U.S. Vision Zero Cities: modal fatality trends and strategy effectiveness

Figures & data

Table 1. Fatal collisions per year in Vision Zero study cities (pledge years highlighted).

City	State	2007	2008	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	2019
Anchorage	AK	25	15	21	12	15	12	16	25	25	20	17	24	16
Austin	TX	62	58	70	53	54	79	70	57	100	93	77	74	93
Boston	MA	28	25	13	16	17	19	18	19	24	27	21	14	20
Chicago	IL	159	158	142	125	109	133	119	106	111	114	129	114	133
Denver	CO	39	47	37	36	31	32	38	43	49	51	46	58	58
Fort Lauderdale	FL	34	32	30	25	16	28	19	20	28	25	26	34	45
Fremont	CA	8	9	7	7	7	5	8	11	12	7	17	6	8
Los Angeles	CA	248	261	225	209	199	229	225	229	224	307	236	256	252
New York City	NY	263	284	257	256	250	249	255	239	225	218	190	187	208
Philadelphia	PA	118	87	83	83	83	97	86	89	85	93	91	103	86
Portland	OR	33	18	30	23	34	31	35	20	34	41	42	36	45
Richmond	VA	25	19	14	15	17	14	12	9	16	15	21	15	14
San Antonio	TX	102	110	114	107	107	109	152	135	138	182	141	137	147
San Diego	CA	85	82	72	66	63	67	79	76	90	88	67	90	82
San Francisco	CA	50	33	37	28	27	29	33	30	38	33	25	23	34
San Jose	CA	43	43	45	34	40	38	48	55	67	56	44	58	70
Seattle	WA	20	24	31	23	19	22	27	18	21	27	30	20	21
Washington	DC	37	33	26	24	23	14	19	20	23	23	28	29	20
TOTAL USA (000s)		37.4	34.2	30.9	30.3	29.9	31.0	30.2	30.1	32.5	34.7	34.2	33.7	33.2

Table 2. Descriptive statistics.

					Commute Mode (%)
	Adoption Year	2019 Pop.	2007→2019 Pop. Change	Pop. Density (average 2007–2019)	Single-Occupancy Vehicle	Transit	Bike	Walk
Anchorage	2016	0.3	4.4%	6.5	75.8	1.7	1.2	2.9
Austin	2014	1.0	34.6%	99.5	72.9	4.4	1.4	2.3
Boston	2015	0.7	12.5%	508.9	39.0	33.2	1.8	14.7
Chicago	2012	2.7	-5.1%	466.8	50.1	27.3	1.4	6.3
Denver	2016	0.7	26.2%	157.5	69.6	7.2	2.1	4.4
Fort Lauderdale	2015	0.2	3.4%	192.8	73.7	4.8	1.4	2.2
Fremont	2015	0.2	19.7%	108.5	73.8	8.4	0.4	1.3
Los Angeles	2014	4.0	5.4%	316.8	67.9	10.5	1.0	3.6
New York City	2014	8.3	1.2%	1,066.7	22.6	55.8	0.9	10.1
Philadelphia	2016	1.6	3.7%	444.0	50.7	25.8	1.9	8.5
Portland	2015	0.7	20.0%	170.9	59.1	12.3	6.0	5.6
Richmond	2016	0.2	15.1%	135.2	70.7	6.4	1.9	4.6
San Antonio	2015	1.5	20.8%	114.4	78.9	3.2	0.2	1.9
San Diego	2015	1.4	11.1%	158.1	75.2	3.9	0.9	3.0
San Francisco	2014	0.9	11.2%	677.7	36.2	33.0	3.5	10.3
San Jose	2015	1.0	10.4%	210.7	77.0	3.8	0.9	1.7
Seattle	2015	0.8	28.4%	292.6	50.9	19.7	3.4	9.5
Washington	2015	0.7	20.7%	394.9	34.9	36.8	3.3	12.4

Population is in millions. Population density is persons per km².

Table 3. T-test results for annual fatal collision counts in before vs. after periods (statistically significant at 95% confidence in bold; sorted by percentage change in total fatal collisions).

