All bent bars are formed using stirrup bends except for the Type D #5-R1 bars.
−
[[image:751.12.2.3 continuous 1.jpg|center|700px]]
 
−
[[image:751.12.2.3 continuous 2.jpg|center|700px]]
 
  
−
=== 751.12.2.4 Slip-Form Reinforcement Details ===
+
All values may be used with both 2.0% and 3/16 inch-per-foot cross slopes.
 +
[[image:751.12.1.3.2.jpg|center|750px]]
  
−
Optional slip-form safety barrier curb details shall be placed on all jobs (except prestressed double-tee structures) where applicable.  
+
====751.12.1.3.3 End of Barrier Reinforcement====
 +
See [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier standard drawings] for the required details.
 +
 
 +
All bent bars are formed using stirrup bends. 
  
−
Add #5 cross bracing C bars for slip-form option.
+
All dimensions shown may be used with both 2.0% and 3/16 inch-per-foot cross slopes.
  
−
In each span, the length of the C bars is based on the shortest distance between the joints for that span.
+
=====751.12.1.3.3.1 Type D Ending on Integral End Bents=====
 +
Use when distance between upper and lower construction joint in wings is at least 28½ inches.
 +
[[image:751.12.1.3.3.1.1.jpg|center|700px]]
 +
[[image:751.12.1.3.3.1.2.jpg|center|700px]]
  
−
The length of the C bars above the wings (above the approach slab for median barriers) shall provide 1 1/2ʺ clearance to the joint at the end bent and 1 1/2ʺ clearance to the start of the transition for the guard rail attachment (to the end of the barrier for median barriers). A series of cross bracing C bars shall be used to limit the length of the C bars to 12 feet.
+
=====751.12.1.3.3.2 Type H Ending on Integral End Bents=====
 +
Use when distance between upper and lower construction joint in wings is at least 28½ inches.
 +
[[image:751.12.1.3.3.2.1.jpg|center|700px]]
 +
[[image:751.12.1.3.3.2.2.jpg|center|700px]]
  
−
List C bars in the Bill of Reinforcing Steel and note that bars are for the slip-form option only.  
+
=====751.12.1.3.3.3 Type D Ending on Shallow Integral End Bents=====
 +
Use when distance between upper and lower construction joint in wings is less than 28½ inches.
  
−
See [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier curb standard drawings] for the required details.
+
Formulas extend bars to within 1½ʺ of lower construction joint.  
  
−
=== 751.12.2.5 SBC for Wing with Detached Wing Wall ===
+
Use Shape 27 for K3 bar in Barbill program to obtain correct weight and length. Revise Shape 27 on plan sheet to Shape 50 and add shape to bending diagrams.
 +
[[image:751.12.1.3.3.3.1.jpg|center|700px]]
 +
[[image:751.12.1.3.3.3.2.jpg|center|680px]]
  
−
If the detached wing wall has more than one section, see the Structural Project Manager for possible additional joints in the safety barrier curb (between sections).
+
=====751.12.1.3.3.4 Type H Ending on Shallow Integral End Bents=====
 +
Use when distance between upper and lower construction joint in wings is less than 28½ inches.
  
−
The following details are for illustration purpose only:
+
Formulas extend bars to within 1½ʺ of lower construction joint.
  
−
[[image:751.12.2.5 Non-integral.jpg|center|550px]]
+
Use Shape 27 for K3 bar in Barbill program to obtain correct weight and length. Revise Shape 27 on plan sheet to Shape 50 and add shape to bending diagrams.
 +
[[image:751.12.1.3.3.4.1.jpg|center|680px]]
 +
[[image:751.12.1.3.3.4.2.jpg|center|700px]]
  
−
[[image:751.12.2.5 Integral.jpg|center|550px]]
+
=====751.12.1.3.3.5 Type D Ending on Non-Integral End Bents=====
 +
Use when distance between upper and lower construction joint in wings is at least 28½ inches.
 +
[[image:751.12.1.3.3.5.1.jpg|center|700px]]
 +
[[image:751.12.1.3.3.5.2.jpg|center|680px]]
  
−
=== 751.12.2.6 Guardrail Attachment Detail ===
+
=====751.12.1.3.3.6 Type H Ending on Non-Integral End Bents=====
 +
Use when distance between upper and lower construction joint in wings is at least 28½ inches.
 +
[[image:751.12.1.3.3.6.jpg|center|700px]]
  
