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Oxford ring road crossings

I’ve had this post in mind for a while now; a Twitter conversation persuaded me to move it up the list. The Oxford ring road is a loop around (most of) the city. It is a dual carriageway for almost its whole length, as are some associated roads leading away from the city while remaining inside or adjacent to the urban area – the A40 to Sandhills, the A420 to Cumnor, the A34 south to Bagley Wood and north past Kidlington, and the A4074 southeast to Sandford. It has a combination of speed limits over its length – much of it 70 mph, some of it 50, 40 or 30. It has a variety of pedestrian crossings, varying from a road safety perspective from the completely secure (bridges, underpasses) via the mostly secure (light-controlled) to the crazily insecure (just walk across the fast traffic please). Here I’ll describe broad trends, and make examples of the worst.

Geometry

Sections of the road are variously described as “Northern”, “Southern”, “Western”, or “Eastern”, but for historical reasons these terms don’t match its shape perfectly and are inconsistently used. We’ll travel anticlockwise around the ring from the Hinksey Hill Interchange, labelling segments by an alphabetical code according to the junctions that they lie between (Picture 1), and then add radiating road segments at the end according to the same anticlockwise scheme. We’ll include crossings associated with a junction at the start of a segment in that segment. Some junctions (e.g. Hinksey Hill interchange) have crossings of both the ring road and of an attached dual carriageway; these crossings will be separated according to the section of road that they cross.

Picture 1: Oxford annotated with ring road and associated dual carriageways (imagery from Google Maps)

Itemising pedestrian crossings that are ‘official’ along with those that are a little ‘unofficial’ but still useful for the walker (mostly slipping under a bridge along a stream), we find that there are 78 such crossings; here’s my spreadsheet.

As mentioned, these divide into three types: underpasses, bridges, and traverses of the carriageway. The first two of these categories can be hazardous for reasons other than motor traffic (e.g. isolation or blind bends around which cyclists can be met), but are not in general risk sites for being struck by a car. The last category contains the greatest risk, with traverses varying in quality from fully light controlled with generous timings all the way down to a map directing a footpath across 70 mph lanes without further safeguards.

These 78 crossings comprise 32 underpasses, 14 bridges, and 32 traverses, and are quite unevenly distributed per mile of road, both in quantity and in quality. Sometimes the reason is obvious in the local geography (e.g. the water meadows to Oxford’s western side have few cross routes), but sometimes it seems obscure and probably due to developmental chance (e.g. the large number of unprotected footpath crossings on the A40 northern bypass).

Rating crossings

We’ll rate them out of 10 by several criteria, which we’ll combine below to make an overall rating:

Road safety: How safe is the crossing? 10 = No concerns about the traffic (motor or bicycle) at all; 5 = Crossing here may raise the risk to your life if you are careless; 0 = Crossing here is guaranteed to raise the risk to your life substantially.

Personal safety: Would a vulnerable person avoid being here regardless of the crossing nature? 10 = Would feel safe in the middle of the night; 5 = One might sometimes have concern; 0 = One would avoid this place in order not to get mugged.

Maintainedness: How good is the upkeep at current? 10 = Everything works, signs clear and not obscured, surfaces level and clean; 5 = Needs work; 0 = Abandoned.

Accessibility: How spry do you need to be to use it? 10 = no concerns for the mobility challenged; 5 = only easy for the fit; 0 = impossible to use.

Road safety – most dangerous

This is quite a long preamble, detailing the most dangerous available crossings.

Of the 32 traverses, 16 are completely uncontrolled, and of those 16, 8 cross 70 mph sections. Of those 8, one (Water Eaton Lane footpath at Cutteslowe) is closed (I suspect because of its intrinsic hazard, allied with the availability of the excellent nearby bridge, which is used by many children). This leaves us with 7 uncontrolled 70 mph dual carriageway traverses, which group tightly into two geographic subsets – short spells of both the A40 northern bypass and the A420 Cumnor Hill bypass (Picture 2):

Picture 2: Uncontrolled 70 mph dual carriageway traverses around Oxford. The first letter of the second column refers to the road segment. “3e” is my classification code for this crossing type.

