1. The historic integrity of covered bridges should be preserved to the maximum extent possible.
2. Covered bridges should remain in use on the state's network of roads whenever possible.
3. Towns provide the best opportunities for continued stewardship of covered bridges. Partnerships between towns and the State of Vermont should be established to assure consistent application of appropriate preservation practices.
4. The Historic Covered Bridge Committee will implement this plan through participation in the development and review of all projects involving historic covered bridges when state or federal funding is used.
5. An effective management system must be implemented and sufficient funding obtained. This strategy should be balanced, on the one hand, identifying bridges in very good condition and maintaining them adequately and, on the other, identifying bridges in very poor condition and preventing deterioration from becoming irreversible.

1. Special Use on Roads. Bridges will remain in use on roads but will be limited to very light traffic, primarily cars. This category of use assumes that alternative routes are available or are capable of being built at locations near enough to historic bridges to minimize inconvenience and to eliminate, or reduce to an acceptable level, any risk of damage by overweight vehicles. At the same time, alternative routes must not compromise the settings for these historic bridges. Creative designs for bridge approaches, intended to prevent use by overweight vehicles, are encouraged. However, these designs must also avoid damage to settings.
   
   Structural Integrity. This category of use assumes that the structural integrity of historic members of these bridges will be preserved to the maximum extent possible. If bridges suitable for this category of use have been compromised by extensive alterations, they should be restored to their original design.
   
   Capacity: The capacity sought is the maximum amount obtainable under the preservation treatments permitted for bridges in this category. Most bridges should be confined to one-lane traffic.
   
   Preservation Treatments: Superstructure preservation treatments 1, 2, 3 and 4, in that order of priority, are preferable for brides in this category.
2. Limited Use on Roads. Bridges will remain in use on roads and will be limited to vehicles that do not exceed 40,000 lbs. This category of use also assumes that alternative routes are available or are capable of being built at locations that accommodate vehicles weighing in excess of 40,000 Ibs. The proximity of alternative routes, the degree of risk that bridges will be damaged by overweight vehicles, and the historic structural integrity of bridges are the decisive factors in choices between Category A and Category B - Limited Use on Roads.
   Structural Integrity.This category of use assumes that the structural integrity of historic members of these bridges will be preserved. If bridges suitable for this category of use have been compromised by extensive alterations, restoration should be considered.
   Capacity: The maximum capacity for bridges in this category is 40,000 lbs.
   Preservation Treatments: Superstructure preservation treatments 1, 2, and 3, 4, 5, and 6, in that order of priority, are acceptable for bridges in this category.
3. Alternative Transportation Use. Bridges will be adapted to alternative uses at their existing sites and restored. The setting of the bridge, including its approaches, should be preserved to the maximum extent possible. This category of use will require alternative routes. However, the design of any new bridge in close proximity to the historic bridge should avoid changing the setting of the historic bridge and should avoid interfering with views of the historic bridge. This category of use assumes that the structural integrity of historic members of these bridges will be preserved to the maximum extent possible.
   Structural Integrity.This category of use assumes that the structural integrity of historic members of these bridges will be preserved. If bridges suitable for this category of use have been compromised by extensive alterations, restoration should be considered.
   Capacity: The minimum capacity for bridges in this category is that required to carry dead load, snow load, and anticipated pedestrian or snow machine loading.
   Preservation Treatments: Superstructure preservation treatments 1, 2, and 3, 4, in that order of priority, are preferable for bridges in this category.
4. Relocation. This alternative presumes that none of the three preceding categories of use is feasible, and it is an alternative of last resort. Relocation may be considered for any of the first three categories of use, and all requirements for the category selected will apply.
5. Bridges Subject to Exceptional Constraints. The circumstances of some bridges pose exceptional constraints. A few have been so drastically altered that repairs required for an acceptable carrying capacity would necessitate reconstruction of the entire bridge. In other cases, bridges have been reinforced by systems that make the historic structure redundant. Bridges subject to such constraints shall be assigned to this category with the hope that acceptable alternatives for preservation will develop in the future. During the interim, a greater variety of preservation treatments are available for preserving these bridges.
   Preservation Treatments: All preservation treatments are available for bridges in this category.

