Vessel traffic service
A vessel traffic service (VTS) is a marine traffic monitoring system established by harbour or port authorities, similar to air traffic control for aircraft. Typical VTS systems use radar, closed-circuit television (CCTV), VHF radiotelephony and automatic identification system to keep track of vessel movements and provide navigational safety in a limited geographical area.
Vessel traffic services 
A service implemented by a competent authority, VTS is designed to improve the safety and efficiency of navigation, safety of life at sea and the protection of the marine environment. VTS is governed by SOLAS Chapter V Regulation 12 together with the Guidelines for Vessel Traffic Services [IMO Resolution A.857(20)] adopted by the International Maritime Organization on 27 November 1997.
The VTS traffic image is compiled and collected by means of advanced sensors such as radar, AIS, direction finding, CCTV and VHF or other co-operative systems and services. A modern VTS integrates all of the information in to a single operator working environment for ease of use and in order to allow for effective traffic organization and communication.
In areas that are covered with VTS there are certain procedures for vessels to follow such as Area Procedures, Sector Areas, Arrival and Departure Reports, Approach Procedures, Pilotage Procedures and many more. Each of the above procedures are named with respect to the area that they serve. For example in Norway, Oslofjord the Area Procedures are called "OSL1" and "OSL3" and in Netherlands, Rotterdam, Maas Approach and Maas Entrance are called "RTM2" and "RTM6" respectively.
A VTS should always have a comprehensive traffic image, which means that all factors influencing the traffic as well as information about all participating vessels and their intentions should be readily available. By means of the traffic image, situations that are developing can be evaluated and responded upon. The data evaluation depends to a great extent on the quality of the data that is collected and the ability of the operator to combine this with an actual or developing situation. The data dissemination process exists of conveying the conclusions of the operator. Three forms of data dissemination are possible:
VTS personnel 
The VTS guidelines require that the VTS authority should be provided with sufficient staff, appropriately qualified, suitably trained and capable of performing the tasks required, taking into consideration the type and level of services to be provided in conformity with the current IMO guidelines on the subject.
IALA Recommendation V-103 is the Recommendation on Standards for Training and Certification of VTS Personnel. There are four associated model courses V103/1 to V-103/4 which are approved by IMO and should be used when training VTS personnel for the VTS qualifications.
Information service 
An information service is a service to ensure that essential information becomes available in time for on-board navigational decision-making.
The information service is provided by broadcasting information at fixed times and intervals or when deemed necessary by the VTS or at the request of a vessel, and may include for example reports on the position, identity and intentions of other traffic; waterway conditions; weather; hazards; or any other factors that may influence the vessel's transit.
Traffic organization service 
A traffic organization service is a service to prevent the development of dangerous maritime traffic situations and to provide for the safe and efficient movement of vessel traffic within the VTS area.
The traffic organization service concerns the operational management of traffic and the forward planning of vessel movements to prevent congestion and dangerous situations, and is particularly relevant in times of high traffic density or when the movement of special transports may affect the flow of other traffic. The service may also include establishing and operating a system of traffic clearances or VTS sailing plans or both in relation to priority of movements, allocation of space, mandatory reporting of movements in the VTS area, routes to be followed, speed limits to be observed or other appropriate measures which are considered necessary by the VTS authority.
A navigational assistance service is a service to assist on-board navigational decision-making and to monitor its effects.
The navigational assistance service is especially important in difficult navigational or meteorological circumstances or in case of defects or deficiencies. This service is normally rendered at the request of a vessel or by the VTS when deemed necessary.