Station Road – May 2022

Residents have reported high volumes of motor traffic and delays on Station Road, with this often being attributed to the effect of closing a number of minor roads to through traffic in 2020. In this blog we take another look at local traffic count data to see what is going on.

Closing local bridges – Recap

In May 2022, we looked at traffic levels on Station Road after local bridges were closed to through traffic. We found that traffic levels on Station Road did not increase after local bridges were closed to traffic, and in fact stayed at a similar level to 2018, as shown in the graph below.

Traffic Volumes on Station Road, measured 30m west of Bowsden Terrace – Data Extract May 2022

Traffic levels remained similar right up to March 2022, the latest month we had data for at the time, 19 months from when the bridges were closed in August 2020 and 12 months from when schools reopened (and traffic fully returned to normal) following Covid lockdowns in March 2021.

What happened then?

Now we have another year of data and we can see traffic levels on Station Road did increase after April 2022, by up to 10% in some months. This is shown on the red line (2022) and higher blue line (2023) in the graph below.

Traffic Volumes on Station Road, measured 30m west of Bowsden Terrace – Data Extract May 2023

In November 2022, traffic levels on Station Road were extremely high, averaging 18,525 vehicles per day over the month.

Why did traffic increase?

If the bridges were to have an effect it would most likely have been immediately after they were closed to traffic i.e. August/September 2020, and not at some random time over two years later, and they wouldn’t explain the unusually high traffic levels in November 2022.

One explanation could be overall growth in traffic, and consequently growth in traffic jams, aided by the Government’s fuel duty freeze. Since the start of the freeze in 2010 up to 2019, miles driven in Newcastle increased by nearly 7%, but again this would not explain the unusually high traffic levels in November 2022.

There was a local traffic ‘event’ in the autumn of 2022 – emergency roadworks for gas repairs on Jesmond Dene Road. These works lasted from May to December 2022, with the main works (and greatest disruption) between 24 October and 2 December.

A189 Jesmond Dene Road, reports of failed temp traffic signals at the junction of Moorfield for the works being carried out by @NGNgas #Newcastle pic.twitter.com/9roIBPVP0k

— North East Live Traffic (@NELiveTraffic) November 29, 2022

Between 4 – 14 November Jesmond Dene Road was closed to all traffic at the junction with Moorfield.

🚧Jesmond Dene Road (A189) will be closed to all traffic at the junction of Moorfield from midnight (4 Nov) for up to 10 days for emergency repairs by @NGNgas

✅ Access remains open for people on foot. Diversions will be in place. pic.twitter.com/rYaS5Wjp0K

— NewcastleCityCouncil (@NewcastleCC) November 4, 2022

We reported at the time that Google Live Traffic was showing heavy traffic on The Grove and, to a lesser extent, Ilford Road. The maps in the tweets below also show slow moving traffic on Station Road.

Google Live Traffic shows lots of driving on residential streets. We need low traffic neighbourhoods so that main road traffic stays on the main road network. pic.twitter.com/rWFzwKLdS8

— space for gosforth (@space4gosforth) November 7, 2022

Residents of The Grove also reported traffic was very busy, as well as higher noise levels and a collision as a result of the additional traffic.

Comment on Gosforth Traffic Facebook 11 November 2022

Traffic using The Grove as an alternative route would have been picked up by the Station Road traffic counter, explaining the increase in traffic levels between May and December. We can see from weekly traffic counts that the most traffic on Station Road was the week where Jesmond Dene Road was closed completely (7 November).

Displaced traffic

We also have traffic volumes for Haddricks Mill Road for the same period. The graph below shows that, from the start of roadworks in May 2022, there is a corresponding reduction in traffic levels on Haddricks Mill Road.

This may come as a surprise to residents of Haddricks Mill Road, for whom this whole period (apart from when the road was fully closed) was marked by continual traffic jams due to the road works.

This is to be expected though, as a temporary reduction in road capacity caused by temporary traffic lights will cause both traffic jams and a reduction in traffic volumes on the affected roads as some people take alternative routes.

