vvEPA
United States
Environmental Protection
Agency
Office of Transportation and Air Quality
EPA-420-F-21-009
March 2021
Port Operational Strategies: Virtual Vessel Arrival
This fact sheet is one of a series of documents produced by the EPA Ports Initiative to inform port
stakeholders about potential emission reduction strategies.1 Each fact sheet contains basic
information about the strategy, emission impacts, cost components, and example programs. While
each strategy can achieve benefits on its own, implementing them together could create synergies.2
Strategy Summary
Description: Ocean-going vessels can experience significant delays entering their destination ports, resulting
in increased fuel consumption and emissions while they idle at anchorage. It is common practice for vessel
operators to travel full speed to their destinations and then wait for berths, sometimes for several days.
Virtual vessel arrival systems inform vessel operators of expected delays at their destination ports, helping
them align arrival times with berth availability. This adjustment reduces or eliminates wait times and
corresponding offshore anchorage emissions and fuel consumption. In addition, these systems can inform
optimal voyage speeds, resulting in further potential fuel savings.
Virtual vessel arrival is a low-cost strategy that has several basic requirements including enhanced vessel
traffic planning and communication systems, and program monitoring improvements. This strategy is
relatively new and has only been demonstrated for a few vessels worldwide, but is a promising approach for
increasing vessel operational efficiency and reducing emissions. Figure 1 summarizes the virtual vessel
arrival process.3
Advantages: Delays are common for ocean-going vessels, as illustrated in Figure 2 (showing dozens of
tankers awaiting entry into the Port of Houston) and Figure 3 (showing the large variability in on-time
arrivals for container ships, globally and for two tradelanes).4 While delayed, vessels wait offshore at nearby
anchorages, using their auxiliary engines and potentially dragging their anchors and suffering collisions. They
may also use their main engines, depending on weather.
1	The emissions evaluated in these fact sheets include nitrogen oxides (NOx), particulate matter (PM), hydrocarbons
(HC), carbon monoxide (CO), carbon dioxide (CO2), and sulfur dioxide (SO2).
2	See the Ports Initiative's fact sheets on vessel speed reduction (https://www.epa.gov/ports-initiative/marine-
vessel-speed-reduction-reduces-air-emissions-and-fuel-usage), port management information systems
(https://www.epa.gov/ports-initiative/management-information-systems-improve-operational-efficiencies-and-air-
quality), and gate management (https://www.epa.gov/ports-initiative/port-gate-management-strategies-improve-
air-qualitv-and-efficiencv-ports).
3	Adapted from Intertanko and OCIMF. 2011. Virtual Arrival: Optimising Voyage Management and Reducing Vessel
Emissions—an Emissions Management Framework. https://www.ocimf.org/media/115960/Virtual-Arrival.pdf.
Accessed 3-5-2021.
4 Ibid.

