Author: Lorella Angelini, Angelini Consulting Services, LLC
Jeffrey Milton, Bridge Preservation Specialist with Virginia DOT (VDOT), is a bridge preservation leader in his State and at national level.
Jeffrey is member of the AASHTO Subcommittee on Maintenance chairing the Technical Working Group on Bridges. He is also part of the FHWA Bridge Preservation Expert Task Group and actively involved with TRB and NCHRP, where is covers a number of Committee Memberships.
- TRB Standing Committee on Structures Maintenance – AHD30 Member
- TRB Standing Committee on Bridge Preservation – AHD37 Member
- NCHRP Project Panel on Development of Guidelines for Uniform Service Life Design for Bridges D12108 Chair
- NCHRP Project Panel on Condition Assessment of Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods D1428 Member
- NCHRP Project Panel for Extending the Life of Highway Bridge Coating Systems Through the Use of Spot Painting with Minimal Surface Preparation D1430 Member
Jeffrey is a member of the FHWA Technical Panel for update of NHI Bridge Maintenance Training Course and development of NHI web-based Bridge Preservation Training Course. He is also member of the TSP2 oversite panel.
I recently had the opportunity to speak with Jeffrey about VDOT bridge preservation program.
How does bridge preservation fare at VDOT?
Using Virginia structure data as of September 1, 2017, the total number of structures in Virginia inventory sums up to 21,124, of which 13,113 bridges and 8,010 culverts. Out of these structures, 19,469 entail VDOT owned/maintained structures, of which 11,910 bridges and 7,559 culverts. The number of city, county and town owned/maintained structures is 1,463, including 1,044 bridges and 419 Culverts
VDOT defines Condition Categories for structures as Good, Fair and Poor.
- Good Condition means a low General Condition Rating of 6 or greater
- Fair Condition: a low General Condition Rating equal to 5
- Poor Condition: a low General Condition Rating of 4 or less
Condition Categories for the 19,469 VDOT Owned/Maintained structures currently report a limited number of structures in Poor Condition.
- 13,891 (71.3%) of the structures are in Good condition
- 4,818 (24.7%) of the structure are in Fair condition
- 760 (3.9%) of the structures are in Poor condition
What does bridge preservation entail at your DOT?
At VDOT bridge preservation is part of a comprehensive Bridge Program that includes preventive and restorative maintenance, painting, rehabilitation and replacement.
Examples of preventive maintenance are bridge cleaning, deck sealing, sealing joints, thin deck overlays and spot and zone painting.
Restorative maintenance includes deck patching, rigid deck overlays, reconstructing/closing joints, superstructure repairs, substructure repairs, fatigue retrofitting, scour repairs, cathodic protection and electrochemical chloride extraction.
Painting encompasses spot and zone painting, over-coating, complete removal and repainting.
Superstructure replacements, deck replacements and culvert rehabilitation are examples of rehabilitation. Rehabilitation and replacement are not part of VDOT Bridge Preservation Program, which focuses exclusively on preventative maintenance, restorative maintenance and painting.
What criterion does VDOT use to determine actions that should be implemented?
Our criterion can be outlined in three points.
- Preventive maintenance candidates are structures in Good Condition (a low General Condition Rating of 6 or greater)
- Restorative maintenance candidates are structures in Fair Condition (a low General Condition Rating equal to 5)
- Rehabilitation and replacement candidates are structures in Poor Condition (a low General Condition Rating of 4 or less).
We also use element level condition states and defects to develop specific maintenance and preservation treatment options. We previously used AASHTO Pontis for our bridge Management system, and we are now investigating the use of AASHTO BrM.
As a general guideline, we want to make sure that preventive, painting, and restorative works are performed before the onset of serious deterioration while the structures are still in good or fair conditions.
We adopted a breakdown for the allocation of bridge structure funds that foresees 15% for preventive maintenance, 10% for painting, 25% for restorative maintenance and 50% for rehabilitation / small structure replacement. This balanced breakdown helps select efficient and effective actions, as it is essential in order to maintain a healthy bridge structure inventory.
Can you outline key bridge preservation strategies at VDOT?
Some VDOT structure/bridge preservation strategies include:
- Eliminate deck expansion joints. The designer must evaluate the feasibility of joint elimination. When elimination is not possible, the designer will have to submit justification, including supporting calculations, to the Assistant State Structure and Bridge Engineer for Maintenance.
- Reconstruct concrete adjacent to joints and install strip seals. When joints cannot be practically eliminated, specific activities should be performed such as perform concrete substructure surface repair and apply waterproofing coating/treatment to pier and abutment seats and ends of beams/girders.
- Install asphalt plug joints with back-up sealers on decks having asphalt overlays.
- Prepare concrete decks using hydro demolition and place rigid concrete overlays.
- Coat beam ends and substructure caps under joints.
What challenges have VDOT encountered in the implementation of bridge preservation strategies?
Like many Agencies, our corporate culture has previously taken a worst first approach to the bridge program, with major emphasis on structurally deficient structures. We have made great progress with our management in promoting a preservation approach focusing on preventive, painting, and restorative works for extending the service life of our inventory.
Can you inform of new technologies that have been recently adopted by VDOT?
We have started using hydro demolition and placement of rigid concrete overlays to protect the concrete deck. We are also investigating the use of hydro-demolition and hydro-milling for concrete removal on substructures.
VDOT Structure and Bridge Division and the Virginia Transportation Research Council are investigating the use of remotely operated data gathering devices and remotely operated maintenance devices. These devices, which include Microsoft HoloLens, unmanned aerial vehicles (drones) and crawling devices designed for bridges and culverts, can be outfitted with various sensing technologies, such as infrared, high resolution cameras and impact (sound).
We are in the process of conducting a research project in order to investigate the use robotic devices in conjunction with lasers for the removal of paint from steel beams and girders.
How can TSP2 help VDOT reach its goals?
TSP2 provides a very valuable platform for sharing information of treatment methods, best practices and research projects among the States, especially when participating in regional and national working groups. The TSP2 staff provides support to the preservation program in Virginia and throughout the nation.
Chapter 32 of the VDOT Manual of the Structure and Bridge Division (File 32.01-9-12) shows the VDOT Bridge Planned Preventive Maintenance Program. A link to this document follows: http://www.virginiadot.org/business/resources/bridge/Manuals/Part2/Chapter32.pdf
VDOT is in the process of reviewing and updating this document (Ed Note).
A link to the FHWA Bridge Preservation Guide follows: https://www.fhwa.dot.gov/bridge/preservation/guide/guide.pdf
This guide will be updated by the FHWA Bridge Preservation Expert Task Group (Ed Note).