Category: Why not SkyRail

Visual bulk and impact

You don’t need many words to describe Skyrail or “Hybrid Solution”. It’s huge, enormous. It’s out of proportion. It’s height will dwarf the entire neighbourhood. The ugly, massive concrete pylons aren’t pretty and will inevitably be covered with graffiti.
There is a document, issued from the “Office of Victorian Government Architect”  called  “Level Crossing Removals – Lessons Learned” – Click here to view. The document states: “An elevated road or rail structure will have a significant physical presence and impact on a place and is typically not a preferred solution. New elevated structures, including ramps and retaining walls, can impact on visual amenity, permeability, the viability of activity areas, the value of land and appetite for future private development. They often provide a cheaper solution but a poorer outcome and therefore a false economy.”

So the government admits Skyrail is not a preferred solution. So why push it on Seaford and Carrum? We know rail under road can be built here.

Hybrid skyrail

The Health Impact of Elevated Rail on Bayside Communities

The Health Impact of Elevated Rail on Bayside Communities

The academic literature shows that proposed elevated rail bridges negatively impact the health of
individuals and communities. The World Health Organisation recommends ‘health in all policies’ which includes consideration of the health impacts of large infrastructure projects on populations (Leppo, Ollila,Pena, Wismar, & Cook, 2013.)

Elevated rail adjacent to residential areas increases noise and vibration, reduces natural light,
reduces property values, increases air pollution, impacts green space and clashes with local amenity. It also attracts crime, compromises safety and impacts the social determinants of health. All of these factors negatively impact health. A ‘rail under road‘ or ‘rail trench option’ will not have these deleterious effects on health.

Noise and Vibration
The literature indicates that noise and vibration increases significantly and travels greater distances
with elevated rail. Xia et al. (2009) reports noise concerns and vibration impacts on the environment and people near elevated rail. Research shows a link to sleep disturbance resulting in fatigue, impaired judgement, poor decision-making and an increased risk of occupational and road accidents. (Killgore, Balkin & Wesensten, 2006; Lamond et al; 2004.) Stickgold, Hobson, Fosse & Fosse (2001) state good quality sleep is a public health issue, essential for optimal health. Insufficient sleep is linked to diabetes, cardiovascular disease, obesity and depression (Unruh et al. 2008; Babisch, 2006.) Passchier-Vermeer and Passchier (2000) associate noise with decreased school performance. The negative health impact associated with noise pollution from rail bridges will impact thousands of homes and community facilities such as schools, kindergartens, churches and aged care homes.

Mental Health
Elevated rail bridges will significantly overshadow homes. The impact of reduced sunlight on mental
health is well supported in the literature (Halpern, 2013.) Multiple studies assert that a lack of natural light increases the risk of mental health issues including depression and anxiety (Edwards & Torcellini, 2002.)
The Office of the Victorian Government Architects (OVGA) reported on lessons learned with level
crossing removals (2014.) They state that an elevated rail structure will have a significant impact on a place and is typically not a preferred solution. Elevated rail is often a cheaper solution but offers a poorer outcome for the community. Rail bridges also impact negatively on visual amenity, permeability, viability of activity areas and the value of land. Close proximity to rail infrastructure (particularly heavy diesel) reduces property values due to noise, visual intrusion and the perception of crime (Diaz, 1999.) These factors would be exacerbated by elevated rail. On the Dandenong line it is predicted that elevated rail sections are likely to reduce property values by 20-25% and negatively affect the revenue of small businesses (Zhou & Robb, 2016, Ferguson, 2014.) Uncertainty about income is proven to induce emotional strain, anger, anxiety and depression (Schonfeld & Mazzola, 2015.) In other contexts mortgage stress and financial strain is a risk factor for conflict, mental illness and domestic violence (Pattavina, Socia & Zuber, 2015.)

Air Pollution
Elevated rail carrying diesel trains is likely to increase the amount and distance travelled of airborne
pollution because height facilitates greater drift. Diesel exhaust emissions contain hundreds of chemical compounds that are associated with irritation of the eye and the respiratory and gastrointestinal systems (Balmes, 2011.) The long term effects of exposure to exhaust and brake particulate matter are poorly understood and therefore best avoided. (Morawska, Moore & Ristovski, 2004, Stenfors et al., 2004; Abbasi, Jansson, Sellgren & Olofsson, 2013.) The International Agency for Research on Cancer has recognised diesel exhaust soot as a carcinogen (Abbasi et al., 2013.)

