Watching Ice Road Truckers tonight I noticed that some of the permanent bridges on the haul roads were timber decked. What's the reason for this? Improved weather resistance?

Probably just loads of local timber lying around.

There are still many timber bridges on minor country roads in Australia. They were cheap and easy to build in the first place, they are not difficult to maintain, and there is no need to spend scarce road funds on an expensive concrete replacement.

Here is an example at Morpeth, about 100 miles north of Sydney. http://g.co/maps/hgdru

In the mid 90's I went on a bus from southern Venezuela to Manaus in Brazil. Many of the bridges were just logs; they didn't even plane a flat surface. This road only carried trucks and buses - I don't think cars were banned, it was just impassable by car.

When I was there in the late 90s the road between Kranjska Gora and Vršič pass in Slovenia had wooden-decked bridges on the couple of river crossings before the hairpins start. Looking at Google Maps now suggests these have been replaced with conventional tarmac decks, although the resolution isn't that good and the GSV car doesn't seem to have reached there yet.

I remember those - nearly skidded off one of them: having negotiated it several times before, I hadn't bargained for how slippery it would be after a heavy shower.

Jubilee bridge between Thorne and Fishlake, in Doncaster Borough is timber decked.

Don't forget Trericket bridge either

Think there's one in Nottingham, always scared me when I was young. Then there's the famous one at penmaenpool

While driving between Sydney and Brisbane a couple of years back, the GPS diverted me off the Pacific Highway to cut out a few KM near Ballina in north NSW.

There are two wooden bridges on this road, this was the more spectacular of the two.

http://maps.google.com.au/maps?hl=en&ll ... 61,,1,2.34

Looks amazing. Going to Slovenia for a holiday this summer, so I'll be heading that way now

Oh yes, if you're in the area I'd definitely recommend Vršič, both for its Sabristic interest, the views and the fact that the summit is a good starting point for various mountain walks, if you're into that sort of thing. I've only driven it once (in each direction) but have got the bus up there several times. Watching the bus drivers negotiate the hairpins with tourist buses driven by people who seem more at home in East Anglia or the Netherlands getting in the way is entertainment in itself...

I imagine there were quite a lot of significant timber bridges in the UK approx 80-100 years ago - Australian bridge engineering would have borrowed significantly from UK practice as most of our engineers were ex-pat Britons.

There was a substantial hardwood export industry from Western Australia in the period 1870s-1930s and I imagine some of this would have ended up in bridges in the UK? Significant volumes of Jarrah and Karri were used for block paving streets in the UK.



That's not exactly true - they cost substantially more to maintain, particularly in recent years as timber is more expensive and the expertise to maintain bridges is not readily available.

Generally once they require major overhauls they are replaced by concrete structures. The Morpeth example is heritage listed and is being maintained as a heritage item. Others with less significance simply get demolished.

The NSW State Government has actually funded a special timber bridge replacement programme over the past 3 years to help Councils renew their dilapidated timber bridges.



Both replaced by concrete structures now.

Because they are much cheaper than the alternatives. Simple as that.

I went over one yesterday (on foot), I commented to someone from the estate that I would not like to have taken my car over it as so many holes and rotten pieces of timber but a Land Rover and car went over it.

Out of interest what is the alternative? Cold-resistant tarmac?

I wouldn't have thought concrete decks would hold up as well in super cold temperatures? Timber's a bit more flexible so can handle the changes in temperature?

</my limited understanding of engineering>

I didn't manage to find the time to do the whole pass, but did about 4 miles of the route from Kranjska Gora towards Bovec.

No wooden-decked bridges on the bits I drove I'm afraid. An awesome drive though (even in a 1.2l Renault Twingo hire car) and just a stunning place to be. Scenic-wise, it was my highlight of the holiday compared to the better half who fell in love with Piran.

Timber-decked bridges are alive and well in northern Sweden.

I've just come back from an epic train trip from Gothenburg to Kiruna and back, and we crossed two combined road and rail bridges, both of which were timber decked:

1. Sveg, joint Inlandsbanan and RV504 over the Ljusnan river
2. Piteälvsbron, joint Inlandsbanan and RV638 over Pite älv north of Moskosel.

Some of the railway-only bridges were also timber decked, e.g. at Mora in Dalarna.

How do people avoid getting stuck in the middle of those bridges if they act like a giant level crossing? (which is what it looks like to me)