	Total				Pedestrian				Bike
	Annual Fatal Collision Counts		Before→After % Change	T-test p-value (before vs. after)	Annual Fatal Collision Counts		Before→After % Change	T-test p-value (before vs. after)	Annual Fatal Collision Counts		Before→After % Change	T-test p-value (before vs. after)
	Before	After			Before	After			Before	After
New York	259.1	205.6	−20.6	<0.001	144.9	115.2	-20.5	0.003	17.9	17.2	-3.9	0.427
Chicago	138.6	118.0	−14.9	0.024	40.6	39.4	-3.0	0.408	5.2	5.4	3.8	0.376
San Francisco	33.9	30.6	−9.7	0.233	17.6	17.6	0.0	0.496	2.0	2.4	20.0	0.283
Washington	24.5	25.0	2.0	0.453	10.8	9.0	-16.7	0.224	0.9	1.5	66.7	0.138
Anchorage	18.4	19.0	3.3	0.440	5.4	6.0	11.1	0.383	0.8	0.3	-62.5	0.209
Philadelphia	90.1	93.3	3.6	0.333	30.4	35.3	16.1	0.044	3.4	2.7	-20.6	0.279
Boston	19.4	20.5	5.7	0.361	7.6	10.3	35.5	0.081	1.6	0.8	-50.0	0.182
Richmond	15.7	16.7	6.4	0.370	3.2	6.0	87.5	0.048	0.3	1.0	233.3	0.025
Seattle	23.0	24.5	6.5	0.298	8.0	9.3	16.3	0.267	1.6	2.0	25.0	0.276
San Diego	73.8	81.8	10.8	0.084	24.4	37.5	53.7	0.001	3.1	2.0	-35.5	0.187
Los Angeles	228.0	255.0	11.8	0.053	86.0	115.6	34.4	<0.001	8.0	17.2	115.0	<0.001
Fremont	7.8	9.5	21.8	0.192	2.8	3.3	17.9	0.279	0.3	0.3	0.0	0.500
Fort Lauderdale	25.5	32.5	27.5	0.079	8.8	14.0	59.1	0.023	1.5	2.0	33.3	0.288
San Antonio	117.0	151.8	29.7	0.006	31.9	52.5	64.6	0.003	2.0	4.0	100.0	0.040
San Jose	43.3	57.0	31.6	0.009	15.0	21.8	45.3	0.043	2.1	3.8	81.0	0.006
Austin	63.7	87.4	37.2	0.001	18.6	30.2	62.4	0.002	1.7	2.8	64.7	0.121
Denver	39.1	54.0	38.1	0.003	12.4	16.3	31.5	0.021	1.7	3.3	94.1	0.064
Portland	28.0	41.0	46.4	0.003	9.6	15.3	59.4	0.004	1.6	2.5	56.3	0.184

Table 4. T-test results for annual fatal collision rates in before vs. after periods (total and pedestrian per 1,000k residents, bicycle per 10,000k residents; statistically significant at 95% confidence in bold; sorted by percentage change in total fatal collision rates).

	Total				Pedestrian				Bike
	Annual Fatal Collision Rates		Before→After % Change	T-test p-value (before vs. after)	Annual Fatal Collision Rates		Before→After % Change	T-test p-value (before vs. after)	Annual Fatal Collision Rates		Before→After % Change	T-test p-value (before vs. after)
	Before	After			Before	After			Before	After
New York	31.5	24.4	-22.5	<0.001	17.6	13.6	-22.7	0.001	21.7	20.4	-6.0	0.377
San Francisco	42.3	35.6	-15.8	0.124	21.9	20.5	-6.4	0.330	24.9	28.1	12.9	0.353
Chicago	49.8	43.5	-12.7	0.031	14.6	14.5	-0.7	0.492	18.8	20.0	6.4	0.326
Washington	41.0	36.8	-10.2	0.289	18.0	13.2	-26.7	0.125	14.5	21.9	51.0	0.199
Seattle	37.9	35.0	-7.7	0.274	13.2	13.1	-0.8	0.482	26.8	28.5	6.3	0.434
Richmond	76.6	74.3	-3.0	0.439	15.7	26.8	70.7	0.072	16.3	44.5	173.0	0.041
Boston	31.1	30.5	-1.9	0.446	12.2	15.2	24.6	0.156	26.2	11.1	-57.6	0.165
Philadelphia	58.8	59.2	0.7	0.467	19.9	22.4	12.6	0.081	22.4	16.9	-24.6	0.260
Anchorage	63.9	64.5	0.9	0.481	18.8	20.3	8.0	0.405	26.9	11.6	-56.9	0.208
San Diego	56.5	58.5	3.5	0.321	18.6	26.8	44.1	0.003	24.0	14.1	-41.3	0.146
Los Angeles	60.1	64.7	7.7	0.136	22.7	29.3	29.1	<0.001	21.1	43.7	107.1	<0.001
Fremont	36.8	40.8	10.9	0.324	13.0	13.9	6.9	0.408	11.4	10.4	-8.8	0.470
Austin	82.3	94.6	14.9	0.062	24.0	32.6	35.8	0.026	21.9	30.3	38.4	0.216
San Antonio	88.0	102.5	16.5	0.047	23.9	35.4	48.1	0.010	15.0	26.9	79.3	0.070
Denver	64.7	77.1	19.2	0.037	20.6	23.3	13.1	0.168	27.6	47.5	72.1	0.113
San Jose	45.6	55.9	22.6	0.026	15.8	21.3	34.8	0.074	22.3	36.7	64.6	0.013
Fort Lauderdale	147.2	181.6	23.4	0.092	50.8	78.1	53.7	0.029	84.9	111.9	31.8	0.290
Portland	48.9	64.5	31.9	0.017	16.7	24.0	43.7	0.012	29.0	39.5	36.2	0.272

Figure 1. Temporal patterns of annual fatal collision rates (total fatalities per capita) relative to baseline years.