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no
yes
not acceptable
no
yes
no
acceptable
no
yes
yes
Select a suitable
clause and review for
acceptability
Calculate reduced
anchorage times/
fuel savings
Delay identified at
discharge port
Calculate new
arrival time
Arrive at port and notify
all parties
Are owners/operators/
receivers in agreement to
reduce vessel speed?
Monitor performance
and weather
Do not proceed with
this process
Do you wish to engage
a weather analysis
service provider?
Agree to suitable contract
performance clause
Agree to new arrival time
Do you have an agreement that
will avoid disputes over
performance claims?
Figure 1. Virtual Vessel Arrival Process
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Figure 3. Percentage of Container Ship Sailings with On-time Arrivals6
Parker, B. 2014. Busy Days at Galveston as Tankers Crowd the Anchorage. Seatrade Maritime News.
https://www.seatrade-maritime.com/americas/busv-davs-galveston-tankers-crowd-anchorages. MarineTraffic
holds the original rights to the graphic. Accessed 3-5-2021.
Mongelluzzo, B, 2018. New APL Service to Test Expedited Demand on Trans-Pacific. Journal of Commerce,
https://www.ioc.com/maritime-news/trade-lanes/trans-pacific/new-apl-service-test-expedited-demand-trans-
pacific 20180717.html. Accessed 3-5-2021.
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Virtual vessel arrival reduces or eliminates the emissions generated while waiting at anchorage, improving
air quality and the health of port workers and nearby communities.7 These emissions can be a significant
part of total marine vessel port emissions. For example, emissions at anchorage contributed about 7 percent
of PM2.5, 5 percent of NOx, 8 percent of SOx, and 7 percent of C02e emissions from ocean-going vessels at the
Port of Los Angeles in 2016.8 In addition, advance information regarding port delays allows a vessel to
reduce its speed, using less fuel and generating fewer emissions en route.
Virtual vessel arrival systems can provide critical information about arrival times, which can then be used to
help coordinate services between ports, terminal managers, and charter agencies. Once an arrival time is
agreed upon, the weather analysis service provider works with the vessel operator using Automatic
Identification System (AIS) data to recompute speed and fuel consumption rates and monitor ocean currents
and weather data to determine the optimal route and vessel speed for the revised arrival time. The weather
analysis service provider also provides designated stakeholders (such as beneficial cargo owners, terminal
operators, and the port) with regular updates on vessel locations and projected arrival times, ensuring that
dock and cargo handling equipment are readily available.
Virtual vessel arrival can also save time and money for ship operators and charterers. The ability to direct
ships to a terminal with little or no delay, followed by quick freight transfer on arrival, means ports can
operate more efficiently and vessels can get back to sea faster. Virtual vessel arrival information can be
integrated with other systems such as gate management strategies9 and port management information
systems10 to help improve scheduling for drayage truck pickups and rail transfers, and may offer additional
benefits during extreme weather events such as hurricanes, allowing weather analysis service providers to
reroute vessels to other ports more easily.
Ship owners and charterers adopting virtual vessel arrival can reduce fuel costs due to slower underway
speeds at sea and less auxiliary engine use at anchor. Charterers may also see savings through reduced
penalties paid for early vessel arrival.11 Because virtual vessel arrival is still new, how potential cost savings
will be shared among vessel operators, charterers, and the ports is yet to be determined.
Considerations: A virtual vessel arrival system requires more accurate dockside planning by port officials
and terminal operators to project when berth space will be available for arriving vessels. It also requires
better communication with port stakeholders, as well as vessel operators and weather analysis service
