M1 junction 45 five-year post-opening project evaluation (POPE)
A summary of our evaluation of this major road project against its objectives five years after opening.
For more details of our evaluation methods, please refer to the Major Enhancements evaluation approach.
For information on limitations, contextual factors and data constraints that may affect project performance assessment in POPES, see our POPE factsheet.
Glossary of terms used in POPE evaluations.
Evaluation summary
Five years after opening, the M1 junction 45 project has largely achieved its objective of providing additional junction capacity to support development and growth within the Aire Valley. Traffic demand has increased across the junction since opening, particularly on the M1 northbound off-slip, reflecting the continued development of the surrounding area and increased demand associated with the Leeds Skelton Lake motorway services area.
The evaluation found mixed outcomes for journey times and journey time reliability. Some movements through the junction have experienced improvements, particularly between the M1 northbound and A63 Pontefract Lane. However, journey times and reliability have worsened for movements between the A63 Pontefract Lane and M1 southbound. Overall, changes in journey times, whether positive or negative, have been relatively small and were influenced by wider changes at the junction, including the introduction of traffic signals through a separate project completed after the M1 junction 45.
Safety outcomes have improved, with reductions in collision rates, serious collisions and casualty severity recorded within the study area. Environmental outcomes were generally achieved as expected, although continued maintenance of landscape planting will help ensure mitigation measures remain effective over the long term.
While traffic flows were generally lower than forecast across most movements, reflecting factors such as changes in travel patterns following the COVID-19 pandemic, the project continues to support growth within the Aire Valley and provide benefits for road users. The project was expected to deliver poor value for money at appraisal, and the evaluation indicates that this remains the case. Higher construction costs and lower realised journey time benefits have influenced the outcome, but the overall value for money category remains consistent with the original forecast.
Overview of objectives
The project was developed to provide additional junction capacity to support planned growth within the Aire Valley development area and to improve journey times and journey time reliability through the junction.
The table below assesses the extent to which these objectives have been achieved based on the evidence collected through the evaluation.
| Objective | Result |
|---|---|
| Provide additional junction capacity to assist in delivering the development proposals in the Aire Valley. |
Traffic demand has increased across the junction since opening, particularly on the M1 northbound off-slip. The evidence indicates the additional capacity has supported growth associated with development in the Aire Valley and the Leeds Skelton Lake motorway services area. |
| Improve journey times and journey time reliability through the provision of additional traffic capacity. |
Journey time outcomes were mixed. Average journey times between the M1 northbound off-slip and A63 Pontefract Lane reduced by between 7 and 14 seconds. However, journey times between the A63 Pontefract Lane and M1 southbound on-slip increased by between 13 and 33 seconds following the introduction of new traffic signals at Lakeside Way. Overall, observed changes in journey times, whether up or down, have been small. Journey time reliability improved for movements between the M1 northbound and A63 Pontefract Lane but worsened for movements between the M1 southbound and A63 Pontefract Lane, largely due to the introduction of traffic signals at Lakeside Way. |
Project outcomes compared to forecasts
Appraisal forecasts set out the impacts anticipated during project development. This evaluation compares these forecasts with the outcomes observed five years after opening to understand the extent to which expectations have been met.
Overall, the project has achieved its intended outcomes, although some outcomes differ from those forecast at appraisal. Traffic volumes were generally lower than forecast across most movements, while journey time and journey reliability outcomes were mixed. Safety and environmental outcomes were broadly in line with expectations. The table below compares forecast and observed outcomes across each evaluation theme.
Customer journeys
| Sub-area | Outcome vs forecast | Key notes |
|---|---|---|
| Traffic Growth | Lower than forecast |
Traffic volumes were generally lower than forecast across most junction movements, with the exception of the M1 northbound off-slip where morning peak traffic exceeded forecast levels, reflecting development within the Aire Valley and increased demand associated with the new motorway services area. |
| Journey Time | Mixed outcomes |
Journey time outcomes were mixed, with improvements for some movements through the junction and increases for others. Overall, average journey times changed very little. |
| Journey Time Reliability | Mixed outcomes |
No material change to journey time reliability, which has improved for some movements through the junction and worsened for others. |
Safety
| Sub-area | Outcome vs forecast | Key notes |
|---|---|---|
| Safety | Not assessed at appraisal |
Safety is National Highways' highest priority. Although safety was not a specific objective of this project and was not assessed at appraisal, the five-year evaluation considers observed safety outcomes within the project extent to understand how the project may have influenced road user safety. Our analysis indicates that collision rates, serious collisions and casualty severity reduced following project opening. |
Environment
| Sub-area | Outcome vs forecast | Key notes |
|---|---|---|
| Noise | Could not be evaluated | Due to the lack of comparable traffic data, it has not been possible to complete the quantitative evaluation of impact of traffic changes on noise. |
| Air Quality | In line with forecast | A traffic data comparison was not possible and as such air quality has not been evaluated quantitively. However, as local authority monitoring indicates pollutant concentrations are below the relevant standards, the significance of impacts has not changed. Furthermore, the nature of the project means that it is not likely to have significantly affected air quality. On this basis, this evaluation has concluded that the impact is as expected on a qualitative basis. |
| Greenhouse Gases | Could not be evaluated |
Due to the lack of comparable traffic data, it has not been possible to complete the quantitative evaluation of impact of traffic changes on greenhouse gas. |
| Landscape | In line with forecast |
Landscape mitigation is as expected. Planting issues identified at the one-year after evaluation have been addressed and vegetation is becoming established. |
| Heritage | In line with forecast |
The project was unlikely to have affected Temple Newsam House due to intervening woodland and landscape. All works were within the highway boundary and so impacts to the setting of the registered park and garden were likely to be negligible as expected. |
| Biodiversity | In line with forecast |
Habitat reinstatement and planting have been completed, and mitigation measures are providing replacement habitats as intended. |
Value for money
| Sub-area | Outcome vs forecast | Key notes |
|---|---|---|
| Value for Money | In line with forecast | The project was expected to deliver poor value for money at appraisal stage despite unlocking regional growth in the Aire Valley through improved capacity. The evaluation indicates that despite higher construction costs and lower realised journey time benefits than originally forecast, the project remains within this value for money category. Outcomes with respect to regional growth and junction capacity have been realised. |
Why do some outcomes differ from the original forecasts?
