Accredited official statistics

Road goods vehicles travelling to Europe: Revisions to published data from October 2021 to June 2023

Published 23 May 2024

1. Introduction

This report summarises the outcome of a quality review of information provided by ferry operators to the Department for Transport (DfT) for the Road Goods Vehicles Travelling to Europe (RoRo) publication.

When quality reviewing the data in Autumn 2023, it became evident that vehicles that did not comply with the RoRo definitions had been included in data provided by one ferry operator from October 2021 to June 2023.

This report summarises these revisions which have been implemented in the Road Goods Vehicles Travelling to Europe: 2023 statistical publication.

We are grateful to receive any feedback on this topic, which can be given at road freight statistics.

2. Background

The RoRo census is designed to collect information on road goods vehicles travelling by ferry and Channel Tunnel from Great Britain (GB) to Europe. The census covers trips by powered heavy goods vehicles (HGVs) that weigh more than 3.5 tonnes, and unaccompanied trailers not accompanied by a powered unit.

When quality reviewing the data supplied for 2023 quarter 3 (July to September) it became evident there were some issues with data from one operator. Upon further investigation of the supplied data, it became apparent that the data did not comply with agreed RoRo definitions.

The supplied data for powered vehicles included some light goods vehicles (LGVs) under 3.5 tonnes, whereas the survey definition meant that only data on heavy goods vehicles (HGVs) over 3.5 tonnes should have been supplied. In addition, for unaccompanied trailers, the supplied data had included some shipping containers. This led to an over estimation of the number of vehicles travelling on routes covered by this operator.

Following the discovery of the erroneous data, the road freight statistics team worked closely with the ferry operator to determine the cause of this issue and when this occurred. The results of this investigation concluded that a change in the IT system used to extract the data supplied to DfT had caused these extra vehicles to be included in the data supplied and published for October 2021 to June 2023.

The supplier has re-provided data for this period, ensuring that only vehicles falling within the correct definitions are now included in the data supply.

We have also taken this opportunity to confirm with all our suppliers of RoRo data that the information they supply adheres to the correct RoRo definitions, including:

• the classification of vehicles to be included in reported numbers

• the classification of the vehicle country of registration

• the direction of traffic reported

3. Summary of changes

Definition

Quarter: a calendar year quarter. In this report, quarter 1 refers to January to March, quarter 2 refers to April to June, quarter 3 refers to July to September, and quarter 4 refers to October to December.

Note: Figures are rounded to the nearest thousand. Figures may not sum due to rounding.

The total impact of the revision to data from October 2021 to June 2023 was a decrease of 258,000 trips made by all vehicles (4.6%), from 5.560 million trips to 5.301 million.

The largest impact has been on the reported number of unaccompanied trailers, with a decrease of 187,000 trips (9.1%) seen across the period. Smaller decreases of around 2% occurred from October 2021 to March 2022 with the larger downward revisions of around 12% being seen from April 2022 onwards. Decreases in the number of unaccompanied trailers were seen across all routes provided by this ferry operator. This included one route where all reported unaccompanied trailers were shipping containers, and so this route did not carry any reportable RoRo traffic.

The decrease in unaccompanied trailers has unsurprisingly most impacted those routes which carry a larger proportion of this type of traffic. The North Sea port group saw the largest decrease with a fall of 181,000 trips (10.2%) across the period October 2021 to June 2023, the main driver of this being the reduction from unaccompanied trailers which accounted for 83% of traffic through North Sea ports in 2023. Trips made to Belgium also saw a significant fall due the large proportion of traffic being unaccompanied trailers, accounting for 99% of traffic to this country in 2023, with trips decreasing by 149,000 (34.9%) from October 2021 to June 2023.