Unprotected crossings 1) A40 northern bypass

All three of these are within 1.3 km along the same stretch of the A40 (and the Water Eaton Lane crossing that would also have fallen into this category if not closed is only another half km away), a road that here fulfils multiple functions: Oxford ring road, long distance sub-motorway route to South Wales, and near-motorway-standard spur of the M40 to Oxford. It is not a road that one crosses particularly happily. Picture 3 shows the layout.

Picture 3: A40 northern bypass unprotected 70 mph crossings (imagery from Google Maps)

Butts Lane, D2

Approaching from inside the ring, we walk through a mobile home park, and then climb an old wooden gate to the ring road footpath. An official footpath sign points back the way one has come, but there is no equivalent sign pointing across the visible near carriageway of the A40. Visibility in the direction of approaching traffic is not bad – limited by the curve of the slip road from Marsh Lane and Old Marston at 430 m, and by the shadow of the junction bridge to 660 m along the main carriageway. If there’s any saving grace to this cluster of crossings, it’s that they take place along a long flat straight, promoting visibility – although also of course promoting thoughts of speeding in some drivers. I well recall being given a lift years ago by someone fond of cars and of racing. They reached 130 mph along this straight in a bid to impress their passengers (who did not want to be impressed so).

At that absurd speed, the walker has 11.4 s to complete their crossing of this side of the A40 if we assume the traffic is clear to the Marsh Lane bridge when they step out. If the car clearing the bridge is maintaining 70 mph, they have 21.1 s. Verge to verge, it is 10 m across the carriageway, requiring only an ambly 2 mph to escape my speed fiend friend. The ideal logistics are not as daunting as they might immediately be imagined to be due to the good visibility, but in practice the problem tends to arise that one must wait for a long time for 660 m of two clear lanes.

The central reservation has been gained! But wait, there is no indication of path. A moderately dense single line of trees runs down it. There is no helpful zagging of the crash barrier to create a foot route, as is normal when a path crosses so. So we push through the foliage, step over the crash barrier, and repeat the operation for east-bound traffic. This way our visibility is even better – over 1 km, long enough to prompt a reassuring back-of-the-envelope calculation of the curvature of the earth. If one finds a traffic-free moment, one can amble across in perfect safety. If. In practice, one ends up hurrying to cross under any normal road conditions.

When one has crossed, one looks around for the footpath continuation, and realises that it is a few metres west of where it was on the other side. It’s signed clearly, and usually well-maintained by the farmer. This all leaves questions in the mind – the signed path runs up to both sides of the road in the same place and then stops. Without crossing the road, there is little point to either path approach; there is nowhere to leave a vehicle at either side, so one cannot begin or end a walk there. It is good that the path has not been lost, but the failure to install either an underpass or a bridge means that its usefulness has become so diluted that it is now all but unusable.

Mill Lane, D3

If one has only travelled around this area by car, it takes a few moments to make the connection between the road through Old Marston village and the disconnected rural lane that incongruously interfaces with the northern carriageway of the A40 here. Looking across the road, the connection is more clear – this is another route that was sliced in two when the dual carriageway came though. It may have been that originally there was a junction here at which one could turn every way, but that then increasing traffic made that problematic? No footpath signs, but there is an area of cleared greenery in the central reservation and a zagged barrier; it is evidently permissible to walk from one half of Mill Lane to the other.

Visibility is good clockwise (>1 km) and still pretty good anticlockwise (450 m). Under the same caveat as before, being patient enough to wait for a clear view will mean that you can amble across very gently in safety.

