The roads people got it easy - they were able to do it with a bridge, something that won't really work with rail.

A bridge won't really work with rail????

Do you have engineering qualifications?
Or can you provide a web link to support this claim?

I think you statement claiming a rail bridge can't be done is simply garbage, until proven otherwise.

A sea bridge could be built for the railway. Of course it would cost huge amount of dollars, but I would think a 15km sea bridge / sky rail is cheaper than a 15km tunnel.
The sea bridge would start just south of the clifton tunnel / sea cliff road bridge. It would go past Stanwell Park Beach and go back over land near Bulgo Beach / Otford Lookout. The bridge would then have to continue to just south of Waterfall station. I measured it at approx 15km long. The bridge would save about 15-20 minutes travel time.

Some people will try and say a rail bridge over the sea can't be done. If there is evidence the geology of the seabed is unstable, then yes I agree it's not possible. If its possible to build Hong Kong-Zhuhai bridge then it is possible to build this bridge as well.

It would be a visual eyesore marring a beautiful coastline. Not on.

Would be fun to ride during an East coast low.

It's certainly not impossible, but I think there are a coupe of issues. One is that part of its potential footprint is occupied by the Seacliff bridge. A pity they couldn't have thought ahead and designed a road-rail bridge. The other issue is that, whereas that Hong Kong bridge seems to be in a fairly placid marine environment, the south coast gets smashed by the Tasman Sea which, in full force, is very powerful, leading to potential damage and service interruption. Either way, it's all subject to geological studies.

It seems to me that the drift of things here is the the Waterfall-Thirroul section of the line will be a difficult one to solve. There will doubtless be a solution but it will be expensive and government has so far shied away from tackling it. The best path for discussion in the shorter term is to look at performance along the potentially fast sections of the line (which actually constitute about 80% of its length) between Sydney and Waterfall and between Thirroul and Bomaderry. These sections, which contain nothing serious in curvature or gradient that would inhibit the performance of electric trains, are presently run waaaay too slowly. How to fix that?

We are not talking new stations which are obviously built in high density areas with all the bells and whistles, we are talking about the issues of upgrading older stations with very small patronage, say less than 100 per day and avoiding DAA compliance where economically it simply doesn't stack up.

Yeah we are talking about new stations. That was the whole original point bought up by someone on this topic as to why we don't have more new stations. Older stations obviously have grandfather clauses but anything that is done to them in regards to upgrades must be DDA compliant. Whether that means lifts or fixing the ramp grade.

Anyway back to topic I think duplicating to shellharbour should solve many issues south of Wollongong where trains are waiting for other trains on the current single track sections for much longer then they should be increasing travel times.

Reducing the travel time further will require a new twin tunnel to be built. Using the old tunnels is just a silly idea as they are single tunnels for a start and nowhere near meeting the needs for a modern rail system. They also way to steep and a longer tunnel to Thirroul will help with reduced travel time for passenger and freight.

Lifts would still add a significant cost compared to a station without no lifts, a station with no lifts has no moving parts, and only needs electricity to run the lights, opal readers, and PA system.

Lets look at the most recent lines built, where stations are (in bold) and where they should also be (in normal text) but with less extravagant stations i.e: no lifts):

EAST HILLS TO GLENFIELD: East Hills, Voyager Point, Holsworthy, Wattle Grove, Glenfield
SOUTH WEST RAIL LINE: Glenfield, Bardia, Edmondson Park, Edmondson Park West, Leppington East, Leppington
NORTH WEST METRO: Epping, West Pennant Hills, Castle Hill East, Castle Hill, Showground, Norwest, Bella Vista, Parklea, Kellyville, Beaumont Hills, Rouse Hill, Tallawong

Some of these stations might get less patronage than the existing ones, and the costs of lifts might discourage their construction, but their construction would reduce car depending and discourage urban sprawl.

I'm not saying these stations should NEVER have lifts, but rather they should be opened without lifts and have the lifts added when the demand and need is there.

What a load of crap. No cheap and nasties should ever be built. New stations need to be fully compliant and to say otherwise is just discrimination against the disabled. Putting stations so close to one another is no good unless you are running metro rolling stock which is the reason why these stations don't exist but lets look at some of the stations you mentioned.

Voyager point - This suburb literally came in to existence the year the east hills line was extended to Holsworthy and it wasn't planned. Do you really think they didn't build a station here because they had to include lifts.

Wattle Grove - I agree this station should exist but if you think it doesn't exist because of lifts increasing the cost of the station you are mistaken. This has more to do with the position of the station and the proximity to houses. I also think this has more to do with no room for a car park then anything to do with lifts. I have no issues with a station that has no significant car park.

