Trail Structures
Scope Tip
Trail structures vary widely in materials, construction methods, complexity, and design requirements. They may be built in the field, assembled on site from prefabricated components, or transported to the site largely complete. Clearly define the intended users and loads, applicable plans and specifications, required engineering or approvals, responsibility for materials and installation, and how the structure will connect with the surrounding trail tread.
Scope Item Definition
Construct trail structures needed to cross obstacles or wet areas, retain soil, accommodate changes in grade, support the trail, or provide specific trail functions.
Structures may include bridges, boardwalks, puncheons, retaining walls, steps or stairs, raised trail structures, and other structural elements. They may be constructed from rock, natural or dimensional wood, metal, fiberglass-reinforced polymer (FRP), concrete, or other materials.
Structures may be built in the field using natural or manufactured materials, assembled on site from prefabricated components, or fabricated off site and transported largely complete for installation. Some structures, particularly bridges, may require engineered or stamped plans or use of agency-approved standard designs.
When / Where It Applies
Trail structures may be needed where terrain, water, soils, grade, or other site conditions cannot be adequately addressed through trail tread construction alone, or where a structure is necessary to achieve the intended trail design or user experience.
Structure requirements vary based on the type and scale of the structure, site conditions, materials, intended trail users and loads, land-manager requirements, and applicable codes or standards. Intended uses may also affect structure width, surface, railings or barriers, approaches, and other construction details.
Scope Considerations
Depending on the project, the scope should consider and clearly define:
Structure type, location, purpose, dimensions, and anticipated quantities.
Applicable plans, drawings, standard details, specifications, and design criteria.
Intended users and anticipated loads, including maintenance or emergency vehicles where applicable.
Required materials, components, hardware, treatments, and finishes.
Construction approach, including whether structures will be field-built, assembled on site from prefabricated components, or delivered largely complete for installation.
Responsibility for supplying, fabricating, delivering, transporting, assembling, and installing materials or components.
Foundations, footings, abutments, anchoring, and other supporting elements.
Integration with the trail tread, including approaches, transitions, grades, drainage, surfacing or hardening, and responsibility for work at the trail-to-structure interface.
Applicable engineering, stamped-plan, agency-standard, inspection, or approval requirements.
Access, equipment, staging, material handling, lifting or rigging, and other construction constraints.
Permit, BMP, resource-protection, and seasonal requirements.
Where field adjustments are allowed and when owner, designer, or engineer approval is required.
Whether a pre-bid site visit should be required or strongly encouraged.
Owner-Provided Information
The owner should provide the following, if available and applicable:
Approved trail alignment and structure locations.
Structure plans, drawings, standard details, specifications, and design criteria.
Intended users and anticipated loads.
Required engineering, stamped plans, structural calculations, agency reviews, inspections, or approvals.
Known site, soil, rock, water, foundation, or other conditions that may affect construction.
Material specifications and responsibility for supplying materials or prefabricated components.
Requirements for approaches, transitions, drainage, surfacing, hardening, or other work connecting the structure to the trail.
Applicable permits, BMPs, resource-protection requirements, and seasonal restrictions.
Access, equipment, staging, storage, and material-transport constraints.
Available site photographs, surveys, or other documentation of existing conditions.
Construction Specifications + Field Decision-Making
The solicitation should identify which structure locations, dimensions, materials, and construction details are fixed and which may be determined or adjusted in the field.
Where structures are constructed from approved or engineered plans, the scope should establish how field conditions requiring changes will be addressed. Where field-built structures allow contractor decision-making, define the applicable design intent, performance requirements, materials, dimensions, and approval requirements.
The contract should also establish how unforeseen foundation, soil, rock, water, or other site conditions will be addressed.
Completed Work / Deliverables
Depending on the scope, completed work may include:
Structures constructed or installed at approved locations and to applicable plans and specifications.
Required foundations, abutments, anchoring, decking, railings, hardware, and other components.
Prefabricated components furnished, transported, assembled, and installed where included.
Approaches, transitions, and adjacent trail tread constructed and integrated with the structure as required by the scope.
Associated excavation, backfill, drainage, stabilization, and finishwork completed.
Disturbed areas stabilized and adjacent resources protected.
Required material certifications, inspection records, as-built information, or other construction documentation.
Quality Assurance + Acceptance
The solicitation should define how completed structures will be evaluated and accepted, including consistency with approved plans, specifications, materials, dimensions, locations, and authorized field adjustments.
Where applicable, identify required engineering or agency inspections, material certifications, testing, or other documentation. Acceptance should also consider whether the structure and its connection with the trail tread function appropriately for the intended users and loads.
Pricing & Payment Considerations
Trail structures may be included in the overall construction price or separately quantified and priced. Common approaches include:
Priced per structure or feature.
Priced by linear foot, square foot, or another applicable unit.
Included within an overall lump-sum construction price.
Prefabricated structures priced to include specified combinations of fabrication, materials, delivery, assembly, and installation.
Time-and-materials where specific conditions or quantities cannot reasonably be determined in advance.
For separately priced structures, clearly define what the price includes, such as materials, fabrication, hardware, delivery, onsite transport, foundations, assembly, installation, approaches, transitions, and finishwork.
Also identify whether materials or prefabricated components are owner- or contractor-supplied and where responsibility for transportation begins and ends. For remote structures, transporting materials or components from the delivery or staging location to the construction site can be a significant part of the work.
Common Scope & Contracting Issues
Not clearly defining structure types, locations, dimensions, quantities, or design requirements.
Not identifying intended users and anticipated loads.
Assuming all structures require the same level of design or engineering.
Not identifying required engineered plans, standard designs, inspections, or approvals.
Not defining whether structures will be field-built, assembled from prefabricated components, or delivered largely complete.
Not defining who supplies, fabricates, delivers, transports, assembles, and installs materials or components.
Not clearly defining where structure construction ends and trail tread construction begins, including responsibility for approaches, transitions, drainage, surfacing, and other work at the trail-to-structure interface.
Underestimating access, material handling, lifting or rigging, and remote transportation requirements.
Not defining what may be adjusted in the field or who must approve changes.
Not establishing how unforeseen site or foundation conditions will be addressed and priced.