Category: Engineering

Changes to the Patterson River rail bridge would NOT require a closure of the Frankston line for up to six months

A new road bridge connecting Station Street to Station Street over the Patterson River is planned.
This can be used as a temporary rail by-pass whilst any changes to the Patterson River rail bridge are completed.

Carrum temporary rail by-pass
Carrum temporary rail by-pass

Allowing for a safety fence 3m from the by-pass rail track access to properties either side of Patterson River remain unaffected.
This will require a stronger bridge for the train use but any additional height caused by deeper spans can be accommodated with the more lenient road design rules and/or service road use.
And this is working on a two-track by-pass where train schedules will not have to be altered.

But even with a single-track by-pass all trains can be accommodated.

Total by-pass length <500
Metro train length 150
Total to travel 650

Use a temporary by-pass speed restriction to suit track transitions:

Transit use time in by-pass
At 40km/hr ~ time 59 secs
At 50km/hr 47 secs
At 60km/hr 39 secs
Add acceleration 10 – 15 secs

Red figures indicate new schedule
All changes within 2 minutes

A minimum of 3 minutes between
entry to by-pass end

All trains serviced ~ No bussing reqd.

Morning peak

Bonbeach By-pass   Carrum
0600 0601
0606
10 11
20 21
22/24
29 30
33
43/42
44 45
47/48
50 51
55
59
0702 0703
0709
12 13
16
 20/19
21 22
24/25
28
31 32
35
 39
43
 43/45 44/46
49
53
53/55 54/56
59
0804 05
0810
16 17
21
26 27
 33
37 38
43
 46 47
 53
54/55 55/56

Evening peak

Bonbeach By-pass Carrum
1702
1704 1705
12
14 15
 22
25 26
 30
35 36
39 40
44
49 50
53
59 1800
1803
1805 1806
10 11
13/14
21 22
23/25
25/27 26/28
32/31 33/32
33/35
36/37 37/38
44/43 45/44
 45/47
 48/49 49/50
 54
54/56 55/57
1906 1907
10
10/12 11/13
16 17
20 21
24
 26 27
 37 38
39/41
 47 48
54
 57 58

Changes to the Patterson River rail bridge DO NOT require a closure of the Frankston line for up to six months.

Carrum: Lowering the Patterson River rail bridge would NOT impact boat access.

Carrum Boats only use the two mid spans.
Carrum: Boats only use the two mid spans.
The southern span can be lowered without impacting on boat access.
The southern span can be lowered without impacting on boat access.

This effectively increases the distance from the Patterson River to McLeod Road.
Additionally, the vertical gradient transition from level to – 2% (or more) can be achieved over the
mid spans of the bridge improving the effectiveness of lowering the southern span and not impacting on boat clearance.

Fact Sheet – Seaford Road

Seaford Road Level Crossing

Rail Under Road

Another 8 level crossings on the Frankston Line are due to be removed. Three have already been grade separated with a Rail Under Road solution: Ormond, Bentleigh and McKinnon. This article explains how Seaford Road can be Rail Under Road also.



Design Considerations

1. Rail Reserve
• A 40m wide railway reserve allowing “parallel” construction, similar to new Springvale station.
• A rail trench can be constructed alongside the current rail line which can remain in use.
• This would cut rail closure to just a few days to dig under the road.
2. Ground Water
• Groundwater levels are similar to current Rail Under Road sites (ie: Ormond) so can be dealt with as per other Rail Under Road projects.
3. Soil Type
• Local soil type (which may or may not be Acid Sulfate Soils) has supported railway operation for over 100 years. A correct concrete mix can be adapted for all conditions.
• Soil type (sand) can be supported with proper pile foundations, correct concrete mix, and soil anchors (as per Ormond.)
4. Roadway Clearance
• Only a 6 metre clearance is required to put Rail Under Road compared with 9 metres for Rail Over Road (aka Elevated Sky Rail.)
5. High Voltage Power Line

Site Assumptions

Groundwater Depth: Could be as low as 4 to 5 metres below average ground level.
(Source: Vic Govt Bore logs, www.vvg.org.au)
Soil Type: Coastal Dune Deposits (sand)
(Source: Victorian geology maps)
Traffic Volume: High, 17,400 vehicles/day 210 trains/day. Boom Gates down for average of 32 mins between 7am and 9am. (Source: LXRA community consultation information displays)
Other Factors: Kananook Creek 200m to the west of the crossing.

