Friday, November 09, 2007

Spaghetti Festival

The letters page of 7DAYS has included some recent correspondence concerning the apparent inability of some drivers to use the correct lane. My own understanding of the rule is that everyone should drive in the most right-hand lane possible. Although officially there’s no ‘slow’ lane or ‘fast’ lane, it is widely understood that faster vehicles should occupy the left lanes and slower vehicles should remain further to the right. For the purposes of my blog, I’ll adopt the UK traffic police convention of calling the slowest, right-hand lane ‘Lane 1’, and number the ‘faster’ ones consecutively to the left. Lane 6 may be found in and around Dubai, although the Al Ain road typically tops out at Lane 2 or Lane 3.

Echo and the Sunnymen may typically be found in the middle, stereotypically burbling along at 70kph in the 120kph limit with traffic whizzing past on both sides. The alleged illegality of ‘undertaking’ on the right seems to be unenforced. Perhaps it’s safer to stay in Lane 1 at 120kph than to move out to Lane 3, make the overtake and then move back into Lane 1.

I think the most useful rule of thumb on the subject is that, if you are undertaken, you're in the wrong lane. Either go faster or move further to the right. I’m always exasperated if I wish to overtake a Sunnyman but can’t use Lane 3 because it’s full of Land Cruisers doing the speed of sound. Eventually the Sunnyman might move over into the empty Lane 1 and then he invariably moves back into Lane 2 once I've gone past and dropped into Lane 1.

Enough of what happens; how about why?

Education is one reason. If student drivers are taught to drive in the middle lane, then this is what they’ll do. And their behaviour is surely reinforced when they see everyone else doing the same. Moreover, there’s zero incentive to drive in an urban Lane 1 when this is seemingly designated the correct lane for random double parking.

But I believe a fundamental cause lies in the design of the highway itself. I refer to it as ‘frivolous use of lane gains and lane drops.’ I’m sure we’ve all been here: Driving along in Lane 1 only to discover that this lane scoops us off on to the service road. Overhead gantry signs are supposed to indicate lane drops, but these are often unreliable indicators. The lane markings should differentiate between the highway main line and the lane drop, but in Dubai it’s only the last 20m or so when the dashed line becomes a continuous marking that any warning becomes apparent.

On a normal diverge taper or, come to that, a side turning, the normal lane line ---------------- should become - - - - - -. What’s wrong with putting this on the last 500m before a lane drop? The purpose of signs and markings is surely to assist driver comprehension, not to obfuscate.

I have an excellent specific example of the lack of lane consistency within new works in Dubai. Try driving from Business Not-Much-Like-A-Bay towards Mirdif. The huge new dual carriageway provides a massive choice of six lanes and a posted 80kph speed limit. Over Business Bay Bridge there are seven lanes, yet Lanes 1, 2 and 3 peel off into Festival City. In order to get on the road to Mirdif you have to be in Lanes 4 to 7. Then Lanes 6 and 7 head off towards the airport tunnel, Lanes 4 and 5 forming the diverge that becomes Lanes 3 and 4 through the interchange between Nad Shamma Park and the Coca-Cola factory.

This next section varies between 4 and 5 lanes wide. The new Lane 1 disappears off towards Nad Al Hamar, there are miscellaneous substandard lane gains and drops within the interchange, including an appalling approach to a petrol station, but in order to get on to the road that becomes Tripoli Street, stay in Lanes 2, 3 or 4. And then, on the approach to the interchange with the Emirates Road, Lane 1 vanishes off towards Abu Dhabi, and Lane 2 tapers away to nothing.

Despite the enormous carriageway width, there are actually only two continuous lanes from Business Bay Bridge to beyond the Emirates Road. To quote from the AASHTO 2001 design manual, the USA rulebook for highway design and the standard upon which the Dubai design manual is based:-

“The basic number of lanes should be established through a substantial length of freeway and should not be changed through pairs of interchanges... In other words, there should be continuity in the basic number of lanes.” (AASHTO page 815)

“Route continuity refers to provision of a directional path along and throughout the length of a designated route. Route continuity [includes] the principle of maintaining a basic number of lanes.

“The principle of route continuity simplifies the driving task in that it reduces lane changes, simplifies signing, delineates the through route, and reduces the driver's search for directional signing.

“Desirably, the through driver, especially the unfamiliar driver, should be provided a continuous through route on which changing lanes is not necessary to continue on the through route.”
(AASHTO page 811).

My point is that in practice, anyone who attempts to drive in Lane 1 will inevitably have to switch lanes at the approach to every junction and interchange. For the sake of an easy life, many drivers simply stay to the left and avoid the problem, one that is in part caused by failure of designers to adhere to the rules governing good highway design practice.

2 comments:

Keefieboy said...

I remember driving that route over Business Canal Crossing, trying to find IKEA and being thooughly confused by, well, everything. However, the Airport Tunnel is very nice, even if it's not where you actually want to go.

Ian-the-Dog said...

Wombling along quietly at 80kph in lane 3 does have its advantages - not that I myself am a womble. It insulates the womble from the perils of unplanned lane drops, and since he is clearly scared witless by the prospect of changing lanes, you can undertake him without the danger of his waking up and side-swiping you.

It does rather become a chicken-and-egg question: are people in the wrong lane because people are zooming past them on both sides, or are people undertaking them becuase they are in the wrong lane? Answers on a postcard, please.

And whatever you do DON'T GET ME TALKING ABOUT ROUNDABOUTS! In my book, anyone who passes an exit from a roundabout in lane 1 should be tortured mercilessly, shot, buried, dug up again and set fire to (pour encourager les autres). It's the only way to deal with these people. You know it makes sense.

 

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