Green Space and Amenity
Elevated rail bridges will negatively impact green space and clash with amenity in the Bayside
suburbs. This area along the line includes 40 km of beachfront, the Edithvale/Seaford ‘Ramsar Convention’ listed wetlands and a 2,070 hectare ‘green wedge’ in the city of Kingston alone. The positive link between green space and health is well documented and most apparent in the elderly and people of lower socioeconomic status, both already vulnerable sub-populations. (Maas, Verhiej, Groenewegen, De Vries & Spreeunwenberg, 2006; Mitchell & Popham 2008.) The visible and audible elevated rail will significantly reduce the health benefits of this green space.

Crime and Safety
Graffiti is a visible form of crime and considered a sign of social decline, representing a threat to
safety and quality of life (Morgan & Louis, 2009; Lorenc et al., 2013.) Elevated railway bridges and pylons attract graffiti because they are prominent, visible and easy to reach with limited surveillance. Controlling and removing graffiti in Australia costs $1.5 billion annually (Morgan and Louis, 2009.)This cost is expected to be borne by local councils along the Frankston line, creating further stress to residents. Railway bridges also attract anti-social behaviour such as dumping, drug use and loitering due to reduced lighting and limited surveillance. This impacts community safety and livability. Under-road stations are easier to illuminate and monitor and are less appealing for anti-social behaviour.
Social determinants of health (SDH)
The SDH will be negatively impacted by elevated rail. A Lancet Commission found that factors which
have the greatest impact on health are social and include community engagement, social inclusion and early life (Marmot, Friel, Bell, Houweling & Taylor, 2008.) Liveable communities create conditions that optimise health and well being outcomes by improving neighbourhood walk-ability, public open space and social facilities (Giles-Corti, Badland, Mavoa, Turrell & Bull, 2014.) An elevated concrete construction will divide communities and impinge on these conditions, negatively impacting the health and well being of the community.

We often assume that what is, has to be. In reality, virtually everything in our built environment is
the way it is because someone designed it that way. Researchers agree that the design of the built
environment holds tremendous potential to address health concerns including cardiovascular disease, diabetes, asthma, depression, violence and social inequity. In short, we have the capacity to build future communities that promote, rather than reduce, physical and mental health (Jackson, 2003.) The OVGA states that lowering a section of the rail corridor is the most supportable solution in most circumstances, is more discrete, has the least impact on the urban environment and improves social and economic outcomes (2014.)
The academic evidence portrays a strong case against elevated rail. A rail trench is the preferred
option for the Bayside suburbs on the Frankston line.