providers, to ensure that cargo handling equipment is readily available when vessels arrive.
7	Exposure to air pollution associated with emissions from diesel engines can contribute to significant health
problems—including premature mortality, increased hospital admissions for heart and lung disease, increased
cancer risk, and increased respiratory symptoms—especially for children, the elderly, outdoor workers, and other
sensitive populations. (See U.S. Environmental Protection Agency. 2014. Near Roadway Air Pollution and Health:
Frequently Asked Questions. https://nepis.epa.gov/Exe/ZyPDF.cgi/P100NFFD.PDF?Dockey=P100NFFD.PDF.
Accessed 3-5-2021.
8	Starcrest Consulting Group, LLC. 2017. Port of Los Angeles: Inventory of Air Emissions—2016.
https://kentico.portoflosangeles.org/getmedia/644d6f4c-77f7-4eb0-b05b-
df4c0fea 1295/2016 Air Emissions Inventory. Accessed 3-5-2021.
9	U.S. Environmental Protection Agency. 2020. Port Operational Strategies: Gate Management.
https://www.epa.gov/ports-initiative/port-gate-management-strategies-improve-air-qualitv-and-efficiency-ports.
10	U.S. Environmental Protection Agency. 2020. Port Operational Strategies: Port Management Information Systems.
https://www.epa.gov/ports-initiative/management-information-systems-improve-operational-efficiencies-and-air-
quality.
11	Under certain contracts, if a vessel arrives early and must wait for a berth, the ship operator is entitled to
compensation for demurrage fees.
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The virtual vessel arrival system can also be beneficial to manage larger container ships to estimate and
identify when dockside unloading space is available.
Implementing such a system may also require substantive changes to incentive structures and contracting
terms for ship operators, charterers, and cargo owners, for the following reasons:
•	Entry at congested ports is generally granted on a first come, first served basis, encouraging vessels to
reach the port as quickly as possible.12
•	Necessary contract modifications will vary depending on the type of charter agreement. Under "time
charter" contracts, the charterer pays for the vessel's fuel and can direct the ship operator to reduce
speed to conserve fuel. However, the charterer may prioritize timely arrival to the port area over cost.
"Voyage charter" contracts typically make the ship operator responsible for fuel charges, providing a
direct incentive to reduce speed and conserve fuel, although the operator is still required to comply with
the arrival times agreed upon with the charterer.13
•	Financial incentives for ship operators can be complicated as they relate to demurrage. Demurrage is a
fee charged by a carrier, port, or railroad company for the storage of containers that exceed free time
offered for loading/unloading. Once free time is expired, the shipper is charged a daily demurrage fee
until the cargo is removed from the terminal. If Virtual Vessel Arrival is efficiently paired with truck
pickup times for containers via truck appointment systems, demurrage fees can be minimized.
Appropriate port size and type: Virtual vessel arrival can be applied to any size and type of port, although
larger ports with traffic congestion problems will benefit the most from adoption.
Emission Reductions14
Primary Pollutants affected: NOx, PM, HC, CO, C02, and S02
Anticipated reductions: Reductions will depend on the number of vessels currently delayed, each vessel's
auxiliary engine specifications, and the number of hours of delay for each vessel. The calculation
methodology below can be used to estimate emission reductions from reduced vessel wait times at port but
does not include emission reductions resulting from slower vessel speeds en route.
Calculation methodology: Calculating the emission reductions resulting from adoption of virtual vessel
arrival is done on a vessel-specific basis and involves two steps: 1) determining vessel-specific emission rates
accounting for the average power rating of the auxiliary engines and boilers used at offshore anchorage;15
12	Price, T. 2011. Shipping Industry Launches "Virtual Arrival" to Save Fuel, Cut Emissions. Renewable Energy
Magazine, https://www.renewableenergymagazine.com/energy_saving/shipping-industry-launches-virtual-arrival-