Total gridlock (and CO2 galore) outside our homes EVERY morning in #SouthGosforth. I guess it makes a change from the dangerous speeding… @NewcastleCC any plans to address?? This isn’t sustainable. pic.twitter.com/iwiPrByUf6

— Ciara Small (@SmallWorldNE) May 24, 2022

This contrasts with permanent or longer-term road capacity reductions where it has been found that “significant reductions in overall traffic levels can occur, with people making a far wider range of behavioural responses than has traditionally been assumed“. This is why traffic changes are often trialled over a 6-18 month period, and why other long-term local road closures have shown no increase in traffic volumes on parallel roads.

Following completion of the road works, traffic counts also show that Haddricks Mill Road traffic levels didn’t immediately return to where they were, taking until March 2022 to return to previous levels.

Conclusion

• Traffic levels did increase on Station Road in 2022, up to about 10%, with a corresponding decrease on Haddricks Mill Road. The most likely reason for this was the road works on Jesmond Dene Road.
• Some of the traffic that would have used Haddricks Mill Road rerouted to use Station Road via The Grove. Roads east of Stoneyhurst Bridge remained largely traffic-free.
• This contrasts starkly with previous local road closures. No additional traffic was recorded on parallel routes following Stoneyhurst Road, Castle Farm Road or Killingworth Road closures. This may be because the roadworks on Jesmond Dene Road were announced with very short notice, and were only for a short period, so people weren’t able to or didn’t feel the need to adjust.
• Traffic using The Grove instead of Jesmond Dene Road will have created additional delay for people travelling by car/bus from Gosforth High Street to Haddricks Mill.
• Where there is short-term disruption, traffic will divert via whatever routes are available. While these routes are open to through-traffic, neither residents nor people wishing to walk or cycle away from heavy traffic can rely on them remaining low-traffic routes.
• Traffic levels on Station Road and Haddricks Mill Road appear to be returning to closer to historical (still very busy) levels since March 2023, however while motoring is relatively cheap compared to public transport and there is a lack of safe cycling routes, traffic levels are likely to continue to rise. Higher levels of traffic contribute to increased pollution, carbon emissions and danger for other road users, much more than localised congestion.

Reference – Other Traffic Reports

• Temporary traffic lights due to gas main work and roadworks on A189 Jesmond Dene Road at Moorfield – May 2022.
• Temporary traffic lights due to gas main work on A189 Matthew Bank at Jesmond Dene Road – September 2022
• Temporary traffic lights due to gas main work on A189 Jesmond Dene Road at Moorfield –  December 2022

The post Station Road traffic went up – what happened? appeared first on SPACE for Gosforth.

Looking south down Haddricks Mill Road – Photo from Tyne and Wear UTMC

In our last blog we looked at traffic levels on Station Road. We found that neither Station Road nor Sandy Lane were busier or more congested following the closure of Stoneyhurst and Salters bridges.

In this blog we assess the impact of Haddricks Mill roadworks and closing Dene Bridge to motor vehicles.

Just like for Stoneyhurst Road and Salters Bridge, a large proportion of people who responded to the Dene Bridge consultation thought that it would result in displaced traffic and additional congestion on surrounding roads.

Dene Bridge Closure: Main Themes from ETRO Correspondence

Key Points

Traffic levels on Haddricks Mill Road are now back to (but not higher than) pre-2017 levels. This suggests that closing Dene Bridge to motor traffic hasn’t led to additional traffic on Haddricks Mill Road.

While the roadworks were clearly inconvenient to many, they had some positive side effects of fewer injuries, reduced traffic levels on Haddricks Mill Road and most likely a substantial, though temporary, cut in carbon emissions from less driving.

Traffic levels and air pollution measurements on Station Road (measured at the entrance to Haddricks Mill roundabout) remained high during the roadworks, but did reduce in 2020 due to Covid.

What has changed?

Three major changes have been implemented.

1. Between 2017 and 2019, Killingworth Road and the Metro bridge were widened allowing the addition of a bus lane and separate cycle path.
2. During 2020, Haddricks Mill roundabouts were moved slightly to increase traffic throughput. New traffic lights have a dual function of helping people cross, and controlling traffic flow to prioritise the busiest vehicle routes. Pavements have been widened and made to be shared between people walking and cycling.
3. From August 2020, Dene Bridge on Castles Farm Road can no longer be used by motor traffic, but can be used by people walking or cycling.