Powered vehicles saw a decrease of 71,000 trips (2.0%) across the period October 2021 to June 2023, with the majority of this decrease being foreign-registered powered vehicles. Foreign-registered powered vehicles saw a drop of 58,000 trips (2.1%) compared to UK-registered powered vehicles which saw a fall of 5,000 trips (1.2%). The percentage changes seen for foreign-registered powered vehicles were largest for vehicles registered in Poland, Romania and Slovakia. Previously published annual rankings by country of registration for 2021 and 2022 remain unchanged with Polish vehicles remaining the most common, followed by UK and Romanian vehicles.

The following tables show the effect of these revisions for each quarter in the period October 2021 to June 2023. In our 2023 annual publication, we have updated the data covering the period October 2021 to June 2023 to contain the revised data as well as newly releasing 2023 quarter 3 and 4 data which were delayed in publishing while conducting this investigation, to ensure correct data was supplied.

4. All vehicles

Definition

All vehicles: the sum of powered heavy goods vehicles and unaccompanied trailers.

The largest contributor to the fall in total vehicle numbers was the decrease in the number of unaccompanied trailers as shown in section 5 below. Previously the total number of vehicles was fairly stable across the period October 2021 to June 2023, whereas numbers now show a slight decline.

Table 1 shows the effect of these revisions on the total number of trips being made by all vehicles across the period October 2021 to June 2023. The net change across this period was a decrease of 258,000 trips by all vehicles (4.6%), from 5.560 million trips to 5.301 million. The largest change seen across this period was a decrease of 6.4% in 2023 quarter 1.

Table 1: Impact of revisions on the total number of trips made by all vehicles, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	810,000	791,000	-18,000	-2.3%
2022 Q1	786,000	777,000	-9,000	-1.2%
2022 Q2	831,000	790,000	-42,000	-5.0%
2022 Q3	791,000	746,000	-45,000	-5.7%
2022 Q4	810,000	762,000	-48,000	-5.9%
2023 Q1	758,000	709,000	-48,000	-6.4%
2023 Q2	774,000	727,000	-48,000	-6.2%
Total trips	5,560,000	5,301,000	-258,000	-4.6%

Chart 1: Number of trips made by all vehicles travelling from GB to Europe before and after applying revisions, 2019 Q1 to 2023 Q2

5. Unaccompanied trailers

Definition

Unaccompanied trailers: include tow-bar trailers and articulated semi-trailers, not accompanied on the ferry by a powered unit.

The largest changes were seen for unaccompanied trailers. Previously, unaccompanied trailers showed some recovery between October 2021 and June 2023, whereas after the data revision, the numbers now show a stable trend since 2021.

Table 2 shows the effect of these revisions on the number of trips being made by unaccompanied trailers between October 2021 and June 2023. The net change across this period was a decrease of 187,000 trips by unaccompanied trailers (9.1%), from 2.052 million trips to 1.865 million. The largest change seen across this period was a decrease of 12.4% in 2022 quarter 4.

Table 2: Impact of revisions on the total number of trips made by unaccompanied trailers, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	276,000	270,000	-6,000	-2.0%
2022 Q1	271,000	266,000	-5,000	-1.8%
2022 Q2	317,000	279,000	-39,000	-12.2%
2022 Q3	308,000	272,000	-37,000	-11.9%
2022 Q4	301,000	264,000	-37,000	-12.4%
2023 Q1	284,000	252,000	-33,000	-11.5%
2023 Q2	294,000	263,000	-31,000	-10.6%
Total trips	2,052,000	1,865,000	-187,000	-9.1%

Chart 2: Number of trips made by unaccompanied trailers travelling from GB to Europe before and after applying revisions, 2019 Q1 to 2023 Q2

6. Powered Vehicles

Definition

Powered vehicles: are heavy goods vehicles (HGVs) that weigh more than 3.5 tonnes and can be driven by a driver. This includes rigid lorries, tractors and trailers (counted as 1 unit) and tractive units only.

The fall in powered vehicle numbers was relatively small, largely driven by a decrease in the number of foreign registered vehicles as shown in section 7 below. The declining trend in powered vehicles seen previously between October 2021 and June 2023 has remained unchanged after revision.

