| Topic: | Re:Re:New traffic tunnel from Chiswick | |
| Posted by: | Michael Robinson | |
| Date/Time: | 05/02/16 09:56:00 |
| "if nothing is done, congestion is going to increase and the city will effectively grind to a halt." Congestion is inevitable in London, There will always be more demand for road space than road space available. The average speed of traffic in central London is only about 9mph and that hasn't changed since the days of horse drawn carriages. I'd argue that trying to "solve" congestion by building more roads is a pointless exercise. There is a well known effect called "induced demand" that means building more roads actually creates more journeys so the new roads just end up congested again, except with more people stuck in traffic than there were previously. There should be more focus on demand management rather than thinking construction provides an answer. That means more extensive road pricing than just the current congestion charge zone and other measures such as freight consolidation and moving freight out of peak hours (many convenience supermarkets use vans as mobile stock rooms so they can maximise shelf space so they aren't paying the full price of their use of the roads to do this) It was interesting that an Evening Standard editorial this week called upon the mayoral candidates to propose road pricing schemes indicating this is becoming mainstream politics. "In fifteen years time it may be the case that car technology will have advanced to the extent that congestion can be reduced by centrally managed journeys" It is impossible to achieve anything more than marginal improvements out of the road network when it comes to private cars Bus lanes and cycle lanes increase the people carrying capacity of roads as these modes of transport are a lot more efficient uses of road space. It is more likely that a centrally managed journey system will tell you "if you want to make your journey now, that will cost you £15. If you make it at 6am in the morning, it will cost you £2.50". Think of it as Oystercard for cars with price depending on vehicle type, time and zones. "The A4 between here and Hammersmith must offer potential for a project of this nature. " The trouble with that scheme is that only just over half of the traffic on the A4 west of the gyratory would be using the tunnel and the scheme had no solution for what would happen to the rest of the traffic. That is, only just over half of the traffic on the A4 west of the gyratory is travelling to or from Barons Court where the tunnel goes and the remaining traffic is going to and from other destinations. Assuming surface roads are still needed for this traffic, then the tunnel doesn't release much land. The benefit cost ratio for the tunnel at Hammersmith was only marginally beneficial and fell below TfL's normal thresholds for investment. Additionally, the analysis did not consider costs such as removal of the flyover or what happens to the existing storm drain system with a tunnel so the business case looked less than compelling. Which is not to say TfL would never do it, just that at the moment it would be a political decision, not an economic one. |