Posted By Ron Hunter Peter - not enough info to hazard a guess at an answer, but bear in mind that DDA requires a change in level on a walkway or stair to be suitably marked (e.g. contrasting colour to a stair nosing) for those with visual impairment. Designers should avoid changes in level in favour of gradual slopes, all steps and stairs must be of equal height - etc.

Posted By Dave Dowan Hi I don’t know the answer but edge protection on a roof should be between 910mm and 1100mm high (above hip height) so that if you fall against it you won’t tip over the barrier. So likewise maybe a low wall should be assessed on those criteria? Hope that helps Dave

Posted By Pete48 Peter, am I right in thinking that you are talking of a low obstruction across an (informal?)access route? A low wall that people will step over rather than go around. I have not sourced any specific technical ref to back up my opinion. I would think about a level that people would clearly assess passively as an obstruction. So more than the standard step riser of 8/9 inches. Then think about the difference between stepping over and stepping onto. So my starting point for a discussion would be about 12 inches and going up to a height that is clearly an obstruction at say 18 inches. An interesting brain teaser for the festive season, I hope someone does have a definitive answer now that you have sown the seed.

Posted By graeme12345 How about when someone crosses a road and meets the kerb

Posted By peter gotch 1 Hi Fornhelper My question has national relevance, so I was anxious not to be over specific. I have no problems with recognising that a roadside kerb is DEFINITELY a tripping hazard reflected in the amount of damages paid out by e.g. the public sector when they get in wrong. MOD paid out £500k less about a third for an accident at Rosyth. Main LA insurers in public presentation which I do not have to hand commented that over 50% of their settled claims dealt with slips and trips including when e.g. pavement slabs get out of alignment or where there are potholes in the road - different authorities have varying "intervention" levels e.g. 25 or 50mm trips - I have no problems in recognising either of these as often presenting a reasonably forseeable trip hazard. What I am interested in is the view of fellow practitioners as to what height of obstruction remains a TRIP hazard to those with adequate vision and in adequate lighting assuming approx same level each side in relation to public access. Obviously, I recognise that if there is a 5m sheer drop on the other side, that in many cases a 600mm wall is insufficient protection in a highly populated scenario. Conversely, I would not wish to see this {or any protection} in many rural locations. [My dog would be very annoyed if he could not swim anywhere in the Rivers Clyde or Kelvin!!! (or various other waters)] HYN and regards, Peter

Posted By Tabs If you want a physical answer, rather than a convenient one ("stopping conkers bonkers") perhaps you should consider the words used? You ask when a tripping hazard becomes a striking hazard. Imagine a person walking with a light but large box in their arms, obscuring view. When they encounter the wall what is the likely outcome? There will be a point at which the most susceptible person (tallest) will not trip over the wall but will simply crumple against it. This may well be the 910mm Dave referred to - or it may be considerably lower with a front-on approach (knee-height perhaps?). To consider your "eyes open" comment, one should reasonably assume that trips are not undertaken on purpose, so some distraction or visual hindrance is implied. Even yellow/black striped steps trip people up - I have seen the accident reports.

Posted By peter gotch Tabs, sorry, but I did not ask when a trip hazard becomes a strike against hazard - in many cases it could be both. Instead I asked for views as to what height an obstruction stops being a trip hazard, in defined circumstances, as regards visibility and vision - these obstructions will usually be in locations where DDA issues are unlikely to set the agenda. I think it is probably about knee height or slightly below, so grateful for your input re this. Mike - your accident reminds me of one of my own. Reflection was such that I couldn't see the glass door that I walked into. Regards, Peter

Posted By peter gotch Hi Tabs I am trying to get views as to when it is unlikely that a person would trip and land beyond the obstruction. I would class Mike's accident as "struck against", not trip or fall. [Ditto my walking into a glass door!!] Regards, Peter

Posted By peter gotch OK Mike, I think I will classify that as a trip! How high was the wall? Regards, Peter

Posted By peter gotch 1 Hi those of you who were sensible enought not to be online over the hols. Any other views? Happy New Year, Peter