Table 3 shows the effect of these revisions on the total number of trips made by powered vehicles across the period October 2021 to June 2023. The net change across this period was a decrease of 71,000 trips by powered vehicles (2.0%), from 3.507 million trips to 3.436 million. The largest change seen across this period was a decrease of 3.4% in 2023 quarter 2.

Table 3: Impact of revisions on the total number of trips made by powered vehicles, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	534,000	521,000	-13,000	-2.4%
2022 Q1	515,000	511,000	-4,000	-0.9%
2022 Q2	514,000	511,000	-3,000	-0.6%
2022 Q3	483,000	474,000	-9,000	-1.8%
2022 Q4	508,000	498,000	-10,000	-2.0%
2023 Q1	473,000	458,000	-16,000	-3.3%
2023 Q2	480,000	464,000	-16,000	-3.4%
Total trips	3,507,000	3,436,000	-71,000	-2.0%

Chart 3: Number of trips made by powered vehicles travelling from GB to Europe before and after applying revisions, 2019 Q1 to 2023 Q2

7. Country of registration

Note : This section only covers powered heavy goods vehicles. The country of registration is not collected for unaccompanied trailers.

Foreign-registered vehicles showed larger changes than UK-registered vehicles, though the previous trends seen for both have remained unchanged after revision.

7.1 UK-registered powered vehicles

Table 4 shows the effect of these revisions on the number of trips being made by UK-registered powered vehicles across the period October 2021 to June 2023. The net change across this period was a decrease of 5,000 trips by UK-registered powered vehicles (1.2%), from 464,000 trips to 459,000. This decrease was evenly spread across quarters since April 2022, with approximately 1,000 fewer trips in each quarter from 2022 quarter 2 to 2023 quarter 2.

Table 4: Impact of revisions on the number of trips made by UK-registered powered vehicles, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	59,000	59,000	0	-0.6%
2022 Q1	64,000	63,000	0	-0.3%
2022 Q2	73,000	72,000	-1,000	-0.8%
2022 Q3	69,000	68,000	-1,000	-1.6%
2022 Q4	68,000	67,000	-1,000	-1.6%
2023 Q1	65,000	64,000	-1,000	-1.3%
2023 Q2	67,000	65,000	-1,000	-1.7%
Total trips	464,000	459,000	-5,000	-1.2%

Chart 4: Number of trips made by UK-registered powered vehicles travelling from GB to Europe before and after applying revisions, 2019 Q1 to 2023 Q2

7.2 Foreign-registered powered vehicles

Table 5 shows the effect of these revisions on the number of trips made by foreign-registered powered vehicles across the period October 2021 to June 2023. The net change across this period was a decrease of 58,000 trips by foreign-registered powered vehicles (2.1%), from 2.802 million trips to 2.744 million. The largest change seen across this period was a decrease of 4.1% in 2023 quarter 2.

Among foreign countries with at least 1,000 vehicle trips from Great Britain to Europe during the period October 2021 to June 2023, the percentage changes were largest for vehicles registered in Poland (-5%), Romania (-4%) and Slovakia (+5%). The increase in Slovakian vehicles was due to a reallocation of vehicles previously classified as country of registration unknown. Previously published annual rankings by country of registration for 2021 and 2022 remain unchanged with Polish vehicles remaining the most common, followed by UK and Romanian vehicles.

Table 5: Impact of revisions on the number of trips made by foreign-registered powered vehicles, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	454,000	450,000	-4,000	-0.9%
2022 Q1	424,000	420,000	-4,000	-1.0%
2022 Q2	404,000	401,000	-2,000	-0.6%
2022 Q3	376,000	368,000	-8,000	-2.1%
2022 Q4	400,000	390,000	-10,000	-2.5%
2023 Q1	373,000	358,000	-15,000	-4.0%
2023 Q2	372,000	357,000	-15,000	-4.1%
Total trips	2,802,000	2,744,000	-58,000	-2.1%

Chart 5: Number of trips made by foreign-registered powered vehicles travelling from GB to Europe before and after applying revisions, 2019 Q1 to 2023 Q2

8. Port groups

Definitions

Dover Strait: ferry routes from ports in Dover, Folkestone and Ramsgate; along with road goods vehicles using the Channel Tunnel.