Rail Under Road – Advantages

Less Pollution
• Rail Under Road will also reduce, rather than increase, air-borne pollution.
• A rail trench will be much quieter than elevating the rail 9 metres in the air.
• Less visual pollution and less opportunity for graffiti
Retain Property Values
• Property values will be preserved or increased, rather than facing a 20% decline as predicted with Sky Rail, “elevated rail” or railway bridges
Less Council maintenance and increased rate revenue
• No extra cost to council for cleaning (graffiti, removing dumped rubbish, etc) under an elevated railway bridge if the crossings are put in trenches.
• No loss in rate revenue as property values will not decline.
Legacy Solution
• A Rail Under Road option will be a proper long-term infrastructure solution that will increase the amenity of area and leave a lasting legacy that will not be an eye sore for generations to come.

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What would you prefer?

No Sky Rail Frankston Line - NSRFL - Springvale Station Design
Rail Under Road station at Springvale
No Sky Rail Frankston Line - NSRFL - Skyrail over Hawaii
Sky Rail under construction in Hawaii

Fact Sheet – Bonbeach & Carrum

Bonbeach & Carrum Level Crossings
Bondi Road, Carrum Station, Eel Race Road

Rail Under Road

Another 8 level crossings on the Frankston Line are due to be removed. Three have already been grade separated with a Rail Under Road solution: Ormond, Bentleigh and McKinnon. This article explains how the Bonbeach & Carrum level crossing removals can be Rail Under Road also.

UPDATE: The LXRA have updated their position. Current public proposals claim the Bon Beach and Carrum Sky Rail sections will be separated. This only means there will be a ramp down from Bon Beach and another ramp up before Carrum, creating a small reduction in visual impact for the residents in between the two ramps. However, this will do nothing to reduce other impacts, such as those caused by increased diesel noise propagation.

 

UPDATE: The LXRA have released their design proposal to the Carrum community. The proposal claims a Rail Under Road solution must descend to 8 metres below grade and that there is not enough distance to ramp down from the Patterson River.

The LXRA documents have not included any justification for claiming 8 metres depth, when the bridge clearance required by the governing standards is only 5.75 metres*. Even at 7 metres deep, the structure supporting the road crossing could be more than a metre thick! Further, more supporting thickness could be achieved with a minor rise in the road crossing height, without effecting any existing road infrastructure.

Without providing supporting evidence, we can only assume that the extra depth the LXRA are claiming for Rail Under Road is a misrepresentation to make Rail Under appear less desirable and justify their Sky Rail Only claim to the Carrum community.

[*Victorian Rail Industry Operators Group Standards (VRIOGS) 001 Section 7, Figure 2, Envelope F-V5, relating to bridges, retaining walls, piers and structures adjacent to and above tracks used for passenger and or/freight services, other than interstate freight services.]

Community Preferences

Low Traffic Count
• The Bondi Road rail crossing has never been considered dangerous or congested by local residents.
• Low traffic count suggests the only reason this crossing was included was as a means of getting an elevated railway (Sky Rail) over the Patterson River.

Extend Station Street
• Carrum residents and business owners have stated their priority is to see a bridge extending Station Street over Patterson River to join Bonbeach to Carrum.
• Extending Station Street over Patterson River eliminates the need to do anything with Bondi Road saving $250M to $300M and further relieve perceived congestion.

Rail Under Road at Carrum Station
• Rail Under Road at Carrum is a sensible way to remove congestion and improves the amenity of the area by allowing relocation of the current crossing to a logical alignment south of McLeod Road.

Eel Race Road
• Continue Rail Under Road cutting south of relocated Carrum Station under Eel Race Rd.• This would ensure both these major thoroughfares have their crossings removed.

nsrfl_fs_bb-carrum_pc_1_0

Design Considerations

1. Ground Water
Groundwater levels are similar to current Rail Under Road sites (ie: Ormond) so not an issue.

2. Soil Type
Local soil type (which may or may not be Acid Sulfate Soils) has supported railway operation for over 100 years. Concrete mix can be adapted for all conditions.

