Tuesday, 19 November 2013

King Duncan's Road: A Slippery Slope Or A Bridge Too Far?

Zenbike has been looking at how to connect the Raigmore Estate in Inverness with the rest of the world for walking and cycling and has asked twitter for help. here are are a couple of ideas at each end of the scale.

The Raigmore Estate. The yellow line is the Golden Bridge which
crosses the A9 to connect to The Inverness Campus. The blue line
is a potential cycle route through the estate which then heads west
towards Inverness City Centre.
Image adapted from Google Maps.
The Raigmore estate on the eastern edge of Inverness is surrounded by large roads and sits on a bit of a hill. It has recently been connected to The Inverness Campus by the Golden Bridge to the east which is a 290 tonne walking and cycling bridge. The problem is how this new pedestrian and cycle route can be connected up to the west of the estate towards the city.

King Duncan's Road is the only road access to the estate and as it heads north-west to the A865 Milburn Road, the road becomes narrow and goes downhill steeply.

King Duncan's Road as it approaches Milburn Road. You can just
see a roundabout in the distance, but the road bends right and joins
the main road to the east of the roundabout. No space for cycling
Image from Google Streetview.
Looking north-west, the right hand side of the road has a retaining wall holding back a steep bank and on the left hand side, there is a footway with a steep bank behind. This may all be fun for goats, but for people trying to cycle on the road here it must feel unsafe and heading south-east, it is literally an uphill struggle!

View looking back up the hill towards King Duncan's Road from the
roundabout on Milburn Road. The arrow points at the retaining wall
in the previous image. here is a path (with steps) down the bank
which gives a more direct route than follow King Duncan's Road all of
the way to the bottom.
Image adapted from Google Streetview.
So, the problem is how we create a safe cycling route between the estate and Milburn Road. I haven't especially looked at the estate itself, but the estate roads are wider (beyond the hill). A safe cycling route might include the road itself if vehicle flows and speeds are low, or there may need to be some redesigns and possibly use of some of the green space through the estate. The traffic data isn't available, but I would suggest that it is needed to be able to make a proper informed feasibility.

Not sure I like this layout with the bend and the hill. The idea is
vehicles only go into the cycle lanes when they have to, but it might

work. Needs more traffic flow data.
If the speeds and traffic flow are low on King Duncan's Road, the stock answer may have been putting in some advisory cycle lanes with coloured surfacing and the centre line removed. This has been used elsewhere in Europe (link to As Easy as Riding a Bike), but relies on very low traffic flows. I think that here, the traffic flows might be a little high and certainly it won't feel like there is much protection.

The Golden Bridge - heavy engineering and big boy's* toys.
Image from urbanrealm.com
*yes, I know, don't write in!
Next up the "traditional" UK food chain would be a shared-use cycle track as in widen the footway a bit and put up some signs. Again, it might be OK if there are not a lot of pedestrians, but the current footway is narrow and not really up to a proper job. I think I am leaning towards something a bit better as after all, we have a new bridge over the A9! The big problem with King Duncan's Road is that it sits on the side of a hill and any widening needs some engineering. But frankly, if that is the right answer, then that is what needs to be worked up and promoted as the solution.

OK, to widen, it would be easier on the left hand side as building a structure to retain the widening would be easier than building a higher wall into the existing embankment on the right hand side. We could have a separate cycle track with a kerb upstand between the carriageway and the track and in turn, the track and the footway. Width would need to be about 2 metres for the footway and 3 metres for a two-way track.

From the other direction.
Image adapted from Google Streetview.
A proper job would have a decent survey and I am sure levels would need to be played with to get reasonable gradients in terms of pedestrian comfort and cyclist safety (i.e. going downhill quickly!). Given the huge bridge and also the fact that a retaining structure has been built on the right side of the road, why shouldn't some proper funding be invested in a decent layout for walking and cycling?

I think what I am trying to get at is that there is always more than one way to skin the proverbial cat. If we want to try and make people feel safe, then we might have to spend some money. In the cycle lane example, the traffic flows might be so low that actually it works. After all, the estate goes nowhere for vehicles. But, I suspect that it might be get busy enough to put people off and that means getting the civil engineering tools out.

There might be some middle ground in slight footway widening to make it just enough for a shared-use track and that might be enough for the estate's community, but with the bridge over the A9, then surely something a bit more substantial will be needed to get cycling numbers up without affecting pedestrians?

Of course, the idea which is beyond my "Option 2" may well be to connect the estate directly to Milburn Road with a long bridge which bypasses the roundabout altogether for a direct route towards Inverness. But that would be a whole other bit "armchair design". If you have any suggestions then please do comment or tweet!


  1. Hello,

    Would a less direct route dropping down to the Old Perth Road and following it back up to Milburn Road not make sense?

    Old Perth is a steep climb towards the top, but nothing a bike would have trouble getting up. It also appears to have the width to accommodate a separate footpath and cycle track along its length.

    Issuing out onto Milburn Road closer to the City Centre might off-set any time savings made by building new retaining walls/decks along King Duncan, but more data is certainly required to make an informed engineering decision.

    Just a thought, from a fellow cycle commuter and engineer in London.

  2. Thoughts are exactly what we need. The idea of the post was to get people thinking about how to solve a problem made rather tricky by the topography!

  3. I don't fully understand why they didn't link up to the bridge by going all the way up Millburn road and then connecting it to the footway beside the roundabout that goes up the hill to the Raigmore estate. Granted that's a short steep pull in itself but not impossible to cycle up if they carried out some fairly minor (in my eyes!) adjustments.

    1. That I don't know - this was armchair engineering at its best/ worst!