Cherwell footpath, D4

Now this is a disappointing moment for the walker. After a refreshing lunch on the bucolic riverbank at the Victoria Arms in Old Marston (a pub it’s hard to go wrong with), one sets off upriver, further away from Oxford. There are a couple of path options, one closer to the river but a little longer. Both are delightful. A bare kilometre later, a field gate deposits one among the fumes and noise of the A40. Looking around, one sees the traditional denuded patch of the central reservation with a zagged barrier within it. There’s another delightful footpath on the far side. Again, it’s the same path, chopped in two by the road, and the walker has only their personal senses of conviction and derring-do to connect the two with.

Visibilities are not quite as good as for the previous two crossings, but still good enough to amble if traffic co-operates – 700 m clockwise and 310 m anticlockwise.

Water Eaton Lane, D5 (CLOSED)

In measuring visibilities for this closed crossing, we immediately see one possible reason for its closure – it’s on a bend, albeit a long slow bend suitable for a fast road. The 150 m visibility eastwards means that the walker would need to cross at a speed in excess of 4 mph to be safe.

Unprotected crossings 2) A420 Cumnor Hill bypass

Again, these cluster together tightly, this time four such crossings within 1.2 km between the junctions for Eynsham and Cumnor, clearly shown on the ground with footpath signs and zagged barriers. Picture 4 shows the layout; in contrast to the situation with the A40 unprotected crossings, the road bends significantly, and also passes through a cutting. This also is a stretch where drivers can speed, releasing tension after the long undualled road from Swindon has inevitably resulted in a slower journey than hoped for. Naughty three figure speeds occur here too.

Picture 4: A420 Cumnor Hill bypass unprotected 70 mph crossings (imagery from Google Maps)

Nobles Lane footpath, K4

Connecting Orchard Road in Dean Court with the mobile home park at Nobles Lane, this crossing is excessively surprising. Shielded from the road by large fences, one slips between them, takes one’s life in one’s hands by crossing the road, then finds a lovely footpath through a wood on the far side. An easy and pleasant amble for the occupants of the housing estate made seriously uninviting to explore by the insertion of the road.

Measuring visibilities immediately makes clear that we are in a different situation here. The traffic coming from Oxford requires a little walking hurry, but the traffic coming from Swindon down the hill rounds the bend only 60 m away, not enough time to cross safely, requiring nearly 10 mph crossing speed if it is moving at the speed limit, faster if it is exceeding it. This crossing is not safe.

Longmoor Brake Trail Spur, K5

Only a few metres up the road, but crucially around the curve of the band from K4, the visibility here is a great deal better for traffic from Swindon. Given the choice of crossing here or at K4, choose this crossing. However, the path connection between K4 and K5 on the north side of the A420 is somewhat tenuous (overgrown and unofficial), so a choice may not be practically available.

Chawley Lane, K6

Chawley is a lovely little rural oasis tucked away up Cumnor Hill, and Chawley Lane is the road that runs to it. At its end, the lane runs alongside a field, then drops down steeply to cross the A420, where it emerges problematically, on the inside of a bend. The view down the hill is truncated at around 80 m distance, meaning that it is possible to have to run to get across safely.

Norreys Road footpath, K7

Just a few metres further up the hill, on the same bend, deeper in the cutting, is this final troublesome footpath crossing. Here the view down the hill is even shorter, around 70 m, even a little less if a lorry is parked at the front of the lay-by. These are not safe crossings either.

Table of needed walking speeds

Let us now include all crossings with any uncontrolled sections (i.e. adding type 3d to the 3e list), and with all speed limits (i.e. adding those with lower limits than 70 mph). The speed limit is not practically attainable in a motor vehicle at various of these crossings – exactly those that occur at roundabouts, in my estimation, and so I have made two parallel lists – one calculating from the posted speed limit, the other calculating from my judged maximum attainable speed within that limit.

The ordered list of needed walking speeds to evade a vehicle travelling at these speeds that comes into sight (and doesn’t decelerate – which one would hope that they would!) as one steps off the kerb is shown in Picture 5.