Cities with pre-pledge means with statistically significant differences from post-pledge means (as identified in Table 4) have thick trendlines. Cities with statistically insignificant differences have thin trendlines.

Table 5. Most significant regression models (linear, quadratic, or cubic) for post-pledge periods. Regressions explore fatal collision rates (total fatalities per capita) versus year from baseline (statistically significant at 95% confidence in bold).

	Degrees of most significant regression model	p-value	R^2	Cubic Coefficient	Quadratic Coefficient	Linear Coefficient
New York	3	<0.001	0.997	0.163	0.218	−0.642
San Francisco	3	0.067	0.881	0.653	−0.033	−0.699
Chicago	2	0.055	0.620	n/a	0.427	0.168
Washington	3	0.004	0.997	−0.313	−0.611	0.275
Seattle	2	0.094	0.792	n/a	−0.786	−0.335
Richmond	2	0.036	0.964	n/a	−1.550	−0.253
Boston	3	0.074	0.950	0.596	−0.567	−0.777
Philadelphia	3	0.046	0.999	−0.158	−0.240	0.158
Anchorage	1	0.104	0.639	n/a	n/a	−0.949
San Diego	3	0.445	0.675	0.358	0.109	−0.203
Los Angeles	2	0.086	0.706	n/a	−0.480	0.491
Fremont	2	0.043	0.877	n/a	−0.971	−1.159
Austin	3	0.550	0.461	0.653	−0.982	0.265
San Antonio	2	0.156	0.710	n/a	−0.916	−0.920
Denver	1	0.041	0.799	n/a	n/a	0.601
San Jose	3	0.182	0.875	0.738	0.840	0.227
Fort Lauderdale	1	0.005	0.889	n/a	n/a	7.829
Portland	2	0.022	0.921	n/a	−0.840	1.518

Table 6. Spearman’s rank-order correlation results for fatal collision rates (fatalities per capita) versus city characteristics (statistically significant at 95% confidence in bold).

	Total		Pedestrian		Bicycle
	rs	p-value	rs	p-value	rs	p-value
Commute Modes
Single-Occupancy	0.70	0.002	0.66	0.004	0.18	0.472
Transit	−0.66	0.004	−0.67	0.003	−0.22	0.379
Bike	−0.21	0.398	−0.24	0.327	0.03	0.895
Walk	−0.72	0.001	−0.60	0.019	−0.25	0.322
Population	−0.33	0.185	−0.23	0.348	−0.03	0.895
Population density	−0.60	0.010	−0.52	0.028	−0.20	0.422
Time since pledge	0.20	0.427	0.26	0.294	−0.04	0.876

Table 7. Regression results for fatal collision rates (fatalities per capita) versus city characteristics (statistically significant at 95% confidence in bold).

	Total R^2 = 0.679 p-value = 0.003		Pedestrian R^2 = 0.541 p-value = 0.029		Bicycle R^2 = 0.170 p-value = 0.626
	Coef.	p-value	Coef.	p-value	Coef.	p-value
Single-occupancy vehicle commute mode share	14.380	<0.001	21.663	0.009	33.959	0.130
Population	1.858	0.600	2.351	0.753	19.975	0.376
Time since pledge	0.347	0.899	−0.968	0.867	−2.597	0.880

Table 8. T-test results for action plan strategies versus fatality rates (fatalities per capita) (statistically significant at 95% confidence in bold).

	Total		Pedestrian		Bicycle
	% Difference in Fatality Rates for Low-Frequency vs. High-Frequency Action Plans	T-test p-value (Low-Frequency vs. High-Frequency Action Plans)	% Difference in Fatality Rates for Low-Frequency vs. High-Frequency Action Plans	T-test p-value (Low-Frequency vs. High-Frequency Action Plans)	% Difference in Fatality Rates for Low-Frequency vs. High-Frequency Action Plans	T-test p-value (Low-Frequency vs. High-Frequency Action Plans)
Modes
Pedestrian	−2.4	0.401	−17.7	0.069	−29.0	0.147
Bicycle	−0.9	0.441	−7.2	0.315	−51.1	0.041
Transit	−1.1	0.447	8.5	0.281	11.2	0.346
Strategies
Collaboration	6.8	0.189	17.0	0.037	−6.8	0.405
Education	7.9	0.119	10.3	0.213	−6.5	0.430
Enforcement	2.1	0.383	20.5	0.036	17.7	0.310
Speed	0.1	0.495	−6.9	0.275	10.0	0.374
Street	7.1	0.124	14.4	0.111	−6.8	0.408
Technology	−3.4	0.348	−15.1	0.077	−33.6	0.049
Treatments
Arterial	−4.2	0.297	−21.7	0.092	−27.6	0.214
Camera	−0.4	0.482	−13.3	0.225	−30.9	0.175
Crossing	11.8	0.080	1.9	0.449	−17.9	0.229
Intersection	6.9	0.238	−3.3	0.416	−33.0	0.085
Light	9.6	0.131	5.7	0.347	−40.9	0.093