The locations of these changes are shown on the map below.

Roadworks timeline

The new Haddricks Mill junction was completed in the summer of 2020, marking the end of three years of roadworks at Haddricks Mill and on Killingworth Road.

• January 2017 – Northern Gas Networks (NGN) carry out initial exploratory work
• July 2017 – Killingworth Road and Salters Bridge close to traffic
• May 2019 – Killingworth Road opens southbound
• July 2019 – Killingworth Road open in both directions
• October 2019 – Salters Bridge re-opens to traffic
• October – December 2019 – Single lane operation on Killingworth Road
• November 2019 – Drivers warned on Salters Bridge
• February 2020 – Resurfacing works Haddricks Mill
• March 2020 –  Further warnings issued on Salters Bridge
• July 2020 – Resurfacing Haddricks Mill
• August 2020 – Castles Farm Road closes to motor traffic

Haddricks Mill Road Traffic

It is clear that the roadworks had a substantial effect on traffic on Haddricks Mill Road. Almost as soon as Killingworth Road was closed, traffic levels on Haddricks Mill Road dropped from about 17,500 vehicles per day down to 12,000 – 14,000. This is shown on the graph below.

While there are some big gaps in the data between 2018 and 2020, the counts we have remained low until mid-2021.

As carbon emissions are correlated with total miles driven, this is also likely to have temporarily reduced overall carbon emissions from traffic.

Since July 2021, traffic levels have been back where they were before 2017, but no higher. This suggests that closing Dene Bridge to motor vehicles has not caused any extra traffic on Haddricks Mill Road.

This is consistent with traffic counts that showed there was no increase in traffic on Station Road when Salters Bridge and Stoneyhurst Road were closed to motor traffic. We also previously found that traffic did not increase on either Great North Road or on Benton Lane after Killingworth Road was closed for roadworks.

These are all examples of ‘disappearing traffic’.

Haddricks Mill junction from Killingworth Road

Road Safety

Using the TADU Road Safety dashboard we counted injuries due to traffic collisions at Haddricks Mill junction. Between 2005 and 2016, there were 12.4 injuries on average per year making this one of the most dangerous junctions in the NE.

In 2018 and 2019 there were only two injuries in total, and only two in 2017.

The number of injuries remained lower in 2020 and 2021, which might be due to there being less traffic due to Covid, or possibly the changes the Council believed would improve safety at the junction are having an effect.

In 2019, we wrote to the Council to express our concerns that the new junction would not reduce collisions as (a) cycle routes were too slow and wiggly so people who already cycled would most likely continue to use the road, (b) multiple entry lanes are known to make roundabouts less safe, and (c) high corner radii mean vehicles can enter and exit the roundabout at a higher speed.

The new pavement, cycle lane and bus lane on Killingworth Road

Air Pollution

With traffic back to pre-2017 levels, and no obvious mitigations to reduce pollution in place, we remain concerned that pollution will return to previous levels.

Fears pollution levels will be dangerously high again at controversial Killingworth Roadhttps://t.co/eAJBUIAUOb

— The Chronicle (@ChronicleLive) June 4, 2019

There are two sites where Nitrogen Dioxide (NO₂) air pollution is monitored near Haddricks Mill. These are at the end of Station Road and by Dene Park House on Killingworth Road.

The graph above shows that the road works had little effect on air pollution on Station Road. This is perhaps not surprising as traffic levels on Station Road were fairly constant throughout.

While pollution wasn’t measured on Killingworth Road between 2018 and 2020, almost certainly it would have been much lower due to the complete absence of traffic. Pollution measurements for 2021 should be released in the autumn.

