13-10-2012, 10:35 AM
Automatic Identification Systems (AIS) Data Use in Marine Vessel
Emission Estimation
[attachment=36273]
ABSTRACT
Eastern Research Group, Inc. (ERG) used Automatic Identification Systems (AIS) data to create
a state-of-the-art inventory of 2007 commercial marine vessel emissions in Texas State waters. AIS is a
unique program that provides a means for ships to electronically broadcast ship data at regular intervals
including: vessel identification, position, course, and speed. These and other data are transmitted
continuously, providing a comprehensive and detailed data set for individual vessels which can be used
to estimate and allocate emissions based on improve traffic pattern data.
ERG used a Geographic Information System (GIS) to map and analyze both individual vessel
movements and general traffic patterns on inland waterways and within 9 miles of the Texas coastline.
ERG then linked the vessel tracking data to individual vessel characteristics from Lloyd’s Register of
Ships, American Bureau of Shipping, and Bureau Veritas to match vessels to fuel and engine data,
which were then applied to the latest emission factors to quantify criteria and hazardous air pollutant
emissions from these vessels. The use of AIS data provides the opportunity for highly refined vessel
movement and improved emissions estimation, however, such a novel and detailed data set also provides
singular challenges in data management, analysis, and gap filling, which are examined in depth in this
paper along with potential methods for addressing limitations.
INTRODUCTION
With over 600 miles of tidewater coastline, Texas requires a clear picture of commercial marine
vessel emissions to develop accurate State Implementation Plan (SIP) emission inventories, risk
assessments, dispersion modeling, and proactive planning. Activity and emissions within state waters
are of particular importance given potential air quality and human health impacts. However, unlike
activity in other mobile source categories such as on-road and rail traffic, the category of marine vessel
emissions poses particular challenges as the location of these activities remain relatively uncertain.
The Texas Commission on Environmental Quality (TCEQ) contracted with ERG to develop the
2007 inventory of commercial marine vessel (CMV) emissions for counties not included in the
Houston/Galveston/Brazoria nonattainment area1. The intent of this project was to compile activity,
vessel traffic pattern and vessel characteristics data, emission factors, and information about operating
load required to estimate emissions of criteria and hazardous air pollutants.
BODY
Automated Identification System
Among the numerous security regulations that came into effect after September 11, 2001 was the
requirement for most commercial marine vessels to be fitted with Automatic Identification Systems
(AIS). AIS provides a means for ships to electronically send data including vessel identification,
position, speed, and course with Vessel Traffic Services (VTS) stations as well as with other ships. AIS
uses Global Positioning Systems (GPS) in conjunction with shipboard sensors and digital VHF radio
communication equipment to automatically exchange navigation information electronically. Vessel
identifiers such as the vessel name and VHF call sign are programmed in during initial equipment
installation and are included in the transmittal along with location information originating from the
ship's global navigation satellite system receiver and gyrocompass. AIS is used by marine vessels in
coordination with VTS to monitor vessel location and movement primarily for traffic management,
collision avoidance, and other safety applications.
AIS Data Query Customization
To obtain AIS data for use in quantifying CMV activity, ERG worked with AIRSIS, Inc., a
maritime technology company with particular experience in Texas state waters. AIRSIS developed the
PortVision data, which leverage the existing AIS technology and process each unique signal – more than
one million records a day along the Sabine-Neches ship channel, providing real-time information about
the location and status of vessels on the waterway. In 2000, AIRSIS used satellite-based technology in
the Houston ship channel to optimize the movements of tankers within the Houston/Galveston Area
(HGA). By 2003, waterway users relied on this technology to optimize scheduling and communications
for over 60% of tanker activities in the region.4 The points of interest (POI) noted in Figure 2 are the
locations where AIRSIS maintains vessel monitoring stations, such that the data files report vessel
activity as they approach and pass the POIs. Each POI has a coverage radius of approximately 40 miles,
though depending on the receiver’s location and elevation and current atmospheric conditions, reliable
coverage can reach 60 miles or more.
Data Processing
Since AIS data quantified individual vessel activities, significant processing was required to
summarize and prepare the data for use in developing a comprehensive emission inventory. The AIS
data were matched to vessel characteristics data obtained from vessel classification associations such as
Lloyds or the American Bureau of Shipping. The vessel characteristics data include information about
the horsepower rating of individual vessels and information concerning auxiliary engines. By evaluating
the AIS time stamp data and applying the hours of operation to the vessels horsepower rating, it was
possible to quantify the horsepower-hours of operation for individual vessels and to assign them to
shipping lanes and port areas where they operate. The horsepower-hours were applied to emission
factors from the Swedish EPA to provide emission estimates for criteria and hazardous air pollutants.
Ultimately, the emission estimates were applied to specific shipping lane segments where they occurred
using GIS shapefiles and data analysis tools, and the data were summarized both at the shipping lane
segment and county level. This process is illustrated in Figure 4 below.
CONCLUSIONS
There have been several detailed and comprehensive emission inventories of the
Houston/Galveston/Bazoria port area; but considerably less for other coastal counties that include some
very active ports and shipping lanes. The AIS data used to develop this emission inventory provided
reasonably accurate information about vessel traffic patterns outside of the Houston/Galveston
nonattainment area. These AIS data included over 80,000 ship transits for nearly every vessel type.
However, further enhancements are required to more accurately identify and spatially allocate
coastal and intracoastal waterway trips. Until additional POIs are added to statewaters, such allocations
could be improved by using U.S. Army Corps of Engineers domestic traffic data. These data are not
disaggregated by individual vessels but rather estimate total traffic movements. Such information could
be used in conjunction with the tug and towboat data compiled for this inventory to more accurately
assign emissions to all coastal counties.
