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Bridge Overlays

Bridge HMA Paving


As of 2009, documentation did not exist in the Standard Specifications, Construction Manual, or written Bridge Policies for HMA on bridge decks. In April 2010, the Bridge Office began the process to implement Bridge Paving Policies, Bridge Special Provisions and Construction Manual revisions to facilitate better management and construction of HMA on the bridge decks. In general, these “changes” describe pre-existing expectations for bridge HMA management, design, and construction with the addition of construction enforcement by profile surveying when necessary to control planing and paving depths.

Region Materials Lab: Pre-Scoping
Bridge HMA pavement options are discussed at this time with all of the Region Pavement Manager and Bridge Asset Manager. When the Pavement Manager determines the resurfacing limits for programming, Bridge Deck Condition Reports (BCRs) for the biennium are posted as a Resource below for reference by scoping and design. The Bridge List or a BEIST search can be used to identify non-mainline bridges, while the WSDOT Pavement Management System will identify most of the mainline bridges.

Region Scoping and Programming
Scoping must consider all WSDOT managed bridges between the beginning and ending milepost of the project, not just mainline bridges within the paving limits. This includes a bridge crossing the route, near intersections, or off of the mainline entirely. Profile grade settlement and approach slab problems should be identified at this time, as well as a minor bridge joint work. Region should review with Region Bridge Maintenance all of the HMA bridges within paving limits to determine if minor bridge joint work should be completed by Maintenance or the paving contractor. If major bridge joint repairs are required for a bridge, please notify the Bridge Asset Manager. Scoping should include costs for: Full depth or Mill/Fill bridge paving, Transverse Joint Seals (Std. Item 6517), Rail retrofits or guardrail attachments (Rail Specialist for cost), and minor bridge joint maintenance up to $26,000 per bridge.

Region Design for Bridge HMA

Scheduling Bridge Design Work: Region Design must contact the Bridge Projects Engineer as soon as possible to schedule design and detailing of Bridge Sheets for bridge expansion joints, bridge rail retrofits, or other work required for a paving project.

Bridge Deck Condition Reports: Region Design must review BCRs for all HMA bridges within the paving limits to ensure bridge resurfacing is appropriate for the project and verify design data is accurate. BCRs may require updating if there are changes to the paving design after the BCR was printed. Bridges at the end and beginning of paving must be included in the project unless the Bridge Asset Manager and Region Materials Lab agree to exempt the bridge. Bridges classified in the BCR as Restricted or Unrestricted must be listed in the appropriate fill in BSP. The Bridge Special Provision (BSP) Flowchart is an aid posted as a Resource below.

Vertical Clearance: Roadway overlays that add HMA depth to the roadway and raise the grade must verify vertical clearances are safe after paving under a bridge. Mill/Fill of the roadway at the bridge is generally desired unless lowering the grade is required. Design Manual Reference: Section 720.04 Bridge Site Design Elements, (5) Vertical Clearances, (c) Minimum Clearance for Existing Structures, 1. Bridge Over a Roadway.

Plan HMA depth: If Region Materials lab field measures the depth of bridge deck HMA design, depth measurements at the fog line on the four corners of the deck is sufficient. The Bridge Asset Manager should be informed of the measurements and Plans would use an approximate or average value.

Std Plan A60.30.00: Any change in HMA depth at the bridge must transition the grade height using a minimum 1/500 slope as stated in Std Plan A60.30.00. This is common when pavers raise the profile grade by adding 0.15’ HMA overlay and the bridge remains the same and requires a Mill/Fill. Longer transition lengths will be required to correct existing transitions that are a bump in the road to the traveling public.

Bridge Rail Retrofits: The BCR indicates whether a bridge rail meets the criteria stated in the Design Manual: Section 1610.04 Project Criteria, (3) Bridge Rail.

Construction Inspection

Chain Drag Reports: It is very important that Chain Drag Reports be returned to the Bridge Asset Manager (Bruce Thill) for storage with other bridge deck records. The Report provides data that will be used in the next paver and critical information to manage the bridge deck.

Final Grade Profile: HMA depths surveyed under contract will establish a uniform concrete surface profile below the HMA. The approved Final Grade Profile should be parallel to the concrete surface with a uniform HMA depth based on the assumed final HMA depth shown in the Plans. Changes to the Construction Manual, Section 5-4.2B_1 “Duties Before Paving Begins” were submitted April 2010 and are posted as a Resource below until the Construction Manual is revised.