−
See [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier curb standard drawings] for the required details.
+
=====751.12.1.3.3.7 Type D Ending at End of Slab (Redecks)=====
 +
Splice length of #5 K12 and #5 K13 bars with #5 R-bars shall be 37 inches.
 +
[[image:751.12.1.3.3.7.jpg|center|700px]]
  
−
[[image:751.12.2.6.jpg|center|450px]]
+
=====751.12.1.3.3.8 Type H Ending at End of Slab (Redecks)=====
 +
Splice length of #5 K7 bars with #5 R-bars shall be 37 inches.
 +
[[image:751.12.1.3.3.8.jpg|center|700px]]
  
 +
===751.12.1.4 Type B (32ʺ New Jersey Shaped Railing)===
 +
The 32-inch New Jersey shaped railing, previously referred to as safety barrier curb, shall not be used on new construction projects.  This includes redecks and rehabs where the full length of barrier is being replaced. Type B barrier may be replaced in kind where spot work is required (i.e., expansion joint replacements).  For wearing surface projects, where the grade is not being increased more than 2 inches, the existing Type B barrier may be used in place in accordance with [[751.1 Preliminary Design#751.1.3.4 Railing Type, Height and Guidelines for Curb Blockouts|EPG 751.1.3.4 Railing Type, Height and Guidelines for Curb Blockouts]].
  
−
=== 751.12.2.7 Joint Details ===
+
=====751.12.1.4.1 Typical Section=====
 +
[[image:751.12.1.4.1.jpg|center|650px]]
 +
See [[#751.12.1.2.5 Superelevation|EPG 751.12.1.2.5 Superelevation]] for adjustment of values for different cross slopes.
  
−
'''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.
+
=====751.12.1.4.2 Typical Section Reinforcement=====
 +
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.  
  
−
'''Barrier Curb Joints.'''  One-fourth inch 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 placement of curb joints at integral end bents see integral end bent details. The following details provide guidance on locating curb joints near intermediate bents.
+
Splice length for horizontal #5 bars in barrier curb shall be 37 inches.  
  
−
[[image:751.12.2.7.jpg|center|750px]]
+
All bent bars are formed using stirrup bends except for the R1 bars.
−
<center>
+
[[image:751.12.1.4.2.jpg|center|700px]]
−
{| style="margin: 1em auto 1em auto"
 
−
|-
 
−
|'''*'''||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.)
 
−
|}
 
−
</center>
 
−
Joints for conventional-formed barrier curbs may be either formed joints filled with one-fourth inch joint filler or saw cut joints sealed with joint sealant and backer rods.
 
  
−
Joints for slip-formed barrier curbs shall only be saw cut joints sealed with joint sealant and backer rods.
+
=====751.12.1.4.3 End of Barrier Reinforcement=====
 +
See barrier ending on end bents sheets of the [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier standard drawings] for the required details. The bars shown below are for barrier ending on wing walls; see barrier ending at end of slab sheet of the barrier standard drawings for reinforcement details for barrier ending on slabs.  
  
−
The details for saw cut and formed barrier curb joints are included on the [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier curb standard drawings].
+
Splice length of #5-K9 bars with #4 K-bars above wing walls shall be 31 inches (embedment of #5 bars controls over splice length of #4 bars).
  
−
=== 751.12.2.8 Plastic Waterstop ===
+
All bent bars are formed using stirrup bends except for the K4 and K11 bars.  
  
−
To eliminate water seepage problems, use a plastic waterstop, as specified, and in accordance with details shown below.
+
'''Ending on Integral End Bents and Semi-Deep Abutments'''
 
   
 
   
−
Use a plastic waterstop at all formed barrier curb joints on grade separations, except over railroads and county roads.  
+
Use when distance between upper and lower construction joint in wings is at least 28½ inches.
 +
[[image:751.12.1.4.3.1.jpg|center|600px]]
 +
[[image:751.12.1.4.3.2.jpg|center|650px]]
  
−
Use a plastic waterstop on lower formed barrier curb joints only, for structures with superelevation on grade separations.
+
'''Ending on Shallow Integral End Bents'''
  
−
The detail for plastic waterstop is included on the [http://www.modot.org/business/standard_drawings2/Barrier_curbs_new_title_block.htm barrier curb standard drawings]. The detail shall be removed if not required.
+
Use when distance between upper and lower construction joint in wings is less than 28½ inches.
 +
[[image:751.12.1.4.3.3.jpg|center|600px]]
 +
[[image:751.12.1.4.3.4.jpg|center|650px]]
  