English Channel: all ports on the south coast of GB, west of Folkestone.

Irish Sea: all ports on the west coast of GB.

North Sea: all ports on the east coast of GB, north of and including the Thames estuary.

The largest relative impact for any port group has been a reduction on North Sea routes, largely due to the number of unaccompanied trailers carried on these routes. In 2023, unaccompanied trailers accounted for 83% of road goods vehicle traffic on North Sea routes, compared to 1% for the Dover Strait, 36% for the English Channel and 67% for Irish Sea routes.

8.1 North Sea port group

Table 6 shows the effect of these revisions on the number of trips being made through the North Sea port group across the period October 2021 to June 2023. The net change across this period was a decrease of 181,000 trips through the North Sea port group (10.2%), from 1.771 million trips to 1.591 million. The largest change seen across this period was a decrease of 13.7% in 2022 quarter 4.

Table 6: Impact of revisions on the number of trips made through the North Sea port group, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	237,000	232,000	-6,000	-2.3%
2022 Q1	227,000	222,000	-5,000	-2.1%
2022 Q2	279,000	242,000	-38,000	-13.4%
2022 Q3	269,000	233,000	-36,000	-13.3%
2022 Q4	259,000	224,000	-35,000	-13.7%
2023 Q1	245,000	214,000	-31,000	-12.8%
2023 Q2	254,000	224,000	-30,000	-11.8%
Total trips	1,771,000	1,591,000	-181,000	-10.2%

Chart 6: Number of trips made by vehicles travelling from GB to Europe through the North Sea port group before and after applying revisions, 2019 Q1 to 2023 Q2

8.2 English Channel port group

Table 7 shows the effect of these revisions on the number of trips being made through the English Channel port group across the period October 2021 to June 2023. There was a decrease of 4,000 trips in 2023 quarter 2 for trips through the English Channel port group, from 20,000 trips to 16,000 trips (17.8%). There was no change to data before this quarter. The net effect of the 4,000 trip change across the whole period was a 2.9% decrease, from 124,000 trips to 120,000.

Table 7: Impact of revisions on the number of trips made through the English Channel port group, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	17,000	17,000	0	0.0%
2022 Q1	17,000	17,000	0	0.0%
2022 Q2	20,000	20,000	0	0.0%
2022 Q3	16,000	16,000	0	0.0%
2022 Q4	17,000	17,000	0	0.0%
2023 Q1	16,000	16,000	0	0.0%
2023 Q2	20,000	17,000	-4,000	-17.8%
Total trips	124,000	120,000	-4,000	-2.9%

Chart 7: Number of trips made by vehicles travelling from GB to Europe through the English Channel port group before and after applying revisions, 2019 Q1 to 2023 Q2

8.3 Dover Strait port group

Table 8 shows the effect of these revisions on the number of trips being made through the Dover Strait port group across the period October 2021 to June 2023. The net change across this period was a decrease of 64,000 trips through the Dover Strait port group (2.2%), from 2.957 million trips to 2.893 million. The largest change seen across this period was a decrease of 3.7% in 2023 quarter 1.