Evaluation compares what happened with what was expected during appraisal. While the project has achieved its objective of supporting growth within the Aire Valley, several external factors have influenced the outcomes observed five years after opening:
- The change in travel demand following the COVID-19 pandemic, which affected traffic levels across the strategic road network. As a result, traffic volumes at M1 junction 45 were lower than forecast across most movements, reducing the scale of journey time benefits realised during the evaluation period.
- Traffic conditions at the junction have changed since the M1 junction 45 opened. A separate project completed in 2019 introduced Lakeside Way and new traffic signals on the south-eastern side of the junction. These changes altered the operation of the junction and contributed to increased journey times and reduced reliability for movements through the new signals, particularly those travelling to the M1 southbound.
- The opening of the Leeds Skelton Lake motorway services area in early 2020 has also increased traffic demand at the junction, particularly on movements associated with Lakeside Way and the M1 northbound off-slip. This additional demand was not fully reflected in the original forecasts prepared during project development.
Despite these changes, the evaluation shows that the project has supported growth within the Aire Valley, improved safety outcomes and provided additional capacity to accommodate increasing traffic demand at the junction.
These factors help explain why some benefits, particularly journey time savings, were lower or more variable than expected.
Continuing to maximise benefits
The evaluation shows that the M1 junction 45 project has achieved its intended outcomes. Continued maintenance and monitoring will help ensure these benefits are sustained over the long term.
Project overview
The M1 junction 45 is located to the south-east of Leeds city centre within the ‘Aire Valley’ development area of West Yorkshire. The junction forms the interchange between the M1 to the north-east and south-west, the A63 Pontefract Lane to the north-west and Lakeside Way to the south-east. The A63 Pontefract Lane is a main route into and out of Leeds city centre and provides access points to the Aire Valley development area.
The M1 junction 45 improvement project started construction in January 2017 and was opened in March 2018.
Following completion of the project, additional changes have taken place around the junction. These include the construction of Lakeside Way and associated signal-controlled entry on the south-eastern side of the junction in 2019. This was followed by the opening of the Leeds Skelton Lake motorway services area in 2020, both of which have influenced traffic demand and travel patterns at the junction.
The project included:
- widening of the M1 northbound on-slip from one to two lanes and provision of a ghost island where it merges with the M1 motorway
- widening of the southbound off-slip from two to three lanes at the roundabout
- widening of the start of the southbound on slip from one to two lanes
- widening of the A63 Pontefract Lane at the roundabout from two lanes to three lanes
- widening of the roundabout carriageway from two lanes to three lanes
- provision of new footways/cycleways with toucan crossing facilities at the south-eastern portion of the roundabout.
The project also included alteration to overhead gantries on the M1 and bridge structures at the junctions.
Location map
Why was the project needed?
Prior to the project, M1 Junction 45 experienced increasing traffic demand associated with planned development and economic growth within the Aire Valley. The junction forms a key gateway between the strategic road network and one of the largest development areas in Leeds, including the Leeds City Region Enterprise Zone and other major employment and commercial sites.
Forecasts indicated that continued development would place additional pressure on the junction, resulting in increased congestion, longer journey times and less reliable journeys for road users. Without intervention, the existing layout was unlikely to provide sufficient capacity to accommodate future growth and support planned investment in the area.
The project was designed to provide additional junction capacity to support development and growth across the Aire Valley development area, while also improving journey times and journey time reliability through the junction. This includes growth within the Leeds City Region Enterprise Zone, which along with other development in the area is estimated to have delivered over 7,000 new jobs.
