A new model to estimate pedestrian deaths from speed-related interventions

Figures & data

Figure 1. Individual and aggregate models of pedestrian fatality risk.

Table 1. Changes in mean and standard deviation (SD) of speed for each intervention, model predicted changes in pedestrian fatalities and ratio of relative change in fatalities to relative change in mean speed.

Case study	% Change in mean and SD of speed		% Change in pedestrian fatalities		% change in fatalities/ % change in mean speed
	Mean of speed	SD of speed	Individual	Aggregate	Individual	Aggregate
Mackie (1998): Before vs After (4 months)	−7.4%	−16.1%	−40%	−31%	−5%	−4%
Mackie (1998): Before vs After (9 months)	−1.3%	−12.9%	−18%	−7%	−14%	−5%
Kidd and Radalj (2003) 50 km/h: Before vs After (9 months)	−3.7%	−1%	−21%	−23%	−6%	−6%
Kidd and Radalj (2003) 50 km/h: Before vs After (12 months)	−2.4%	−2.6%	−17%	−16%	−7%	−7%
Kidd and Radalj (2003) 60 km/h: Before vs After (9 months)	−2.9%	0.9%	−17%	−20%	−6%	−7%
Kidd and Radalj (2003) 60 km/h: Before vs After (12 months)	−1.6%	1.8%	−9%	−12%	−6%	−8%
Bornioli et al. (2018)	−17.3%	−1.5%	−60%	−64%	−3%	−4%
Khatoon et al. (2013)	−3.7%	82.2%	276%	13%	102%	4%

Table 2. Sensitivity analysis of fatality risk models.

Case study	Hussain	Zhao	Garrett
Mackie (1998) Before vs After (4 months)	−40%	−37%	−46%
Kidd and Radalj (2003) 50 km/h; Before vs After (6 months)	−21%	−21%	−20%
Kidd and Radalj (2003) 60 km/h; Before vs After (6 months)	−17%	−17%	−16%
Bornioli et al. (2018)	−60%	−57%	−62%
Khatoon et al. (2013)	276%	208%	369%

Table 3. Sensitivity analysis of travel speed conversion to impact speed.

Case study	Impact speed as a proportion of travel speed $(\eta )$
	0.5	0.64	0.7	0.8	0.9	1
Mackie (1998) Before vs After (4 months)	−36%	−40%	−42%	−44%	−45%	−45%
Kidd and Radalj (2003) 50 km/h Before vs After (6 months)	−20%	−21%	−22%	−21%	−20%	−19%
Kidd and Radalj (2003) 60 km/h Before vs After (6 months)	−17%	−17%	−17%	−17%	−16%	−15%
Bornioli et al. (2018)	−57%	−60%	−61%	−62%	−62%	−61%
Khatoon et al. (2013)	193%	276%	307%	340%	346%	329%

Mackie A. 1998. Urban speed management methods. Transport Research Laboratory. TRL Report 363.

 Google Scholar

Kidd B, Radalj T. 2003. Post 50 km/h implementation driver speed compliance: Western Australian Experience in Perth Metropolitan Area. In: Road Safety Research, Policing and Education Conference, 2003, Sydney, New South Wales, Australia.

 Google Scholar

Bornioli A, Bray I, Pilkington P, Bird EL. 2018. The effectiveness of a 20 mph speed limit intervention on vehicle speeds in Bristol, UK: a non-randomised stepped wedge design. J Transp Health. 11:47–55. doi:https://doi.org/10.1016/j.jth.2018.09.009

 Web of Science ®Google Scholar

Khatoon M, Tiwari G, Chatterjee N. 2013. Impact of grade separator on pedestrian risk taking behavior. Accid Anal Prev. 50:861–870. doi:https://doi.org/10.1016/j.aap.2012.07.011

 PubMed Web of Science ®Google Scholar