Traffic Separation Schemes

Rule text#

(a)This Rule applies to traffic separation schemes and does not relieve any vessel of her obligation under any other Rule in subchapter E.

(b)A vessel using a traffic separation scheme shall:

(i)Proceed in the appropriate traffic lane in the general direction of traffic flow for that lane;

(ii)So far as practicable keep clear of a traffic separation line or separation zone;

(iii)Normally join or leave a traffic lane at the termination of the lane, but when joining or leaving from either side shall do so at as small an angle to the general direction of traffic flow as practicable.

(c)A vessel shall, so far as practicable, avoid crossing traffic lanes but if obliged to do so shall cross on a heading as nearly as practicable at right angles to the general direction of traffic flow. (d)(i) A vessel shall not use an inshore traffic zone when she can safely use the appropriate traffic lane within the adjacent traffic separation scheme. However, vessels of less than 20 meters in length, sailing vessels, and vessels engaged in fishing may use the inshore traffic zone.

(ii)Notwithstanding paragraph (d)(i) of this Rule, a vessel may use an inshore traffic zone when en route to or from a port, offshore installation or structure, pilot station, or any other place situated within the inshore traffic zone, or to avoid immediate danger.

(e)A vessel other than a crossing vessel or a vessel joining or leaving a lane shall not normally enter a separation zone or cross a separation line except:

(i)In cases of emergency to avoid immediate danger;

(ii)To engage in fishing within a separation zone.

(f)A vessel navigating in areas near the terminations of traffic separation schemes shall do so with particular caution.

(g)A vessel shall so far as practicable avoid anchoring in a traffic separation scheme or in areas near its terminations.

(h)A vessel not using a traffic separation scheme shall avoid it by as wide a margin as is practicable.

(i)A vessel engaged in fishing shall not impede the passage of any vessel following a traffic lane.

(j)A vessel of less than 20 meters in length or a sailing vessel shall not impede the safe passage of a power-driven vessel following a traffic lane.

(k)A vessel restricted in her ability to maneuver when engaged in an operation for the maintenance of safety of navigation in a traffic separation scheme is exempted from complying with this Rule to the extent necessary to carry out the operation.

(l)A vessel restricted in her ability to maneuver when engaged in an operation for the laying, servicing, or picking up of a submarine cable, within a traffic separation scheme, is exempted from complying with this Rule to the extent necessary to carry out the operation.

Where Inland differs#

Inland Rule 10 is structurally different — titled 'Vessel Traffic Services' (33 CFR §83.10), it requires compliance with a USCG-regulated VTS rather than an IMO-adopted TSS. The text addresses lane discipline within VTS-monitored waters.

Authoritative source#

Source links checked against the current public rule corpus on 2026-05-16.

• 33 CFR §83.10 — the section this text comes from, with its neighbours.
• International COLREGs Rule 10 verbatim text is published by the IMO and is authoritative for international waters.

Practice this rule#

One real exam question on this rule, cited to source. No sign-up.