SECTION 5

INTRODUCING LOWER SPEEDS LIMITS

5.1 Suffolk County Council village speed limit initiative

In 1994 Suffolk County Council set up a Speed Management Panel of council members to consider a speed management strategy for the County. The question addressed by the Panel was: ‘What can the County Council do to bring about a change in attitudes about speed?’ The Panel agreed that the needs and expectations of the local community were of paramount importance, rather than those of passing motorists (Suffolk County Council, 1997).

The County Council introduced its village speed limit initiative between November 1994 and December 1996. The Council rejected the advice of the Department of Transport’s Circular 1/93 on existing driver speed and set out with the presumption that each village or location where groups of people live should have a 30mph speed limit. The policy was to introduce a consistent speed limit for all residential areas, even tiny hamlets. The Council hoped that the implementation of the policy would lead to an improvement in safety and the quality of life of residents in the county.

By December 1996 an estimated 700km of 30mph limit had been introduced in Suffolk – probably the largest recent implementation of new speed limits by any local authority in the UK. Over 450 new 30mph speed limits were installed within the two-year period, at a cost of approximately £4,500 per speed limit. A total of 280 new speed restrictions were established, and 85 parishes introduced significant extensions to already existing 30mph limits. A further 85 parishes had speed limits reduced from 40 to 30mph. The overall cost was £1.2 million, averaging £2,500 per village. The initial estimate for the work had been £2 million, but economies of scale and geographic grouping of the work programme managed to reduce the total by 40% (Jeanes, 1997).

There was poor awareness of the local speed limit before the installation of the new signs, but almost total awareness after implementation, according to a survey of village residents carried out by the Transport Research Laboratory (TRL, 1996a). The extent of the speed limits was agreed with local people, overseen (and sometimes arbitrated) by the Speed Management Panel. The TRL survey found that 66% of village residents were enthusiastic about the policy, although a further quarter disapproved. Three quarters of all respondents had noticed changes to the speed limit in Suffolk villages other than their own.

The major area of concern was danger to pedestrians and cyclists, especially child pedestrians, with at least a third of respondents strongly agreeing that traffic was dangerous to these groups both before and after the new speed limits were introduced. A fifth of respondents also believed their quality of life had improved with the implementation of the new signs, although 77% felt it remained the same as before.

Speed reductions within the new speed limit areas were found to have resulted in 20% fewer crashes compared to Suffolk roads on which there had been no change of limit. Comparisons were also made between unrestricted roads in Suffolk and Cambridgeshire, and it was found that there were proportionately fewer crashes in Suffolk. The County Council has concluded, therefore, that the 30mph restrictions did not lead to an increase in crashes on adjacent unrestricted roads.

The reduction in the number of crashes was estimated at 130 across all the speed limit areas in the period since implementation of the new limits. This equates to a reduction of 45 crashes per year across the speed limit areas. It was found that reductions in crashes were greater where the speed limit was reduced from the national speed limit of 60 to 30mph than where the change was from 40 to 30mph. Where speed limits were reduced from 60 to 30mph there was an average speed reduction of 6.2mph, while where speed limits were reduced from 40 to 30mph there was an average speed reduction of 4mph. Suffolk County Council’s county-wide approach was acknowledged in the government’s Review of Speed Policy for its success in reducing casualties.

Contact:Mike Jeanes
Environment and Transport Department
Suffolk County Council
St Edmund House
County Hall
Ipswich IP4 1LZ
(tel: 01473 583 145)
 

5.2 Oxfordshire County Council 30mph limits

In August 1997 Oxfordshire County Council resolved to introduce 30mph limits in most Oxfordshire settlements, subject to agreement with parish and town councils. A settlement was defined as a continuous built-up area of at least 20 houses, but schools and businesses generating greater vehicular or pedestrian flows than an average house can compensate for fewer dwellings.

Starting in the Vale of the White Horse and West Oxfordshire, the County Council has acknowledged the work undertaken by Suffolk County Council in its resolve to implement 30mph speed limits across the county. It has also planned to monitor sites in order to provide ‘before’ and ‘after’ data.

Contact:

Geoff Barrell
Environmental Services
Oxfordshire County Council
Speedwell House
Speedwell Street
Oxford OX1 1NE
(tel: 01865 810 450)
 

5.3 20mph zones

The first three 20mph zones in the UK were implemented in January 1991. Five years later the Transport Research Laboratory reviewed the results from 250 zones in England, Wales and Scotland (TRL, 1996b), with the following major findings:

• average speeds had fallen by 9mph
• the annual total of crashes had fallen by 60%
• the number of crashes involving children had fallen by 67%
• crashes involving cyclists had fallen by 29%
• Traffic flows in the zones had been reduced by 27%, but flows on the surrounding boundary roads had increased by 12%. There had been little crash migration to surrounding roads.

