It’s been rightly pointed out that our story on the Royal Canal Greenway only included one of many issues, another issue is the gradients of ramps at road crossing and canal locks.
There’s two great blogs showing how the Dutch do things — bicycledutch.wordpress.com and aviewfromthecyclepath.com but sometimes the comments are even more insightful… Like one comment by Herbert Tiemens who is a traffic engineer based in Utrecht in the Netherlands. He said:
“The Dutch recommendations (CROW 230) say a ramp for cyclists shouldn’t have more than 5%. When the vertical climb is very short, a higher grade can be used. When the total vertical slope is more than 4 meters, a maximum of 4% is recommended. Also the horizontal parts are suggested, they should be at least 25m horizontal. As a cyclist with a good condition I don’t like the horizontal parts on a longer slope that much, it gets you out your rhythm. But for less powerful people the horizontal platforms are ok.”
A large planned ramp between Castleknock and the M50 on the Royal Canal Greenway is proposed to be 1 in 12 or 8.333%, 48 meters long, and — according to the planning drawings — have four flat rest areas (the horizontal parts referred to by Tiemens above).
Therefore the planned ramp is over twice the maximum recommended gradient CROW, by the Dutch design manual.
If the drawings are correct and there is going to be four horizontal sections, than to reach the minimum recommend length by CROW the horizontal would be longer than the planned ramp!
We’re not saying it’s realistic to expect Dutch standards, but is it acceptable to be so far from the minimums and maximums outlined in their manual?
The gradients for other ramps are not shown – although these are shorter ramps than the one mention above.
Another issue is gates or barriers. The planning drawing says a cycle friendly arrangement will be put in place — will this force cyclists to stop or dismount? Will cargo bikes, cargo trikes, and child trailers fit?
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