to-save. Accessed 3-5-2021.
13	Lindholm, E. 2014. Efficient Charterparties: Notice of Readiness, Slow Steaming and Virtual Arrival Agreements.
https://www.academia.edu/9785488/Efficient charterparties -
Notice of readiness slow steaming and virtual arrival agreements. Accessed 3-5-2021.
14	The information in this section is for illustration: although the types of inputs and methods used in this section are
generally consistent with EPA established methodologies, it does not constitute official EPA technical guidance for
regulatory purposes. Please note that EPA has comprehensive guidance on developing inventories of emissions
from ports and port-related goods movement. EPA's Port Emissions Inventory Guidance, September 2020, EPA-420-
B-20-046, is available at EPA's web site at: www.epa.gov/state-and-local-transportation/port-emissions-inventory-
guidance. Accessed 3-5-2021.
15	Average power ratings account for rated power as well as average load factor. For example, a 100 kW auxiliary
engine operated at an average load of 50 percent would be assumed to operate at 50 kW for calculation purposes.
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and 2) estimating the decrease in vessel wait times using data from the charterer or weather analysis service
provider provided in the trip virtual vessel arrival summary reports. Individual trip calculations can be
summed to determine fleet-wide benefits. The inputs required to calculate ship-specific emission
reductions, and potential sources of data, are listed below.
•	Average auxiliary power for each vessel (kW) for anchorage modes from vessel operators, classification
societies, or default values provided in Table 1.
•	Average boiler power (kW) for anchorage modes from vessel operators or default values provided in
Table 1.
•	Auxiliary engine emission factors (g/kW-hr) based on engine type, fuel type, and fuel sulfur
concentration provided in Table 2.
•	Boiler emission factors (g/kW-hr) based on fuel type and fuel sulfur concentration provided in Table 2.
•	Estimated hours the vessel would spend at anchorage based on anticipated arrival time at full speed and
the actual arrival time provided by the charterer or weather analysis service provider
Table 1. Average Auxiliary Engine and Boiler Loads at Anchorage by Ship Type16
Ship Type
Subtype
Aux
fkWl
Boiler
fkWl
Bulk carrier
Small
190
50
Handysize
190
50
Handymax
260
100
Panamax
420
200
Capesize
420
200
Capesize largest
420
200
Chemical tanker
Smallest
80
125
Small
230
250
Handysize
230
250
Handymax
550
250
Container ship
1,000 TEU
300
120
2,000 TEU
820
290
3,000 TEU
1,230
350
5,000 TEU
1,390
450
8,000 TEU
1,420
450
12,000 TEU
1,630
520
14,500 TEU
1,960
630
Largest
2,160
700
Cruise
2,000 ton
450
250
10,000 ton
450
250
60,000 ton
3,500
1,000
100,000 ton
11,480
500
Largest
11,480
500
Ferry/passenger
(C3)
2,000 ton
186
0
Largest
524
0
Ferry/roll-on/
passenger (C3]
2,000 ton
105
0
Largest
710
0
Fishing fC3]
All C3 fishing
200
0
Ship Type
Subtype
Aux
fkW)
Boiler
fkW)
General cargo
5,000 DWT
60
0
10,000 DWT
170
75
Largest
490
100
Liquified gas
tanker
50,000 DWT
240
200
100,000 DWT
240
300
200,000 DWT
1,710
600
Largest
1,710
600
Miscellaneous
fC3]
All C3 misc.
190
0
Offshore
support/drillship
All offshore
support/drillship
320
0
Oil tanker
Smallest
250
100
Small
375
150
Handysize
625
250
Handymax
750
300
Panamax
750
300
Aframax
1,000
400
Suezmax
1,250
500
VLCC
1,500
600
Other service
All other service
220
0
Other tanker
All other tanker
500
200
Reefer
All reefer
1,170
270
RORO
5,000 ton
600
200
Largest
950
300
Vehicle carrier
4,000 vehicles
500
268
Largest
500
268
Yacht
C2/C317 yacht
130
0
16	U.S. Environmental Protection Agency. 2020. Port Emissions Inventory Guidance: Methodologies for Estimating
Port-Related and Goods Movement Mobile Source Emissions, https://www.epa.gov/ports-initiative/port-and-
goods-movement-emission-inventories. Accessed 3-5-2021.
17	C2 = Category 2 propulsion engines; C3 = Category 3 propulsion engines.
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Table 2. Default Auxiliary Engine and Boiler Emission Factors (g/kW-hr)1S
Engine
Fuel/Sulfur %*
Tier
Engine
Type
NOx
PMio
HC
CO
C02
SO2


