As per Federal Highway Administration mandate, the Roadway Standard Drawings have been revised to include guardrail transition and attachment details that satisfy the requirements of NCHRP Report 350. Type III guardrail anchor units will be used at all four corners of all bridges to attach a thrie-beam guardrail transition section to a vertical concrete face. For metal rails, this attachment will occur at the end post. For New Jersey Barrier Rail, this attachment will occur at the end of a concrete barrier rail transition section on the approach slab. The approach slabs have been widened to accept either an 8" (200 mm) wide curb or the concrete barrier rail transition section. Accordingly, revisions have been made to all approach slab and metal rail Structure Standards. These revisions are effective with the January 2002 letting.

The appropriate BAS Standards to use are dependent upon the type of structure, approach pavement, and bridge rail. The new standards are attached and are available for your use as follows:

For cored slab structures:

• With One or Two Bar Metal Rail, use BAS7(SM). The approach slab width will be equal to the gutterline to gutterline distance plus an additional 8" (200 mm) for each curb.
• With New Jersey Barrier Rail, use BAS8(SM) in conjunction with BAS9(SM). The approach slab width will be equal to the gutterline to gutterline distance plus an additional 1'-6" (457 mm) for each barrier rail. To accommodate traffic loading on the rail, detail #5 (#16) 'A' bars spaced at 6" (150 mm) centers for the top mat of transverse reinforcing steel in the approach slab. Include quantities of reinforcing steel and concrete for the barrier rail transition in the Approach Slab Bill of Material.

For other structures:

• With One or Two Bar Metal Rail, use BAS1(SM) or BAS4(SM). The approach slab width will be equal to the gutterline to gutterline distance plus an additional 8" (200 mm) for each curb.

• With New Jersey Barrier Rail, use either BAS2(SM) in conjunction with BAS3(SM) or BAS5(SM) in conjunction with BAS6(SM). The approach slab width will be equal to the gutterline to gutterline distance plus an additional 1'-6½" (470 mm) for each barrier rail. To accommodate traffic loading on the rail, detail #5 (#16) 'A' bars spaced at 6" (150 mm) centers for the top mat of transverse reinforcing steel in the approach slab. Include quantities of reinforcing steel and concrete for the barrier rail transition in the Approach Slab Bill of Material.

If the bridge has a sidewalk, continue the sidewalk onto the approach slab and modify the above standards as necessary.

All BAS Standards now reflect reinforced bridge approach fill. Details are available in the Microstation files for unreinforced bridge approach fills. Also note that Section T-T and the associated dowels are no longer necessary on these drawings for attaching shoulder berm gutter. Plan views of the barrier rail transition section have been developed for various skews and are included in the applicable BAS Microstation files. An example of such a plan view is attached.

Detail end bents to accommodate the changes in approach slab width and curb dimensions as follows:

• Increase the length of the backwall that accepts the approach. Do not increase the overall length of the end bent.
• For approach slabs with curbs, lower the top of wing elevations to match the top of the 4" (100 mm) high curb and reduce the blockout area in the wing as shown on BAS10(SM). For approach slabs with barrier rail transition, lower the wing elevations to the top of the approach slab and eliminate the blockout in the wing.

All Metal Rail Standards have been revised to complement the above changes. BMR9(SM) and GRA1(SM) were deleted due to the discontinued use of the five bolt anchor assembly and a consolidation of the details. Furthermore, CBR1(SM) and PCS3(SM) have been revised to eliminate the tapered end of rail details.

The limits of the asphalt on approach slabs with flexible pavement have been revised to extend from gutterline to gutterline and to a line 2'-6" (750 mm) from the beginning of the approach slab, as measured perpendicular to the end bent. For the construction elevations along the outside edge of the approach slab, provide elevations at the base of the curb or barrier rail and modify construction elevation sketches accordingly.

The standard drawings are available on both the S: drive and the Structure Design Homepage. The Design Manual and NCBDS will be revised at a later date.

TVR/RDR/

Attachments

"For changes to Standards click here"

"Plan View Example"