3. Roadway Clearance
Only 6m clearance is required for Rail Under Road compared to 9m for Elevated Sky Rail.

4. Construction Method
Parallel construction utilising adjoining car parks similar to Springvale Rail Under Road.

5. Total Project Cost
Cheaper solution with $300m saving by not removing Bondi Road (local traffic can use extended Station St to access Carrum shopping centre).

Site Assumptions – Bondi Road, Bonbeach

Groundwater Depth: At least 6.5m below grade (Maybe lower).
(Source: Vic Govt Bore logs, www.vvg.org.au)
Soil Type: Coastal Dune Deposits (sand)
(Source: Victorian geology maps)
Traffic Volume: Low = 4,400 vehicles/day, 210 trains/day. Boom gates down for an average of 45 minutes from 7am to 9am (Source: LXRA community consultation information displays)

Site Assumptions – Station St, Carrum

Groundwater Depth: Approximately 5.5m below grade (Note: the pedestrian underpass is dry and many buildings have underground carparks).
(Source: Vic Govt Bore logs, www.vvg.org.au)
Soil Type: Coastal Dune Deposits (sand)
(Source: Victorian geology maps)
Traffic Volume: High, 11,800 vehicles/day, 210 trains/day. Boom gates down for an average of 49 minutes from 7am to 9am. (Source: LXRA community consultation information displays)
Other Factors: Minimum Right of Way = 23m. Distance from the river to the north side of McLeod/Thompson Rd is approximately 350m (allows 7 metre depth for rail under road). Distance from south side of McLeod/Thompson to Eel Race Road is 664m.

Site Assumptions – Eel Race Rd, Carrum

Groundwater Depth: Approximately 5m below grade (track level)
(Source: Vic Govt Bore logs, www.vvg.org.au)
Soil Type: Coastal Dune Deposits (sand)
(Source: Victorian geology maps)
Traffic Volume: Low, 5,500 vehicles/day, 210 trains/day. Boom gates down for an average of 21 minutes from 7am to 9am. (Source: LXRA community consultation information displays)
Other Factors: Minimum Right of Way = 23m. Kananook Creek 500 metres on the south side of Eel Race Road. Keep depth to 6 metres at Eel Race Road, so rail can return to grade in 300m, well before Kananook Creek.

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No Sky Rail Frankston Line - NSRFL - Sky Rail over beach community

 

Fact Sheet – Charman Road

Charman Road Level Crossing

Rail Under Road

Another 8 level crossings on the Frankston Line are due to be removed. Three have already been grade separated with a Rail Under Road solution: Ormond, Bentleigh and McKinnon. This article explains how Charman Road can be Rail Under Road also.

No Sky Rail Frankston Line - NSRFL - Charman Road Level Crossing

 

Design ConsiderationsNo Sky Rail Frankston Line - NSRFL - Charman Road Level Crossing

1. Park Road
• Logic suggests that Park Road should be included in any Level Crossing removal. This would ensure both these major thoroughfares have their crossings
removed.

2. Raised Topography
• Cheltenham station is on a slight hill with the railway line rising up to the station and dropping off at both sides.
• Starting before Charman Road, a cutting would could be eased into the ground and only require a small gradient on the other side of Park Road to meet the existing track.

3. Ground Water
• Groundwater levels are similar to current Rail Under Road sites (ie: Ormond) so not an issue.

4. Soil Type
• Soil type (sand) can be supported with proper pile foundations, correct concrete mix, and soil anchors (as per Ormond).

5. Roadway Clearance
• Only a 6 metre clearance is required to put Rail Under Road compared with 9 metres for Rail Over Road (aka Elevated Sky Rail).

Site Assumptions

Groundwater Depth: Approximately 12m below grade (track level)
(Source: Vic Govt Bore logs, www.vvg.org.au)
Soil Type: Swamp and Lake Deposits / Inland Dune Deposits (silty clayey sand or sand)
(Source: Victorian geology maps)
Traffic Volume: High, 12,300 vehicles/day, 222 trains/day, Boom gates are down for an average of 35 minutes between 7am to 9am
(Source: LXRA community consultation information displays)
Other Factors: Distance from Park Road to the new Southland Station is over 1km.
Car parks surrounding station allow for parallel construction as carried out at Springvale.

