Norm48327 Paul_D_North_Jr I understand that the NS fire on the trestle was caused by sparks from a welder that weren't noticed and put out becasue the 'fire watch' wasn't done as it should have been, IIRC. Same thing could have (and has) happened with creosoted wood trestle timbers. So it wasn't a flaw specific to the polymer ties/ timbers. - PDN. True, but I was led to believe they burned hotter and faster.
Paul_D_North_Jr I understand that the NS fire on the trestle was caused by sparks from a welder that weren't noticed and put out becasue the 'fire watch' wasn't done as it should have been, IIRC. Same thing could have (and has) happened with creosoted wood trestle timbers. So it wasn't a flaw specific to the polymer ties/ timbers. - PDN.
I understand that the NS fire on the trestle was caused by sparks from a welder that weren't noticed and put out becasue the 'fire watch' wasn't done as it should have been, IIRC. Same thing could have (and has) happened with creosoted wood trestle timbers. So it wasn't a flaw specific to the polymer ties/ timbers.
- PDN.
True, but I was led to believe they burned hotter and faster.
Wood and plastic burn in different ways. Large section pieces of lumber, such as a tie, tend to carbonize to charcoal which then slowly smoulders away. Polythene and other plastics melt when they burn. On a wooden trestle burning plastic ties could send streams of fire down from the track onto the structure, making the fire worse.
mudchicken No - Limited application. The science needs to evolve some more, especially where the tie finds itself in some limited tension.
No - Limited application. The science needs to evolve some more, especially where the tie finds itself in some limited tension.
I wonder if the wrong approach is being used - trying to find a use for recycled common plastics (mainly polythene with some polystyrene) rather than considering how to replicate the engineering properties of good-quality hardwood.
In Japan, many ties are made from a material called FFU Neolumber. This is a rigid polyurethane foam reinforced with long glass fibres. FFU ties have been in use for about 30 years and show little evidence of deterioration after decades of service. FFU ties can be sawn and drilled like wood, are strong and light in weight and attenuate vibration well. There is of course one major obstacle to the wider use of FFU ties - high cost.
Although polythene, polystyrene, polypropylene, nylon etc. make up the greatest proportion of plastic waste the most awkward materials to recycle are fibre-reinforced composites. These do not have a high energy content so are not attractive as fuels. Unlike (e.g.) polythene they cannot be melted and remoulded. Because fibre-reinforced composites have a high strength-to-weight ratio they are increasingly used in automotive and other transport applications, and so the volume of these materials heading for landfill will pose a growing problem in the future.
It might be possible to shred fibre-reinforced composite waste in such a way that a reasonable fibre length is retained. By binding this shredded waste with a small quantity of fresh polyurethane something resembling FFU could be produced at a lower cost.
Norm
IslandMan Is the market for polymer ties healthy? No. It's quarantined due to the Asian Flu.
Is the market for polymer ties healthy?
No. It's quarantined due to the Asian Flu.
Given NS's very bad experience with them catching fire several years ago I'm surprised the composite ties are still in production.
A minor observation - polymer ties are mentioned only in the entry for CSX (that for UP does not mention the type of tie). Is the market for polymer ties healthy?
Thumb nail of class 1 maintenance report.
http://www.progressiverailroading.com/mow/article/2017-MOW-Spending-Report-Class-Is--51294
Our community is FREE to join. To participate you must either login or register for an account.