Table 8: Impact of revisions on the number of trips made through the Dover Strait port group, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	453,000	441,000	-13,000	-2.8%
2022 Q1	442,000	438,000	-4,000	-1.0%
2022 Q2	429,000	427,000	-2,000	-0.5%
2022 Q3	405,000	397,000	-8,000	-1.9%
2022 Q4	431,000	421,000	-10,000	-2.2%
2023 Q1	398,000	383,000	-15,000	-3.7%
2023 Q2	399,000	386,000	-13,000	-3.2%
Total trips	2,957,000	2,893,000	-64,000	-2.2%

Chart 8: Number of trips made by vehicles travelling from GB to Europe through the Dover Strait port group before and after applying revisions, 2019 Q1 to 2023 Q2

8.4 Irish Sea port group

Table 9 shows the effect of these revisions on the number of trips being made through the Irish Sea port group across the period October 2021 to June 2023. The net change across this period was a decrease of 10,000 trips through the Irish Sea port group (1.4%), from 708,000 trips to 698,000. There was no change to data from 2021 quarter 4 to 2022 quarter 1, with revisions starting from 2022 quarter 2. The largest change seen across this period was a decrease of 2.5% in 2022 quarter 4.

Table 9: Impact of revisions on the number of trips made through the Irish Sea port group, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	102,000	102,000	0	0.0%
2022 Q1	100,000	100,000	0	0.0%
2022 Q2	103,000	101,000	-2,000	-1.9%
2022 Q3	102,000	100,000	-2,000	-1.9%
2022 Q4	103,000	100,000	-3,000	-2.5%
2023 Q1	99,000	96,000	-2,000	-2.3%
2023 Q2	101,000	99,000	-1,000	-1.3%
Total trips	708,000	698,000	-10,000	-1.4%

Chart 9: Number of trips made by vehicles travelling from GB to Europe through the Irish Sea port group before and after applying revisions, 2019 Q1 to 2023 Q2

9. Country of disembarkation

Definition

The country of disembarkation is the country of the foreign port where the vehicle leaves the roll-on roll-of ferry. This is not necessarily the final destination of the vehicle.

Only countries served by routes run by this ferry operator were affected by these revisions. These were Belgium, the Republic of Ireland, France and the Netherlands. The largest impact was for routes to Belgium, largely due to the amount of unaccompanied trailers carried on routes to this country. In 2023, unaccompanied trailers accounted for 99% of road goods vehicle traffic on routes to Belgium, compared to 67% for routes to the Republic of Ireland, 3% for routes to France and 76% for routes to the Netherlands.

9.1 Belgium

Table 10 shows the effect of these revisions on the number of trips being made to Belgium across the period October 2021 to June 2023. The net change across this period was a decrease of 149,000 trips to Belgium (34.9%), from 428,000 trips to 279,000. The largest change seen across this period was a decrease of 42.0% in 2022 quarter 2.

Table 10: Impact of revisions on the number of trips made by vehicles travelling from GB to Belgium, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	46,000	41,000	-6,000	-12.0%
2022 Q1	45,000	40,000	-5,000	-10.7%
2022 Q2	74,000	43,000	-31,000	-42.0%
2022 Q3	71,000	42,000	-29,000	-41.1%
2022 Q4	69,000	41,000	-28,000	-40.4%
2023 Q1	62,000	36,000	-26,000	-41.3%
2023 Q2	62,000	36,000	-26,000	-41.3%
Total trips	428,000	279,000	-149,000	-34.9%

Chart 10: Number of trips made by vehicles travelling from GB to Belgium before and after applying revisions, 2019 Q1 to 2023 Q2

9.2 The Netherlands

Table 11 shows the effect of these revisions on the number of trips being made to the Netherlands across the period October 2021 to June 2023. The net change across this period was a decrease of 31,000 trips to the Netherlands (2.8%), from 1.120 million trips to 1.088 million. There was no change to data from 2021 quarter 4 to 2022 quarter 1, with revisions starting from 2022 quarter 2. The largest change seen across this period was a decrease of 4.9% in 2022 quarter 4.