−
=== 751.12.2.9 Details of Mounting Light Poles on Safety Barrier Curbs ===
+
'''Ending on Non-Integral End Bents '''
  
−
[[image:751.12.2.9 part 2019.jpg|center|750px]]
+
Use when distance between upper and lower construction joint in wings is at least 28½ inches.
−
[[image:751.12.2.9 section 2019.jpg|center|750px]]
+
[[image:751.12.1.4.3.5.jpg|center|600px]]
 +
[[image:751.12.1.4.3.6.jpg|center|650px]]
  
−
Anchor bolts and nuts shall be in accordance with ASTM A449. Anchor bolts, nuts and washers shall be fully galvanized.
+
===751.12.1.5 Type C (42ʺ Single Sloped Median)===
 +
====751.12.1.5.1 Typical Section====
 +
[[image:751.12.1.5.1.jpg|center|275px]]
  
−
'''Note to Detailer:''' Extend slab transverse steel to edge of slab in blister region often shown with an additional detail with the slab details.  
+
====751.12.1.5.2 Typical Section Reinforcement====
 +
[[image:751.12.1.5.2.jpg|center|650px]]
  
−
'''Note:''' Conduit not shown for clarity.
+
===751.12.1.6 Type A (32ʺ New Jersey Shaped Median)===
 +
Note: Use same grade reinforcing steel in barrier as in slab.
 +
::: Splice length for #5-R bars in barrier  = 37".
 +
::: Do not use this barrier over precast prestressed panels.
 +
[[image:751.12.1.6.jpg|center|375px]]
  
−
=== 751.12.2.10 Superelevation Details ===
+
'''Twin Bridge Median Barrier Details'''
 +
[[image:751.12.1.6.1.jpg|center|375px]]
  
−
[[Image:751.12.2.10 1.jpg|center|700px]]
+
==751.12.2 Two Tube Rail (Top Mounted) TL-4 (NCHRP 350)==
−
[[Image:751.12.2.10 2.jpg|center|700px]]
 
−
[[Image:751.12.2.10 3.jpg|center|700px]]
 
  
−
{|align="center"
+
'''Guidance'''
  
−
|"A"|| = 32'-8" + S.E. x 16"
+
:* Meets TL-4 (NCHRP 350)
−
|-
+
:* Typically used on spread box beam bridges.
−
|B|| = 32'-8" - S.E. x 16"
+
:* May be used on adjacent box beam bridges where reinforcement is embedded in the beam.
−
|-
+
:* Use only in certain applications because of cost. Consult the Structural Project Manager.
−
|C|| = 8 1/2" + S.E. x 16"
+
:* 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.
−
|D|| = 8 1/2" - S.E. x 16"
 
−
|}
 
  
−
== 751.12.3 Medians ==
+
'''Details'''
−
 
+
<center>
−
 
+
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"
−
=== 751.12.3.1 Double Faced Median Barrier Curb (NJ Shape) ===
+
|+
−
 
+
| style="background:#BEBEBE" width="300" |'''[http://www.modot.org/business/consultant_resources/bridgestandards.htm Bridge Standard Drawings]'''
−
{|
 
−
|valign="top"|Note:||Use same grade reinforcing steel in barrier curb as in slab.
 
 
|-
 
|-
−
|&nbsp;||Splice length for #5-R bars in barrier curb = 37".
+
|align="center"|[http://www.modot.org/business/standard_drawings2/TwoTubeRail.htm Two Tube Rail]
−
|-
 
−
|&nbsp;||Do not use this barrier curb over precast prestressed panels.
 
 
|}
 
|}
  
 +
</center>
  
−
{|
+
==751.12.3 Median Curbs==
−
|width="100pt" valign="top"|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.
+
[[image:751.12.3.1.jpg|center|550px]]
−
|}
+
:::'''Note:''' All reinforcement shown shall be epoxy coated.  
−
 
 
−
 
 
−
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:center"
 
−
 
 
−
|[[Image:751.12 double-faced median barrier curb reinforcement-r2 bar.gif]]
 
−
|[[Image:751.12 double-faced median barrier curb reinforcement-r4 bar.gif]]
 
−
|-
 
−
!R2 Bar<br/>Shape 15
 
−
!R4 Bar<br/>Shape 27
 
−
|-
 
−
|colspan="2"|[[Image:751.12 section thru double faced median barreir curb.gif]]
 
