dodgy said:
Hi bollo,
Reading your post above I would hazard a guess that you're using Garmin's Topo map? That might explain the poor experience you're having with autorouting. To fully exploit the autorouting capabilities of the Garmin Edge 605 and 705, you need Garmin City Navigator (Europe) 2008. Garmin's Topo map is neither one thing nor the other, it doesn't come anywhere close to matching an OS map (as you've already said) and it doesn't carry the detail required for address searching and autorouting that City Navigator 2008 has (be careful, older versions of City Navigator lack autorouting, too).
Dave.
Hi D,
You're right, I am using the topo maps. After reading your post I went away and had another play with some interesting results. Just setting the routing to 'Bicycle' will still direct you on motorways. ALSO setting the 'Avoid major roads' options will avoid motorways except of a stretch of the M3 near Winchester under certain circumstances. I'm guessing this is either some sort of error in the tagging of this section of the M3 or the routing algorithm just can't cope with its 'Berlin Wall' nature. The M3 drops to two lanes at this point (between J8 and J9) so that might explain it. My big gripe with the 705 here is that the documentation is shocking and doesn't give any real indication of the effect of either the 'Bicycle' or the 'Avoid major roads' option. Is an 'A' road major? Is a dual carriageway major but single carriageway minor. The 'manual' doesn't say.
I think you've pegged the topo maps, they're certainly not up to off-road navigation. I only got them because I wanted a view of possible gradients on the route. I can imagine someone who'd bought them for mountain-biking or general hiking would be a bit pissed off. There's no indication of rights-of-way and the 'paths' data is sketchy at best - more of this later. However, my version of the topo maps (V2 I think) DOES support full autorouting and address searches - honest!
That's the techy stuff - now my gripe against the general concept of autorouting for cycling. The classification of a road is only ever a rough guide to its suitability for cycling, and there's no way the basic rules used by the route search algorithms can get this. Here's a real example.....
My occasional 'full' commute takes me from Winchester through a place called Alresford. There are three basic route choices.
(a) Along the A31 - a fast dual carriageway
(B) Along the B3047 - a narrow single lane road bordered by high hedgerows
(c) Along NCN23 on an unclassified open road alongside the river Arle.
Option (a) is ok, but not a huge amount of fun. The road has reasonable sightlines so would be safe enough to ride despite the high traffic speeds.
My mate refers to Option (B) as the 'road of death' and he travels along it in a Mondeo! High speeds, tight bends and little passing space for cars. I've done it once on a bike - never again.
Option (c) is beautiful - makes you glad to be alive and on a bike.
Suppose I choose to let the 705 lead the way from my house. If I uncheck the 'Avoid Major Roads' option, it'll take me along Option (a). If I check this option (the choice that most cyclists would use), it picks (B). Option (c) is a no go, as the Garmin Topo Map has not captured the section of NCN 23 path/bike-track under the M3 J9 roundabout and on to Easton.
You can see from this example that the autorouting reverses the order that I'd choose for these routes. I can appreciate that it might be more suitable for different areas (for example it works quite well around my parents in Lincs, as road classification pretty much ties in with how busy/fast/safe any road is) but around here, local knowledge and/or research is usually the best guide.
I don't post often, but when I do...............