Picture 5: Ordered list of crossings by needed walking speeds to avoid worst legal (left) and actually possible (right) situations

Three of the four A420 crossings that we’ve already noted top the list, with needed speeds high enough that one would be running across from a standing start. As already said, these are not safe crossings for this reason.

There follow five crossings of roundabout slip roads. These speeds are overestimated in the left-hand table, because it is not possible to drive at the speed limit around these roundabouts / corners. More realistic maximum speeds are: Hinksey Hill 45 mph (rounding the corner from the A423 to the A34 slip road), Pear Tree 50 mph (entering or exiting the slip road joining the A34 heading north, similar heading south, or entering the A44 towards Oxford), and Littlemore 35 mph (rounding the roundabout from the Heyford Hill direction). However, even after adjustment, none of these crossings make for a guaranteed comfortable amble.

How suitable?

I’ve coloured crossings by 2 mph increments. The internet tells us that 3 mph is a normal walking speed for younger adults and 2 mph a normal speed through one’s eighties. So crossings with required speeds of under 2 mph we can take as broadly suitable for all of standard mobility, though crossing a dual carriageway unregulated is never a friendly exercise.

The long lines of sight for the group of three A40 paths we noted above place all of them in this ‘most accessible of the least accessible’ group, despite the 70 mph limit. We might quibble over whether the average 85 year old walker’s eyesight would be strong enough to see quite as far as possible at these crossings, but those shaded black in the list on the right of Picture 5 are surprisingly safe, if treated with respect.

The next tranche (blue) require speeds of between 2 and 4 mph. This is I think boundary territory – even a fit elderly walker cannot guarantee to be able to double their pace, but most people will be able to cross so if necessary.

Above 4 mph are several more colourings (red, orange, purple) indicating increasing danger, but at this point, we are already in trouble – few people walk comfortably at speeds above this. My brisk pace on a good flat surface is around 3.6 mph, and I walk quite a lot these days. To achieve 4 mph, I must exert myself. And to achieve the 9.3 mph potentially required at Nobles Lane requires from me the unpleasantness of a full sprint! Thus, there are 9 crossings that we judge very problematic here on this ground: Nobles Lane, Norreys Road, Chawley Lane, Pear Tree north south and east, Hinksey Hill south, Littlemore, and Brasenose Driftway.

Back to road safety rating

That was quite a lengthy introduction, but I hope an interesting one. For the purposes of the road safety rating, we’ll score the above uncontrolled crossings thus: 8+ mph: 0/10; 6-8 mph: 1/10; 4-6 mph: 2/10; 2-4 mph: 3/10; 0-2 mph; 4/10. The sole type 3c crossing (cars are controlled by lights, but pedestrians are uncontrolled) we’ll score as 5/10. These fit our original definition quite well. Traverses with full pedestrian light control (type 3a) we’ll score as 6/10 – safe, but still less safe than segregation from the traffic.

Proceeding from the other direction, a road bridge with pavements will score 10/10 for road safety, and a road underpass with pavements 9/10 for the lower light conditions. A point (or more if appropriate) may be dropped for e.g. narrow pavements, or tendency of cars to park on pavements, or indeed bicycles to ride on them. Other categories of crossing that have a base road safety score of 10/10: pedestrian only underpass (type 1b) and pedestrian only bridge (type 2a).

Space shared between pedestrians and cyclists is intermediate in safety here – less safe than a space with no non-foot traffic, but more safe than a space shared with motor vehicles, noting that cycle traffic is never controlled in the way motor traffic is. A shared bridge (type 2b) rates 8/10 base score, and a shared underpass (type 1a) 7/10 (or 8 if wide and well-lit, as in the Tesco underpass at Cowley).