−
|-
 
−
!colspan="2"|Section Thru Double Faced Median Barrier Curb
 
−
|-
 
−
|colspan="2"| &nbsp;
 
−
|-
 
−
!colspan="2"|Twin Bridge Median Barrier Curb Details
 
−
|-
 
−
|colspan="2"|[[Image:751.12 section thru median curb with open joint.gif]]
 
−
|-
 
−
!colspan="2"|Section Thru Median with Open Joint
 
−
|}
 
−
 
 
−
=== 751.12.3.2 Concrete Median Curbs ===
 
−
 
 
−
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:center"
 
−
 
 
−
|[[Image:751.12 concrete median curbs-open joint (twin bridges typ).gif]]
 
−
|-
 
−
!Open Joint (Twin Bridges Typ.)
 
−
|-
 
−
|[[Image:751.12 concrete median curbs-barrier class (no joint).gif]]
 
−
|-
 
−
!Barrier Class (No Joint)
 
−
|-
 
−
|[[Image:751.12 concrete median curbs-mountable class.gif]]
 
−
|-
 
−
!Mountable Class
 
−
|-
 
−
|'''Note:''' All reinforcement shown shall be epoxy coated.
 
−
|-
 
−
|Details shown are very general.  Consult Design Layout for specific details for each individual structure.
 
−
|}
 
−
 
 
  
−
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:center"
+
Details shown are very general. Consult Design Layout for specific details for each individual structure.  
−
|+'''Concrete Median Curbs (Permissable Alternates)'''
 
−
|colspan="2" align="left"|'''Bent Bar:'''
 
−
|-
 
−
|[[Image:751.12 concrete median curbs (permissalbe alternates)-open joint (twin bridges typ.).gif]]
 
−
|[[Image:751.12 concrete median curbs (permissalbe alternates)-barrier class (no joint).gif]]
 
−
|-
 
−
!Open Joint (Twin Bridges Typ.)
 
−
!Barrier Class (No Joint)
 
−
|-
 
−
|[[Image:751.12 concrete median curbs (permissalbe alternates)-detail a.gif]]
 
−
|[[Image:751.12 concrete median curbs (permissalbe alternates)-detail b.gif]]
 
−
|-
 
−
!Detail "A"
 
−
!Detail "B"
 
−
|-
 
−
|rowspan="2"|[[Image:751.12 concrete median curbs (permissalbe alternates)-field bent bar.gif]]
 
−
|align="left" valign="bottom"|Add note to plans:
 
−
|-
 
−
|align="left" valign="top"|No additional payment will be allowed for the usage of<br/>either alternate anchoring systems.
 
−
|-
 
−
|colspan="2" align="left"|'''Resin Anchor:'''
 
−
|-
 
−
|colspan="2"|[[Image:751.12 concrete median curbs (permissalbe alternates)-resin anchor choice.gif]]
 
−
|-
 
−
|colspan="2"|'''Note:''' All reinforcement shown shall be epoxy coated.
 
−
|}
 
  
−
== 751.12.4 Chain Link Fence ==
+
[[image:751.12.3.2.jpg|center|700px]]
 +
[[image:751.12.3.3.jpg|center|650px]]
  
−
'''Design Criteria:'''
+
==751.12.4 Chain Link Fence==
 +
'''Design Criteria: '''
  
−
Dead load of fence fabric weight: 10 lbs/lin. ft.
+
Dead load of fence fabric weight: 10 pounds per linear foot.  
  
−
Wind load for chain link or metal fabric fence: GREATER OF 0.015 ksf acting normal to the entire surface per LRFD 13.8.2 OR 0.11 x entire surface x calculated wind pressure (11% is effective surface area per MoDOT practice).
+
Wind load for chain link or metal fabric fence: GREATER OF 0.015 ksf acting normal to the entire surface per LRFD 13.8.2 OR 0.11 x entire surface x calculated wind pressure (11% is effective surface area per MoDOT practice).  
  
  
Line 388: Line 321:
 
!colspan="2"|Details of Expansion Device Gap
 
!colspan="2"|Details of Expansion Device Gap
 
|-
 
|-
−
|colspan="2"|(**) May conflict with any proposed expansion device sidewalk, consult Structural Project Manager.
+
|colspan="2"|(**) May conflict with any proposed expansion device sidewalk, consult Structural Project Manager.  
 
|-
 
|-
 
!colspan="2"|&nbsp;
 
!colspan="2"|&nbsp;
Line 396: Line 329:
 
!colspan="2"|Typical Section Near Splice Gap
 
!colspan="2"|Typical Section Near Splice Gap
 
|-
 
|-
−
|colspan="2" align="left"|'''Note:''' 8'-0" max. post spacing for superstructure.
+
|colspan="2" align="left"|'''Note:''' 8'-0" max. post spacing for superstructure.  
 
