In the last decade there have been huge changes on some of England's busiest motorways. Where once you could rely on three lanes and a hard shoulder, now there are countless new electronic signs, road markings and rules.
These schemes have gone by various names in the past but now the Highways Agency refers to them all as "Smart Motorways". This page explains what they are.
What are Smart Motorways?
Any section of motorway that has been upgraded with new technology — electronic signs, intensive CCTV monitoring, enforcement cameras and so on — is now considered a "Smart Motorway", regardless of the different ways in which these schemes operate across the country. This work is done to help reduce congestion and keep traffic moving.
A rose by any other name...
There have been many names for the various control systems that have been installed on English motorways since the early 1990s. These are just a few of the terms you may have come across before.
- Variable Speed Limits were introduced on the M25 in 1995.
- Ramp Metering has been on use on the M6 in the West Midlands for about 20 years and was trialled in further locations nationwide in the early 2000s.
- Active Traffic Management was the name of the pilot scheme operated on the M42 incorporating Variable Speed Limits, Ramp Metering and other new ideas.
- Controlled Motorways was used for a short time to refer to ATM schemes and is still sometimes used in reference to areas where Variable Speed Limits operate.
- Managed Motorways referred to ATM schemes for several years.
- Smart Motorways was adopted in 2013 as the name for all ATM and variable speed limit schemes of any kind, so that every system that uses increased technology to improve traffic flow now operates under this name.
What might I see on a Smart Motorway?
Overhead control signals
On any type of Smart Motorway, the ability to relay information to motorists is vital, and this is almost always done using overhead signals mounted on gantries spanning the road. These are often very frequent.
Variable speed limits are a feature of all Smart Motorway schemes. They are used to reduce congestion by reducing the speed limit in order to prevent stop-start traffic jams. By slowing traffic they also increase the capacity of the road, because slower vehicles travel more closely together, making better use of the available road space.
All variable speed limits are enforced by digital speed cameras mounted over every traffic lane.
Part time hard shoulder running
This tends to happen on sections of motorways that are so busy — and so frequently overloaded or congested — that hard shoulder running would be necessary for most or all of the day. In these circumstances it's considered simpler and easier to just use the hard shoulder as an extra lane all the time and avoid the need to make such heavy use of the electronic signalling.
ALR is, arguably, a way of widening a motorway without having to actually widen it, and instead just settling for an increase in width at the expense of the standard of the road.
Almost all Smart Motorway schemes will also require the installation of signal gantries — which at a minimum will require a closure of the motorway to lift the overhead beams into place. The construction of supports and foundations often involves lane closures and other roadworks that affect traffic. Depending on their location and the work needed to make space for them, Emergency Refuge Areas can also require considerable work and disruption.
If hard shoulder running will feature, it's usually the case that there needs to be work to strengthen the hard shoulder so that it can carry a full traffic load. In many places the hard shoulder was originally built on a shallower foundation than the main carriageway, and stripping the surface away to reconstruct its foundation can mean months of lane closures and traffic restrictions.
Some Smart Motorway schemes have taken years to install — far longer than the work above could explain. This is where the installation of the Smart Motorway infrastructure has happened when the motorway was already due for major maintenance work. In these cases, the Smart Motorway scheme might be combined with full-depth carriageway reconstruction, in which the whole road surface and road bed of the entire motorway is stripped away to its foundation and rebuilt again. This work can take years. Very often, Smart Motorways also come with the removal of the existing central reservation and its replacement with new drainage channels and continuous concrete barrier.
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With thanks to Toby Speight for information on this page.