8-22 Section 807. Guardrail, Guardrail Terminals, and
Miscellaneous Posts 807.01. Description This work consists of constructing, reconstructing , and erecting guardrail, guard posts, guide posts, guardrail terminals, guardrail anchorages , and mailbox posts ; and excavating, backfilling, and disposing of surplus materials. 807.02. Materials Provide material in accordance the following sections : Sound Earth .......................................................................................... 205 Guardrail Beam Elements and Hardware .............................................. 908 Reflectors .............................................................................................. 908 Steel Posts ............................................................................................ 908 Wood Posts ........................................................................................... 912 Guardrail Blocks .................................................................................... 912 807.03. Construction
A.Grading and Drainage . Before constructing guardrail elements, grade the shoulder and berm to provide drainage. For approach guardrai l terminals, grade to Class A slope tolerances. Remove excess material and dispose in accordance with subsection 205.03.P . The Engineer may allow this material to be spread thinly over the roadway slopes, provided it does not kill vegetation or block drainage.
B.Placing Posts. Drive posts or set posts in augered holes . For posts located within 3 feet of existing culverts, set posts in drilled holes . The bottom of the holes must be within 3 inches of the dimension shown on the plans . Compact the bottom of drilled holes to provide a stable foundation. Verify that the exposed portion of posts meet s plan dimensions . Backfill the posts with sound earth compacted in 12- inch layers . The posts must be plumb after installation is complete. Rem ove and replace posts damaged during driving that would prevent proper functioning of the guardrail, as determined by the Engineer . Do not damage nearby structures, shoulders, or slopes during driving. Replace damaged posts and repair damage to structures, shoulders, and slopes at no additional cost to the Department. Use the same material for all posts in a discrete run of guardrail, except where the plans require wood posts . Do not burn or weld posts in the field. MDOT Standard Specifications for Construction Section 807
8-23 C. Guardrail Beam Elements, Blocks and Hardw are. Erect beam guardrail
to conform to the line and grade shown in the contract. Bolt the beam elements and blocks to each post . Make splices only at posts by lapping in the direction of traffic . Do not burn or weld beam elements in the field. Where placi ng guardrail on a curve with a radius between 150 and 1, 000 feet, tighten splice bolts before attaching to the posts. Shop bend beam elements for curves with a radius of 150 feet or less . Identify each shop- bent curved beam element with a metal tag or perm anent marking showing the radius of curvature to the nearest 5 feet as shown on the MDOT Standard Plan R -60 series. Bolt lengths shown on the plans are based on the standard dimensions given for the materials and do not include manufacturer's tolerances . Draw bolts tight and flush with the nuts . If using wood posts, do not leave bolts for Type BD, Type TD, and Type MGS-8D guardrail extending more than ½ inch beyond the nuts . Do not leave bolts for other types of guardrail extending more than 1½ inch beyond the nuts.
D.Repair of Wood Posts and Blocks . Field treat cuts, holes, and damage to posts and blocks that occur after pressure treatment, in accordance with subsection 912.03.
E.Repair of Damaged Galvanized Surface. Repair zinc coating on beam elements, steel posts, and fittings damaged in transporting, handling, or erection. Apply zinc coating to bare metal surfaces after dril ling holes or slots on beam elements . Make repairs to galvanized surfaces in accordance with subsection 716.03.E and at no additional cost to the Department.
F.Guardrail Terminals and Anchorages. For guardrail terminals, the Engineer will allow field drilling of galvanized beam elements to attach terminal end shoes and anchor plates . Install the reflectorized obstacle marker panel on the nose of each terminal in accordance with the manufacturer’s specifications. For structure anchorages, either sleeve or core drill bolt holes through concrete. Avoid spalling concrete during coring. If spalling occurs, remove the fragments and loosened concrete before installing the bolt. Install curved guardrail anchorages when specified on the plans or when specified by the Engineer . Place the guardrail on a curve as shown on the plans or directed by the Engineer .
G.Adjusting or Reconstructing Guardrail . Disassemble, sort , and stockpile the existing guardrail beam elements and endings . Sort the MDOT Standard Specifications for Construction Section 807
8-24 stockpiles of different elements into reusable and unusable material .
