It has always been the job of the transport secretary to announce daft ideas which have no basis in reality and this week, Chris Graying continued the tradition.
It was reported that Grayling wants to;
'[C]reate a default that you have to look first at laying the utilities under the pavements rather than under the roads.’
and 'that companies would not be allowed to dig up pavements on both sides of road at the same time, to ensure that pedestrian routes were retained where possible.'
The reason for this piece of thinking was that;
'[P]otholes are far more likely to appear on sections of roads that had been recently dug up.'
Perhaps it was a populist dead cat thrown around before the local elections where local candidates make the clarion call for investment in Roads'n'Pavements and announce the inevitable War On Potholes.
Perhaps he was just poorly briefed because believe it or not, this is already pretty much the default position. The reason I make this statement is based on three things;
(i) Cost - utilities laid under the carriageway (in the road) is more expensive than laying them under the footway (pavement) and utility companies don't want to spend more than they have to,
(ii) Space - footways generally provide less space than is available with a carriageway and large utility mains need a lot of space,
(iii) Legislation - there is legislation which dictates how and when streetworks should take place; partly to prevent (motor traffic) congestion and partly to ensure temporary works are safe.
We have been laying utilities under, on and over our streets for well over 100 years and so the problem of digging up the street isn't new. These days, we have guidance and laws to manage the process and so Grayling isn't adding anything useful here.
Different utilities are laid at different depths. For example, water needs to be deep enough to avoid freezing temperatures, high voltage power tends to be laid deep in order to dissipate heat and sewers are relatively deep compared to everything else to prevent structural damage from traffic action. Trunk supplies (water, gas, power) also tend to be laid quite deep because of risk of damage during other works.
On the other hand, telecoms, low voltage electricity and supply/ service pipes will be more shallow because they need to be got at more often, or they don't need so much protection. When utilities are taken across a carriageway, then the shallower ones will have to be laid lower to take them below (where possible) the structural layers. There are also rules on how trenches should be reinstated and statutory guarantee periods.
A long-used document is the National Joint Utilities Group "Guidelines on the positioning and colour coding of underground apparatus" (pdf) which amongst the detail provides a handy diagram. The idea is to promote consistency in how utilities are laid out which helps future works planning and execution;
Of course, in many places a 2m wide footway is a dream! For areas which are already established and for new build streets (assuming the guidance in followed) it is pretty clear that the space under footways is already pretty crowded!
In terms of the congestion that Grayling (and transport secretaries in general) is obsessed with, then we have legislation such as the New Roads & Street Works Act 1991 and the Traffic Management Act 2004. In general, they are about keeping traffic moving (in its widest sense, including people walking and cycling) and so each street will have a classification in terms of how utility works are planned as well as there being classes of works (in terms of how long they will take).
For example, a water meter installation in a side street will cause minimum disruption and doesn't need much notice whereas a major sewer replacement on a main road will require lots of planning and extensive traffic management. Graying's suggestion that "pavements" won't be dug up on both sides of a street is also daft. If the highway authority and utility are both doing their job right, then this shouldn't happen anyway.
The pothole issue does happen, but in many cases, this is due to planning and sometimes due to the way in which utilities are regulated. Highway authorities are skint and funding is often stop-start with the political cycle. This often means fits and starts in funding which makes planning a nightmare. The utilities are regulated because in passing costs onto the consumer, they are expected to pace themselves.
Putting this together means that the funding horizons don't match up. The best highway authorities will have long-term asset management-based programmes which transcend the politics and this means they can let the utilities know their plans well in advance so they can do upgrade works before resurfacing or structural repairs. Good highway authorities will also use legislation to ban utility works for prescribed periods of time after significant works have taken place.
We really should be moving to a position where we perform street renewals. This would mean programmes being planned over a very long horizon. We could start with any layout redesign, utility diversions and upgrades and then the new layouts being deployed. However, this would require significant investment in our highway network, locked-in multi-year funding which is longer than the political cycle and an alignment of highway and utility investment. If Grayling wanted to make a difference, that's where he should be investing his energy, but I can't see him or any other transport secretary being bothered about doing it properly because that doesn't suit the soundbite managed short-termism so rife in the UK.