Summary

• Traffic has returned to 2016 levels now that the Haddricks Mill and Killingworth Road roadworks have finished.
• The roadworks had a positive side-effect in that, between 2017 and 2020, fewer people were injured in road traffic collisions and there was a temporary reduction in carbon emissions.
• Pollution levels, where measured, were largely unchanged due to the roadworks.
• Consistent with what we found for Salters Bridge and Stoneyhurst Road, closing Dene Bridge to motor traffic did not lead to any additional traffic on Haddricks Mill Road.

The post Haddricks Mill – Return of the Traffic appeared first on SPACE for Gosforth.

Church Avenue, Gosforth, just west of Station Road

Newcastle City Council confirmed in February, following an eighteen-month trial and six-month consultation, that the arrangements at Stoneyhurst, Dene and Salters Bridges would be made permanent to help make local streets safer, cut carbon emissions from driving and promote active travel.

The map below shows the location of Salters and Stoneyhurst Road bridges and average annual daily traffic levels on Station Road between 2013 and 2021. Both bridges were closed to motor traffic in August 2020. Salters Bridge was previously closed to traffic during the Killingworth Road roadworks between July 2017 and October 2019.

Station Road traffic count shows 2021 was lower than all years other than 2016 and 2020.

One of the main concerns raised by people responding to the Council consultation was that (they believed) these closures would lead to “displaced traffic / congestion”. We now have nineteen months of traffic data since August 2020 that shows traffic levels on Station Road and Sandy Lane (north of Gosforth Racecourse) are broadly unchanged from previous years.

Station Road and Sandy Lane are neither busier nor more congested following closure of the bridges. Meanwhile Hollywood Avenue and Stoneyhurst Road have much less traffic.

Traffic Volumes on Station Road, measured 30m west of Bowsden Terrace

This is one reason why the Council could “set aside” any objections due to displaced traffic, as there simply isn’t any evidence of additional traffic on adjacent main roads. The Council needs to share this information so people commenting on future LTN consultations better understand the likely impact on traffic in their local area.

Even if traffic levels had increased on Station Road (which didn’t happen), there still wouldn’t be a good case for using Stoneyhurst Road or Hollywood Avenue as overflows for ‘displaced’ main-road traffic, as these minor roads are neither intended nor designed for high levels of vehicle traffic. 

Despite this, the Council was still (in our view unfairly) accused of “ignoring” residents’ views. Clearly there is still a need for education so that people more widely understand how traffic reacts (and has reacted) to road changes. Local Councillors and community groups could help with this, and reduce community tensions, by sharing facts and relevant information in local leaflets. 

This effect of “disappearing traffic” is well known and understood by traffic professionals. Researchers looking at over 70 case studies found that “predictions of traffic problems are often unnecessarily alarmist, and that, given appropriate local circumstances, significant reductions in overall traffic levels can occur, with people making a far wider range of behavioural responses than has traditionally been assumed.“

Station Road looking towards South Gosforth Metro with longstanding “modal filter” at the end of Church Road

While the traffic levels on Station Road will have benefited from more home-working and people travelling less due to fuel costs, the study shows that “disappearing traffic” would happen even without these.

We can conclude that the bridge closures have helped to reduce traffic levels locally in Gosforth and have contributed towards the necessary 20-50% reduction in miles driven by 2030 to help achieve net zero targets.

That doesn’t mean that traffic levels on Station Road are ok. Just like before 2019, it still has high levels of traffic making it hard to cross and dangerous to cycle. These could be mitigated, for example with additional crossings and protected cycle lanes. The east end of Station Road is also part of the South Gosforth Air Quality Management Area and in 2016, before Killingworth Road roadworks, pollution measurements exceeded the legal limit. 

If you live on the A191 – Church Road, Church Avenue or Station Road, or other main roads around Gosforth – please let us know what you think could be done to cut traffic and/or make the road safer.

Further information is provided below about feedback to Newcastle City Council’s Stoneyhurst Road and Salters Bridge consultations, and on traffic levels on Station Road and Sandy Lane. 

Stoneyhurst Bridge closure: main themes from ETRO correspondence

Main feedback themes – Support

• Walking / cycling shift enabled – 13% of responses*
• Pedestrian and cyclist safety improved – 12%
• Reduced traffic / air pollution – 11%

Main feedback themes – Opposition

• Displaced traffic / congestion – 72% of responses*
• Road access needed – 48%
• Longer journeys – 15%
• Discriminatory – 13%

* NB there was no geographical restriction on who could respond, nor any limit on the number of responses per person. 

