18 of july 1879 they opened the Smaalens Banen(Østfolsbanen)
Ye old tracks, photo supplied by HundenHera:

The trains passed Ljansdalen on a large iron viaduct. In 1925
the tracks was altered via Holmlia, and the viaduct was sold to
Christiania Spikerverk. They tore it down in 1929.
Today you can see the stone fundations, and to the south of
Ljanselva there are some traces of the old tracks. This is where
the cache is hidden.
For more information on railroads in Norway you can check out this
website:
"http://www.dmmh.no/~ses/www-rwy/utvikling/index.htm">
And for for more usefull/useless information on Ljansdalen and the
old tracks I have found these links for you:
"http://www.miljolare.no/osloelveforum/ljanselva/">http://www.miljolare.no/osloelveforum/ljanselva/
and
"http://www.slf.no/Tur_ferie/Aktuelt/6608/6633">http://www.slf.no/Tur_ferie/Aktuelt/6608/6633
To make a trip of it , you can park your car at
N 59 50.518 E 010 46.935 (Ljansbanen, close to
Herrgårdsveien)
AS OF AUGUST 16, THIS CACHE CONTAINER IS A 2,5
BY 15 CM CYLINDER COVERED IN GREY DUCT TAPE
The cache is a 1 liter icecreambox wrapped in a green
plasticbag.
Initial contents:
Carabinhook
wetwipe
Danish 10 krone
small lighter
Treepin; courtesy of Team Gekko
Big shiny ringthing
icefishing lure
Lysehooks
TB Woodspell