[Talk-GB] Modal Filters and Low Traffic Neighbourhoods

David Woolley forums at david-woolley.me.uk
Sat Apr 10 22:51:32 UTC 2021


On 10/04/2021 22:41, Stephen Colebourne wrote:
> Thus in the example in the OP (a diagonal modal filter) the short
> cycleway joining the two sections of residential highway would be the
> bit tagged with traffic_intervention=modal_filter (because that is the
> bit necessary to change in order to revert the road network as
> perceived by routers).

Reversing the changes in the OP's example needs more that, as it would 
result in a router instructing the driver to bear left, turn 90 degrees 
right at the junction, go forward, turn right at the junction, and bear 
right, rather than no direction at all.

I also see that as a problem for emergency vehicles, and in the OP's 
case, orange badge holders, even with the filter in place.

That's why I think, in cases where there is no locking bollard, a more 
accurate description is as conditional turn restrictions.  With a 
locking bollard, the adjacent curves and connecting link is probably 
reasonable, given the need to get out and unlock, but the whole 
structure still needs to be reverted if the anti-LTN lobby gets the 
final victory; you can't just remove the bollard and upgrade the link, 
for the reasons given above.  Even then it is probably more accurate to 
retain the cross-roads.

In the straight through examples I have near me, the restricted road is 
only the width of a planter in length, so, at normal levels of 
abstraction has negligible size; this is the same as long established 
modal filters for emergency vehicles.  Also, technically, bicycles 
aren't allowed in the central opening, but rather in small gaps in the 
gutters, even though, in practice it is easier for them to risk the 
oncoming traffic, ignoring the stop signs, and go through the centre.

Also, I don't think the ones done with temporary traffic regulation 
orders are actually intended to be temporary, although the backlash 
against them, from people who can't do without cars may result in that. 
  The reason was to get them in quickly, as it takes many months for a 
TRO to go through consultation.



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