Modelling the Stonehenge makeover in SimCity

When I compared the traffic-modelling capabilities of SimCity and SimCity 2000 earlier this year, I said I was done. I'd already modelled my home town, GTA IV's Liberty City, and Sao Paulo, and realistically, 50+ hours of SimCity was more than enough for any person to take.

But an email from the Mayor of Amesbury was enough to make me come out of retirement one last time. Ian Mitchell had seen my SimCity modelling of Northenden, and wondered if I could have a crack at putting together a model of Amesbury's pride and joy - the incredible Stonehenge. There are big plans afoot for the prehistoric wonder, and Mitchell was looking for opinions on how these would affect the surrounding area.

It's worth watching the video on this page before we begin. Essentially, English Heritage plans to close the A344 road, which Stonehenge is currently accessible from. An alternate route will be used instead, which goes around the back of Stonehenge, around a new roundabout, and into a new visitor center that is positioned 1.5 miles away from the monument. Visitors are then carted back and forth between the visitor center and Stonehenge via a low-key transit system.

All this is in aid of attempting to revitalise the sights and sounds of Stonehenge. Right now you're treated to cars whizzing by while you visit, and English Heritage is looking to essentially revert the area back to a time when Stonehenge was a place to approach and admire, with gorgeous countryside backdrops all around.

What Mitchell wonders is how exactly this new setup will affect the nearby town of Amesbury. If you check out Stonehenge on a map, you can see that the vast majority of visitors to the site drive along the main routes just to the North of the main Amesbury town, utilizing the A303 road, and the large roundabout that connects Amesbury to the outside world.

Amesbury is already a fairly busy place anyway, thanks to the numerous interesting locations in the area -- the airfield at Boscombe Down; the artillery impact area to the North West; Training areas in the North; and the Woodford Valley just off to the South West. The World Heritage Site to the West is also part of what is essentially a countryside jigsaw puzzle too, since it has the busy A303 cutting through it, and congestion on the A303 is a common occurrence.

And that's without mentioning the tourist attractions in the town of Amesbury itself, including the Mellor Hall which offers Stone Age exhibits, and the aviation museum at the Geoge Hotel. What this all boils down to is that playing about with the surrounding roads is not something to be taken lightly. No wonder it's taken so many years for English Heritage to get these latest Stonehenge plans down.

Before I start describing how I went about modelling the area in SimCity, I have a number of huge caveats. Out of all the models I've done up to this point, this Stonehenge model was the least akin to its real-life counterpart. There were so many issues that made modelling the real-life area difficult in SimCity, that I eventually was forced to use any method I could to wrangle it all together.

The size of the towns you can build in SimCity, for example, was once again an issue here - after building and rebuilding, and then rebuilding once again, I was forced to dramatically cut down the scale of the area such that roads are far shorter than they should be.

It's also notable that Stonehenge is obviously not available to build in SimCity, so in the end I was forced to build a whopping big stadium in its place to replicate the tourists flocking in from the nearby highway to Amesbury (although Mitchell noted that "A football stadium seems a good analogy to the crowd that I saw on Solstice morning, about 21,000 in total.") This is just two examples of issues I had, and I'll mention more later.

As such, I would categorically state that Mayor Mitchell should not consider using any of this as even close to proof of anything, nor should anyone else reading think that the following analysis could be used to make tweaks to the real-life plans. In the end, I did this for a bit of fun.

The A303 where it meets Stonehenge Road. The traffic is heavy in the direction of Stonehenge

I started off by laying out the roads. With SimCity on one screen and Google Maps on the other, I attempted to recreate the area leading from Amesbury town and the main roads to the North, to Stonehenge in the West. The idea was that the connecting highway in SimCity would represent the entry point for tourists coming in from London and the other surrounding cities.

As mentioned, I was forced to cut down the scale dramatically, but I made sure to keep the general shape and notable features intact, such as the roundabouts.

Ah yes - as for the various roundabouts featured in this model, note that SimCity can't actually do roundabouts properly. Essentially, instead of having traffic go around the circle in one direction, SimCity allows traffic to go both ways around a roundabout. Please do not ask me how exactly this works, because it clearly doesn't.

The main roundabout in Amesbury. Roundabouts: This is not how they work

Once I had Amesbury laid out, and people had moved into the town (the population of Amesbury at last count in 2001 was nearly 9000, so I made sure to have at least 10,000 people living in my SimCity Amesbury before I proceeded), I placed a whopping great stadium where Stonehenge should be, to echo the daily tourist attendance count that Stonehenge would normally see. I then sat back and watched the traffic roll in from the highway to the East.

Very soon, large amounts of traffic had built up going all the way back along the A303, up to the roundabout that connects the A345, and even back onto the highway. It meant that anyone coming up from Amesbury town was met with reams of traffic heading in the direction of Stonehenge. Looking into the real-life situation, it seems as though it's a similar story, although perhaps not quite as dramatic as SimCity makes it out to be.

I then put the new plan into action. I closed the A344 (the road that Stonehenge sits on), and replaced the junction that connects the A360 with the A344 with a roundabout. I set it up such that tourists would now need to use this roundabout to access my stadium (aka Stonehenge).

Here's the new roundabout where the A360 and the A344 connect. Note the Stonehenge visitor center on the left, and the oodles of traffic pouring out onto the A360.

The move did have an effect, but not exactly in a streamlining sort of way. The traffic now continued along the A303, instead of turning off at the A344, moved up along the A360, and then went around the roundabout to reach the stadium next to it. What this meant was that the A360 was now also congested with traffic, as well as the A303.

However, the area around Amesbury town was notably less congested. Since the usual level of traffic had been forced to shift further along, the roundabout the North of Amesbury wasn't so chock full of cars, and further down the line the A303 saw far less traffic. The traffic no longer backed up onto the highway either.

English Heritage doesn't appear to be 100 percent certain of how exactly the closure of the A344 road will affect traffic. Indeed, on a FAQs page on the official website, the question "Closing the A344 will result in more traffic remaining on to the A303 - how will it cope?" pops up, and while the answer refers to improvements to two junctions, it's difficult to predict whether these will provide a major improvement. My SimCity model suggests otherwise, but as I said, you should really take my findings with a massive pinch of salt.

What it does seem like is that this solution may help to quell the traffic directly around Amesbury, but that traffic on the A303 to Stonehenge will remain a congestion issue. Of course, there are many ways that English Heritage can look to battle these problems that I can't play around with in SimCity. A vastly improved car park, for example, and multiple coach parking spaces should help to solve traffic issues at the visitor center itself. The site is also talking about forcing tourists to book a space in the car park in advance of their trip, so this will also surely cut traffic numbers down dramatically.

As for my model, attempting to put together Amesbury really showed me just how limited SimCity truly is. I would have loved to have been able to provide some real analysis of what would happen once the road to Stonehenge was closed, but in the end, the only real progression I saw was "long line of traffic is shifted to nearest neighbour point."

A nice scenic shot rammed with cars to finish us up