Obtain the Engineer’s approval for reuse prior to installation. Remove concrete anchor blocks at the end of turned- down guardrail anchorages and concrete footings for old guardrail cable anchorages . Unless otherwise indicated on the plans, any unusable material will become the property of the Contractor. Drill new slots in the beam elements and anchorages when needed in accordance with the MDOT Standard Plans . Re-erect the reusable beams or new beams, offset/spacer , or wood block outs on new or existing posts in accordance with the MDOT Standard Plans . Backfill and compact the old post holes and voids caused by removal of concrete anchor blocks and footings in layers no greater than 12 inches. Adjust guardrail heights as shown on the MDOT Standard Plan R -60 series . Make height adjustments in the block mounting location only . Do not lift existing posts to adjust rail height . Ensure that the post bolt (for Guardrail, Type B and Guardrail, Type MGS -8) or upper post bolt (for Guardrail, Type T) is not closer than 2 inches from the top of the wood or steel post. Field drill new holes in the existing post if necessary. Make height adjustments to usable, existing guardrail approach terminals by reconstruction (complete removal and reinstallation) only . Replace unusable and substandard terminals with new standard terminals.
H.Incomplete Guardrail Installations. Within 5 calendar days, complete a continuous section of guardrail, including structure anchorages and guardrail terminals, or bridge thrie beam retrofit guardrail . This time period begins with the start of work on a continuous section of guardrail, and ends with the completion of work on a continuous section of guardrail. Deliver adequate materials on the project before removing sections of guardrail or beginning new installations . Leave existing guardrail in place until preparatory work such as widening, embankment, and other construction items are complete . To reduce exposure of unprotected areas, coordinate and expedite shoulder construction where guardrail removal and replacement will occur. If a guardrail section cannot be completely removed or installed by the end of the working day and the exposed beam element ending would face oncoming traffic, temporarily attach a terminal end shoe in accordance with the MDOT Standard Plan R -66 series . A terminal end shoe of appropriate type based on the beam guardrail installed must be used on all guardrail installations . A cable assembly and strut are not required. MDOT Standard Specifications for Construction Section 807
8-25 Attaching the terminal end shoe does not waive the 5-day completion
requirement. If the bridge approac h guardrail cannot be properly attached to the bridge railing or connected to the bridge thrie-beam retrofit guardrail, fit the free end of the rail with the required special end shoe or thrie-beam terminal connector and temporarily attach to the bridge rail in accordance with the following:
1.Fit the exposed thrie-beam retrofit beam ending that faces oncoming traffic with a thrie-beam terminal connector . Attach the terminal connector to the reinforced concrete railing. Install and tighten splice bolts . Secur e the terminal connector to the railing with at least one bolt extending completely through the railing in accordance with the MDOT Standard Plan R -67 series.
2.Attach bridge approach guardrail that cannot be properly attached to the bridge railing, to a por tion of reinforced concrete railing in accordance with the MDOT Standard Plan R -67 series, except that only one bolt will be required to secure the special end shoe or thrie-beam terminal connector to the railing. Install and tighten splice bolts . Extend the rail at least 3½ feet onto the bridge. If the Engineer approves, this temporary attachment may remain beyond the 5 -day requirement stipulated above.
3.If the area of incomplete or removed guardrail is not behind traffic control devices installed f or other work, install a lighted SHOULDER WORK (W21 -5) sign and lighted, steady -burn, plastic drums, spaced at maximum intervals of 100 feet to delineate the incomplete portion of the guardrail section during the time it is exposed to traffic . Place plasti c drums near the edge of the shoulder . Other traffic control devices may be required by the contract, or as directed by the Engineer.
I.Temporary Beam Guardrail and Temporary Guardrail Terminals. Construct temporary beam guardrail and temporary guardrail terminals in accordance with subsection 807.03 for beam guardrail and guardrail terminals . The Engineer may approve the use of salvaged or new materials for temporary installations; ensure that the Engineer approves before us ing salvaged materials. Remove the guardrail and terminals when no longer required. Backfill and compact the post holes in lifts no greater than 12 inches. Take possession of the materials, disassemble, and remove them from the project.