   
 
   
−
(*) Locate at about 30'-0" centers with at least one splice gap between pull posts.
+
(*) Locate at about 30'-0" centers with at least one splice gap between pull posts.  
 
   
 
   
 
'''(Add the following notes to the plans.)'''<br/>The maximum spacing allowed between pull posts and end posts is 100 ft. Post brace and 1/2ӯ truss rod are required for panels adjacent to pull posts and end posts only.<br>
 
'''(Add the following notes to the plans.)'''<br/>The maximum spacing allowed between pull posts and end posts is 100 ft. Post brace and 1/2ӯ truss rod are required for panels adjacent to pull posts and end posts only.<br>
−
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.  
+
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.
 
|}
 
|}
  
Line 407: Line 340:
  
 
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:center"
 
{|border="0" cellpadding="5" cellspacing="1" align="center" style="text-align:center"
−
|+'''(112") Curved top Pedestrian Fence (Structures)'''
+
|+'''(112") Curved Top Pedestrian Fence (Structures)'''
−
|(Optional fence detail when requested by district or railroad personnel)
+
|(Optional fence detail when requested by district or railroad personnel)  
 
|-
 
|-
 
|[[Image:751.12.4 section aa.jpg|700px]]
 
|[[Image:751.12.4 section aa.jpg|700px]]
Line 442: Line 375:
 
|align="left"|'''Note:''' 8'-0" max. post spacing for superstructure.
 
|align="left"|'''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.
+
(*) Locate at about 30'-0" centers with at least one splice gap between pull posts and end posts.
−
|}
 
−
 
 
−
<div id="751.12.5 Two Tube Rail"></div>
 
−
 
 
−
==751.12.5 Two Tube Rail (Top Mounted) [[:Category:606 Guardrail and Guard Cable#Testing Criteria.|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.
 
−
 
 
−
'''Details'''
 
−
<center>
 
−
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"
 
−
|+
 
−
| style="background:#BEBEBE" width="300" |'''[http://www.modot.org/business/consultant_resources/bridgestandards.htm Bridge Standard Drawings]'''
 
−
|-
 
−
|align="center"|[http://www.modot.org/business/standard_drawings2/TwoTubeRail.htm Two Tube Rail]
 
 
|}
 
|}
−
 
−
</center>
 
  
  

Revision as of 09:50, 9 June 2020

To be found eligible for Federal-aid funding, new roadside safety devices should meet the crash test and evaluation criteria contained in the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH). Since neither FHWA nor AASHTO has a system in place to approve roadside devices, the responsibility is left with the States. In response, MoDOT has developed a MASH Implementation process. All roadside devices that are submitted after November 1, 2019, will be reviewed by the MASH Team for approval to use on Missouri roadways. Prior to November 1, 2019 roadside devices were considered using the criterion set forth in NCHRP Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway Features”. While MASH requirements are only applicable to the NHS, the following guidelines are recommended for all bridges.

Contents

751.12.1 Concrete Barriers

Type D barrier replaced Type B barrier (previously safety barrier curb) as the standard railing for bridges awarded after December 31, 2019. Similarly, Type C barrier replaced Type A barrier (previously median barrier curb). Types H and G shall be used respectively for situations where Types D and C is considered impractical.

751.12.1.jpg

Single sloped barriers have been shown to reduce vehicle climb and increase vehicle stability during redirections when compared to New Jersey shaped barriers. See the following sections for more details on standard barriers. Details for Type G have not been developed, but that does not prevent its use if need dictates.

Concrete barriers were approved for TL-3 or TL-4 test levels in accordance with the MASH 2016 standards. The required MASH 2016 test level for bridges on the National Highway System (NHS) is TL-3, but the expectation is that the TL-4 requirement will be mandated in the next publication.

Test level TL-3 is defined by AASHTO as being “generally acceptable for a wide range of high-speed arterial highways with very low mixtures of heavy vehicles and with favorable site conditions.”

Test level 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”.