1. Retain all existing materials that have not deteriorated beyond the point of repair. Where existing rot or other damage is not severe enough to require replacement, the materials should be repaired rather than replaced. This treatment should be applied to each member individually, and deterioration of a large number of bridge elements should never justify the replacement of any single member capable of being repaired.
2. Replacement of existing materials in kind, meaning identical in species, quality, and dimension to the maximum extent feasible, or restoration of original materials and design. Prefereably, material origins should be from the Northeast region of the country. If a different species or quality is considered and/or materials from the Northeast are not available, substitutions may be considered with justification.
3. Application of historic methods of strengthening such as the application of sister lattices in Town lattice truss bridges.
4. Introduction of glu-laminated beams as a co-functional, reversible structural system. The beams must be designed to work in conjunction with the historic structural system to achieve required load capacity, and the historic structural system must be restored according to Preservation Treatments 1, 2, and 3.
5. Replacement of limited pieces of existing load-bearing members with materials identical in species, quality, and origin, preferably from the Northeast region of the country, to the maximum extent feasible. Dimensions may be larger but must not cause alterations to the dimensions of any other important bridge components. For example, increasing the depth of bottom chords of Town lattice trusses may increase capacity without requiring alteration to either overall bridge dimension or the design of the floor system.
6. Replacement of existing load-bearing members with glu-laminated members (beams or chords) of identical dimension.
7. Reinforcement of existing load-bearing members with non-obtrusive modern materials such as steel rods or plates, glass fiber, carbon plates, or other materials.
8. Protection of load-bearing members by the introduction of steel beams that provide a safety-net for the bridge. The redundant structure must allow the existing timber frame to continue functioning, and a minimum clearance between steel beams and floor beams should be designed. The purpose of this treatment is to protect the historic bridge in case of structural failure, not to increase carrying capacity.
9. Replacement of load-bearing members with, in order of priority: (a) timber of larger dimension but otherwise identical in terms of species and quality; or (b) timber of larger dimension and different species.
10. Replacement of existing load-bearing members with modern materials.

1. Masonry abutments, whether rubblestone or ashlar, shall be retained whenever possible and repaired rather than replaced. Repairs should be undertaken with like-kind materials, and all repointing should apply appropriate mortar. Bearing seats should be repaired in kind whenever possible. Drainage tubes or weep holes should be installed to channel runoff in all cases to avoid hydrostatic pressure behind the abutments.
2. If masonry abutments, or portion of abutments, have deteriorated to the point where repair with like-kind materials is not feasible, alternative materials may be considered. Where abutments have been undermined by stream flow, concrete underpinning may be installed. Where bearing seats are inadequate, concrete caps may be added.
3. If masonry abutments have deteriorated beyond the point of repair, they may be reconstructed with modern materials such as concrete. Ornamental treatments to produce texture such as veneers, form liners, acid washing, pneumatic blasting, bush-hammering, mechanical stamping or special form-work may be considered.
4. Existing concrete abutments should be repaired whenever possible or replaced in kind if deteriorated beyond the point of repair.

1. Preparing and advocating for an agenda that fully funds and implements this plan as part of the Vermont Historic Bridge Program.
2. Identifying suitable funding programs for special needs such as stabilization and repair of bridges threatened with collapse.
3. Submitting recommendations for assigning each historic covered bridge to a specific category of use together with the appropriate preservation treatments applicable to that category.
4. Advocating that a plan is prepared for the maintenance and repair of each historic covered bridge.
5. Resolving any conflict among various parties concerning specific bridge projects.
6. Participating as needed during both the design and construction phases of each bridge project affecting an historic covered bridge.
7. Participating in presentations to the VTrans Transportation Research Committee when appropriate.
8. Evaluating the merits of innovative products and ideas available for the preservation of historic covered bridges.
9. Such other tasks as the committee, from time to time, determines are appropriate.