5.4 Scottish trial programme of advisory 20mph speed limits

Indications to date suggest that schemes with fewer physical measures have a lesser impact on speed than schemes with more physical restrictions, both in urban and rural locations (DETR, 1999; Silcock, 2000). In Scotland, however, the Society of Chief Officers of Transportation in Scotland (SCOTS) invited councils to participate in a trial of advisory 20mph speed limits, using 20mph signs and markings in areas where the official speed limit remains 30mph. The 18-month trial began in spring 1998, and involved 75 sites from 27 councils. The Scottish Office (now Scottish Executive) commissioned consultants to carry out research into the impact of the advisory speed limits, including attitudinal surveys among residents.

Results show that even these ‘signs only’ measures have been successful in bringing or keeping average speeds under 20mph. The advisory 20mph limits have been particularly effective where the ‘before’ speeds were in the upper range of the sample. Interim results from a sample of speed surveys (see Table 5) show that at seven survey sites there were decreases in average speed, one site recorded an increase, and five sites experienced no change. Final results seem to bear out the interim findings, and to confirm that local residents are pleased with the overall drop in speeds.

Table 5: Average speed and severity factor changes in Scottish advisory 20mph limits trial (interim results)
 
 

	average speed			severity factor
location	before	after	change	before	after	change
Lochside/Denmore Park, Aberdeen	29	17	-12	0.466	0.121	-0.345
Broomfield Road, Portlethen	21	17	-4	0.200	0.128	-0.072
Wallamhill Road, Dumfries & Galloway	16	16	0	0.076	0.081	+0.005
Buckstone Crescent, Edinburgh	26	25	-1	0.354	0.326	-0.018
Buckstone Loan, Edinburgh	26	26	0	0.360	0.338	-0.022
Buckstone Loan East, Edinburgh	22	20	-2	0.232	0.182	-0.050
Oliver Road, Falkirk	23	21	-2	0.267	0.191	-0.076
Moncks Road, Falkirk	21	20	-1	0.200	0.177	-0.023
Hawley Road, Falkirk	18	20	+2	0.147	0.204	+0.057
Cromwell Road, Falkirk	22	21	-1	0.241	0.219	-0.022
Marchburn Drive, Midlothian	19	19	0	0.156	0.152	-0.004
Milton Quadrant, Kilbirnie	24	24	0	0.285	0.265	-0.020
Stockbridge Cresc, Kilbirnie	21	21	0	0.212	0.185	-0.027

Table 5 also provides a calculation of the severity factor, calculated from the likely degree of severity of injury to a pedestrian struck by a motor vehicle at various speeds. This is intended to allow a comparison between sites and the effectiveness of the measures. As a benchmark, if all vehicles travelled at 20mph then the severity factor would be 0.100.

Contact:

Janet Ruiz
Central Research Unit
Scottish Executive
Victoria Quay
Edinburgh EH6 6QQ
(tel: 0131 244 0377)

5.5 Kingston Upon Hull: 20mph zones programme

In the mid-1990s Hull City Council launched a programme of implementing 20mph speed limit zones, and by summer 2000 a total of 80 zones had been established. One reason for their widespread introduction was that the city has casualty rates for child pedestrians and cyclists well above the national average. It also has a relatively high level of cycle use, with a modal share of 14% for the journey to work. In addition, 51% of households in Hull have no car, which is also well above the national average.

Typical speed reductions in 20mph zones vary according to the types of measures applied. Schemes using road humps only have been most effective, bringing down mean speeds to 17mph. Speed cushions together with road narrowing have brought speeds down to 20mph, while schemes using cushions only have brought speeds down to 22mph.

As the result of concerns expressed by the Ambulance Service, the City Council has agreed that from 1999:

• all vertical measures will be a maximum 75mm high
• all cushions will be 2.1m wide with 550mm side slopes
• all speed table ramps will be 1800mm long
• all schemes will include the minimum number of measures to achieve objectives
• bollards will be placed adjacent to humps/ cushions as markers on local distributor roads
• the Council will revisit earlier schemes to make them ambulance-friendly

Questionnaires have typically met with response rates of around 25-40%, of which:

• 80-90% are in favour of 20mph zones
• 70-80% are in favour of humps/cushions
• 60% are in favour of narrowings/priority workings

The results of Kingston Upon Hull’s 20mph zone programme have been impressive, particularly in 13 zones installed in 1996/97. The total number of crashes within these zones has fallen by 56%, while the number of people killed and seriously injured has fallen by 90%. The Council also saw a first year economic rate of return from these schemes of 1,160%.

Contact:
Tony Kirby
Road Safety Unit, Traffic Services
Kingston Upon Hull City Council
Kingston House
Hull HU1 3ER
(tel: 01482 612 108)

5.6 City of Edinburgh Council: 20mph zones

Since August 1998 City of Edinburgh Council has primarily focused on converting existing traffic calming schemes to self-enforcing 20mph speed limits. The first tranche of traffic calming schemes approved for conversion required additional measures costing between £4,000 to £75,000 per scheme, depending on the extent of the work required (City of Edinburgh, 2000):

Broomhouse £20,000
Calders £15,000
Devon Place £6,000
Duddingston Village £4,000
Dundee Street £6,000
Grange £24,000
Royston/Wardieburn £75,000

The Council has also consulted widely with interest groups in the different residential districts affected by proposals to change traffic calming schemes into 20mph zones. In South East Edinburgh, for example, 104 groups were consulted. Out of the 20 responses, only Lothian Regional Transport objected to the proposals, whilst other groups sought extensions of the pilot area (City of Edinburgh, 1999).