As we have said, traffic levels on Station Road and Sandy Lane did not increase. Road access for vehicles was retained to all properties. We have also previously looked at journey lengths and our analysis was that very few journeys would be noticeably longer as a result of this change. 

The Council’s Integrated Impact Assessment says “data does not indicate an impact on the operation of the wider highway network from any of the bridge closures to vehicles to indicate that they need to be reopened to alleviate this issue. Despite having been closed, (even when three bridges impact on the same surrounding highways), those highways have not seen significant differences in journey times or speeds.“

The fact that traffic in Newcastle grew by 14% between 2010 and 2019, which has never been the subject of consultation, is much more likely to have negatively impacted journey times.

Salters Bridge closure: main themes from ETRO correspondence

Main feedback themes – Support

• Reduced traffic / air pollution – 46% of responses
• Pedestrian and cyclist safety improved – 45%
• Walking / cycling shift enabled – 38% 

Main feedback themes – Opposition

• Displaced traffic / congestion – 36% of responses
• Increased air pollution – 35%
• Longer journeys – 33%
• Impact on local businesses – 30%

As there is no additional traffic, there is no reason to think air pollution will be any worse on Station Road as a result of these changes. There is substantial evidence that investing in active travel benefits local businesses, for example this report from Transport for London or our blog Can protected cycle lanes be good for business? 

Station Road, looking towards Haddricks Mill

Traffic Volumes – Station Road 

Traffic Volumes on A191 Station Road, Gosforth, measured 30m west of Bowsden Terrace

The graph above shows that traffic volumes in 2021 and 2022 are largely unchanged compared to 2018 and 2019. These traffic volumes are also largely unchanged from 2013-2017.

Traffic Volumes – Sandy Lane 

Traffic Volumes on A1056 Sandy Lane, Gosforth, measured east of the MOT station.

Traffic on Sandy Lane in 2021 and 2022 is also unchanged from 2018 and 2019.

Reports setting out the Council’s decisions for each of the five bridges are published here:

• Argyle St – https://democracy.newcastle.gov.uk/ieDecisionDetails.aspx?ID=10801
• Haldane – https://democracy.newcastle.gov.uk/ieDecisionDetails.aspx?ID=10799
• Dene Bridge / Castle Farm Rd – https://democracy.newcastle.gov.uk/ieDecisionDetails.aspx?ID=10798
• Stoneyhurst – https://democracy.newcastle.gov.uk/ieDecisionDetails.aspx?ID=10802
• Salters Bridge- https://democracy.newcastle.gov.uk/ieDecisionDetails.aspx?ID=10800

Further information on low traffic neighbourhoods In Newcastle can be found at https://www.newcastle.gov.uk/neighbourhoods

Most people in #Tyneside (65%) support the creation of more low traffic neighbourhoods, according to data in the #WalkingCyclingIndex.

You can read the Tyneside report here 👇https://t.co/1FHgAA1tWM@gateshead@NewcastleCC@NTCouncilTeam@Sustrans pic.twitter.com/ThDUUZtJ4e

— Sustrans North (@SustransNorth) May 20, 2022

The post Station Road Traffic appeared first on SPACE for Gosforth.

In our last blog we shared the results of the 2017 Council air quality monitoring, showing that Gosforth High Street had the highest recorded nitrogen dioxide (NO₂) air pollution in the whole of Newcastle.

In this blog, we take a look at three key questions that came up in discussion following release of the 2017 air pollution figures. These questions are:

1. Why has air quality on Gosforth High Street deteriorated?
2. Does restricting traffic flow cause more pollution?
3. What happens to traffic when roads are shut?

The better understanding we collectively have of the answers to these questions, the better chance there is to bring pollution down to legal limits as soon as possible.

