Vertical Sightline Requirements for driveway?

Jamesys

Trying again as my last post seemed to have failed!
I'm in the early stages of looking at building a new house on my family farm. My favourite spot at the moment is on a hill. I can get 90m sightline each side with the correct set back with some hedge trimming (road is 80km/h limit but I'm told the design speed is 60km/h and that's what counts?).
My friend tells me that he thinks there is also a vertical sightline requirement and because the site is on a steepish hill that I wouldn't be able to comply. I can't find any details on a vertical requirement on Meath CC website, does anyone know if this really exists and what the requirements are? Thanks.

sydthebeat

Jamesys wrote: »

Trying again as my last post seemed to have failed!
I'm in the early stages of looking at building a new house on my family farm. My favourite spot at the moment is on a hill. I can get 90m sightline each side with the correct set back with some hedge trimming (road is 80km/h limit but I'm told the design speed is 60km/h and that's what counts?).
My friend tells me that he thinks there is also a vertical sightline requirement and because the site is on a steepish hill that I wouldn't be able to comply. I can't find any details on a vertical requirement on Meath CC website, does anyone know if this really exists and what the requirements are? Thanks.

if you cannot see to a height of 1.5 m continuously of on coming traffic then your in trouble.

Lumen

This might be useful:


SIGHT LINES: VERTICAL ALIGNMENT/VISIBILITY
* Distance/length of unobstructed clear vision required. If the road being accessed is not flat for the appropriate sight line distance on either side, then vertical sightlines need to be considered and demonstrated to the Planning Authority.


Avoid: VERTICAL ALIGNMENT/VISIBILITY IMPAIRMENT
* Distance/length of unobstructed clear vision required. Vertical visibility impaired by contour of the road, sight line not achieved.

Source: http://dnoonan.ie/surveying/site-access

Jamesys

Thanks, looks like requirements do exist. Any idea where I could find the distances represented by the red astrix? I've been researching a lot of approved planning permission applications online and I don't see any giving these details, even for ones on hills bigger than the one I have.

Schorpio

I don't know about private access - but I would imagine it's linked to the SSD (sight stopping distance) of the highway the access it connecting to. Basically the ability of a car traveling on the highway to see someone pulling out and stop in time.

Page 106/107 of the Design Manual for Urban Streets gives the SSDs and outline the visibility measurements (here). Whether that's overkill for a private access I don't know.

Lumen

Jamesys wrote: »

Thanks, looks like requirements do exist. Any idea where I could find the distances represented by the red astrix? I've been researching a lot of approved planning permission applications online and I don't see any giving these details, even for ones on hills bigger than the one I have.

"Distance/length of unobstructed clear vision required", i.e. the normal horizontal sight lines, listed in the linked article, ultimately sourced from "Table 7/1, Section TD 41-42/09 of the NRA Design Manual for Roads and Bridges (DMRB)."

90m for 60kph design speed, in both directions.

Regarding the 1.05m height...

National Roads Authority Volume 6 Section 1
Design Manual for Roads and Bridges
http://www.tiipublications.ie/library/DN-GEO-03031-06.pdf

2.2 Stopping Sight Distance shall be measured from a driver's eye height of between 1.05m and 2.00m, to an object height of between 0.26m and 2.00m both above the road surface, as shown in Figure 3. It shall be checked in both the horizontal and vertical planes, between any two points in the centre of the lane on the inside of the curve (for each carriageway on dual carriageways).

Schorpio

Lumen wrote: »

"Distance/length of unobstructed clear vision required", i.e. the normal horizontal sight lines, listed in the linked article, ultimately sourced from "Table 7/1, Section TD 41-42/09 of the NRA Design Manual for Roads and Bridges (DMRB)."

90m for 60kph design speed, in both directions.

Regarding the 1.05m height...

National Roads Authority Volume 6 Section 1
Design Manual for Roads and Bridges
http://www.tiipublications.ie/library/DN-GEO-03031-06.pdf

Whilst all of that is correct, the use of DMURS vs. DMRB is very situational. It really depends on the kind of carriageway. A family farm may not adjoin a National S2 carriageway, in which case DMURS may be more appropriate (59m for 60kph). It really depends on OP's specific situation.

Jamesys

Thanks all, it looks a little more complicated than I thought, will go and do some more research.
Just to throw another spanner in the works I'm considering using the new gateway as new access to the field as well. It would only be occasionally as there are other ways into the field. It looks like that means I might have to use a bigger setback for the sightline measurements. Again similar applications I checked online don't seem to use the bigger set back, is it something that is routinely ignored?