Posted by: wesleyjohnston | February 13, 2017

Improving the A2 Bangor to Belfast Road

The A2 Bangor to Belfast Road is an astonishingly busy road. At Cultra the weekday traffic count is over 35,000 vehicles, making it busier than the A1 to Newry (28,000 at Dromore), the M1 at Dungannon (21,000) or the A26 between Antrim and Ballymena (31,000). It was also one of the earliest roads to be widened to two lanes each way during the era of cars.

The thing that makes the Bangor to Belfast road particularly scary is that it has no central crash barrier for several miles between Holywood and Ballyrobert. Along here there are two lanes each way with only a hatched white line between them. While this design is very common in urban areas, it’s a relatively rare design on inter-urban routes (because it’s so unsafe) the only other significant example being the A24 between Belfast and Carryduff.

With a speed limit of either 40 or 50mph along the stretch, the closing speed of vehicles passing a few feet from each other in the central lane is between 80 and 100mph – and that’s assuming drivers are sticking to the speed limit. Then add in vehicles stopped in the overtaking lane to turn right. If you have ever driven the A2 in the rush hour, and you have seen the hundreds of vehicles travelling along it nose-to-tail every day, it is startling that collisions do not occur more frequently than they do. Since 2012 four people have been killed on the stretch from Bangor to Holywood.

One of the difficulties TransportNI face in managing the road is the amount of development along either side  – literally dozens and dozens of private driveways, residential homes, hotels, museums and other properties litter both sides  – which severely limits what can be done in engineering terms. The result is a dangerous cocktail of fast through-traffic and slow or stationary local traffic trying to turn on and off the road. In an ideal world the road would be upgraded to a modern grade-separated dual-carriageway but this is clearly impossible without an enormously costly and socially unacceptable level of destruction to the area.

Instead TransportNI have tried to control vehicles through a combination of an elaborate average speed camera system (though the jury is out as to whether or not these are actually operational) and traffic signals at the main side roads. A short stretch of central barrier has also been added for about a hundred metres at the Devil’s Elbow, the most notorious section of the road (and one which was considerably worse in years gone by before the curve was partly smoothed out). There is also one 1960s-era grade-separated junction at the Folk and Transport Museum.

However, a recent road upgrade on the Shore Road at Greenisland has revealed a possible answer to the conundrum of how to improve the A2 Bangor to Belfast Road in a meaningful, but realistic, way. The Greenisland scheme involved upgrading the Shore Road to an urban dual-carriageway that eliminated dangerous right turn movements while still allowing access to dozens of private properties as follows:

  • Provide two lanes in each direction.
  • Install a continuous central crash barrier.
  • Consolidate side roads and private driveways where possible, and limit the remainder to left-in/left-out movements only so that nobody has to turn right either in or out of a side road.
  • Major junctions converted to compact signalised roundabouts. The reason they are built as roundabouts rather than standard T-junctions is to facilitate u-turns – so that people wishing to turn right in or out of a driveway can turn left and then do a u-turn at a strictly controlled location.

Here is an example of one of these new compact signalised roundabouts at Greenisland:

It’s a wonderfully simple idea, but at a stroke it resolves the main problem we face when proposing to improve safety on the A2 Bangor to Belfast Road, namely, the need to maintain access to all the properties along the road.

So I set myself a challenge – to find out if is it technically feasible to upgrade the A2 Bangor to Belfast Road to dual-carriageway standard using the Greenisland model. Any road enthusiast can have fun drawing lines on maps and creating beautiful, and completely impractical, road upgrades. But I wanted to create a feasible scheme, one that had a good chance of passing a cost/benefit analysis, so for that reason I gave myself some restrictions:

  • Limited to the stretch from Whinney Hill to Ballyrobert where there is no barrier.
  • Only use the existing route of the A2 – no heading off cross-country!
  • No grade-separated junctions – everything on the level to keep the cost down.
  • Signalised roundabouts of the same dimensions as those used at Greenisland.
  • No more than 800 metres between junctions – so that residents don’t have an excessive detour.
  • Minimal land take – land in Cultra is expensive!
  • Re-use existing road space wherever possible.

With these restrictions I set about coming up with a proof of concept.

The result? I believe it could be done.

The road would need the addition of:

  • Five compact signalised roundabouts sited at Cultra Station Road, Station Road, Glencraig Park, Seahill Road and Ballyrobert Road.
  • Two compact gyratory (like stretched roundabouts) sited at Whinney Hill and Craigdarragh Road.
  • Approximately one metre of land take along the length of the road to facilitate the addition of a central barrier. In some cases where the pavement is wide, this could be taken from the pavement. In most cases, however, it would need to be vested.
  • A 40mph speed limit along the whole stretch.
  • With slightly more land take there would be an opportunity to provide a cycleway along one or both sides of the road (not shown in my design).

Here is an example of how the Seahill Road junction could look (red is the kerb line, yellow are the locations of painted lane markings):

screen-shot-2017-02-13-at-21-25-51

And here’s a gyratory-style junction at Craigdarragh Road. Remember, the point of the design is to facilitate u-turns for people who would now be limited to left turn movements by the presence of the central safety barrier.

Screen Shot 2017-02-13 at 21.27.11.png

How much would it cost? Very difficult to judge, since land would be such a large component of the price. But if you assumed £1m per junction, that would be £7m, plus £15m to add a central barrier, you could be talking in the ballpark of £20m, which is not a huge amount of money when compared to other road schemes currently in planning.

Here is the full design (JPG image compressed as a ZIP) – click to view. (background images are from Google Earth).

Anyway, this is not a formal design proposal (I will leave that up to the professionals). But I do believe I have demonstrated that it is technically feasible to significantly improve the safety of this road by this type of upgrade without excessive cost or disruption.

 

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