1. Why has air quality on Gosforth High Street deteriorated?

The government estimates that 80% of roadside air pollution is generated by vehicle traffic so, even without looking at any data, it is reasonable to suggest that vehicle traffic has been the source of the additional pollution. The question then is whether the increase has been due to more traffic, or because traffic has been held up and is waiting longer and emitting more while it is waiting.

We do have some data that can help us to answer this. In the graph below the two lines represent average daily vehicle volumes on Gosforth High Street  (red line / right axis) and air pollution (blue line / left axis) between January 2016 and December 2017. Each point represents the average of two months. The gap in the red line is because we don’t have vehicle volumes, measured by The Grove, for either January or February 2017.

It is pretty clear that the more vehicles there are on Gosforth High Street the worse the air pollution is, as the two lines follow each other quite closely, and that the increase in air pollution in 2017 compared to 2016 is almost certainly a result of more traffic using the High Street.

It is also clear that in both 2016 and 2017 air pollution was significantly worse than the legal limit of 40μg/m³ NO₂ averaged over a year. We don’t have data for pollution at this location prior to 2016, as 2016 was the first year air quality was measured in this location, but based on vehicle counts we can be reasonably sure air quality wasn’t any better prior to 2016 as traffic levels have been declining on Gosforth High Street since 2010.

Diesel buses are often mentioned as a specific cause of pollution on the High Street and we hope that low-emission buses will form part of the Newcastle City Council Air Quality Plan due early 2019.  This data suggests however, that having cleaner buses may not be sufficient by itself to resolve air pollution concerns on Gosforth High Street, as pollution was worse after August 2016 even though Arriva had introduced new cleaner buses about that time.

2. Does restricting traffic flow cause more pollution?

The Government’s 2017 Draft Air Quality Plan suggested “Improving road layouts and junctions to ‘optimize’ traffic flow” as a way of tackling air pollution. Improving traffic flow and reducing pollution were also described in the Council’s 2014 Air Quality Progress Report as objectives for the Salters Road / Church Road junction. 

In the SPACE for Gosforth response to the Government’s Air Quality Consultation we asked that the the Government prioritise the most effective measures to reduce pollution, which according the Government’s own assessment did not include optimising traffic flow. The Government’s final plan acknowledged that there is “there is considerable uncertainty on the real world impacts of such actions“. This is because rather than reducing air pollution, changes that are designed to improve or optimise flow can lead to more traffic (and more pollution).

We can use the same traffic data to see what the effects were of the roadworks at Salters Road junction between about February and August 2016, and the effect of Killingworth Road being closed to traffic from July 2017.

This next graph shows week-day traffic in 2016 and 2017 compared to the average for the same month between 2013 and 2015. The dotted lines indicate months in which traffic was measured on fewer than half of the days in that month.

During the Salters Road junction roadworks (March-August 2016), when traffic was controlled by temporary traffic lights, there were 1032 fewer vehicles per day on average compared to 2013-2015.

During the second half of 2017, at the start of the Killingworth Road roadworks, the Council’s mitigation included “Timings on traffic signals on key routes programmed for longer green lights on routes that will see extra vehicles during peak periods” i.e. enabling more north-south traffic flow. During this period (August, October, November, December 2017) there were 1240 additional vehicles per day on average compared to 2013-2015. We have excluded September 2017 from this average as traffic volumes were counted on fewer than half of the days in September.

So when traffic was constrained (via roadworks) there were fewer vehicles and lower pollution, and when Killingworth Road was closed, and there were longer green lights for north-south traffic on the High Street, there were more vehicles and more pollution. It appears that rather than causing more pollution, the 2016 roadworks had the opposite effect and actually reduced pollution on Gosforth High Street.

To know whether the Killingworth Road effect is due to the mitigation that increased flow or due to rerouted traffic we need to answer our third question.

3. What happens to traffic when roads are shut?

In our blog about the Killingworth Road Metro Bridge Replacement from Jun 2017 we included this map below. In it we highlighted The Great North Road and Benton Lane as roads to avoid during the works as we thought these were most likely to be impacted by traffic re-routing as a result of the Killingworth Road closure.