1999 and
MSD
10.9
0.188632
0.4
1.1
695.702
0.424248


earlier
HSD
13.8
0.188632
0.4
0.9
695.702
0.424248


2000-2010
MSD
9.8
0.188632
0.4
1.1
695.702
0.424248

MGO/O.1%
(Tier I]
HSD
12.2
0.188632
0.4
0.9
695.702
0.424248

2011-2015
MSD
7.7
0.188632
0.4
1.1
695.702
0.424248


(Tier II]
HSD
10.5
0.188632
0.4
0.9
695.702
0.424248


2016 and
later (Tier
III]
MSD
2.0
0.188632
0.4
1.1
695.702
0.424248


HSD
2.6
0.188632
0.4
0.9
695.702
0.424248
Auxiliary

1999 and
MSD
14.7
0.077007
0.4
1.1
706.878
0.443799


earlier
HSD
11.6
0.077007
0.4
0.9
706.878
0.443799


2000-2010
MSD
13.0
0.077007
0.4
1.1
706.878
0.443799

RM/HFO/2.7%
(Tier I]
HSD
10.4
0.077007
0.4
0.9
706.878
0.443799

with scrubbert
2011-2015
MSD
11.2
0.077007
0.4
1.1
706.878
0.443799


(Tier II]
HSD
8.2
0.077007
0.4
0.9
706.878
0.443799


2016 and
later (Tier
III]
MSD
2.0
0.077007
0.4
1.1
706.878
0.443799


HSD
2.6
0.077007
0.4
0.9
706.878
0.443799

LNG
Any
LNG
1.3
0.03
0.0
1.3
456.5
0.0
Boiler
MGO/O.1%
Any
Boiler
2.0
0.201687
0.1
0.2
961.8
0.586518
RM/HFO/2.7%
2.1
1.871383
0.1
0.2
949.77
16.09992
* MGO—marine gas oil, RM/HFO—residual marine/heavy fuel oil, LNG—liquified natural gas, MSD—medium speed diesel,
HSD—high speed diesel
t For control technology using higher-sulfur fuel alternative than ECA-compliant fuel
Use the following equation to calculate the emission reductions associated with virtual vessel arrival:
ERi = YR{APZ X DRZ X AEFZ + VBZ X DRZ X BEFZ) X C
Where:
ERi = Emission reduction for pollutant i (tons)
AP: = Total auxiliary power for vessel z (kW)
DR: = Anticipated time at anchorage for vessel z, based on the difference between the anticipated
time of arrival at full speed and the actual time of arrival obtained from the weather analysis
service provider or charterer (hours)
AEF:i = Auxiliary engine emission factor for vessel z and pollutant i (g/kWh)
VB: = Total boiler power for vessel z (kW)
BEF-j = Boiler emission factor for vessel z and pollutant/'(g/kWh)
C = Conversion factor from grams to short tons (1.1023 x 10 s tons/g)
z = Individual vessel being evaluated
18 U.S. Environmental Protection Agency. 2020. Port Emissions Inventory Guidance: Methodologies for Estimating
Port-Related and Goods Movement Mobile Source Emissions, https://www.epa.gov/ports-initiative/port-
and-goods-movement-emission-inventories. Accessed 3-5-2021.
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Example calculation: An oil tanker (smallest category) with Tier 1 MSD propulsion engines using marine gas
oil (0.1% sulfur) is originally scheduled to arrive at port in 184 hours. While en route, its total trip time is
increased to 196 hours to avoid an anticipated wait time of 12 hours at anchorage.
ERnok= (250 kW x (196 - 184 hours) x 9.8 g NOx/kWh + 100 kW
x (196 - 184 hours) x 2.0 g NOx /kWh) x 1.10231 x 10 6 tons/g
Where:
ERnox = 0.0351 tons of NOx
Repeat this calculation for each pollutant and each vessel using virtual vessel arrival. For smaller ports with
fewer vessels at offshore anchorage locations, these calculations can be performed on a simple spreadsheet.
Cost Components19
Capital costs: Additional capital investment will likely be limited to:
•	Enhancements to existing vessel traffic monitoring and scheduling systems
•	Communications system upgrades
Capital costs should be annualized over the expected lifetime of equipment and software to estimate the
annual costs of the program.
Operational costs: Operational costs should be limited to:
•	Contract agreement development (one-time cost for standard contract template)
•	The potential additional staffing needed to administer the program, including training port or
charter staff to support enhanced vessel traffic monitoring and scheduling
However, unexpected vessel delays could result in significant additional effort to manage complex
scheduling changes.
Cost savings: Costs savings may be realized from multiple sources:
•	Vessel fuel savings from reduced voyage speed and engine use at port while waiting for a berth
•	Vessel operational cost savings (beyond fuel) from reduced time at port waiting for a berth if the
vessel operator chooses later departure rather than slower speed en route to port
•	Potential safety improvements with fewer vessels in the port area at the same time potentially
reducing the cost of collisions, repairs and legal fees.
•	Minimized demurrage fees if Virtual Vessel Arrival is efficiently paired with truck pickup times for
containers via truck appointment systems.
19 The information in this section is for illustration: it does not constitute official EPA technical guidance for regulatory
assessments.
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Example Program
BP conducted a pilot study that involved 50 successful virtual vessel arrival voyages, including a tanker route
from Batumi on the Black Sea to the Isle of Grain in the United Kingdom (see Figure 4), Because the pilot
study was conducted for the shipping industry, the analysis focused on the fuel savings and emission
benefits associated with slow steaming along the total route rather than the benefits associated with
reduced anchorage.20 Results included reduced fuel consumption by 64,8 tons (27 percent) and reduced
emissions of NOx by 4.9 tons, C02 by 202 tons, and S02 by 3.9 tons.21 Impacts associated with the reduction
in vessel wait times and safety improvements at the port were acknowledged but not quantified.
le of Grain
Batumi

Figure 4. Virtual Vessel Arrival Pilot Study Route22
20	At the time of this writing, no studies have been identified specifically quantifying fuel and emissions benefits
associated with reduced anchorage time.
21	Intertanko and Oil Companies International Marine Forum (OCIMF). n.d. Virtual Arrival.
https://www.ocimf.org/media/115960/Virtual-Arrival.pdf. Accessed 3-5-2021.
22	Ibid.
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