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Lane discipline - road markings partly at fault?

  • 17-12-2019 4:05am
    Registered Users Posts: 8,051 ✭✭✭

    On some thread here, I think the M50 congestion, we read yet more complaints about lane discipline, that is, drivers using the overtaking lane/lanes when the driving Lane 1 is free. We can knock the drivers who do this with good cause, but I think that the design and marking of a lot of our dual carriageways bears a lot of responsibility for encouraging overtaking lane hogging and punishing motorists who try to adhere to correct lane discipline.

    The problems I am referring to happen mainly at the M50 junctions but there are probably others. The worst example I can think of is if you take the old N4 (R148) from Palmerston via the N4 and M4 to Maynooth or points West.

    Just out of Palmerston and in the middle of the N4/M50 interchange, there is a bus lane for 50 meters. Stupid and pointless, but it's marked so that if you are in the driving lane, you must merge right into the overtaking lane which then becomes the driving lane - of course, yielding to traffic already in the merging lane. Then 50 metres ahead, the bus lane sort of ends? but continues as an entry merging lane from the M50 that becomes the new driving lane/lane 1. So if you want to adhere to proper lane discipline, you again have to merge, this time left, to get out of the overtaking lane and into the driving lane. Then, a few miles down the road, the 3 lanes become 2 and this is accomplished by turning the driving lane into an exit lane, again, forcing you to merge right into the overtaking lane before it becomes the driving lane and the old driving lane becomes the exit at Junction 5. Now, if traffic is heavy and you're not exactly hammering down the accelerator, those merges can be a major PIA. Frankly, I wouldn't blame anyone doing 80kph through the N4 outbound if they just merged right once at that stupid bus lane and stay in the middle lane until the motorway starts. See the route here. Three stupid lane changes forced in less than five miles, on a continuous road.

    And then going towards Santry on the M50, you have this lovely gem. This is a 2 lane merge into 1 lane deal. But again, instead of forcing people using the overtaking lane to merge into the driving lane, they punish people actually using the driving lane properly and force them to yield to drivers in the overtaking lane!

    For heaven's sakes why? :mad: If you want motorists to "keep left unless overtaking" then why in blazes should TII design these routes to reward middle/right lane hogging and penalise people trying to adhere to lane discipline by forcing lane changes all over the place and making them yield at every junction? :mad: Why? What in blazes does that accomplish?


  • Registered Users Posts: 8,779 ✭✭✭Carawaystick

    How would you design J6 to have no unnecessary lane changes for trafic coming both directions off the M50 and the r148 to the N4?
    How would you have a bus travel through with little delay?

    There's no yield sign in the M50 example, overtaking vehicles always have overtake safely.

  • Registered Users Posts: 8,051 ✭✭✭SeanW

    In the M50 Santry example the signage and the road markings clearly indicate that the onus is on those in the driving lane to merge into the overtaking lane and to yield to traffic already therein. The fix for that appears (at least to me) to be very simple, just replace those blue signs with signs showing the overtaking lane merging into the driving lane and replace the arrow marked in the driving lane pointing right, with an arrow in the overtaking lane pointing left.

    As to the N4 junctions, I recognise that the N4/M50 junction is one of the more complicated junctions out there, but I'd make changes generally along the following lines:
    1. Either or both, create the 50M bus lane to the left of the driving lane, then merge traffic from the onramp from the M50 Northbound into the driving lane. If having 3 lanes approaching the onramp from M50 Northbound is too much, then force traffic from M50 Southbound to merge into lane 2 as opposed to creating lane 3 at that junction as today.
    2. At Junction 4 on the N4, build signs to indicate that Lane 3 is ending and instruct drivers in Lane 3 to merge left. Then at Junction 5, phase out lane 3, leaving a normal exit lane branching off from Lane 1 and continuing Lanes 1 and 2 onto the motorway.

  • Registered Users Posts: 8,779 ✭✭✭Carawaystick

    I was harsh there, the M50 should be marked as you say.

  • Registered Users Posts: 3,610 ✭✭✭stoneill

    Rather than poor road markings, I would say poor road design and engineering for the surface area available.
    There is no need for a dedicated bus lane at that particular stretch of the N4 you mention and all buses will be pulling to left lane directly after this anyway to service Liffey Valley bus stop.

    On the opposite side of the N4 at the Deadmans (Heading east) I always think that there should be a dedicated M50 North lane rather than having to change lane for the M50. Because of the sweep of the road, when you are approaching this area, the overhead gantry positioning has the M50 arrow actually pointing down onto a lane for Palmerstown, it is only when you are almost at the gantry does the arrow than appear above the correct lane.
    Again, bad design and bad engineering.

  • Moderators, Business & Finance Moderators, Motoring & Transport Moderators, Society & Culture Moderators Posts: 64,252 Mod ✭✭✭✭L1011

    That bus lane is an artificial construct to increase the merging volume from the m50 NB. I could probably find the mails from the NRA confirming as such if I can remember where I have my archives, and can find a computer old enough to read them..

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