Turning of the tide?

[snorri]

Interesting article on road building, or not road building.
https://www.citymetric.com/transport/it-time-end-road-building-4784

If you haven't time to read it all, I think this sentence is worthy of highlighting.
A Department for Transport report boasts of a £4 return on investment for every £1 spent on certain major road schemes, but the average return on investment for cycling is £13 for every £1 spent.

 

[raleighnut]

About time too.

 

[Slick]

I wasn't going to read it all but in the end I did, only to be left frustrated again. We keep hearing about what we need to do and I know most of the figures quoted come from England, but anyone who has driven nearly anywhere down there couldn't have failed to notice the upgrade to smart motorways and I'm still waiting on a single cycle path.

 

[classic33]

I wasn't going to read it all but in the end I did, only to be left frustrated again. We keep hearing about what we need to do and I know most of the figures quoted come from England, but anyone who has driven nearly anywhere down there couldn't have failed to notice the upgrade to smart motorways and I'm still waiting on a single cycle path.

Will cycle paths have variable speed limits, access controlled from a central location with lights saying where and when you can enter them?

M62 is "smart" in places, but you still see the traffic building up. Driving can be slower on these parts. With delays on a daily basis, which aren't improving.

 

[al78]

Will cycle paths have variable speed limits, access controlled from a central location with lights saying where and when you can enter them?

M62 is "smart" in places, but you still see the traffic building up. Driving can be slower on these parts. With delays on a daily basis, which aren't improving.

The point of smart motorways is to improve traffic flow by keeping the speed of vehicles as steady state as possible (by regular speed camera enforcement). This reduces the likelihood of propagating traffic waves which happen when people accelerate than hit the brakes, causing those behind to overcompensate ultimately causing a temporary localised halt. This wave propagates backward along the motorway and results in those grind to a halt moments which have no apparent cause. The traffic will always build up at peak times, smart motorways don't magically increase capacity beyond making the hard shoulder into an extra lane.

 

[classic33]

The point of smart motorways is to improve traffic flow by keeping the speed of vehicles as steady state as possible (by regular speed camera enforcement). This reduces the likelihood of propagating traffic waves which happen when people accelerate than hit the brakes, causing those behind to overcompensate ultimately causing a temporary localised halt. This wave propagates backward along the motorway and results in those grind to a halt moments which have no apparent cause. The traffic will always build up at peak times, smart motorways don't magically increase capacity beyond making the hard shoulder into an extra lane.

Never suggested they did. But they do also limit what can enter onto them, and where. Which was my point.

 

[mjr]

The traffic will always build up at peak times, smart motorways don't magically increase capacity beyond making the hard shoulder into an extra lane.

It ain't magic but it does increase capacity simply because a vehicle at 40mph requires a fraction of the stopping distance of one at 70mph. Vehicles are moving more slowly but while number of vehicles falls linearly with speed, stopping distance falls faster at first, roughly quadratically, so the maximum safe density (aka capacity) increases.

 

[hatler]

I'm sad enough to have done the maths on this one. If it is assumed that cars keep the HC stopping distance apart, and the average vehicle is 20' long, then maximum capacity for a road is achieved when the traffic is doing 18mph.