1. Project managers assigned to work on specific bridge projects should provide all documentation necessary for committee consideration. This may include, but is not limited to:
   1. identification of all major structural problems and major failures;
   2. estimates of structural capacity assuming all components are in good condition; and
   3. engineering standards for determining all features and materials to be replaced in order to achieve the required capacity.
2. In the case of projects for which detailed plans have not been developed by an engineer, the bridge owner should require the contractor to provide a detailed statement identifying all features and materials to be replaced. That report should be supplemented by one or more field inspections by the committee during any disassembly phase.
3. Contractors or engineers should notify the VTrans Historic Preservation Officer immediately in the event that new information is uncovered during the construction phase.
4. Towns should notify the committee about any proposed work prior to the commencement of that work.

1. Cleaning bridge components with compressed air and removing with hand tools any deposits of debris or dirt that may hold moisture.
2. Keeping drainage areas free of debris and channeling deck drains and approach run-off away from bridge elements below.
3. Removing all small trees and shrubs growing in, on, or near substructure units or under bridges.
4. Removing any debris that accumulates in the channels beneath bridges.
5. Maintaining proper load posting and advance warning signs and keeping all signs visible.
6. Maintaining a water-tight roof system and repairing any damaged siding.
7. Removing any accumulated snow when such snow is of a depth to cause concern for the stability of the structure.
8. Maintaining smooth transition between approach roadway and bridge decks, maintaining straight and continuous rails, and repairing minor damage caused by accidents.
9. Reporting significant problems concerning bridges to the co-managers of the Vermont Historic Bridge Program and to the appropriate District Transportation Administrator.
10. Consulting with the co-managers of the Vermont Historic Bridge Program prior to initiating any emergency repairs.

1. Educate towns about the importance of consistent preservation treatments for the state's collection of covered bridges and encourage town officials to enroll eligible bridges in the Vermont Historic Bridge Program.
2. Establish and enforce a consistent policy regarding state and federal funding for town-owned covered bridges that are not repaired according to treatments recommended by this preservation plan.
3. Increase public awareness about the need to enforce load restrictions on historic bridges, undertake any legislative initiatives required to assure enforcement, and develop attractive, familiar signage that will notify track drivers at appropriate locations to select alternative routes.
4. Conduct periodic training programs for state employees, town officials, and other interested individuals or organizations covering a broad range of topics, including but not limited to project administration and maintenance.

1. Develop VTrans engineering expertise in the preservation, restoration, and rehabilitation of historic covered bridges.
2. Develop the ability to apply new technology and treatments to the preservation of historic covered bridges, as those technologies and treatments become available.
3. Conduct research and develop design specifications for the preservation, restoration, and rehabilitation of historic covered bridges. Research should focus on analysis of structural materials and the interaction of components and should lead to evaluation of structural components in place through non-destructive testing.
4. Develop design specifications for the construction of new timber framed covered bridges and the rehabilitation of existing historic covered bridges.
5. Prepare design criteria for roadway approaches to historic bridges that remain in use on the state's network of roads and for bridges that are placed in alternative transportation uses. Criteria should address a number of issues including, but not limited to, discouraging large vehicles from using these bridges. For bridges in alternative transportation use, criteria should seek to preserve the bridge's original setting to the greatest extent possible.
6. Develop an appropriate policy for privately owned historic covered bridges. Preservation of these bridges is desirable, but a public interest in these structures must be assured through partnership agreements, preservation easements, or outright conveyance. Legislative initiatives may be necessary to achieve these objectives.

Federal Highway Administration
       Signed 4/10/03 by Division Administrator
Vermont Agency of Transportation
       Signed 4/02/03 by Secretary
Vermont State Historic Preservation Officer
       Signed 4/07/03 by S.H.P.O.