No Sky Rail: Frankston Line
October 27th 2016

Reference List
● Abbasi, S., Jansson, A., Sellgren, U. and Olofsson, U. (2013.)Particle emissions from rail traffic: A
literature review. Environmental Science and Technology.
http://dx.doi.org/10.1080/10643389.2012.685348
● Babisch, W. (2006) Transportation noise and cardiovascular risk: Updated Review and synthesis of
epidemiological studies indicate that the evidence has increased. Noise Health, 8, 1-29
● Balmes, J.R (2011) How does diesel exhaust impact asthma? Thorax, 66(1), 4-6.
● Diaz, RB (1999) Impacts of Rail Transit on Property Values. Booz-Allen & Hamilton Inc. McLean VA
● Edwards L. & Torcellini P (2002) A literature review of the effects of natural light on building occupants. National Renewable Energy Laboratory.
● Ferguson, I. (2014.) Compensating for Economic Loss Caused By New Projects. Australia and New
Zealand Property Journal, June 589- 592.
● Giles-Corti, B., Badland, H.M., Mavoa, S., Turrell, G. & Bull, F. (2014.) Reconnecting urban planning with health: a protocol for the development and validation of national liveability indicators associations with noncommunicable disease risk behaviours and health outcomes. Public Health Research Practice, 25(1), 1-5.
● Groenewegen, P., van den Berg, A.E., de Vries, S. & Verheij, R.A. (2006) Vitamin G: effects of green space on health, well-being, and social safety. BMC Public Health, 23(2), 109-123.
● Halpern, D. (2013>)Mental Health and the Built Environment. Routledge, London.
● Jackson, R.J (2003) The impact of the built environment on health: An emerging field. Editorial.
American Journal of Public Health, 93(9.)
● Killgore, W.D.S., Balkin, T.J., & Wesensten, N.J. (2006) Impaired decision making following 49h of sleep deprivation. Journal of Sleep Research, 15(1), 7-13.
● Lamond, N., Dorrian, J., Burgess, H.J., Holmes, A.L., Roach, G.D., McCulloch, K., Fletcher, A. & Dawson, D.
(2004) Adaptation of performance during a week of simulated night work. Ergonomics, 47(2), 154-165.
● Leppo, K., Ollila, K., Pena, S., Wismar, M. & Cook, S. (2013) Health in all policies – seizing opportunities,implementing policies. WHO.
● Lorenc T., Petticrew, M., Whitehead, M., Neary, D., Clayton, S., Wright, K., Thomson, H., Cummins, S., Sowden, A., Renton, A. (2013) Fear of crime and the environment: systematic review of the UK
qualitative evidence. BMC Public Health, 2013, 13, 496.
● Office of Victorian Government Architects (2014) Level crossing removals lessons learned.
http://www.ovga.vic.gov.au/news/100-lessons-learned-level-crossing-removals.html
● Maas J, Verhiej R.A., Groenewegen P.P., De Vries S. & Spreeunwenberg P. (2006) Green space, urbanity and health: how strong is the relation? Journal of Epidemiology and Community Health, 60(7), 587-592.
● Marmot, M., Friel, S., Bell, R., Houweling, T. A. J. & Taylor, S. (2008) Closing the gap in generation:
health equity through action on the social determinants of health. Lancet, 372(9650), 1661-1669.
● Mitchell, R & Popham F. (2008) Effect of exposure to natural environment on health inequalities: an
observational population study. Lancet, 372(9650), 1655-1660.
● Morawska, L., Moore, M.R. & Ristovski, Z.D. (2004) Health Impacts of Ultrafine Particles: Desktop
Literature Review and Analysis. Australian Government; Department of Environment and Heritage.
● Morgan, A. & Louis, E. (2009) Key Issues in Graffiti. Research in Practice. Australian Institute of
Criminology, No. 6
● Passchier-Vermeer, W. & Passchier, W.F. (2000) Noise exposure and public health. Environmental
Health Perspectives, 108(1), 123-131.
● Pattavina, A., Socia, K.M. & Zuber, M.J. (2016) Economic Stress and Domestic Violence: Examining the Impact of Mortgage Foreclosures on Incidents Reported to the Police. Justice Research and Policy, December 16, 147-164.
● Schonfeld, I.S. & Mazzola, J.J. (2015) A qualitative study of stress in individuals self-employed in solo businesses. Journal of Occupational Health Psychology, Vol 20(4), 501-513.
● Stenfors., Nordenhall, C., Salvi, S.S., Mudway, I., Sorderberg, M., Blonberg, A., … Sandstrom, T. (2004) Different airway inflammatory responses in asthmatic and healthy humans exposed to diesel. European Respiratory Journal, 23, 82-86.
● Stickgold, R., Hobson, J., Fosse, R. & Fosse, M. (2001) Sleep, learning and dreams: off line memory reprocessing. Science, 294(5544), 1052.
● Unruh, M.L., Redline, S., Ming-Wen, A., Buysse, D.J., Nieto, F.J., Yeh, J. & Newman, A. (2008) Subjective and objective sleep quality and ageing in the sleep heart health study. Journal for the American Geriatrics Society, 56(7), 1218-1227.
● Xia, H., Gao, F., Wu, X., Zhang, N., De Roeck, G. & Degrande, G. (2009) Running train induced vibrations and noises of elevated railway structures and their influences on the environment. Frontier Architecture Civil Engineering China, 3(1), 9-17.
● Zhou, C., Robb, K. (2016) Melbourne Skyrail and railway crossing removal impact property prices.
http://www.domain.com.au/news/melbourne-sky-rail-and-railway-crossing-removal-impact-propertyprices-20160219-gmwpfb/

Overshadowing

Elevated rail bridges will significantly overshadow homes. The impact of reduced sunlight on mental
health is well supported in the literature (Halpern, 2013). Multiple studies assert that a lack of natural light increases the risk of mental health issues including depression and anxiety (Edwards & Torcellini, 2002.) Overshadowing of homes and a reduction of open sky reduces our sense of space, access to natural light and enjoyment of our outdoor environment.