Personal safety rating

Intended to capture a sense of personal security in making this crossing in this place. 0 = would avoid, 5 = one might sometimes have concern, 10 = feels safe at night. In evaluating this, I have more or less asked myself how lonely a place feels, and how safe the area around it is. Necessarily, this is subjective, and I am sure I have some of these somewhat wrong; please let me know if you think something needs adjusting. Also folded in to this is e.g. the risk of falling into the river from a narrow muddy path.

Maintainedness rating

A maintained highway scores 10. An unofficial and lightly-used footpath scores 0. Some interpolation / guessing necessary here, e.g. for the currently closed Joe White’s Lane footpath in Wolvercote. Tell me if I guessed wrong…

Accessibility rating

Wheelchair-usable scores 10. Needing physical fitness scores 5. Not usable scores 0. Again, these are necessarily subjective at times; please tell me of any that you consider wrong.

Combining ratings: Usability

Totalling up these four categories gives us a total out of 40. A little juggling of the data suggests a sensible way to proceed is to declare any crossing that scores 30 or more satisfactorily usable (i.e. 10/10), and any that scores 10 or fewer unusable (i.e. 0/10), scaling linearly in between. On this metric, 44 of the 78 crossings are good enough to score 10/10 for usability. Only the closed Water Eaton Lane crossing at Cutteslowe scores 0.

Avoidability

If a crossing is less suitable, we may wish to detour to another that is more suitable. This is a more involved consideration, one that is a function of not only the overall crossing in question, but also of those adjoining it, and the routes to them. We compile a list of the shortest routes from one side of a lower rated crossing to another that only cross at crossings rated 30 or higher. Then we add a couple of empirical cutoffs as for usability – a 2.5 km detour is too much to be used if the original crossing is too much to face, while a 200 m detour is so little as to not be counted. In reality, one would not tend to travel from one side of a crossing to the other in this way, as the end of one’s intended route would be elsewhere, but using the crossing-to-crossing-and-back-on-the-far-side journey averages over the problem when approached from both directions.

Performing the above analysis results in the table shown in Picture 6, ordered from worst to best.

Picture 6: Pedestrian crossings on the Oxford ring road and associated urban-area dual carriageways, ordered from least to most usable. The rest of the table (“most usable” end) is snipped off.

This bears a little comment. Note that the 70 mph unprotected crossings we discussed above do not take the very top placings. D5 we discount because it is closed (it scored 0 for both maintenance and accessibility). E7 is an underpass between two meadows, is very overgrown, somewhat flooded, and last time I checked was also somebody’s home. C3 is another path not maintained across the A40, and on the far side is often blocked by the current building site at Barton Fields and also a quagmire. D2 appears high here due to its failure to be maintained across the A40 central reservation. E5 I do not think is on public land! But there is an informal access to Duke’s Lake down there, as well as a handy canvas for graffiti artists. In 5th place (discounting D5) we find our ‘winner’ from the 70 mph list above, K4.

In other words, the higher placings tend to be paths that one has to go looking for; not many are useful connections between two places, and still fewer are also hard to avoid (with low avoidability scores). I would from this list flag the following as of particular concern:

  1. Stoke Place footpath, C3 – could be a nice route from Headington to Barton Fields; currently unmaintained and near unusable, both crossing the A40 and beyond
  2. Nobles Lane footpath, K4 – 70 mph dual carriageway on a bend, the most dangerous of our list of uncontrolled crossings above. See also K5, K6, K7.
  3. Collinwood Road crossing, I2 – schoolchildren crossing the A40 on foot without a light isn’t a great idea, even if the limit is 30 mph
  4. Mill Lane, D3 – two parts of Old Marston thoroughly disconnected, and no alternative path for miles
  5. The various sides of both Pear Tree and Hinksey Hill interchanges that require the pedestrian to cross sometimes numerous lanes of A34 traffic with only implicit light control upstream (and sometimes not even that)

We’ll close with an honourable mention for the transit that sparked this thought, A9b, the Littlemore roundabout crossing. It is a poor enough crossing that it took 13th place in the above list, and in the absence of the adjoining underpass (which was flooded at the time of the Twitter conversation) its avoidability decreases to 7.7. In normal service, its condition doesn’t matter, as the underpass is close by, but when the underpass is unavailable (and one might avoid it for security reasons in the middle of the night), it becomes important. Adding pedestrian lights would be a very good idea. However, the Littlemore roundabout is a bad junction in several other ways that are more readily apparent, mostly when one is driving. I would submit that it needs remodelling wholesale.