Emission Estimation
[attachment=36273]
ABSTRACT
Eastern Research Group, Inc. (ERG) used Automatic Identification Systems (AIS) data to create
a state-of-the-art inventory of 2007 commercial marine vessel emissions in Texas State waters. AIS is a
unique program that provides a means for ships to electronically broadcast ship data at regular intervals
including: vessel identification, position, course, and speed. These and other data are transmitted
continuously, providing a comprehensive and detailed data set for individual vessels which can be used
to estimate and allocate emissions based on improve traffic pattern data.
ERG used a Geographic Information System (GIS) to map and analyze both individual vessel
movements and general traffic patterns on inland waterways and within 9 miles of the Texas coastline.
ERG then linked the vessel tracking data to individual vessel characteristics from Lloyd’s Register of
Ships, American Bureau of Shipping, and Bureau Veritas to match vessels to fuel and engine data,
which were then applied to the latest emission factors to quantify criteria and hazardous air pollutant
emissions from these vessels. The use of AIS data provides the opportunity for highly refined vessel
movement and improved emissions estimation, however, such a novel and detailed data set also provides
singular challenges in data management, analysis, and gap filling, which are examined in depth in this
paper along with potential methods for addressing limitations.
INTRODUCTION
With over 600 miles of tidewater coastline, Texas requires a clear picture of commercial marine
vessel emissions to develop accurate State Implementation Plan (SIP) emission inventories, risk
assessments, dispersion modeling, and proactive planning. Activity and emissions within state waters
are of particular importance given potential air quality and human health impacts. However, unlike
activity in other mobile source categories such as on-road and rail traffic, the category of marine vessel
emissions poses particular challenges as the location of these activities remain relatively uncertain.
The Texas Commission on Environmental Quality (TCEQ) contracted with ERG to develop the
2007 inventory of commercial marine vessel (CMV) emissions for counties not included in the
Houston/Galveston/Brazoria nonattainment area1. The intent of this project was to compile activity,
vessel traffic pattern and vessel characteristics data, emission factors, and information about operating
load required to estimate emissions of criteria and hazardous air pollutants.
BODY
Automated Identification System
Among the numerous security regulations that came into effect after September 11, 2001 was the
requirement for most commercial marine vessels to be fitted with Automatic Identification Systems
(AIS). AIS provides a means for ships to electronically send data including vessel identification,
position, speed, and course with Vessel Traffic Services (VTS) stations as well as with other ships. AIS
uses Global Positioning Systems (GPS) in conjunction with shipboard sensors and digital VHF radio
communication equipment to automatically exchange navigation information electronically. Vessel
identifiers such as the vessel name and VHF call sign are programmed in during initial equipment
installation and are included in the transmittal along with location information originating from the
ship's global navigation satellite system receiver and gyrocompass. AIS is used by marine vessels in
coordination with VTS to monitor vessel location and movement primarily for traffic management,
collision avoidance, and other safety applications.
AIS Data Query Customization
To obtain AIS data for use in quantifying CMV activity, ERG worked with AIRSIS, Inc., a
maritime technology company with particular experience in Texas state waters. AIRSIS developed the
PortVision data, which leverage the existing AIS technology and process each unique signal – more than
one million records a day along the Sabine-Neches ship channel, providing real-time information about
the location and status of vessels on the waterway. In 2000, AIRSIS used satellite-based technology in
the Houston ship channel to optimize the movements of tankers within the Houston/Galveston Area
(HGA). By 2003, waterway users relied on this technology to optimize scheduling and communications
for over 60% of tanker activities in the region.4 The points of interest (POI) noted in Figure 2 are the
locations where AIRSIS maintains vessel monitoring stations, such that the data files report vessel
activity as they approach and pass the POIs. Each POI has a coverage radius of approximately 40 miles,
though depending on the receiver’s location and elevation and current atmospheric conditions, reliable
coverage can reach 60 miles or more.
Data Processing
Since AIS data quantified individual vessel activities, significant processing was required to
summarize and prepare the data for use in developing a comprehensive emission inventory. The AIS
data were matched to vessel characteristics data obtained from vessel classification associations such as
Lloyds or the American Bureau of Shipping. The vessel characteristics data include information about
the horsepower rating of individual vessels and information concerning auxiliary engines. By evaluating
the AIS time stamp data and applying the hours of operation to the vessels horsepower rating, it was
possible to quantify the horsepower-hours of operation for individual vessels and to assign them to
shipping lanes and port areas where they operate. The horsepower-hours were applied to emission
factors from the Swedish EPA to provide emission estimates for criteria and hazardous air pollutants.
Ultimately, the emission estimates were applied to specific shipping lane segments where they occurred
using GIS shapefiles and data analysis tools, and the data were summarized both at the shipping lane
segment and county level. This process is illustrated in Figure 4 below.
CONCLUSIONS
There have been several detailed and comprehensive emission inventories of the
Houston/Galveston/Bazoria port area; but considerably less for other coastal counties that include some
very active ports and shipping lanes. The AIS data used to develop this emission inventory provided
reasonably accurate information about vessel traffic patterns outside of the Houston/Galveston
nonattainment area. These AIS data included over 80,000 ship transits for nearly every vessel type.
However, further enhancements are required to more accurately identify and spatially allocate
coastal and intracoastal waterway trips. Until additional POIs are added to statewaters, such allocations
could be improved by using U.S. Army Corps of Engineers domestic traffic data. These data are not
disaggregated by individual vessels but rather estimate total traffic movements. Such information could
be used in conjunction with the tug and towboat data compiled for this inventory to more accurately
assign emissions to all coastal counties.