Please find a simulation of the shadow cast by a single 11 m high pole at the crossing Seaford Road. You need to mentally move the shadow along the train line, to see how much of Seaford will be in shadow earlier.

The simulation is based on an 11 meter structure which would be the Skyrail and the train but doesn’t include the additional over head infrastructure.

The 11m tall Skyrail would cast a minimum 212 meter long shadow at 4:45 pm on 23rd June 2017, please follow the link below and check this for yourselves.

https://www.suncalc.org/#/-38.1105,145.1304,17/2017.06.23/16:45/11/0

Graffiti and crime

Graffiti is a visible form of crime and considered a sign of social decline, representing a threat to safety and quality of life.

Graffiti at Beach St.in Frankston

Graffiti is a visible form of crime and considered a sign of social decline, representing a threat to
safety and quality of life (Morgan & Louis, 2009; Lorenc et al., 2013.) Controlling and removing graffiti in Australia costs $1.5 billion annually (Morgan and Louis, 2009.) This cost is expected to be borne by local councils along the Frankston line, creating further stress to residents. Railway bridges also attract anti-social behaviour such as dumping, drug use and loitering due to reduced lighting and limited surveillance. This impacts community safety and liveability. Under-road stations are easier to illuminate and monitor and are less appealing for anti-social behaviour.

 Elevated rail bridges and pylons would likely attract graffiti because they are prominent, visible, easy to reach and may have limited surveillance.
• Railway bridges may attract other antisocial behaviour such as dumping, drug use and loitering due to reduced lighting and limited surveillance.
• Fear for safety impacts mental health, outdoor exercise and community access and engagement.

• Reduced community participation is linked to obesity, mental illness, cardiovascular and respiratory disease and diabetes.

Graffiti along a train line in Melbourne

Rail under road options require patrolled, well lit stations and therefore limit areas for antisocial behaviour.
Rail under road options maintain social inclusion, walk-ability and amenity.

Seaford Rd Rail Under Solution

LXRA claims Seaford rail under road option is not feasible, as it will require a railway trench -a “kilometre long bath tub” analogy. This is not true!

Please check Geodetic survey at Seaford rd crossing.

The designs below have been created by our engineering team to show how a Rail Under Road solution would work at the Seaford Rd level crossing.

Cross section of Rail Under Road solution under Seaford Road

A Rail Under Road solution would have the railway line lowered under Seaford Road.
This is similar to other Rail Under Road solutions such as at Darebin Road on the Hurstbridge line as shown below

Rail under at Darebin

Our solution would have the Railway level with the Rf Miles Reserve by Johnstone St:

Cross section at Johnston st

Sky Rail proposal will decimate your neighbourhood

Hybrid skyrail

The tracks for Sky Rail will be 7 metres above Railway Pde and 8 metres higher than RF Miles Reserve
The wiring and overhead gantry will be up to 17 metres high

  • Sky Rail will tower over all nearby housing, overshadowing them during the day.
  • Noise will travel across rooftops for miles around.
  • Pollution from the freight trains will be caught on the sea breezes and become airborne.
  • The total structure will be 17 metres high. This is the same as a 5-story office building.

Save our businesses and 100 local jobs

The relocation of the railway sidings from Carrum to Seaford will destroy 7 local businesses with the loss of over 100 Seaford jobs. None of the businesses have been issued a notice of acquisition. This is a short-term solution as new sidings will eventually be built at Baxter.

Keep Eel Race Road Open with RUR

There is also great concern about the closure of Eel Race Road as this will drive traffic north to McLeod Road or south to Armstrongs Road. We want Eel Race Road to remain open with the
railway line lowered below the road as it should be at every other crossing on the Frankston Line. We need to push for a RUR solution to avoid an extended Sky Rail from Carrum all the way through Seaford to Frankston

Noise

Version 1, 23 May 2016

dreamstime_m_47668457_thumbIt is important to note that any form of grade separation is likely to reduce some of the existing rail noise as the need for boom gate bells, some train braking and some mandatory train horns are eliminated or reduced by the grade separation.

Since all options would provide the same savings from these kinds of rail noises, most of the discussion below is in relation to other rail noise across the various options (eg. the vibrations of the carriages, the tracks, the freight trains’ engines, etc.).