Table 11: Impact of revisions on the number of trips made by vehicles travelling from GB to the Netherlands, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	159,000	159,000	0	0.0%
2022 Q1	152,000	152,000	0	0.0%
2022 Q2	171,000	165,000	-7,000	-3.9%
2022 Q3	166,000	159,000	-7,000	-4.0%
2022 Q4	159,000	152,000	-8,000	-4.9%
2023 Q1	153,000	147,000	-6,000	-3.8%
2023 Q2	160,000	156,000	-4,000	-2.8%
Total trips	1,120,000	1,088,000	-31,000	-2.8%

Chart 11: Number of trips made by vehicles travelling from GB to the Netherlands before and after applying revisions, 2019 Q1 to 2023 Q2

9.3 France

Table 12 shows the effect of these revisions on the number of trips being made to France across the period October 2021 to June 2023. The net change across this period was a decrease of 68,000 trips to France (2.2%), from 3.086 million trips to 3.018 million. The largest change seen across this period was a decrease of 3.9% in 2023 quarter 2.

Table 12: Impact of revisions on the number of trips made by vehicles travelling from GB to France, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	470,000	457,000	-13,000	-2.7%
2022 Q1	457,000	452,000	-4,000	-1.0%
2022 Q2	451,000	449,000	-2,000	-0.5%
2022 Q3	423,000	415,000	-8,000	-1.8%
2022 Q4	450,000	440,000	-10,000	-2.1%
2023 Q1	414,000	400,000	-15,000	-3.5%
2023 Q2	421,000	405,000	-16,000	-3.9%
Total trips	3,086,000	3,018,000	-68,000	-2.2%

Chart 12: Number of trips made by vehicles travelling from GB to France before and after applying revisions, 2019 Q1 to 2023 Q2

9.4 The Republic of Ireland

Table 13 shows the effect of these revisions on the number of trips being made to the Republic of Ireland across the period October 2021 to June 2023. These revisions mirror the figures shown in section 8.4 for the Irish Sea port group. The net change across this period was a decrease of 10,000 trips to the Republic of Ireland (1.4%), from 708,000 trips to 698,000. There was no change to data from 2021 quarter 4 to 2022 quarter 1, with revisions starting from 2022 quarter 2. The largest change seen across this period was a decrease of 2.5% in 2022 quarter 4.

Table 13: Impact of revisions on the number of trips made by vehicles travelling from GB to the Republic of Ireland, 2021 Q4 to 2023 Q2

Year and Quarter	Original	Revised	Difference	% change
2021 Q4	102,000	102,000	0	0.0%
2022 Q1	100,000	100,000	0	0.0%
2022 Q2	103,000	101,000	-2,000	-1.9%
2022 Q3	102,000	100,000	-2,000	-1.9%
2022 Q4	103,000	100,000	-3,000	-2.5%
2023 Q1	99,000	96,000	-2,000	-2.3%
2023 Q2	101,000	99,000	-1,000	-1.3%
Total trips	708,000	698,000	-10,000	-1.4%

Chart 13: Number of trips made by vehicles travelling from GB to the Republic of Ireland before and after applying revisions, 2019 Q1 to 2023 Q2

10. Ongoing quality assurance

Following the investigative work carried out with this data supplier we are now confident that these revisions bring the data for the period October 2021 to June 2023 within the correct RoRo definitions, although due to the retrospective nature of these revisions, the data may be slightly less precise than we would expect for the data that we currently collect. We expect the effect of this uncertainty on published aggregate analysis to be relatively small.

Contact with our other data suppliers has confirmed that correct RoRo definitions are being applied to all other data supplied to DfT. In keeping with DfT’s strategy of producing and maintaining high quality statistics, the RoRo census moved from spreadsheet returns to an online questionnaire in 2023 quarter 4, which has allowed for better quality assurance of data collected.

The road freight statistics team has also built better relationships with each of our RoRo data suppliers. Regular contact between the DfT team and supplier leads has also allowed for the collection of more business-led intel on changes to ferry routes and other changes, and these open communication channels ensure more proactive quality assurance checks can be conducted.