751.12.1.1 Material Properties

Class B-1 Concrete Epoxy Coated Reinforcing Steel
Unit weight (reinforced), wc = 0.150 kcf Yield strength, fy = 60.0 ksi
Compressive strength, f’c = 4.0 ksi Modulus of elasticity, Es = 29,000 ksi
Modular ratio, n = 8
Modulus of elasticity, Ec = 3644 ksi

751.12.1.2 General Details

Regardless of type of barrier shown the following sections are applicable for all concrete barrier types.

Top of barrier shall be built parallel to grade with barrier joints (except at end bents) normal to grade.

All exposed edges of barrier shall have either a 1/2-inch radius or a 3/8-inch bevel, unless otherwise noted.

751.12.1.2.1 Slip Forming

Conventional or slip forming may be used except for situations where slip forming is considered impractical.

See barrier elevation sheets of the barrier standard drawings for the required details.

Slip forming is impractical for prestressed double-tee bridges.

Cross Bracing C Bars

Slip forming requires two No. 5 cross bracing C bars located each side of all joints and at barrier ends.

List C bars in the Bill of Reinforcing Steel and note that bars are for the slip-formed option only.

For barrier segments on top of the bridge deck, use 12-foot C1 bars.

For barrier segments on top of the end bent wings:

For segments < 14'-4", use C2 bars ending no closer than 29.5" from end of barrier.
For segments ≥ 14'-4" and ≤ 18'-0", use the 12-foot C1 bars.
For segments > 18'-0", use two sets of C2 bars with first set ending no closer than 29.5" from end of barrier.

Textured Fiberglass Bars

Slip forming requires three four-feet long No. 4 textured fiberglass bars centered at each joint.

751.12.1.2.2 Joints

See barrier elevation sheets of the barrier standard drawings for the required details.

One-fourth-inch joints are located in the barrier at locations of negative moments to prevent cracking in the barrier. Barrier joints may be formed using ¼-inch joint filler in accordance with Sec 1057 or saw cut and seal with silicone joint sealant in accordance with Sec 717. Saw cuts joints may be used with the conventional forming option.

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 placement of barrier joints at integral end bents see integral end bent details.

751.12.1.2.2.1.jpg

Additional joints at 12-foot spacing from joint at intermediate bents may be required based on span lengths. The following details provide guidance on locating flexural joints near intermediate bents. This spacing will allow the full yield-line failure pattern to develop for Type D barrier. For simplicity, the 12-foot spacing shall also be used for all other concrete barrier types.

751.12.1.2.2.2.jpg

751.12.1.2.3 Plastic Waterstops

See barrier elevation sheets of the barrier standard drawings for the required details.

Plastic waterstops are typically located inside formed joints to eliminate water seepage problems on grade separations. They shall be excluded over railroads and county roads and are only required on the lower side of superelevated decks.

751.12.1.2.4 Guardrail Attachment

See barrier at end bents sheets of the barrier standard drawings for the required details.

751.12.2.6.jpg

751.12.1.2.5 Superelevation

Superelevated slope, S.E., is in decimal format for the follow calculation, i.e. use 0.04 for 4.0%.

751.12.2.5.1.jpg
751.12.2.5.2.jpg

751.12.1.2.6 Detached Wing Walls

If the detached wing wall has more than one section, see the Structural Project Manager for possible additional joints in the barrier (between sections).

The following details are for illustration purposes only:

751.12.2.6 end bents.jpg

751.12.1.2.7 Light Poles

751.12.2.7.1.jpg
751.12.2.7.2.jpg

Anchor bolts and nuts shall be in accordance with ASTM A449. Anchor bolts, nuts and washers shall be fully galvanized.

Note to Detailer: Extend slab transverse steel to edge of slab in blister region often shown with an additional detail with the slab details.

Note: Conduit not shown for clarity.

751.12.1.3 Type D and H (42ʺ and 32ʺ single sloped railing)

The 42-inch single sloped Type D barrier shall be used for railing on all new or replacement bridge projects except where sight distance is a concern. Type D meets the height requirements for both MASH TL-4 (36ʺ) and Occupational Safety and Health Administration’s OSHA (42ʺ). Type D barrier has been reviewed by the Midwest Roadside Safety Facility (MwRSF) and is compliant with MASH 2016 TL-4. This assessment is applicable for continuous and discontinuous sections of the barrier. Type D barrier shall be used on all redecks and rehabs where the full length of barrier is being replaced with exceptions for the following: 1) sight distance concerns, 2) rating concerns where the weight of the barrier prohibits its use or causes impractical restrictions or costs for the project. The Type D barrier dimensions shall not be adjusted for inclusion of a wearing surface.

