lurkin
20-05-2010, 08:59 PM
Remember key point is to draw polyline in correct direction of traffic flow !
Draw clockwise direction for traffic in UK, Thailand, Malaysia etc or
Counter clockwise direction for traffic in USA, Laos, Vietnam etc
After drawing polyline, make sure that one way box is ticked on both Properties and Routing tab.
Select Roundabout in Properties tab and also under Routing tab (which is actually called Collector/Roundabout)
Must draw this in two sections - ie must not be a single circular polyline as auto routing does not allow polyline to self intersect!
Remember to connect nodes when finished.
When drawing in roundabouts - need to be careful not to place too many nodes closer than 5.4m otherwise it may cause problems in compiling - easy method to overcome this is to make the roundabout slightly larger.
One extra node between two intersections is usually enough for small to medium sized roundabouts (eg. total of 8 nodes in a roundabout with 4 streets should suffice.
If drawing in some one way lanes with triangular dividers, I use 12 nodes to maintain a circular shape.
I have found earlier on that including too many nodes on the roundabout causes the compilation process to arbitrarily generalise the nodes and actually sometimes severely distorting the shape of the roundabout!)
I also set all my roundabouts at 20kph speed limit (could use 40kph at larger ones) as realistically most of the time this is about the speed of traffic going round a busy roundabout. I am trying to aiming for auto routing on the maps to be able to estimate a more accurate time to destination.
Here is an example of a roundabout template I use...
Roundabout (clockwise) drawn for left hand side traffic flow
eg. UK, Malaysia, Australia, NZ etc
NOT USA, Europe, Vietnam, Laos etc
Ignore labeling of roundabout, not necessary to do so.
Source: rcmaps website
Draw clockwise direction for traffic in UK, Thailand, Malaysia etc or
Counter clockwise direction for traffic in USA, Laos, Vietnam etc
After drawing polyline, make sure that one way box is ticked on both Properties and Routing tab.
Select Roundabout in Properties tab and also under Routing tab (which is actually called Collector/Roundabout)
Must draw this in two sections - ie must not be a single circular polyline as auto routing does not allow polyline to self intersect!
Remember to connect nodes when finished.
When drawing in roundabouts - need to be careful not to place too many nodes closer than 5.4m otherwise it may cause problems in compiling - easy method to overcome this is to make the roundabout slightly larger.
One extra node between two intersections is usually enough for small to medium sized roundabouts (eg. total of 8 nodes in a roundabout with 4 streets should suffice.
If drawing in some one way lanes with triangular dividers, I use 12 nodes to maintain a circular shape.
I have found earlier on that including too many nodes on the roundabout causes the compilation process to arbitrarily generalise the nodes and actually sometimes severely distorting the shape of the roundabout!)
I also set all my roundabouts at 20kph speed limit (could use 40kph at larger ones) as realistically most of the time this is about the speed of traffic going round a busy roundabout. I am trying to aiming for auto routing on the maps to be able to estimate a more accurate time to destination.
Here is an example of a roundabout template I use...
Roundabout (clockwise) drawn for left hand side traffic flow
eg. UK, Malaysia, Australia, NZ etc
NOT USA, Europe, Vietnam, Laos etc
Ignore labeling of roundabout, not necessary to do so.
Source: rcmaps website