Road accidents in traditionally designed local authority estates (TRRL Supplementary Report 394)

  • Published: Institute of Highway Engineers, 1978
  • Authors: G.T. Bennett and J. Marland
  • Date Added: 18 Apr 2013
  • Last Update: 25 Oct 2016
  • Format: html


Contribute towards the solution of the problem of the safe design of residential area, and in particular to attempt to assess:

  • The general nature and frequency of RTIs associated with residential access traffic;

  • The overall extent to which the frequency of such road traffic incidents (RTIs) appears to be affected by the design of the road and footpath system and; the extent to which individual design features, such as width of a street, appear to affect the frequency of the RTI.


RTI records for about 9000 streets in local authority residential estates, free from substantial thorough traffic, in 20 towns, were analysed in relation to population statistics, traffic flow, observations of children and park vehicles and design parameters using multiple regression.

Key Findings:

  • RTI rates (per house, or per person, per year) were found to be strongly correlated with traffic flow and with design factors such as street length, highway width, presence of shops, school and buses which were themselves strongly correlate with traffic flow.

  • The multiple regression analysis suggested that the direct effects of factors such as carriageway width and curvature were probably not large.

  • All the zero-order correlation coefficients were ‘significant’ and negative, indicating that the highest RTI rates occur in streets where the parking density is lowest.

  • This effect is no doubt largely due to the effect of traffic flow, because there was a ‘significant’ negative correlation between traffic flow and parking density, and most of the partial correlation coefficients between parking density and RTI were positive, though not significant’.

  • Although parking density may have a slight deleterious effect on the pedestrian RTI risk, it is unlikely to be a great one.


Parking density, road traffic incidents, highway width.


Dated research but shows that parking density affects RTI rates.