The 32-inch single sloped Type H barrier shall be used for railing, upon approval of the SPM or SLE, on all new or replacement bridge projects where sight distance concerns prohibit the use of Type D. Type H has the same front face slope as Type D. The minimum height for MASH TL-3 is 30 inches so there are minimal concerns with Type H for future overlays. The TL-3 height requirement has been updated since the release of SEG 20-001. Type H barrier has been reviewed by the Midwest Roadside Safety Facility (MwRSF) and is compliant with MASH 2016 TL-3. This assessment is applicable for continuous and discontinuous sections of the barrier. When a wearing surface is applied with the newly constructed Type H barrier, a pedestal is recommended to keep the holes for the guardrail attachment in the same location with respect to the top of the barrier.

751.12.1.3.1 Typical Section

All values may be used with both 2.0% and 3/16 inch-per-foot cross slopes.

See EPG 751.12.1.2.5 Superelevation for adjustment of values for different cross slopes.

751.12.1.3.1.jpg

751.12.1.3.2 Typical Section Reinforcement

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.

Splice length for horizontal #5 bars in barrier curb shall be 37 inches.

All bent bars are formed using stirrup bends except for the Type D #5-R1 bars.

All values may be used with both 2.0% and 3/16 inch-per-foot cross slopes.

751.12.1.3.2.jpg

751.12.1.3.3 End of Barrier Reinforcement

See barrier standard drawings for the required details.

All bent bars are formed using stirrup bends.

All dimensions shown may be used with both 2.0% and 3/16 inch-per-foot cross slopes.

751.12.1.3.3.1 Type D Ending on Integral End Bents

Use when distance between upper and lower construction joint in wings is at least 28½ inches.

751.12.1.3.3.1.1.jpg
751.12.1.3.3.1.2.jpg
751.12.1.3.3.2 Type H Ending on Integral End Bents

Use when distance between upper and lower construction joint in wings is at least 28½ inches.

751.12.1.3.3.2.1.jpg
751.12.1.3.3.2.2.jpg
751.12.1.3.3.3 Type D Ending on Shallow Integral End Bents

Use when distance between upper and lower construction joint in wings is less than 28½ inches.

Formulas extend bars to within 1½ʺ of lower construction joint.

Use Shape 27 for K3 bar in Barbill program to obtain correct weight and length. Revise Shape 27 on plan sheet to Shape 50 and add shape to bending diagrams.

751.12.1.3.3.3.1.jpg
751.12.1.3.3.3.2.jpg
751.12.1.3.3.4 Type H Ending on Shallow Integral End Bents

Use when distance between upper and lower construction joint in wings is less than 28½ inches.

Formulas extend bars to within 1½ʺ of lower construction joint.

Use Shape 27 for K3 bar in Barbill program to obtain correct weight and length. Revise Shape 27 on plan sheet to Shape 50 and add shape to bending diagrams.

751.12.1.3.3.4.1.jpg
751.12.1.3.3.4.2.jpg
751.12.1.3.3.5 Type D Ending on Non-Integral End Bents

Use when distance between upper and lower construction joint in wings is at least 28½ inches.

751.12.1.3.3.5.1.jpg
751.12.1.3.3.5.2.jpg
751.12.1.3.3.6 Type H Ending on Non-Integral End Bents

Use when distance between upper and lower construction joint in wings is at least 28½ inches.

751.12.1.3.3.6.jpg
751.12.1.3.3.7 Type D Ending at End of Slab (Redecks)

Splice length of #5 K12 and #5 K13 bars with #5 R-bars shall be 37 inches.

751.12.1.3.3.7.jpg
751.12.1.3.3.8 Type H Ending at End of Slab (Redecks)

Splice length of #5 K7 bars with #5 R-bars shall be 37 inches.

751.12.1.3.3.8.jpg

751.12.1.4 Type B (32ʺ New Jersey Shaped Railing)

The 32-inch New Jersey shaped railing, previously referred to as safety barrier curb, shall not be used on new construction projects. This includes redecks and rehabs where the full length of barrier is being replaced. Type B barrier may be replaced in kind where spot work is required (i.e., expansion joint replacements). For wearing surface projects, where the grade is not being increased more than 2 inches, the existing Type B barrier may be used in place in accordance with EPG 751.1.3.4 Railing Type, Height and Guidelines for Curb Blockouts.

