Posts Tagged ‘speed limits’

On Monday 6 January 2014 the Highways Agency published a public consultation on introducing a maximum mandatory speed limit of 60 mph on the 34-mile stretch between M1 Junctions 28 and 35a. The rationale behind the proposal is to contain possible future rises in air pollution, notably nitrous oxides (NOx) – a response to tightening air quality targets from the EU. Failing to meet the targets could lead to heavy fines from the European Commission.

Reducing motorway speeds from 70 mph to 60 mph potentially has several effects:

  • It reduces air pollution (in this case NOx) by about 20–25% as the following graph shows:
NOx emissions for a Euro 5 Diesel < 2.0 L car (g/km)

NOx emissions for a Euro 5 Diesel < 2.0 L car (g/km)

Source: National Atmospheric Emissions Inventory

  • By the same token, it reduces CO2 emissions and fuel consumption, which saves drivers money.
  • It potentially increases journey times which would result in economic loss, particularly if the affected traffic is moving goods and services. However, this could be negated if as a result of the reduction in speed the traffic runs more smoothly.
  • It potentially reduces the risk of collisions if the traffic runs more smoothly and reduces their severity.

There will be confusion amongst some drivers as to what ministers’ position is on motorway speed limits. After all this government had widely talked up the possibility of raising the limit to 80 mph in places while here the debate is all about cutting it.

The consultation comes at the same time as news from the Society of Motor Manufacturer and Traders (SMMT) that UK car sales in 2013 jumped 10.8% on the year before to reach pre-recession levels – 2.264 million cars. Looking at the composition of the fleet it is interesting to note that the share of mini and supermini as well as dual purpose has increased, while that of lower and upper medium cars has decreased.

Car registrations by segment type

Source: SMMT

This should help with emissions as cars in these segments tend to consume less fuel.

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For drivers continuing to struggle with the winter conditions the speed limit of the road they are trying to travel on will be of little importance – many will be battling to move at all in the snow.

But on Friday the Department for Transport chose to publish new guidance for local authorities on the setting of speed limits. As it stands there are only three national limits:

  • 30 mph speed limit on roads with street lighting (sometimes referred to as Restricted Roads)
  • 60 mph on single carriageway roads
  • 70 mph on dual carriageways and motorways.

But the DfT recognises that these might not be appropriate for all roads of these tpes and they allow leeway for councils to set alternative limits based on local circumstances.

Particularly the Department wants councils to:

“… consider the introduction of more 20 mph limits and zones, over time, in urban areas and built-up village streets that are primarily residential, to ensure greater safety for pedestrians and cyclists, using the criteria in Section 6.”

It also highlights the dangers of rural roads:

“In 2011, 66% of road deaths in Britain occurred on rural roads, and 51% of road deaths occurred on single rural carriageway roads subject to the National Speed Limit of 60 mph limit.”

While the document says that changing speed limits to tackle this problem is only one part of the solution, Table 2 explains where the Department envisages limits below the national standard, for example:

“50 mph should be considered for lower quality A and B roads that may have a relatively high number of bends, junctions or accesses. Can also be considered where mean speeds are below 50 mph, so lower limit does not interfere with traffic flow.”

It also has views on how these limits might be enforced on rural roads:

“While routine enforcement should normally only be considered after other speed management measures have been considered, there may be occasions where the use of average speed cameras may offer a solution through calming traffic speed over a stretch of road. The Department has received a small sample of evaluation data of average speed cameras at non-roadworks sites from some local partnerships, and this data suggests a reduction in the percentage of motorists exceeding the speed limit from 55% before installation of cameras, to 18% afterwards, and an average reduction of killed and seriously injured casualties (KSI) per km of around 69%, and of personal injury collisions (PIC) of around 38%, (not adjusted for national trends and regression to mean effect).”

A lot of ‘mays’ in this paragraph but the door is clearly being left open for councils to roll out more and more of these cameras, assuming of course they have the money.

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