Section 4(f) — Transportation Projects and Protected Land

Legal Authority

• 23 U.S.C. § 138 — Preservation of parklands (highway context): the Secretary shall not approve any program or project that requires use of land from a public park, recreation area, wildlife or waterfowl refuge, or historic site unless there is no feasible and prudent alternative and all possible planning to minimize harm has been included
• 49 U.S.C. § 303 — Policy on lands, wildlife and waterfowl refuges, and historic sites (transit context): parallel prohibition for transit, rail, and non-highway transportation projects requiring DOT approval
• 23 CFR Part 774 — FHWA/FTA/FRA implementing regulations; governs the § 4(f) evaluation process, de minimis impact findings, constructive use, exceptions, and required coordination

Key Mechanics

Section 4(f) prohibits DOT from approving any federal transportation project that uses land from a public park, recreation area, wildlife or waterfowl refuge, or historic site — unless (1) no feasible and prudent alternative to using that land exists and (2) the project includes all possible planning to minimize harm. This is a substantive prohibition, not merely a procedural requirement: the agency must genuinely exhaust alternatives; cost increases and schedule delays do not make an avoidance alternative infeasible; only truly unsurmountable engineering or safety obstacles qualify. Protected properties (§ 774.11): publicly-owned parks, recreation areas, wildlife/waterfowl refuges, and historic sites of national, state, or local significance — including properties listed on or eligible for the National Register of Historic Places; local neighborhood parks qualify. De minimis finding (§ 774.3(b)): for impacts so minor that protected attributes are unaffected, agencies may make a streamlined finding after coordination with the official with jurisdiction and completion of the Section 106 historic preservation review. Constructive use (§ 774.15): a project need not physically take Section 4(f) land to trigger protection; proximity impacts — noise, vibration, visual intrusion — that substantially impair the protected attributes of the property constitute a "constructive use" and require full § 4(f) evaluation. Coordination requirement (§ 774.5): before finalizing a § 4(f) evaluation, the agency must provide it for comment to the official with jurisdiction over the property, the Department of the Interior, and as appropriate USDA and HUD. Exceptions (§ 774.13): temporary occupancy causing no permanent adverse effects; historic bridges whose transportation use creates historic character; net-benefit situations where the project improves the Section 4(f) property.

Current Rule (2026)

What This Rule Does

Section 4(f) prohibits the U.S. Department of Transportation from approving any federal transportation project that uses land from a public park, recreation area, wildlife or waterfowl refuge, or historic site — unless there is no feasible and prudent alternative to the use of that land, and the project includes all possible planning to minimize harm. It is one of the most powerful environmental protections in federal transportation law: not a procedural speed bump, but a substantive prohibition that has re-routed interstates, blocked bridge placements, and reshaped decades of highway and transit planning.

The statute was enacted in 1966 as Section 4(f) of the Department of Transportation Act, responding to the destruction of urban parks and historic neighborhoods during the interstate highway buildout of the 1950s and 1960s. Congress's intent was clear — before the federal government takes protected land for a road or transit line, every alternative must be exhausted. The provision has been codified at 23 U.S.C. § 138 (for highways) and 49 U.S.C. § 303 (for mass transportation) and remains one of the few federal statutes that compels a substantive outcome (route selection) rather than just a process.

The protection applies to any transportation project that requires DOT approval — highway construction, transit lines, bridges, railroads, airport access roads, and bicycle/pedestrian facilities — when federal-aid funds are used or federal permits are required.

Key Provisions

• § 774.3(a) — Section 4(f) approval standard: a transportation agency may use Section 4(f) land only if it makes two findings: (1) no feasible and prudent avoidance alternative exists — meaning no alternative that avoids the use of Section 4(f) land is both technically and economically feasible and prudent from an overall standpoint; and (2) all possible planning to minimize harm to the Section 4(f) property has been included; both findings must be supported by a documented evaluation

• § 774.3(b) — De minimis impact finding: an alternative standard for minor impacts — if the use of Section 4(f) land is so minor (a small sliver for a bridge approach, minor shoulder widening adjacent to a park) that there is no adverse effect on the protected activities, features, or attributes that qualify the property for Section 4(f) protection, the agency may make a "de minimis impact" determination after coordination with the property's official with jurisdiction and, for historic properties, completion of the Section 106 process; de minimis findings streamline review for low-impact projects without eliminating the protections

• § 774.11 — Protected properties: Section 4(f) protection applies to (1) publicly-owned land of a public park, recreation area, or wildlife/waterfowl refuge of national, state, or local significance; (2) land of an historic site of national, state, or local significance — including properties listed on or eligible for the National Register of Historic Places; the significance threshold is deliberately broad — a small neighborhood park counts if it is significant to the local community