751.12.1.4.1 Typical Section
751.12.1.4.1.jpg

See EPG 751.12.1.2.5 Superelevation for adjustment of values for different cross slopes.

751.12.1.4.2 Typical Section Reinforcement

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.

Splice length for horizontal #5 bars in barrier curb shall be 37 inches.

All bent bars are formed using stirrup bends except for the R1 bars.

751.12.1.4.2.jpg
751.12.1.4.3 End of Barrier Reinforcement

See barrier ending on end bents sheets of the barrier standard drawings for the required details. The bars shown below are for barrier ending on wing walls; see barrier ending at end of slab sheet of the barrier standard drawings for reinforcement details for barrier ending on slabs.

Splice length of #5-K9 bars with #4 K-bars above wing walls shall be 31 inches (embedment of #5 bars controls over splice length of #4 bars).

All bent bars are formed using stirrup bends except for the K4 and K11 bars.

Ending on Integral End Bents and Semi-Deep Abutments

Use when distance between upper and lower construction joint in wings is at least 28½ inches.

751.12.1.4.3.1.jpg
751.12.1.4.3.2.jpg

Ending on Shallow Integral End Bents

Use when distance between upper and lower construction joint in wings is less than 28½ inches.

751.12.1.4.3.3.jpg
751.12.1.4.3.4.jpg

Ending on Non-Integral End Bents

Use when distance between upper and lower construction joint in wings is at least 28½ inches.

751.12.1.4.3.5.jpg
751.12.1.4.3.6.jpg

751.12.1.5 Type C (42ʺ Single Sloped Median)

751.12.1.5.1 Typical Section

751.12.1.5.1.jpg

751.12.1.5.2 Typical Section Reinforcement

751.12.1.5.2.jpg

751.12.1.6 Type A (32ʺ New Jersey Shaped Median)

Note: Use same grade reinforcing steel in barrier as in slab.

Splice length for #5-R bars in barrier = 37".
Do not use this barrier over precast prestressed panels.
751.12.1.6.jpg

Twin Bridge Median Barrier Details

751.12.1.6.1.jpg

751.12.2 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. Consult the Structural Project Manager.
  • 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.

Details

Bridge Standard Drawings
Two Tube Rail

751.12.3 Median Curbs

751.12.3.1.jpg
Note: All reinforcement shown shall be epoxy coated.

Details shown are very general. Consult Design Layout for specific details for each individual structure.

751.12.3.2.jpg
751.12.3.3.jpg

751.12.4 Chain Link Fence

Design Criteria:

Dead load of fence fabric weight: 10 pounds per linear foot.

Wind load for chain link or metal fabric fence: GREATER OF 0.015 ksf acting normal to the entire surface per LRFD 13.8.2 OR 0.11 x entire surface x calculated wind pressure (11% is effective surface area per MoDOT practice).


751.12.4 superstructure near steps.jpg
Superstructure Near Steps
 
751.12.4 superstructure near end panel.jpg
Superstructure at or Near End Panel
 
File:751.12 pedestrian overpass-superstructure near steps detail a.gif
Detail "A"  


File:751.12 pedestrian overpass-landing.gif File:751.12 pedestrian overpass-section thru fence.gif
Landing Section thru
Fence
 
751.12.4 handrail bracket.jpg
Details of Handrail Bracket
 
751.12.4 rail post connection.jpg
Rail Post Connection (Typical)
 
751.12.4 plan of floor plate.jpg
Plan of Floor Plate
 
751.12.4 details of expansion device gap.jpg
Details of Expansion Device Gap
(**) May conflict with any proposed expansion device sidewalk, consult Structural Project Manager.
 
751.12.4 typical section near splice gap.jpg
Typical Section Near Splice Gap
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 1/2ӯ 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.


(112") Curved Top Pedestrian Fence (Structures)
(Optional fence detail when requested by district or railroad personnel)
751.12.4 section aa.jpg
Section A-A
 
751.12.4 curved top.jpg
Curved Top Pedestrian Chain Link Fence
(Galv. Steel) on Sidewalk
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.

 
751.12.4 details at expansion device gap.jpg
Details at Expansion Device Gap
(**) May conflict with any proposed expansion device sidewalk, consult Structural Project Manager.
 
751.12.4 typical section near splice gap (112 in).jpg
Typical Section Near Splice Gap
Note: 8'-0" max. post spacing for superstructure.

(*) Locate at about 30'-0" centers with at least one splice gap between pull posts and end posts.

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