We’ll discuss the following below:

  1. Current Government Noise Policy compliance
  2. Overview of Elevated Bridge Noise and Below Ground Bridge Noise
  3. The LXRA Preliminary Noise report for the Dandenong line
  4. Our Response To Noise Impacts

1. Does Government Policy Protect Us?… Maybe

The Good News

Engineering_VicGov_Rail_Noise_Policy_ThumbA grade separation will mean changes to the existing rail infrastructure and would require compliance with the Passenger Rail Infrastructure Noise Policy (State of Victoria 2013). (This is a separate issue to Construction Noise, which operates under the usual EPA rules).

The Passenger Rail Infrastructure Noise Policy (State of Victoria 2013) is available here.

The policy comes into effect if noise levels following the project’s completion is predicted to exceed:
– 65dB(A) during the day (6am-10pm), or
– 60dB(A) at night (10pm-6am), or
– A maximum level of 85dB(A) (at any time).

I wonder why the policy calls “Passenger Rail”, what about the freight trains???

For reference: 60dB is the noise of a conversation, 70dB is approximately the noise of a shower or dishwasher and 85dB is approximately the noise of a passing diesel truck. Hopefully, no one has that noise level in their homes from rail now!

The Bad News

Sadly, this policy only requires that the authorities consider options to avoid, minimize and mitigate. They don’t have to actually do anything!. To quote from page 6 of the policy (underlines are ours):

If an assessment shows that the investigation thresholds will be exceeded, noise impacts should be considered a primary matter. This means that transport bodies and planning authorities should consider options for avoiding, minimising and mitigating rail noise by applying the policy principles set out in Attachment 3 as a set. Transport bodies and planning authorities may find that there are no appropriate options in some cases.

Transport bodies and planning authorities should seek the views of the Minister for Public Transport and the Minister for Planning.

In accordance with section 21 of the Transport Integration Act 2010, transport bodies and planning authorities should consider publishing a report demonstrating how the principles have been applied. (Page 6, Passenger Rail Infrastructure Noise Policy, State of Victoria 2013). 

So, when the LXRA says that they will comply fully with the noise criteria, you can be sure they are meeting it – you just can’t be sure whether all additional noise will be fully mitigated or whether they will “consider” and conclude that there are no appropriate options for that case.  The policy gives them that “wriggle room” while still allowing “full compliance”.

2A. Elevated Rail Bridge Noise

Anyone who has ever stood near an existing rail bridge in use (near the Melbourne Aquarium for instance) can attest that it is certainly no quieter than the current at-grade rail we already experience.

But currently, with the at-grade tracks, the houses immediately on each side of the tracks are the most impacted by noise, as the noise is partially filtered to the houses further back by other houses and vegetation.  This is slightly less obvious where roads occur.  The State government policy noted above mentions this on Page 15 of “Considerations for applying policy principles”: “Shielding provided by other buildings”.

Say NO To Sky Rail (Skyrail) - Frankston Line - Engineering - Noise Effects
Refer also: LXRA CD9 Preliminary Noise Report: Figure 3 – Environmental Noise Propagation

Assuming that the elevated rail bridge produces the same rail noises (as the carriages move over the rails, vibrations etc,), and without additional noise mitigations, the noise from an elevated rail bridge would be noticeably increased for those houses not currently experiencing the full impact.

Say NO To Sky Rail (Skyrail) - Frankston Line - Engineering - Noise Effects

Based on our conversations with LXRA, each one of the grade separations will be around 1 km long (along with the rail line) in total, so a large area would be affected.

In other words,  the neighborhoods who currently walk to the station would now start to hear the trains in a way they have not heard them before.

Engineering_LXRA_Rail_Noise_Doc_ThumbThe LXRA document “Understanding rail noise and vibration” (available here) claims the proposed elevated structure would reduce noise and vibrations through:

  • Walls and screens to mitigate noise transfer
  • New high-quality, continuous smooth tracks
  • Purpose-built resilient fastenings to attach the new tracks directly to the structure
  • Rubber insulators under the track to dampen vibrations.

We did not find any claim that all noise impacts would be mitigated.

  • Walls and screens do help reduce noise but would add cost and visual impact. As a guide, the Caulfield-Dandenong (CD9) report indicates 600-2000mm high sound screens, the expectation being that these are attached to the side of the elevated rail – so screens up to 11m above the ground. (Great for those sea-view balconies!).
  • Continuous tracks could reduce the “clack clack” noises, but could also be used in a below ground option.
  • The use of fastenings and rubber insulators are not new to the rail space and could equally be applied to the below ground option.

