GUARDRAIL SECTION 720 388 SECTION 720 — GUARDRAIL
720.1Description.
This work consists of constructing guardrails.
720.2Materials.
A.PCC, Class B Section 1022
B.Steel Posts, Steel Shapes Section 1070
C.Galvanized Beam Guardrail Section 1070
D.Guardrail Hardware Section 1070
E.Guardrail Reflectors Section 1070
F.Timber Posts Section 1070
G.Offset Blocks
1.Wood Section 1070
2.Recycled Composite Materials
a.As specified by the manufacturer
b.Selected from the Approved Products List (https://www.deldot.gov/Business)
H.Galvanized Steel Pipe Section 1070
720.3Construction.
A.Conduct a pre -installation field meeting prior to placement of guardrail systems if required by the
engineer or noted in the contract.
B.Before installation, provide shop drawings for guardrail components not provided in the contract
including the associated manufacturer’s installation instructions.
C.Provide and install guardrail and components in accordance with the Contract.
720.3.1 Post Installation.
A.Dig test pits to determine utility and storm sewer conflicts before post placement in accordance
with Section 204. Repair damage to subsurface facilities caused by post installation.
B.The Department will allow the driving method for post placement. Seal posts with material
approved by the engineer.
C.If the driving method is not used, excavate post holes of sufficient diameter to allow tamping of
backfill around the posts. Backfill with approved material. Place backfill in compaction lifts not exceeding 6 -inches of uncompacted material.
D.Align the posts to within 1/4 -inch of line and grade before installing rail elements. Install posts
plumb. Repair bituminous concrete that cracks or breaks resulting from post installations in accordance with Section 40 1. GUARDRAIL SECTION 720 389 720.3.2 Rail Assembly.
A.Lap rails in the direction of traffic flow for the closest lane. Draw tight all bolts except those
through expansion joints. Tighten bolts through expansion joints as tight as possible without preventing the beams from sliding past one another longitudinally. Extend bolts at least 1/4 -inch beyond the nuts. Do not extend bolts necessary for adjustment more than 1/2 -inch beyond the nuts. Burr the last thread of post railing bolts to prevent removal.
B.Do not field cut holes in rails unless otherwise directed in the contract. If holes must be field cut,
mechanically punch or drill them. Remove all burs created by field cutting activities from the rail. 720.3.3 Offset Blocks.
A.Install new guardrail, using either wood or approved recycled composite offset blocks. Do not mix
different types of manufactured composite blocks or mix composite and wood blocks. Do not install composite offset blocks at wood posts.
B.Notch wood offset blocks in accordance with the Standard Construction Details only when
installing on steel posts. When installing wood offset blocks on wood posts, toenail the wood offset block in place using a 3 -inch long ceramic coated screw. Place the screw so that it penetrates both the wood offset block and wood post.
C.Install approved recycled composite offset blocks in accordance with the manufacturer’s
recommendations with no modifications. 720.3.4 Guardrail Reflectors.
A.Install guardrail reflectors in accordance with the Standard Construction Details.
720.3.5 Relocating Guardrail.
A.Remove existing guardrail in a manner that prevents damage. Replace hardware with new
hardware.
B.Reinstall and reset the guardrail system at the locations designated in the contract and in
accordance with Section 720.3, and the Standard Construction Details. If the existing guardrail has steel offset blocks, replace the offset blocks with offset bl ocks meeting the requirements of with Section 720.3.4.
6 Guardrail Over Culvert
Provide and install guardrail over culvert in accordance with the Standard Construction Details.
720.4Method of Measurement.
A.The Department will measure:
1.Guardrail from the center of end post to the center of end post, excluding barrier connections
and end treatments;
2.guardrail components as the number of each component provided, placed, and accepted by
limit of payment;
3.guardrail over culverts as the number of each provided, placed, and accepted by limit of
payment;
4.relocated guardrail as the number of linear feet of guardrail relocated and accepted .
Source: Delaware Standard Specifications for Road and Bridge Construction, 2025 Edition. Pages 398–399 of 779.