Handbook of the Nautical Rules of the Road by Llana & Wisneskey

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Rule 10 -- Traffic Separation Schemes


Rule 10 adds an extra dose of traffic management for a number of specially designated areas having high-density traffic, converging traffic, or some exceptional hazard. In these situations, more conventional navigation rules do not provide a desirable margin of safety. Traffic separation schemes have been established all over the world, and are usually associated with the approaches to busy ports and at turning points in crowded sea lanes. International and Inland Rule 10 are now virtually identical, and although no TSSs have yet been established in Inland Rules waters, there are a few inland rules waters, such as the San Francisco Bay area, where a TSS might be placed.


INTERNATIONAL

INLAND

(a) This Rule applies to traffic separation schemes adopted by the Organization and does not relieve any vessel of her obligation under any other rule.

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

 

The Organization mentioned in the International Rule paragraph (a) is the International Maritime Organization (IMO), a body of the United Nations headquartered in London. Traffic separation schemes are adopted by the IMO after a country (or countries) submits a traffic separation scheme proposal, which must meet specific IMO guidelines. Normally a scheme will not be shown on charts until it has been formally adopted by the IMO. The IMO publishes Ships' Routing, which contains design standards and a list (with diagrams and coordinates) of all adopted traffic separation schemes. Check with your local authorities for an up to date list.

The IMO defines "traffic separation scheme" as a plan that organizes traffic proceeding in opposite or nearly opposite directions by means of a separation zone or line, traffic lane, etc. There may be obstructions within the traffic separation scheme. Efforts, however, are made to keep the lanes clear. For known obstructions, such as an oil rig or wreck, within a traffic separation scheme, notice to mariners will be given. Sometimes a traffic separation scheme will be temporarily modified to skirt a short-term obstruction. In some cases off U.S. coasts "safety fairways," in which obstructions are excluded, are superimposed over a traffic separation scheme. (In most cases safety fairways are used independently, usually in areas having concentrations of offshore petroleum production and exploration platforms.)

A vessel is said to be "using" a traffic separation scheme when the vessel is within the boundaries of the scheme and is neither crossing the scheme nor fishing within the separation zone. The language on vessel obligations dispels any notion that once in a traffic lane, a vessel acquires absolute rights over vessels outside of the lane. Rule 8(f)(iii) provides an example of where a vessel in a lane would be obligated to stay out of the way of a presumably less privileged crossing vessel.

 

INTERNATIONAL

INLAND

(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.

(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.

 

The first rule for using a traffic separation scheme is obvious: go with the flow.

The second rule requires vessels "so far as practicable" not to get too close to a traffic separation line or zone so as not to drift accidentally into the lane of oncoming traffic or create doubt about whether or not it is using the traffic separation scheme. Unlike highways on land, traffic separation schemes do not have double yellow lines down the middle or a white line on its outside boundary.

The third rule, governing vessels entering or leaving a traffic separation lane, requires a small angle of approach or departure to differentiate that vessel from one crossing the scheme. (Crossing instructions are in Rule 10(c).)

 

INTERNATIONAL

INLAND

(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.

(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.

 

Many schemes are short, and you can go around, not through them. Crossing long schemes at right angles announces that vessel's intentions and minimizes the time the crossing vessel spends in the scheme. Please note that the angle of crossing is determined by the vessel's heading, not its course (which could be different, usually because of a side current). When a crossing vessel encounters a vessel using a traffic separation scheme, the vessel that is required to stay out of the way is determined by Rule 15 (Crossing Situations).

Fishing vessels, sailing vessels, and power-driven vessels less than twenty meters in length--see paragraphs (i) and (j)--that are crossing shall always stay out of the way of a vessel following a traffic separation lane, but be aware that the larger vessel in the traffic lane does not have absolute rights; see Rule 8(f)(iii).

 

INTERNATIONAL

INLAND

(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 subparagraph (d)(i), 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.

(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 twenty meters in length, sailing vessels, and vessels engaged in fishing may use the inshore traffic zone.

(ii) Notwithstanding subparagraph (d)(i), 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.

 

Segregating large fast ships from smaller coastal vessels lessens the anxieties often felt when big and small vessels share a common waterway. Rule 10(d) provides this separation through "inshore traffic zones," defined as designated areas between the landward boundary of a traffic separation scheme and the adjacent coast intended for coastal traffic. The purpose of inshore traffic zones may be, for example, to keep oil tankers away from merchant shipping.

When an inshore traffic zone has been adopted as part of a traffic separation scheme, large through vessels are in effect required to use the traffic lanes or to stay offshore beyond the traffic separation scheme. The Rule recognizes that sailing vessels and small power-driven vessels often depend on being near the coast.

 

INTERNATIONAL

INLAND

(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.

(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; or

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

 

The paragraph (e) restriction on crossing a separation line or entering a separation zone is similar to the paragraph (b)(ii) restriction, but it explicitly recognizes a right to fish within separation zones.

 

INTERNATIONAL

INLAND

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

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

 

Most traffic separation schemes guiding traffic flow in and out of ports have "precautionary areas" at the inshore end of the scheme. Because of the concentration of meeting and crossing traffic, you should exercise particular care. Paragraph (f) makes it clear that the mariner is also required to proceed with caution near the ends of traffic separation schemes that do not have precautionary areas.

 

INTERNATIONAL

INLAND

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

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

 

Following the reasoning for prohibitions against anchoring in narrow channels, fairways, and the like, paragraph (g) prohibits anchoring in a traffic separation scheme or near its ends.

 

INTERNATIONAL

INLAND

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

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

 

The smooth operation of a traffic separation scheme depends on the absence of outside disturbances. A vessel not using a traffic separation scheme must stay far enough away that vessels within the scheme are not obligated, via any other navigation rule--see Rule 8(f)(iii)--to take action inconsistent with the flow of traffic.

 

INTERNATIONAL

INLAND

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

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

 

Fishing is permitted within a traffic lane so long as the fishing vessel proceeds along the lane with the rest of the traffic and does not "impede" other vessels following the traffic lane. If the vessel engaged in fishing follows a course that obliges a vessel following the traffic lane to alter course or speed, then the fishing vessel had impeded the other vessel and is therefore in violation of this requirement.

 

INTERNATIONAL

INLAND

(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.

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

 

The Rules often distinguish among size and types of vessels. Rule 10 distinguishes between large vessels (power-driven vessels twenty meters and longer) and small (power-driven vessels less than twenty meters and all sailing vessels). Just as paragraph (d) gives priority to small vessels for inshore traffic zones, paragraph (j) gives priority to larger vessels in traffic lanes. Small vessels using traffic separation schemes must stay far away from ships and, whenever possible, should communicate their intentions by radiotelephone. The "shall not impede" language, discussed earlier, operates in this requirement too--see Rule 8(f).

 

INTERNATIONAL

INLAND

(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.

(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.

 

Paragraphs (k) and (l) provide exemptions from Rule 10 requirements for two classes of vessels that, by the nature of their work, cannot always comply with every requirement. Vessels engaged in the maintenance of navigation safety, such as buoy tenders, are exempted only while they are restricted in their ability to maneuver and only to the extent needed to carry out their work. Vessels laying or maintaining submarine cables must go where the cable goes and while working on cable are normally restricted in their ability to maneuver. Operations likely to interfere with normal separation scheme traffic may be publicized by notices to mariners.

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