The provision of 20mph speed limits outside primary schools was agreed by the Council in 1998 and is being taken forward as part of the Safer Routes to Schools programme. Due to cost implications, the progress of the programme will be dependent on future capital budget allocations (City of Edinburgh, 1999). The budget for implementation of 20mph zones in Edinburgh is £510,000 between 2000 and 2003.

By March 2003 roughly 10% of the city’s road network in built-up areas will be covered by 20mph zones.

Contact:

Phil Noble
City Development Department
City of Edinburgh Council
1 Cockburn Street
Edinburgh EH1 1BL
(tel: 0131 469 3803)

5.7 Buxtehude, Germany:speed reduction through area-wide Tempo 30

Buxtehude is a town of 32,000 inhabitants in the north of Germany, 34km south-west of Hamburg. It was one of six locations selected to take part in the national traffic calming demonstration project of the former West Germany. In this context Buxtehude developed one of the most comprehensive examples of area-wide traffic calming and Tempo 30 zones, and became one of the models for the Tempo 30 programme extended across Germany during the 1990s.

Specifically, 30kph limits have been established in the centre and northern districts of the town, where around 11,000 inhabitants live. The Council has used an extensive public relations programme to explain the plans in order to win support from residents.

The measures have been implemented in two main phases. During 1983 two main Tempo 30 areas were established, with narrowing of entrances to the areas. The second stage began in 1986 and was completed in 1987. It included the renewal and part conversion of distributor roads, conversion of a main street into a ‘shopping boulevard’, and conversion of some streets into pedestrian zones in the oldest part of Buxtehude.

A five-tier road hierarchy is used in Buxtehude, as in many other areas of Germany, to provide a guide to the types of measures appropriate in different parts of the network. This comprises:
 

• pedestrian zones (Fussgängerzonen), usually shopping areas, where motor traffic is removed
• residential streets (Wohnstrassen), where traffic calming is often widely applied and where all through traffic is removed
• collector roads (Sammelstrassen), where speed reduction is achieved by reducing space for motor vehicles
• main roads (Hauptstrassen), where there are possibilities for speed reduction measures, tempered by the needs of through traffic, public transport and service vehicles
• limited access roads (Autobahnen), which have speed limits in urban areas only

On residential roads 85th percentile speeds fell from 44 to 35kph on average, and on main roads from 53 to 40kph. On the surrounding roads where there is no 30kph speed limit, speeds have fallen from 54 to 51kph (see Table 6). These changes led to increases in pedestrian and cycle traffic in the area of 17% and 27% respectively. Over the same period car traffic increased by only 2%.

Table 6: Mean and 85th percentile speeds in Buxtehude before and after Tempo 30 (all speeds in kph)
 

	before (1983)		after (1988)
	mean	85th %ile	mean	85th %ile
Residential roads	35	44	32	35
Distributor roads	45	53	34	40
Surrounding traffic roads	54	64	51	60

The conversion of one of the main streets in the centre of Buxtehude, Bahnhofstrasse, into a ‘shopping boulevard’ was achieved by narrowing the road to 6.5 metres and raising all junctions. Cycle paths were built in both directions. The mean speed declined from 42 to 33kph, while the 85th percentile speed fell from 48 to 41kph.
 

5.8 References for Section 5

City of Edinburgh (1999) City Development, Transportation Committee, 20mph speed limits: statutory changes, 9 August 1999

City of Edinburgh (2000) City Development, Transportation Committee, 20mph speed limit zones in existing traffic calmed areas, 10 April 2000

Danish Road Directorate (1993) An improved traffic environment: A catalogue of ideas, Denmark: Herlev

DETR (1999) Traffic Advisory Leaflet 9/99: 20mph Speed Limits and Zones, London: DETR

Jeanes, M (1997) ‘Suffolk’s 30mph speed limit initiative’, (edited and updated version of 1996 PTRC paper), Suffolk County Council

Oxfordshire County Council (1999) Oxfordshire County Council’s 30mph speeds limit project – West Oxfordshire, Oxford: OCC

Scottish Executive (1999) Evaluation of the 20mph speed reduction initiative: Interim report (unpublished)

Silcock, R (2000) ‘Design issues for rural traffic management’, in Design issues for rural traffic management: Conference Proceedings, by Landscape Design Associates and Ross Silcock Limited, Cheltenham: Countryside Agency

Suffolk County Council (1997) 30mph speed limit initiative: Speed monitoring, Ipswich: SCC

Transport 2000 (undated) A set of case study examples of good practice from German speaking countries, unpublished report by Julia Rohrig

Transport Research Laboratory (1996a) Suffolk 30mph speed initiative independent survey, by Farmer, S, unpublished Project Report PR/TT/129/96

Transport Research Laboratory (1996b) A review of traffic calming schemes in 20mph zones, Report 215, by Webster, D and Mackie, A, Crowthorne: TRL

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