J.Salvaging Beam Guardrail . Remove existing single or multiple beam guardrail and posts . Backfill the post holes in layers compacted to no MDOT Standard Specifications for Construction Section 807
8-26 greater than 12 inches . Deliver the beam elements to the locations
designated in the contract, and stack the beams neatly, according to length. Unless otherwise required by the contract, take ownership of posts and hardware.
K.Mailbox Posts. Move existing mailb ox supports and mailboxes, but maintain serviceability during construction. Install a new post at the permanent location after construction is complete. Attach the existing mailbox to the post and dispose of the existing support at the property owner’s opt ion. Set mailbox posts in the ground so the top is 4 feet above the surface of the shoulder of the road or mailbox turnout . The Engineer will determine the exact height . Use posts in accordance with the MDOT Standard Plan R -74 series and saw the top of the post level . The Engineer may approve alternate mailbox support designs that meet the criteria specified in the requirements of the AASHTO Manual for Assessing Safety Hardware (MASH). Remove, store, and provide to the property owner, newspaper boxes and supports that interfere with construction.
L.Guard Posts and Guide Posts . Drive or set guard and guide posts in drilled holes in accordance with subsection 807.03.B. 807.04. Measurement and Payment Pay Item Pay Unit Guardrail, Curved, Type __ ........................................................................ Foot Guardrail, Type __ ..................................................................................... Foot Guardrail Post, Culv .................................................................................. Each Guardrail Approach Terminal, Type __ ...................................................... Each Guardrail Departing Terminal, Type __ ..................................................... Each Guardrail Anch, Bridge, Det __ ................................................................. Each Guardrail Anch, Median ............................................................................ Each Guardrail Reflector .................................................................................... Each Guardrail, Type __, Temp ........................................................................... Foot Guardrail Approach Terminal, Type __, Temp ........................................... Each Guardrail Departing Terminal, Type __, Temp ........................................... Each Guardrail Anch, Bridge, Det __, T emp ...................................................... Each Guardrail, Salv ........................................................................................... Foot Guardrail, Mult, Salv .................................................................................. Foot Post, Mailbox ............................................................................................ Each Post, Wood Guard .................................................................................... Each Post, Wood Guide ..................................................................................... Each Guardrail, Reconst, Type __ ...................................................................... Foot Guardrail Post, Furn and Install, __ inch ................................................... Each Guardrail Height, Adj .................................................................................. Foot MDOT Standard Specifications for Construction Section 807
8-27 Guardrail Anchored in Backsl ope, Type __ ............................................... Each
Guardrail Anch Bridge, Det __, Curved ..................................................... Each
A.Blading. The cost of grading the shoulder and berm to provide drainage and disposing of excess material is included in unit price for related items of work.
B.Guardrail . The Engineer will measure Guardrail, Curved, Guardr ail and Guardrail, Temp along the face of the rail, excluding terminals and end shoes . The unit price for Guardrail, Curved includes the cost of portions of guardrail with shop- bent beam elements. The unit price for Guardrail includes the cost of providing and placing guardrail posts, blocks, and miscellaneous hardware. The unit prices for Guardrail, Temp, Guardrail Approach T erminal, Temp , and Guardrail Departing Terminal, Temp include the cost of removing temporary guardrail and terminals and backfilling postholes . The cost of providing, installing, and removing temporary guardrail beam elements, terminal end shoes , transition elements and hardware, and traffic control items described for incomplete guardrail installations in subsection 807.03. H.3 is included in the unit price for related guardrail pay items. The Engineer will measure Guardrail , Salv and Guardrail, Mult, Salv along the face of the rail (one face for multiple beams), including terminals and end shoes. Guardrail Reconstruction includes guardrail constructed using new or existing posts and reused beam elements of the type specified, measured by length in feet along the face of the rail, including reused existing terminals . The work includes:
1.Remov ing existing guardrail, guardrail approach terminals, guardrail departing terminals, thrie- beam retrofits, and guardrail anchorages ;
2.Furnishing, as necessary, new posts, offset blocks, spacer blocks, wood blockouts, bolts, reflectors, and other pertinent fittings ;
3.Backfilling old postholes ;
4.Field drilling beam elements and repairing damaged galvanized surfaces ;
5.Drilling holes in bridge railings, concrete barriers , and other concrete structures;
6.Transporting beam elements within the project limits ; and MDOT Standard Specifications for Construction Section 807
8-28 7. Dismantling, separating, and stockpiling elements and disposing of
waste or scrap material. Reconstructed guardrail anchorages will be paid for as Guardrail, Reconst, Type __ when rebuilt with existing beam elements . Otherwise, guardrail anchorages constructed with all new components will be paid for as Guardrail Anch, Bridge, Det __ or Guardrail Anch, Median . Reconstructed thrie-beam retrofit will be measured and paid for as Guardrail, Reconst, Type __ when rebuilt with existing beam elements . Bridge Railing, Thrie Beam Retrofit will be paid for separately if it is necessary for the Contractor to furnish new thrie-beam retrofit installations due to insufficient quantities of reusable elements available on the project. Reconstructed long-span guardrail will be measured and paid for as Guardrail, Reconst, Type __ when rebuilt with existing beam elem ents. New long -span guardrail, of specified detail type, will be paid for separately with other pay item(s), as specified in the contract or as specified by the Engineer, if it is necessary for the Contractor to furnish new long-span guardrail installations due to insufficient quantities of reusable elements available on the project. Reconstruction of reusable existing guardrail approach and departing terminals that meet current standards and if approved by the Engineer will be measured and paid for as Guar drail, Reconst, Type __. Payment for removal of existing buried ends is included in the item of Guardrail, Reconst, Type __. Where only the existing terminal or anchorage is removed in a run that is otherwise not reconstructed, the removal will be paid for as Guardrail, Rem . Installing posts within existing guardrail post intervals to modify the guardrail will be measured as units of Guardrail Post, Furn and Install, __ inch of the post length specified. The pay item includes furnishing and installing posts , offset blocks, bolts, and necessary fittings. Guardrail Height, Adj will be measured in feet along the face of the rail adjusted and includes all necessary field drilling of existing posts . Pay quantities will be in increments of the post spacing called for on the plans, excluding anchorages and end shoes. Guardrail Approach Terminal, Type __ of the type specified will be paid for separately when required to replace unusable or substandard existing approach terminals . Guardrail Departing Terminal, Type __ of the type specified will be paid for separately when required to replace unusable or substandard existing departing terminals. MDOT Standard Specifications for Construction Section 807
8-29 Guardrail, Type __ and Guardrail, Curved, Type __ of the type specified
will be paid for separately if it is necessary for the Contractor to furnish new beam elements due to insufficient quantities of reusable elements available on the project. Guardrail Anchored in Backslope, Type __ includes all materials, equipment , labor, including slope excavation, and backfill . When a W-beam rubrail is called for on the plans, the unit price for Guardrail Anchored in Backslope, Type __ includes all materials, labor, and equipment for installation of the W -beam ru brail. Guardrail Anch Bridge, Det__, Curved includes all materials, labor, and equipment to construct a curved guardrail bridge anchorage of specified detail, with the curve radius shown on the plans or as directed by the Engineer.
C.Guardrail Terminals . Each terminal will be considered an individual unit . The unit price for Guardra il Approach Terminal includes the cost of proprietary and standard elements, hardware required for installation, including obstacle marker panel, and terminal end shoes. The unit price for Guardrail Departing Terminal includes all materials, labor, and equipment to construct a departing terminal, excluding curved beam elements requiring shop bending. Curved beam elements requiring shop bending will be paid for separately as Guardrail, Curved, Type__.
D.Miscellaneous Posts. The unit price for Post, Mailbox includes the cost of the following:
1.Removing and relocating the existing mailbox support during construction activities;
2.Maintaining serviceability;
3.Placing a new post at the permanent location after construction activities are complete;
4.Removing the mailbox from the old support and attaching it firmly to the new post;
5.Disposing of the old support at the property owner’s option; and
6.Removing, storing, and providing the existing newspaper boxes and supports to the property owner . The unit price for Guardrail Post, Culv includes all labor, materials , and equipment necessary to complete the installation in accordance with the MDOT Standard Plan R -73 series .
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 583–590 of 1,146.