Coast Guard Drawbridge Operation Regulations

Every drawbridge crossing a navigable waterway in the United States must follow federal rules about when it opens for vessel traffic. 33 CFR Part 117 is the Coast Guard's complete rulebook for drawbridge operations — establishing the baseline rule that drawbridges must open promptly on vessel signal, then setting the hundreds of bridge-specific schedules that balance maritime traffic against road traffic. A bridge in a congested urban corridor may only open on demand during off-peak hours; a remote rural bridge may have no restrictions; a heavily used commercial waterway bridge may require advance notice from tow operators.

Current Rule (2026)

What This Rule Does

Every drawbridge crossing a navigable waterway in the United States must follow federal rules about when it opens for boats and how vessel operators signal their request. 33 CFR Part 117 is the Coast Guard's complete rulebook for drawbridge operations — establishing the baseline obligation that draws must open promptly for any vessel on demand, then setting the hundreds of exceptions and special schedules that apply to specific bridges across the country.

The default rule is simple: when a vessel signals to pass, the bridge opens. But 400+ specific bridges operate on negotiated schedules that balance maritime traffic against road traffic. A busy commuter bridge in a congested city might only open on demand during off-peak hours, remaining closed to vessels during rush hours. A remote rural bridge may have no restrictions at all. A bridge used by commercial barge traffic may have advance-notice requirements. These bridge-specific rules fill Subpart B.

The Coast Guard's District Commanders have authority to modify drawbridge schedules — approving temporary changes (up to 180 days), authorizing closures for emergency repairs, and approving remote or automated operation. When bridge owners want a permanent schedule change, anyone — including mariners or road users — can petition the District Commander, who must balance navigational need against traffic impact.

Key Provisions

• § 117.5 — The baseline obligation: drawbridges must open promptly and fully for vessel passage when signaled, except as otherwise authorized by Part 117
• § 117.7 — Bridge owner responsibilities: maintain the draw in operable condition, provide adequate drawtender service (hours, qualifications), keep required safety equipment and lights
• § 117.9 — No person shall unreasonably delay opening the draw after a proper signal has been given; rail bridges get special treatment since trains are controlled by block signals and can't stop immediately
• § 117.11 — Vessel operators may not signal a bridge to open if the vessel can clear the bridge in its lowered position with all lowerable structures down — this prevents unnecessary openings and traffic delays
• § 117.15 — Signals: vessels request opening with the designated signal (horn, radio, or VHF); the drawtender must acknowledge; the sequence must be completed before the draw opens; whistle signal protocol specified
• § 117.23 — District Commander may require radiotelephone installation on bridges where safety requires it; VHF-FM radio allows direct bridge-to-vessel communication
• § 117.31 — Emergency vehicles: a drawtender who receives notice that an emergency vehicle is responding to an emergency must close the draw if it is open (to allow the vehicle to cross) unless a vessel has already entered the draw
• § 117.33 — Drawbridges need not open during periods of natural disaster or civil disorder declared by the appropriate federal, state, or local official
• § 117.35 — Temporary schedule changes (≤180 days) may be authorized by the District Commander; the bridge owner must publish notice in a newspaper and submit to USCG
• § 117.36 — Emergency repair closures: when a bridge becomes inoperable, the owner must notify the District Commander immediately; USCG may require a Coast Guard vessel to maintain a presence to warn marine traffic
• § 117.39 — If no vessel has requested an opening in at least 2 years, the bridge owner may petition to have the draw permanently closed to navigation
• § 117.40 — Advance notice requirements: for some bridges, vessel operators must notify the bridge owner by phone or radio in advance (ranging from 30 minutes to 24 hours) before the draw will open
• § 117.41 — Bridges permanently maintained in the fully open position may discontinue drawtender service as long as the structure is mechanically locked open and warning lights are maintained
• § 117.42 — Remote and automated drawbridges: upon written request, District Commander may authorize a bridge to operate without an on-site drawtender, using remote cameras and controls or automated vessel detection
• § 117.47 — Clearance gauges: required on bridges crossing waters discharging into the Atlantic south of Delaware Bay (including the Intracoastal Waterway) and in certain Gulf Coast areas — gauges show current water level relative to the bridge's vertical clearance
• § 117.49 — Violations: complaints go to the District Commander; civil penalties may be assessed under 33 U.S.C. § 499 for unreasonable delay; the bridge owner, not the Coast Guard, is responsible for the bridge's operation

How It Affects You

If you operate a recreational vessel: You have the legal right to request drawbridge openings under 33 U.S.C. § 499. Give the proper sound or radio signal and the bridge must open — unless the bridge is on a schedule or requires advance notice. Check the Subpart B section for your specific bridge; some high-traffic crossings have posted hours during which openings are restricted. Penalties apply to you for requesting unnecessary openings when your vessel can clear the bridge without it opening.