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2 responses to “Oxford ring road crossings”

  1. Fascinating!

    I need to print this out and use it alongside my print edition of the Ordnance Survey map for Oxford.

    There was an exercise that might interest you one day. That’s ‘circumnavigating’ the Plain on foot. Doing it two ways….

    1. Just walking around the Plane passing St Clements, Cowley Rd, Iffley Rd and the entrance road to the private school/college, using what I will call the ‘inner circle’ so crossing any road as near to the Plane as possible (there are textured pavements) and checking the length and time. Most fit people will do this.

    2. Walking around the Plane but only crossing the road at pedestrian controlled lights or pedestrian crossings (zebras) which means walking a distance up and back down the three first roads I mentioned. This may well be necessary for the elderly, less abled, blind – or children who have been instructed by their parents _only_ to cross at these safer places.

    The reason for my interest is that it could well be that some elderly or disabled walkers heading to central Oxford from East Oxford might consciously avoid ever doing a full (or more likely partial) circuit due to the additional distance for the ‘safe route’. Limiting their access across Magdalene Bridge into the centre of Oxford. I recall that it was something like 90 paces using the inner ring while it was around 360 paces via the safe route. For some elderly or disable people that additional 270 could be a challenge.

    Theo Hopkins

    FWIW.
    I did this in a very casual way once, just counting my steps, but I lost my notes. :(.

    I’m am elderly and I am aware that I now walk much more slowly than when I was younger and fitter and that maybe within the next five years I’ll need to take the safe but longer route at the Plain.

    Liked by 1 person

    1. Thanks for writing, Theo!

      I see these quantities:
      Crossing the road at Magdalen Bridge: 30 m (or less, but this takes advantage of the traffic island)
      Time at a fit 5 kph: half a minute plus waiting
      https://onthegomap.com/s/19bpndf0
      Simple walk around The Plain at the roundabout, not using crossings: 150 m
      https://onthegomap.com/s/3cchidi8
      Time at a fit 5 kph: 2 minutes plus waiting
      Walk including getting to nearest crossings (zebra or light-controlled): 510 m
      https://onthegomap.com/s/dd2gdah1
      Time at a gentler 3 kph: 10 minutes

      So it’s 3.4 times further to do it using crossings than if one is fit and confident in barging through the traffic, and its 17 times further than if one is able to just cross the road. It goes without saying I think that requiring less fit people to do more work is not a good way round for things to be… As you say, it can be the difference between possibility and impossibility. Whether they be elderly, disabled, or just a 40-something blogger with MS who’s having a bad day.

      Further, some people may not be happy with crossing at zebras, which some drivers do not treat with the mandated respect that they are due. Cowley Place I think we can assume that the zebra is good enough for all, with its lower traffic flows, while the first Iffley Road crossing is light-controlled, but both Cowley Road and St Clements have zebras as their first crossing (and the second, in the case of the Cowley Road). Insisting on light-controlled crossings more than doubles our distance again, pushing us over 1 km, quite a journey just to cross the road (almost USian in its Baroque pedestrian complications – I remember once trying to literally simply cross a road in Indiana to get from my hotel to a food outlet; in the end we gave up! And drove. It just wasn’t possible.):
      https://onthegomap.com/s/tjgkq7vt
      Time at 3 kph: 23 minutes

      Like

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