Cycle.Travel - quiet route default

[maxglide]

I've been using <cycle.travel> as my go-to route planner for the past few years. IMO the best UK route planner, although I use <gpsies> having nicer maps, and <ridewithgps> having more useful features than the first two.

However, the CT software is aggressive in minimising your distance on major roads. In my local area, this can add up
to 25% - 30% extra distance to a ride. Dragging the route-line off the optimal CT route, thus enduring a mile or two on a major road - often just a B road or quiet A - can save a ton of mileage. This only works if you're familiar with the area, and I might hesitate doing this on unknown ground.

If I recall correctly, <gpsies> has 3 filters on its route planner, Fastest, Balanced, Quietest.

[mjr]

Apparently it currently takes four days of a big server to recalculate even the one routing algorithm viewtopic.php?f=16&t=83831&p=956095#p956095 - I'm not sure Richard's hearing would stand calculating three different options, even if he's got the disk space!

[cotswolds]

I agree cycle.travel is good and use it for planning longer rides. I tend to prefer cyclestreets for urban areas, but that can come up with silly ideas in rural areas, such as quiet routes that include footpaths with stiles.

I don't mind a bit of extra mileage to avoid a busy road, but having recently tried cycle.travel for local routes, I've discovered not only can it add miles but also big hills. My bit of the Cotswolds is characterised by narrow valleys, often with a single main road. Avoiding the main road involves a big climb out of the valley. One route it created for me added a 500' climb out of the valley to avoid 4 main road miles. I doubt any cyclist would do this - anyone fit enough to contemplate the climb would probably be a regular cyclist who wouldn't be daunted by a few miles on a main road.

Also, the main roads can often feel safer because they are wide, whereas side roads may be quieter, but are very narrow leading to dangerous overtakes.

I still think cycle.travel is the best route generator and a fantastic achievement but cycle route planning is a really difficult art.

[meic]

I find the problem is much worse on shorter routes, especially ones where I want it to take me along the "flats" where the dual carriageways lurk.
Left to itself it cuts a route through the minor "valleys" on the second flattest option after the taboo main valley. When I encourage it to try and follow the main valley it starts climbing up and down all sorts of nearby hills to try and escape from the dual carriageway.
If I want a really pleasant ride, I would be far better off following its first offering which though 20% hillier is mostly on little used country lanes. The quiet route default has its place and would be much harder to spot (without the computer) than the much more obvious main road route which it tries to avoid.

[Richard Fairhurst]

A lot of this comes down to the routing algorithm (Contraction Hierarchies) that cycle.travel uses, which is part of the open-source OSRM engine it's built on. This precalculates the best routes across the network, so that finding even a trans-American route takes milliseconds.

The main benefit of this isn't so much that the initial route-finding is fast, but that the speed is such that the routes can be draggable. The downside is that all the precalculation assumes a constant set of 'weightings', the types of roads it prefers - to add another set, you'd need a whole new precalculation stage.

mjr is right that this takes a few days on a big, loud server to calculate. But the other clinching factor is the ongoing server memory it requires: currently it's 30GB to run the routing for the UK, Western Europe and North America. Adding (say) a new "direct routes" weighting would mean another 30GB, and hence renting another server; and expanding the coverage to the whole of Europe is in the queue first for that, I'm afraid! (Though I wouldn't rule out adding a direct route option for the largest cities at some time in the future. I've also looked into alternative routing algorithms, but there's nothing yet that comes near to CH's speed without even bigger memory requirements.)

As meic says, short routes can be challenging, simply because there are fewer good options to choose from. Where there's really only one route and that one route is pretty rubbish, it struggles. cotswolds, I'm not sure where you are, but (taking a wild guess!) your comments would apply to the valley around Stroud, for example. The A419, as a heavily-trafficked major A road, gets downrated severely. But since there's no alternative in the valley, c.t chooses the hilly route via Minchinhampton instead. There is a fairly straightforward way to fix this, but it involves giving £50m to the Cotswold Canals Trust so they can restore the Thames & Severn Canal along the valley complete with cyclable towpath.

That said, if there's a plainly silly route that c.t is generating, I'd always like to hear about it so I can see if there's some way to improve the weightings. It sometimes takes a bit of head-scratching but I enjoy it. It doesn't have traffic figures for every B road, either, so if there's a quiet one you think it should be routing along, let me know and I can see if I can find some traffic numbers for it. Similarly, if there's something from RideWithGPS or GPSies (or whatever) that you think c.t should be doing, let me know.

(Sorry for late reply - have been on holiday!)

[MikeF]

I agree cycle.travel is good and use it for planning longer rides. I tend to prefer cyclestreets for urban areas, but that can come up with silly ideas in rural areas, such as quiet routes that include footpaths with stiles.

I don't mind a bit of extra mileage to avoid a busy road, but having recently tried cycle.travel for local routes, I've discovered not only can it add miles but also big hills. My bit of the Cotswolds is characterised by narrow valleys, often with a single main road. Avoiding the main road involves a big climb out of the valley. One route it created for me added a 500' climb out of the valley to avoid 4 main road miles. I doubt any cyclist would do this - anyone fit enough to contemplate the climb would probably be a regular cyclist who wouldn't be daunted by a few miles on a main road.

Also, the main roads can often feel safer because they are wide, whereas side roads may be quieter, but are very narrow leading to dangerous overtakes.

I still think cycle.travel is the best route generator and a fantastic achievement but cycle route planning is a really difficult art.

I agree with much of that. Cycle.travel is also very fast. A route for cycling can also be plotted on Google Maps, and this also gives 3 options. I haven't tried it much, but trying it on routes I already know it's given the route I would use.