Traffic Signs Manual chapter 2 (draft) Introduction

Determination of x-height “C“ is the distance from the sign where a driver is expected to stop reading the sign - i.e the point where a driver would turn his/her head through 10 or more. C = S x cotangent 10 = S x 5.7 “S“ is the off-set distance from the centre of the driving lane to the centre of the sign. On dual carriageways this is measured from the centre of the right-hand- most lane. “R“ is the distance travelled when reading the sign. R = Reading Time x Speed Reading time = 2 + (N/3) seconds where N is the number of words or destinations on the sign. When N equals 6, reading time is 4 seconds. This is taken to be the maximum desirable time for reading the sign. It allows for scanning the sign twice to assimilate the information. It should be remembered that the sign may be obscured for part of the time by high vehicles and that the driver still needs to pay attention to the road ahead. Because 4 seconds is taken as the maximum time to be allowed for reading the sign, the number of destinations should not exceed six. The x-height of the sign depends on the distance the driver is from the sign when he/she starts to read it. It is taken that, on average, at a distance of 60 metres the x-height should be 100 mm (it is proportional so that at a distance of 30 metres the x-height would need to be 50 mm) Worked Example Single carriageway 8 metres wide (lane width 4 metres) 85 percentile speed 50 mph (22 metres per second) Sign 2 metres wide and 1 metre from edge of carriageway S = 2 centre of lane + 1 verge width + 1 half sign width S = 4 metres C = S x 5.7 = 4 x 5.7 = 22.8 metres, say 23 metres R = reading time x speed = 4 x 22 = 88 metres Total distance from sign = R + C = 88 + 23 = 111 metres Required x-height = (100/60) x 111 = 185 mm This is site specific and is more accurate than the table in Local Transport Note 1/94. EAST Basildon Beccles Bedford Bury St Edmunds Cambridge Chelmsford Clacton Colchester Cromer Dartford Crossing Diss Downham Market Dunstable Ely Felixstowe Great Yarmouth Harlow Harwich Hemel Hempstead Hertford Huntingdon Ipswich Kings Lynn Lowestoft Luton Newmarket Norwich Peterborough Southend St Albans Stansted Airport Stevenage Sudbury Swaffham Thetford Tilbury Watford Wisbech EAST MIDLANDS Ashbourne Boston Buxton Chesterfield Corby Derby Gainsborough Grantham Hinckley Kettering Leicester Lincoln Loughborough Mansfield Market Harborough Matlock Melton Mowbray Newark Northampton Nottingham Oakham Skegness Sleaford Spalding Stamford Wellingborough Worksop GREATER LONDON Barking Bexleyheath Brent Cross Brixton Bromley Central London Clapham Junction Croydon Dalston Docklands Ealing Enfield Hammersmith Harrow Heathrow Airport Holloway Hounslow Ilford Kilburn Kingston Lewisham London Peckham Richmond Romford Stratford Sutton The City Uxbridge Walthamstow Wembley West End Westminster Wimbledon Wood Green Woolwich (NB. Primary destinations in Greater London, other than Heathrow Airport, are usually only signed within the boundary of the M25) Primary routes destinations in England by region NORTH EAST Alnwick Ashington Berwick-upon-Tweed Bishop Auckland Consett Corbridge Darlington Durham Gateshead Hartlepool Hexham Middlesbrough Morpeth Newcastle South Shields Stockton Sunderland Teesside Tynemouth Tyne Tunnel NORTH WEST Altrincham Ashton-under-Lyne Barrow-in-Furness Birkenhead Blackburn Blackpool Bolton Bootle Brough Burnley Bury Carlisle Chester Clitheroe Congleton Crewe Ellesmere Port Fleetwood Garston Heysham Huyton Kendal Keswick Kirkby Lonsdale Lancaster Leigh Liverpool Macclesfield Manchester Manchester Airport Morecambe Nantwich Northwich Oldham Penrith Preston Rochdale Runcorn St Helens Salford Skelmersdale Southport Speke Stockport Trafford Park Wallasey Warrington Whitehaven Widnes Wigan Windermere SOUTH EAST Amersham Andover Ashford Aylesbury Banbury Basingstoke Beaconsfield Bognor Regis Bracknell Brighton Canterbury Channel Tunnel Chichester Crawley Dartford Crossing Dorking Dover East Grinstead Eastbourne Fareham Farnham Folkestone Gatwick Airport Guildford Hastings High Wycombe Horsham Lewes Maidenhead Maidstone Margate Milton Keynes Newbury Newhaven Oxford Petersfield Portsmouth Ramsgate Reading Reigate Ringwood Sevenoaks Sheerness Slough Southampton Staines Tunbridge Wells Uckfield Winchester Worthing YORKSHIRE & THE HUMBER SOUTH WEST WEST MIDLANDS Barnstaple Birmingham Barnsley Bath Bridgnorth Bradford Bideford Bromsgrove Bridlington Blandford Brownhills Dewsbury Bodmin Burton-upon-Trent Doncaster Bournemouth Cannock Goole Bridgwater Coventry Grimsby Bristol Dudley Halifax Bude Evesham Harrogate Cheltenham Hereford Huddersfield Chippenham Kidderminster Hull Cirencester Leamington Spa Humber Bridge Dorchester Leek Immingham Exeter Leominster Keighley Exmouth Lichfield Leeds Falmouth Newcastle-under-Lyme Pontefract Frome Nuneaton Ripon Glastonbury Oswestry Rotherham Gloucester Redditch Scarborough Helston Ross-on-Wye Scotch Corner Honiton Rugby Scunthorpe Launceston Rugeley Selby Liskeard Shrewsbury Sheffield Marlborough Solihull Skipton Newquay Stafford Thirsk Okehampton Stoke-on-Trent Wakefield Paignton Stone Wetherby Penzance Stourbridge Whitby Plymouth