• § 774.13 — Exceptions: Section 4(f) review is not required for (1) temporary occupancy of Section 4(f) land that causes no permanent adverse effects; (2) certain historic bridges when the transportation use is the use that gives the bridge its historic character; (3) net benefit situations (a project that restores a Section 4(f) property or improves its protected attributes); (4) projects affecting only common post-1945 concrete or steel highway bridges and culverts with no individual historic significance; and (5) categorical exclusions under NEPA where the agency determines Section 4(f) review is unnecessary

• § 774.15 — Constructive use: a project does not need to physically take Section 4(f) land to trigger the protection; "constructive use" occurs when a project's proximity impacts — noise, vibration, visual intrusion, air quality — are so severe that they substantially impair the activities, features, or attributes that make the property Section 4(f)-protected; a highway next to a historic district that produces noise incompatible with the contemplative character of the site triggers Section 4(f) review even without taking a single square foot; this provision prevents the "halo effect" problem where agencies route projects just outside protected land but destroy its protected values

• § 774.5 — Mandatory coordination: before a Section 4(f) evaluation is finalized, the agency must provide it for comment to (1) the official(s) with jurisdiction over the property; (2) the U.S. Department of the Interior; and (3) as appropriate, the U.S. Department of Agriculture and HUD; the comment period ensures the property managers (park services, wildlife agencies, historic preservation officers) have input before a federal approval is issued

• § 774.7 — Documentation: a full Section 4(f) evaluation must include: a description of the Section 4(f) property and its protected attributes; a detailed evaluation of alternatives; documentation that no feasible and prudent avoidance alternative exists; and a discussion of all possible harm minimization measures included in the project; the evaluation is part of the NEPA environmental document (EIS or EA) and is publicly available

How It Affects You

If you live near a planned transportation project: If the project may use land from a public park, greenway, wildlife area, or historic site in your community, Section 4(f) gives your community leverage. The agency must evaluate all alternatives that avoid the protected land — including shifted alignments, tunnels, elevated structures, and route termination. Commenting during NEPA environmental review is the primary opportunity to raise Section 4(f) concerns: point out which protected resources are affected, document their significance (even local parks count), and push for alternatives the agency may not have analyzed. If you believe the agency has not adequately evaluated a true feasible and prudent alternative, Section 4(f) findings are challengeable in federal court under the Administrative Procedure Act.

If you are developing near parks or historic districts: If your project requires federal approval or funding (federal permits, federal grants, federal land crossing), check whether any portion of your project uses land from or creates constructive use of Section 4(f)-protected properties. The constructive use concept is expansive — a road that generates noise incompatible with a quiet historic district, a transit line that creates vibration near a National Register building, or an access road that visually intrudes on a publicly-owned scenic area can all trigger Section 4(f) review even without physical land taking. Early identification of Section 4(f) issues allows project proponents to design around them rather than discovering them in NEPA review.

As a transportation advocate or planner: Section 4(f) is one of the few statutory provisions that compels substantive route selection outcomes, not just process. The "no feasible and prudent alternative" standard is meaningful — courts have found that inconvenience, cost increases, or longer project timelines are not sufficient to render an avoidance alternative impractical; only truly unsurmountable engineering or safety constraints qualify. The de minimis finding streamlined review for minor impacts but has not weakened the fundamental protection for significant impacts.

Statutory Authority

This rule implements:

• 23 U.S.C. § 138 — Preservation of parklands (highway context): the Secretary shall not approve any program or project that requires the use of land of a public park, recreation area, wildlife or waterfowl refuge, or historic site unless there is no feasible and prudent alternative and all possible planning to minimize harm has been included
• 49 U.S.C. § 303 — Policy on lands, wildlife and waterfowl refuges, and historic sites (transit context): parallel prohibition for transit, rail, and other non-highway transportation projects requiring DOT approval

Recent Rulemakings

2008 amendment (73 FR 13368): Implemented provisions of SAFETEA-LU (2005) that added the de minimis impact finding authority (§ 774.3(b)) — the most significant change to Section 4(f) in decades. The pre-2008 rule required a full Section 4(f) evaluation even for clearly minor impacts; the de minimis pathway allows streamlined processing for impacts so minor they don't affect the protected values, reducing review burden without weakening protection for significant impacts. The 2008 rule also clarified constructive use standards and added guidance on the net-benefit alternative.

2012 regulatory update: Minor clarifications to the coordination and documentation requirements; no change to the substantive standard.

Pending Action

No active rulemaking on Section 4(f) standards as of 2026. FHWA has issued guidance on applying Section 4(f) to shared-use paths and trails (which are themselves Section 4(f)-protected when publicly owned and significant) and to autonomous vehicle infrastructure projects. The Bipartisan Infrastructure Law (2021) did not amend the Section 4(f) statute.