Sunday, 11 October 2015
One of my regular travel routes includes lengthy roadworks where a stretch of motorway is being converted into 'Smart Motorway'. It's one of those phrases that I've always guessed I understood, but finally googled it to be sure. Like I expected, it's all about active traffic management with overhead gantries and automatic speed limits based upon time of day.
Ahah, you think - surely that's a 'controlled motorway', like large pieces of the M25?
Well, the difference appears to be that a smart motorway doesn't have a hard shoulder. Like those bits of motorway around Birmingham, the hard shoulder is converted into a live lane.
It is supposed to be a way of widening a road for less money. I gather the widening cost for changing from hard shoulder into a lane is between £5-15m per mile. That compares with a mile of new three lane motorway costing about £25m per mile. It is all so expensive that that the latest figures are starting to quote the costs in £ per kilometre, which I suppose is designed to make it all sound less.
The curious thing is, the new extra lane is the repurposing of an existing lane, so I'm not quite sure how the figures really stack up? Let's take a figure somewhere in the middle of the £5m-15m quotation for the repurposed lane. £10m for change of purpose from hard shoulder to fourth lane.
Now lets take a mile of typical motorway. Three lanes and a hard shoulder.
Quick sums. One re-purposed lane = £10m. Three lanes = £25m. So one lane = £8.5m (approx) or £6.5m if we take the hard shoulder into account. There's something that doesn't quite add up properly about these numbers (I know I've rounded the figures). Why would the Smart Motorway mile cost be higher than laying a brand new stretch?
Then we get the safety question. No hard shoulder, so cars that conk out have to stop in lane one (if they can make it across).
I already regularly see people going through the red crossed lanes on motorways or down the hard shoulder in traffic jams, so there's going to be some challenges if they move to no shoulder and refuges at presumably one kilometre intervals.
It'll be soon enough that we get to find out. The current roadworks and narrow lanes have been in place for over a year now. Just over one more year of cones to go and then we'll be back to normal, albeit with the smart motorway running.