Rail Under Road – Advantages

Less Pollution
• Rail Under Road will also reduce, rather than increase, air-borne pollution.
• A rail line in a cutting will be much quieter than elevating it 9m in the air.
• Less visual pollution and less opportunity for graffiti

Retain Property Values
• Property values will be preserved or increased, rather than facing a 20% decline as predicted with Sky Rail, “elevated rail” or railway bridges

Less Council maintenance and increased rate revenue
• No extra cost to council for cleaning (graffiti, removing dumped rubbish, etc) under an elevated railway bridge if the crossings are put in cuttings
• No loss in rate revenue as property values will not decline

Legacy Solution
• A Rail Under Road option will be a proper long-term infrastructure solution that will increase the amenity of area and leave a lasting legacy that will not be an eye sore for generations to come.
• Proposed Council development of the Cheltenham streetscape will not be dominated by an elevated rail.

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NSRFL - Kingston Council Cheltenham Proposal

Fact Sheet – Edithvale Road

Edithvale Road Level Crossing

Rail Under Road

Another 8 level crossings on the Frankston Line are due to be removed. Three have already been grade separated with a Rail Under Road solution: Ormond, Bentleigh and McKinnon. This article explains how Edithvale Road can be Rail Under Road also.

No Sky Rail Frankston Line - NSRFL - Edithvale Road Level Crossing

 

Design ConsiderationsNo Sky Rail Frankston Line - NSRFL - Edithvale Road Level Crossing

1. Rail Reserve
One lane of Station St and Nepean Hwy could be used to run a temporary rail line while existing track is lowered.

2. Ground Water
Groundwater levels are similar to current Rail Under Road sites (ie: Ormond) so not an issue.

3. Soil Type
Soil type (sand) can be supported with proper pile foundations, correct concrete mix, and soil anchors (as per Ormond).

4. Roadway Clearance
Only a 6 metre clearance is required to put Rail Under Road compared with 9 metres for Rail Over Road (aka Elevated Sky Rail).

5. High Voltage Power Line
High voltage power lines on both side of railway line will need to be relocated.

6. Wetlands Drainage
Local wetlands are fed by drains to the north-west and discharges north to Mordialloc Creek.

Site Assumptions

Groundwater Depth: Approximately 6m below grade (track level)
(Source: Vic Govt Bore logs, www.vvg.org.au)
Soil Type: Coastal Dune Deposits (sand)
(Source: Victorian geology maps)
Traffic Volume: High, 13,400 vehicles/day, 210 trains/day, Boom gates are down for an average of 42 minutes between 7am to 9am
(Source: LXRA community consultation information displays)
Other Factors: Minimum Right of Way = 20m

Rail Under Road – Advantages

Less Pollution
• Rail Under Road will also reduce, rather than increase, air-borne pollution.
• A rail line in a cutting will be much quieter than elevating it 9m in the air.
• Less visual pollution and less opportunity for graffiti

Retain Property Values
• Property values will be preserved or increased, rather than facing a 20% decline as predicted with Sky Rail, “elevated rail” or railway bridges

Less Council maintenance and increased rate revenue
• No extra cost to council for cleaning (graffiti, removing dumped rubbish, etc) under an elevated railway bridge if the crossings are put in cuttings
• No loss in rate revenue as property values will not decline

Lower Overall Project Cost
• Project costs can be cut by $150 million less for a Rail Under Road solution if you skip one crossing by extending Station Street across Patterson River

Legacy Solution
• A Rail Under Road option will be a proper long-term infrastructure solution that will increase the amenity of area and leave a lasting legacy that will not be an eye sore for generations to come.

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No Sky Rail Frankston Line - NSRFL - Sky Rail over beach community

 

Utilities

Say NO To Sky Rail (Skyrail) - Frankston Line - Engineering
Mc Kinnon Station – Old Service Ducts

Relocation of utilities is a consideration on every large construction project and is business as usual. It is not the insurmountable problem represented in Government and LXRA’s media spin.

We are currently unaware of any large utility easements of concern.

Given the long lead times before construction begins, we would expect that LXRA and the Utility companies would be communicating any concerns.

Water

Updated 11/09/2016

1. Ground Water

So far, our reviews of publicly available information have indicated that the approximate ground water levels are lower than the depth of excavation.  Where the ground water levels are lower than the excavation level, neither dewatering or exclusion walls are required. However, seasonal fluctuations are possible, so we have discussed temporary and permanent exclusion below.

