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Joined: 2-01-14

Topics: 40

Replies: 152

Posted: Fri 24th Jan 2014, 6:27pm

I'm planning new track starting from scratch on largely undisturbed ground, I have read dire warnings about track sinking in to the aggregate if too fine. My feeling is to start off with a coarse aggregate but with some fine material in it so I can form a level base to lay the ready made track modules on then compact with a vibrating roller. After laying the track complete with a coarse aggregate to hold the sleepers in place,
what size aggregate is recommended?

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Joined: 1-01-94

Topics: 24

Replies: 198

Posted: Fri 24th Jan 2014, 6:50pm

We used crusher run as the base compacted with either vibrating plate or roller. When it comes to ballast make sure you get something that is sharp so that it grips, we had some that was useless and ended up digging it all out again as it did not grip the sleepers


Joined: 9-08-09

Topics: 14

Replies: 119

Posted: Fri 24th Jan 2014, 8:57pm

For top ballast 10-15mm clean stone - no dust. Sub base can be crushed concrete, or larger stone but well compacted before putting the top stone. 150mm of base then a little less for the top ballasting - done in 2 stages- half under the sleepers the rest for tamping and shoulders.

I have always used suitable membrane beneath the whole lot to reduce weed growth. Drainage "worms" if needed are a good thing at this stage also.


Joined: 2-01-14

Topics: 40

Replies: 152

Posted: Sat 25th Jan 2014, 9:08am

Thanks Martyn and Frank for the advice, I take the point about a membrane but when I laid my new driveways and footpaths I put a membrane under all then about 150mm depth of aggregate well rolled but the weeds seem happy to grow in the gravel, suppose it keeps the chemical industry in business producing stronger and sronger weed killers?


Joined: 1-01-89

Topics: 10

Replies: 199

Posted: Sat 25th Jan 2014, 2:53pm

At Sheffield we use nominally 14 mm clean limestone chippings (as per Frank's comment) as ballast. We don't use a membrane,I agree that weeds will grow in the ballast if it's not treated. Weeds self seed from above, not from down below, if you've prepared the track bed there aren't any left there to grow up through the ballast. A membrane CAN stop soil migrating upwards into the ballast but what usually happens is that the membrane itself surfaces, particularly along the edges of the track and then looks unsightly. As is often the case, there are more ways than one...


Joined: 1-01-85

Topics: 6

Replies: 35

Posted: Sat 25th Jan 2014, 8:22pm

At East Herts we use 15-20mm granite ballast, which In understand is the size used in the Network Rail stone blower, which is another method for tamping track, as it effectively injects the ballast and cause less disturbance to the track and existing formation.



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