As engineers, our concern is how well these mitigations will be working in 5, 10, or 50 years of constant use.

2B. Below Grade Rail Noise (In Ground Rail Design)

It is perhaps stating the obvious to point out that an in-ground rail line (the top of the train below surrounding ground level) would significantly and noticeably reduce rail noise compared to current “at-grade” noise levels.

Say NO To Sky Rail (Skyrail) - Frankston Line - Engineering - Noise Effects

Other than for those very close by, the noise would be largely contained as it was generated within two side walls.

3. But I heard on the news that an LXRA report for the Dandenong Line says there will be no extra noise if going up?

Engineering_LXRA_Rail_Noise_Doc_ThumbThis is referring to the “Preliminary Noise Report – Overview of Noise Impacts, Caulfield to Dandenong (Report: P03-000-CTD-XEV-0101)“.  The LXRA has published the Executive Summary (available here) and at first glance, it seems to be great news – zero change in noise against the design feature “Elevated structure”.  (See table below from the LXRA web page)

It’s a big claim that seems to say a lot and sounds great when reported in the media, but does it really mean anything significant at all?

We get lots of questions about this. Most people who have read this believe it means that there will be no extra noise from running trains on an elevated structure… What do you think it means?

Well unless you know how to interpret the full detailed report, it is misleading, but not actually a lie… The concrete structure itself, won’t make any extra noise!

“A summary of the potential noise impacts due to design features and the predicted change in noise is presented below:

Design feature Predicted change in noise
New continuously welded rail track 5dB reduction
Direct fix using resilient pads 6dB reduction
New stations 0-5dB reduction
Removal of level crossings 6-8dB reduction
Reduction in horn soundings 3-6dB reduction
Noise wall 5-15dB reduction
Vibration isolation 0-10dB reduction
Change in gradient 4dB reduction to 1dB increase
Elevated structure 0dB increase

The above factors are assumed to act individually. When considered in combination the net increase or decrease will not be equal to the sum of each individual component.

Compared to existing conditions where relevant noise criteria are not applied, the proposed design will achieve full compliance with relevant noise criteria. The proposed design will result in an overall reduction in noise throughout the corridor and surrounding area through the use of considered design measures. “
(LXRA Report: P03-000-CTD-XEV-0101, Page 18, “Table 15 – Summary of Noise Impacts”)

4. Our Response

Since you already know about the limits of the Government Noise Policy (Section 1 above), you’ll realize that “full compliance with relevant noise criteria” is not as comforting as it seems.

As was pointed out at the beginning of this article, ANY grade separation will reduce noise from the level crossing bells and horns.

Of course, the most asked questions we have had, have been about the “Elevated Structure, 0dB increase”. Most people have interpreted this to mean that there is no net increase in noise from putting the train tracks 9 metres in the air.

Look at the detailed report, not just the Executive Summary (you can find it here) and it makes more sense: This is from Page 17:

“Elevated Structures: The existing rail corridor is at-grade with no elevated sections. The proposed design will introduce elevated concrete structures which have the potential to generate structure-borne noise (noise due to the entire structure vibrating). Structure-borne noise is typically more pronounced in steel elevated structures than with concrete structures.”

So the noise assessed is just the noise from the vibration of the structure, not the change in elevation of the rails. Or to put it another way, how loudly the elevated structure hums. (Or maybe it doesn’t know the lyrics…) So not surprisingly, the estimated noise from this is not significant against the current background noise in that area.

We could not find any assessment of the noise impact of raising the rail 9 m in the air. Although, to be fair to the report author, this is something they may not have been asked to evaluate. We wonder, “Why not?”

On page 16 of the report, Noise Walls are discussed:

“The existing rail corridor contains no noise walls or noise reduction measures to reduce rail noise impacting on the surrounding community. The proposed design includes the provision for noise walls and visual screening at a number of locations. The proposed screens will vary in height between 600mm-2000mm. Noise barriers are most effective where they block line of sight between the receiver and the wheel/track interface. ”  

Common sense suggests that noise walls would only be used if the noise of a “Sky Rail” would be greater than the current at grade situation.

We look forward to more detailed noise reporting, in particular the “combination” evaluation of the overall noise impact of raising the rail, and a comparison of this with the current at-grade noise, especially for those not immediately adjacent to the rail line… and without noise walls.