Bardia. - This just shows you how prejudiced you are against the disabled. This station would still require a concourse over the rail line somewhere and it is a ridiculously short distance to Edmondson Park station. You could do more for the people of Bardia by putting in a foot / bike path so they could walk or ride to Edmondson park.

Cowpasture Road - This would be the place to put a station between Edmondson Park and Leppington. There is no way Jose that you could build a station here without having a lift as it would act as a bus interchange and to not include a lift would be borderline criminal.

West Pennant Hills - This station would require Lifts for it to even be possible to exist because the train line is so deep at this point.

All the other proposed NW stations - Your argument is mute on this because any station is going to be either underground or above ground making these stations expensive regardless of if you include a lift or not. Parklea already has the Tway doing what you propose and Beaumont hills isn't even on the rail line and it is also on the tway.

Lifts would still add a significant cost compared to a station without no lifts, a station with no lifts has no moving parts, and only needs electricity to run the lights, opal readers, and PA system.

Lets look at the most recent lines built, where stations are (in bold) and where they should also be (in normal text) but with less extravagant stations i.e: no lifts):

EAST HILLS TO GLENFIELD: East Hills, Voyager Point, Holsworthy, Wattle Grove, Glenfield
SOUTH WEST RAIL LINE: Glenfield, Bardia, Edmondson Park, Edmondson Park West, Leppington East, Leppington
NORTH WEST METRO: Epping, West Pennant Hills, Castle Hill East, Castle Hill, Showground, Norwest, Bella Vista, Parklea, Kellyville, Beaumont Hills, Rouse Hill, Tallawong

Some of these stations might get less patronage than the existing ones, and the costs of lifts might discourage their construction, but their construction would reduce car depending and discourage urban sprawl.

I'm not saying these stations should NEVER have lifts, but rather they should be opened without lifts and have the lifts added when the demand and need is there.

What a load of crap. No cheap and nasties should ever be built. New stations need to be fully compliant and to say otherwise is just discrimination against the disabled. Putting stations so close to one another is no good unless you are running metro rolling stock which is the reason why these stations don't exist but lets look at some of the stations you mentioned.

Voyager point - This suburb literally came in to existence the year the east hills line was extended to Holsworthy and it wasn't planned. Do you really think they didn't build a station here because they had to include lifts.

Wattle Grove - I agree this station should exist but if you think it doesn't exist because of lifts increasing the cost of the station you are mistaken. This has more to do with the position of the station and the proximity to houses. I also think this has more to do with no room for a car park then anything to do with lifts. I have no issues with a station that has no significant car park.

Bardia. - This just shows you how prejudiced you are against the disabled. This station would still require a concourse over the rail line somewhere and it is a ridiculously short distance to Edmondson Park station. You could do more for the people of Bardia by putting in a foot / bike path so they could walk or ride to Edmondson park.

Cowpasture Road - This would be the place to put a station between Edmondson Park and Leppington. There is no way Jose that you could build a station here without having a lift as it would act as a bus interchange and to not include a lift would be borderline criminal.

West Pennant Hills - This station would require Lifts for it to even be possible to exist because the train line is so deep at this point.

All the other proposed NW stations - Your argument is mute on this because any station is going to be either underground or above ground making these stations expensive regardless of if you include a lift or not. Parklea already has the Tway doing what you propose and Beaumont hills isn't even on the rail line and it is also on the tway.

Starting to get off topic but would like to discuss this more so I created a new topic: https://www.railpage.com.au/f-p2187740.htm#2187740

Point taken regarding metro stations and Cowpasture Rd, as for Voyage Point, if the suburb came after, add the station then, I have heard it argued though that it would serve few people (but even 100 people a day would take strain off Holsworthy), it could be possible to create a business case for a small basic unmanned station (like Casula), add in the lifts and then cost may be up for debate.

Please remember personally, I also want every station to have a lift, but if that means a car is required to use public transport then that leads to this discussion.

I'd prefer to continue with the actual topic, but I think some of you should be reading the information linked below. Note that under the DDA, all stations (and buses) must be fully compliant by 31 December 2022 and all trains and trams (which have had an exemption thus far) must be compliant by 31 December 2032. The State may seek exemptions for work that's not likely to be completed by the target dates.

https://www.transport.nsw.gov.au/projects/current-projects/tap-3

https://www.legislation.gov.au/Details/F2011C00213

Given that only a bit over 50% of stations are now DDA compliant, no chance of the December 2022 deadline being met, meaning exemptions will have to be granted. Or the non-compliant stations close, which obviously won't happen.