Traffic volume data is available for these routes so we can now see what that impact was. This shows that the average weekday traffic volumes for The Great North Road and Benton Lane were almost exactly the same in the second half of 2017 as they were in 2016. i.e. there was no additional traffic on these routes when Killingworth Road was shut.

Even if the extra thousand vehicles on Gosforth High Street are a result of the closure, despite traffic levels on the Great North Road were unchanged, that is still a significant reduction in overall traffic levels.

This is almost certainly an effect called Disappearing Traffic where, contrary to what most people might expect, reducing road capacity can lead to substantial reductions in overall traffic levels.  Studies of Disappearing Traffic confirm that this doesn’t necessarily mean that people are travelling less, just that people have a range of choices for how and when to travel.

On Station Road there is a similar picture. Weekday traffic in the second half of 2017 is higher than previous years but by far less than you would expect if all 8,000+ vehicles previously using Hollywood Avenue had re-routed via Station Road, and not substantially more than it was 2013 or 2015.

The dramatic drop in traffic in September 2016 may be because of roadworks by Northern Gas Networks on Station Road. If so, it would be another example of constraining traffic flow leading to fewer vehicles and less pollution (25% less in September than the 2016 average).

Despite vehicle numbers in 2017 being higher than 2016, air quality measured on Station Road in the second half of 2017 was better (35.3μg/m³) compared to the same six months in 2016 (41.9μg/m³). This is most likely because the closure of  Killingworth Road has meant far less traffic on Haddricks Mill roundabout.

Reducing Air Pollution

The data presented above suggests pollution is linked more to traffic volumes than flow, that constraining traffic leads to better air quality, and that closing Killingworth Road hasn’t made any great difference to traffic on The Great North Road or Benton Lane.

That’s not to say Killingworth Road has had no effect. For some people journeys will be worse, and others e.g. those that drive East-West across Haddricks Mill or use the 33 bus on Hollywood Avenue, which is no longer delayed by through traffic, will have better journeys.

It does mean we should be concerned by measures attempting to improve air quality by improving traffic flow, as they might just make it worse. The most effective way of reducing air pollution, according to the Government, is to introduce Charging Clean Air Zones (CAZ). These work by charging for, and therefore discouraging, trips made by the most polluting vehicles.

Newcastle City Council only has one month left to complete its plans to bring air pollution on Gosforth High Street and across Newcastle within legal limits in the shortest possible timescales. We don’t know for certain what this will involve but almost certainly it will need to include some sort of restriction on traffic if it is to have any measurable effect.

Notes

• Air Pollution Data is taken from Newcastle City Council’s annual monitoring reports using measurements taken on Gosforth High Street just south of Woodbine Road.
• Data on traffic volumes is from the TADU website. Gosforth High Street measurements are from near The Grove.
• We don’t have data for traffic queue lengths or journey times so don’t know how those have been affected, although it is a reasonable assumption that more vehicles using the Great North Road after the Salters Road junction works indicates that journey times were slower during the roadworks and faster afterwards, although it is also possible that the additional traffic negated that benefit.
• We do know that it now takes longer to cross Gosforth High Street on foot because  pedestrian lights have been changed to prioritise traffic flow rather than crossing. The tongue-in-cheek Pedestrian Pain Index which estimates costs due to delays to walking journeys on a similar basis to the calculation for driving delays, is worth a read.
• These results are consistent with a world-wide survey of cities published in “Cities and Automobile Dependence” (1989) by Kenworthy and Newman.  This concluded that the goal of “free-flowing” traffic (through such strategies as road widening) actually results in more fuel consumption and air pollution.  For a good summary see the Walkable Streets blog.
• There are many similar studies that confirm that measures to improve flow will not reduce congestion either. This has been called the Fundamental Law of Road Congestion, which essentially states that any additional capacity for vehicles will quickly be filled negating any expected benefit.
• One of the most effective ways of reducing traffic delays while also improving air quality is via congestion pricing.  In Stockholm, a where congestion pricing has received widespread public support, it has been estimated that without “congestion pricing”, children would have suffered 45 percent more asthma attacks. The video below by Jonas Eliasson gives a good overview of the approach taken in Stockholm and shows how public support for the approach grew significantly once  it had been implemented.

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