** 13/10/2011 Update ** Thanks to Ian Smith for alerting me to the fact that the scheme also covers the A92 up to the Crossgates junction. I haven’t been this way myself, so the updated map is my best estimate.
Those of you who have recently travelled to or from the bridge in Fife will have noticed speed restrictions in place and the closure of the hard shoulder. The road works are scheduled to last until the summer of 2012 and are for the installation of an Intelligent Traffic System (ITS), or average speed cameras to most of us. They are in place from the Forth road bridge to Halbeath near Dunfermline along the M90 and also on the A823 on the approach to the M90 from Pitreavie. Transport Scotland say that the initial phase of hard shoulder closures are for the construction of gantries upon which to site the cameras, which use automatic number plate recognition to catch speeding drivers.
new 40mph limit for average speed cameras on approach to forth road bridge
The image above shows the extent of the current road works with the old 40mph limit at the approach to the bridge marked in purple. You can see the zone now extends to the Pitreavie roundabout (blue marker), Halbeath (green) and Crossgates on the A92 (yellow).
Tags: Approach Roads, Forth Crossing Constructors, Forth Replacement Crossing, old forth road bridge
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Why 40 mph? Why do we need an Intelligent Traffic System?
I would love to see the feasibilitty study where the residents of Fife approved the adoption of 44 weeks of miserable 40mph speed restrictions to allow for the building of permanent speed cameras!!! At 40 mph, this current average speed restriction is dangerous due to the excessive bunching of vehicles at important junctions. When the A68 Dalkeith Bypass was being built with a whole new roundabout under the A1, the average speed cameras were set at 50 mph which is a much more realistic speed restriction, so why have we been subjected to 40mph?
Oh and the fact that the new Average Speed camera zone extends all the way to Crossgates is a disgrace, I measured that the distance from the last traffic cone to the speed camera is 1.1miles!! We are all fully in support of restricted speed to protect workers on the roads, but this scheme, as it is currently implemented, risks losing conformity because it restricts traffic flow excessively for no obvious reason. They say it is for narrow lanes, it is simply not true as there are no lane restrictions on this section to Crossgates.
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Just to point out that the Intelligent Transport System (ITS) is not about installing permanent average speed cameras. The average speed cameras are there to enforce the *temporary* 40mph speed limit that is in force while the ITS is being built and will be removed once the new bridge has been built.
The Fife ITS basically extends the existing network of overhead gantries with variable message signs further north, allowing lanes on the M90 from Halbeath southwards to have variable speed limits applied, lanes marked off and so on.
Secondly the hard shoulder southwards from Halbeath is also being modified to allow it to be used as a bus lane at peak periods, and revert to a normal hard shoulder at other times.
Finally traffic lights will be installed on southbound slip roads from Halbeath southwards. These will allow what is called “ramp metering” – restriction of the flow of traffic on the “on ramps” in order to smooth the flow of vehicles.
As far as the extent of the 40mph zone goes, I suspect the extra length at each end is an attempt to stabilise as much as possible the traffic flow through the area at peak times – which is when things get tricky. The longer the lead in and out, the less cars are prone to braking suddenly at the last minute, something which would slow things down even more.
In terms of how much this all slows you down, let’s look at some figures. Let’s say the length of the speed restrictions is 5 miles give or take. And you would normally travel at say 77mph. Let’s say instead that you are restricted to an average speed of 40mph (speed limit plus 10% = 44mph, but let’s assume slower vehicles slow you down a bit).
So,
time taken to travel 5 miles at 77mph is: 3 minutes 53 seconds
time taken to travel 5 miles at 40mph is: 7 minutes 30 secondsSo this scheme would slow you down by about 3 minutes 40 seconds: not exactly a huge hardship.
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