SS321-002020-02.docx
DOCX document 38 KB Posted
- Attached to
- Construction, University Drive Bike Lanes
- Solicitation number
- IFB-114424
- Issued by
- Fairfax County, Virginia
About this file
This document is a supplemental specifications guide issued by the Virginia Department of Transportation on May 4, 2023, establishing standards for trench widening work on roadways. The specifications detail the installation of asphalt concrete mixtures into constructed trenches to widen shoulders and travel lanes, requiring compliance with approved material types including IM-19.0A, IM-19.0D, and BM-25.0 mixtures. Work may only be performed under appropriate weather and surface conditions, with strict requirements regarding base temperature, surface cleanliness, and freedom from standing water. The specifications define three distinct trench widening route types: Type 1 addresses paved shoulders only without traffic requirements and no minimum density enforcement; Type 2 covers widened travel lanes and paved shoulders subjected to traffic without existing pavement removal; and Type 3 addresses repaired travel lanes with removal of existing pavement and traffic exposure. Trench dimensions must range from a 2-foot minimum to 6-foot maximum width, with vertical sides and proper tacking against existing pavement.
Measurement and payment are based on tonnage of asphalt concrete delivered and placed, compensated at contract unit prices that include all costs for furnishing, placing, trenching, tacking, grading, and disposing of excess material. For Type 2 and Type 3 routes where density requirements apply, contractors must obtain and test one core or plug per course within the first 500 feet and every 2,500 feet thereafter, with testing performed by either the contractor or the Department. Payment adjustments apply when achieved density falls below 91.5 percent of maximum theoretical density, calculated according to standard payment adjustment tables. Type 1 paved shoulder installations require no density testing or minimum density enforcement but mandate compaction using steel double drum rollers weighing at least 8 tons with a minimum of five passes.
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Text version
Guidelines: All Projects.
SS321-002020-02 May 4, 2023
VIRGINIA DEPARTMENT OF TRANSPORTATION
2020 ROAD AND BRIDGE SUPPLEMENTAL SPECIFICATIONS
SECTION 321 – TRENCH WIDENING
SECTION 321 – TRENCH WIDENING of the Specifications is amended as follows:
321.01 – Description This work shall consist of installing asphalt concrete mixtures into a constructed trench to widen shoulders and travel lanes up to but not including the surface mix in accordance with the Plans and Specifications and as directed by the Engineer.
321.02 – Material
(a) Materials shall conform to Section 211.02 and 315.02.
(b) Trench widening material IM-19.0A shall be used for IM-19.0A(T) and IM-19.0D shall be used for IM-19.0D(T). Where BM-25.0(T) is designated, either BM-25.0A or BM-25.0D shall be used by the Contractor.
321.03 – Placement Limitations The Contractor shall not place asphalt concrete mixtures when weather or surface conditions are such that the material cannot be properly handled, finished, or compacted. The surface upon which asphalt concrete mixtures is to be placed shall be free of standing water, dirt, and mud and the base temperature shall conform to Section 315.04.
321.04 – Procedure
(a) Trench Widening Route Types: The minimum lift density as determined according to VTM-22 is based on the type of trench widening as defined below and specified in the Contract. Where trench widening is 2 feet in width, compaction may be performed with small single drum walk-behind rollers or other mechanical means acceptable to the Engineer.
| 1. Type 1: | Paved Shoulder Only shall be installed on routes where the widening will serve as a paved shoulder and will not be subjected to constant traffic. The painted edge line will not be on the trench widening. The minimum density requirement will not be enforced and plugs/cores are not required for this type of trench widening. Steel double drum rollers weighing at least 8 tons shall perform compaction of the asphalt concrete. At least five passes shall be completed. |
| 2. Type 2: | Widened Travel Lane and Paved Shoulder shall be installed on routes where the widening will serve as a wider travel lane and paved shoulder that will be subjected to traffic. The widening will not include removal of existing travel lane pavement, i.e., inside the edge line marking. The painted edge line will be on the trench widening. The minimum density applies to this type of trench widening. |
| 3. Type 3: | Repaired Travel Lane and Paved Shoulder shall be used on routes where the widening will include a portion of the existing travel lane, serve as a paved shoulder and will be subjected to traffic as a part of the travel lane. The widening will include removal of existing pavement, i.e., inside the edge line marking. The painted edge line will be on the trench widening. The minimum density applies to this type of trench widening. |
(b) Trench widening routes shall be widened by trenching on one or both sides of the existing roadway and placing Trench Widening Material in accordance with the width and depth specified for that route.
The depth of the base course will be determined by the measurement of cores as described in VTM-32 and 315.07(c), unless otherwise approved by the Engineer.Any remaining material, after final grading, shall be classified as excess material, and will be disposed of according to Section 106.04 of the Specifications or as directed by the Engineer.
The trench shall be shaped to have vertical sides with the width, depth and type specified in the Contract (2-foot minimum to 6-foot maximum width); be free of excess material; and shall be tacked against the existing pavement side before Trench Widening Material is placed.
The Contractor shall ensure that disruption to driveways, entrances, mailboxes, and intersections are minimized and that precautions are taken to ensure that roadway drainage does not pond on the roadway surface.
321.05 - Acceptance Where density requirements apply, the Contractor is responsible for cutting cores or sawing plugs for density testing. One plug or core per course of material shall be obtained within the first 500 feet and every 2,500 feet thereafter of the trench widening route for testing by the Contractor or the Department. Core and plug locations shall be randomly selected within each section. If the density achieved is less than 91.5% of the maximum theoretical density for the Type 2 or 3 trench widening routes, payment adjustment will be made on the actual tonnage within the 500- or 2,500-foot lot according to Table III-6 in Section 315.
321.06- Measurement and Payment Asphalt Concrete Type BM-25.0(T), IM-19.0A(T) or IM-19.0D(T) will be measured in tons and will be paid for at the Contract ton price. This price shall include furnishing and placing the Trench Widening Material, trenching, tack, grading and disposing of excess material.
Payment will be made under:
| Pay Item |
| Pay Unit |
| Asphalt Concrete Type BM-25.0(T) |
| Ton |
| Asphalt Concrete Type IM-19.0A(T) |
| Ton |
| Asphalt Concrete Type IM-19.0D(T) |
| Ton |
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