If you operate a commercial tow or barge: Commercial traffic often receives priority in scheduling rules, but advance notice requirements are more common for commercial vessels transiting bridges on a schedule. Consult the applicable Subpart B section before transiting unfamiliar bridges. Coordination with bridge owners and local Coast Guard sectors is standard practice on major waterway systems (Mississippi, Ohio, Tennessee, Intracoastal).

If you are a drawbridge owner or municipality: You are responsible for maintaining the draw in good operating condition, providing qualified drawtender service during required hours, and complying with all lighting and signal equipment requirements. If you want to change a bridge's operating schedule — to reduce openings during peak road traffic or to shift to remote operation — submit a written request to your USCG District Commander with traffic data justifying the change. Anyone can petition for or against the change, and the Coast Guard weighs marine traffic needs against road traffic.

If you are a maritime planner or waterway manager: Subpart B covers more than 400 named bridges with specific operating requirements — it's the authoritative source for scheduled opening windows, advance notice requirements, and seasonal restrictions on U.S. drawbridges. Coast Guard Sectors publish drawbridge notices (DBN) when temporary changes take effect.

Statutory Authority

This rule implements:

• 33 U.S.C. § 499 (Act to Regulate the Opening and Closing of Drawbridges, 1920) — authorizes the Secretary of the department in which the Coast Guard operates to prescribe regulations for the opening of drawbridges across navigable waters; violations are civil offenses; the statute also authorizes the Secretary to alter, amend, or repeal existing bridge permits

Recent Rulemakings

USCG regularly amends Subpart B to update individual bridge schedules. Amendments are published in the Federal Register as they affect specific bridges. Major structural amendments to Subpart A are infrequent; the general framework dates to regulations established in the 1960s-1980s, with updates for remote and automated bridge technology added in the 2000s.

• Remote and automated drawbridges: Amendments under § 117.42 authorizing automated operation have increased as bridge owners seek to reduce drawtender staffing costs. These require USCG approval and ongoing monitoring to ensure vessel detection systems work reliably.
• Advance notice programs: Several high-traffic bridges in urban waterways (notably in Florida and along the Gulf Intracoastal Waterway) have received authorization for advance notice requirements, reducing disruption to road traffic while maintaining navigational access.

Recent Developments

• Automated drawbridge expansion: USCG has approved an increasing number of automated and remotely operated drawbridges as bridge owners seek to reduce operating costs. The trend reflects labor cost pressures — drawtender staffing for a 24/7 bridge operation can cost several hundred thousand dollars per year. Remote monitoring systems using cameras and vessel detection technology allow one operator to monitor multiple bridges from a central location. USCG approval requires verification that the automation system reliably detects vessel approach and cannot leave boats trapped between opening leaves.
• Climate change and bridge opening frequency: Warmer weather extending the recreational boating season has increased the number of bridge openings required at some locations. Bridge opening data — which USCG uses to evaluate whether schedules remain appropriate — is showing higher annual opening counts at bridges in warmer regions. Some bridge operators have petitioned USCG for modified schedules to reduce road traffic impacts during peak boating season.
• Port security and bridge vulnerability: Post-9/11 port security frameworks include bridge vulnerability assessments, particularly for major movable bridges over navigable waterways serving critical transportation corridors. USCG and DOT coordinate on bridge security through the Area Maritime Security Committees. Physical security modifications at some major bridges — cameras, lighting, structural hardening — have required coordination with USCG's waterway access responsibilities.
• Draw span failures and navigation disruptions: Several high-profile draw span failures or operational malfunctions in recent years — including bridges on the Gulf Intracoastal Waterway and the Atlantic Intracoastal Waterway — have highlighted the aging infrastructure challenge. When a drawbridge fails in the open position, maritime traffic is interrupted; when it fails in the closed position, marine commerce is blocked. USCG coordinates emergency responses to bridge mechanical failures that affect navigation.

Pending Action

No comprehensive Part 117 rulemaking is currently pending. USCG processes individual bridge schedule and operational standard changes through locally initiated rulemakings triggered by petitions from bridge owners, mariners, or local governments — these are published in the Federal Register as direct final rules or proposed rules depending on whether significant opposition is expected. Vessel operators with navigability concerns about specific bridge schedules should submit comments during any pending Part 117 rulemaking for their waterway, or petition the relevant USCG District Commander to initiate a schedule review. Bridge owners planning automation or remote monitoring conversions must obtain advance USCG approval of the operational plan before modifying draw operations.