Temporary exclusion or “dewatering” is often used during construction, to lower the water table in the immediate area with subsoil drainage or wellpoints and pumps.  Once these measures are stopped, the ground water levels return to their original level.  Granular soils like the coastal sand in this area lend themselves to dewatering as water moves easily through the gaps between each piece of sand (pore spaces).

Permanent exclusion requires a low permeability or impermeable barrier to stop the flow of water within the ground, such as slurry walls, sheet piling, and pile walls.  It is likely that the sandy conditions would require the walls of the cutting to be made from such walls, thereby providing exclusion walls by default (see CFA pile wall pictures below).

 

2. Pile Walls

CFA Continuous flight auger
Step by step section of CFA auger in wet and sandy soil – 1. Drilling Down 2 and 3. Center of auger fills hole with concrete as auger comes up 4. Reinforcing cage (if used) is pushed into hole before concrete sets up.

If the diagram to the left is not clear, there are some great youtube clips showing how CFA piles are contructed:

Piling contractors

These are some of the piles that were used on the McKinnon/Ormond grade separation.  A pile wall was also used on the Springvale grade separation, with the same “water table” issues.  The specific pile and foundation design needed will be a matter for the detailed design team – these notes are intended as general explanation.  We note that CFA piles are particularly suited to wet sand, with minimal noise and vibration.  The installation of piles occurs before any excavation takes place – this allows the work to proceed with minimal ground impact until piling is completed.

Once completed, the piles form a wall which can be safely excavated to the desired depth, although the pile length will go past the excavation depth for design reasons.  A base slab (if required) will then be poured to support the rail, and tie-into the walls. The wall face can then be finished as appropriate with pre-cast panels, shotcrete or cast in place concrete.

Drill rigs at Ormond
Drill rigs working at Ormond grade separation, reinforcing cages in the foreground
springvale grade separation under construction piled walls
Springvale Grade Separation under construction – showing pile walls exposed after excavation and prior to wall finishing.
cfawall
Pile wall after excavation, with a soil anchor at bottom
springvale grade separation under construction
Springvale Grade Separation under construction – following completion of walls and base slab

 

 

 

Links:

There are some great youtube clips about this kind of grade separation being constructed, in “high water level” areas:

And so you can imagine what the non-elevated option might look like here are some other “rail under road” options from the LXRA, in the days before “elevated rail” became the main option being marketed.

3. Flood Water

The track area would be a catchment area requiring drainage for heavy rainstorms. Drainage would be provided by a sump at the low point and possibly intermediate cut-off drains and sump, with sump pumps, pumping to the public drainage system after oil removal. (This is a typical arrangement in high rise basements for instance).

There could also be an opportunity for filtration, storage and re-use of this water for landscaping.

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.

Core Design Assumptions

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Engineering_blueprint_480(See also Site Specific Assumptions in the Crossing Proposals pages, links below)

1. Number of existing rail lines in place - two on the Frankston line, and three at Cheltenham Station (per LXRA Consultation boards). We are unaware of any expansion plans for future additional lines at this time .
2. Railway power is supplied by catenary-style overhead wiring at 1500 volts DC
3. Gauge: 1,600 mm broad gauge.
4. Only those crossings nominated by LXRA will be grade separated – in other words those not  mentioned cannot be changed even if that might be a good engineering decision.
Those 11 crossings are:

- North Road in Ormond – Under Construction (Rail Under Road)
- McKinnon Road in McKinnon – Under Construction (Rail Under Road)
- Centre Road in Bentleigh – Under Construction (Rail Under Road)
- Charman Road, Cheltenham
- Balcombe Road, Mentone
- Edithvale Road, Edithvale
- Station Street/Bondi Road, Bonbeach
- Station Street, Carrum
- Eel Race Road, Carrum
- Seaford Road, Seaford
- Skye/Overton Road, Frankston

5. Track gradient is 2% maximum
6. Depth of excavation / height of ballast, track. Train and clearances: 6m
7. Width of excavation / space for two trains, separation, clearances (without platforms): 12m. (The width of the McKinnon road bridge is about 14m).

Design Assumptions

In Ground Design

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Say NO To Sky Rail (Skyrail) - Frankston Line - Engineering
In Ground Design - Section View

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

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Sky Rail - Section View

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Sky Rail - Profile View