Fig.1. Schematic of the Tokyo Vehicle NO_x Emission Model. (From Murdock, 1996)

Table 1 Initial Conditions for the Tokyo Vehicle NO_x Emission Model**

Parameter	Model Value for 1990*	Calc'd Value for 1995	Model Value for 1995	Units
Population	11.86	11.97	11.77	million people
Vehicle Fleet	4.529	4.965	4.617	million vehicles
Vehicle Ownership	0.382	0.415	0.392	veh/cap
Annual Traffic	50.51	53.12	51.55	109 v-km/yr
Mean Vehicle Activity	11,150	11,153	11,165	km/v-yr
Mean Gasoline E.F.	0.602	0.500	0.254	g NOx /km
Mean Diesel E.F.	3.990	3.168	2.099	g NOx /km
Total NOx Emission	52.2	51.2	51.6	kt/yr
Vehicle Fraction	71	71	67	percent
Mean Roadside Conc.	0.041	0.041	0.042	ppm
* adapted from Kruger, et al., 1998. ** data from BEP-TMG, 1994,6,7

Table 2 Traffic Activity and Weighted Mean Emission Factors by Fuel Type*

Fuel		Traffic 1994	Mean 1995 EF	Extrapolated Emission Factors			Estimated EF
Type		(109 vkm/y)	(25km/h)	2000	2005	2010	2020
Gasoline
small car		1.69	0.161	0.161	0.161	0.161	0.161
regular car		25.59	0.183	0.183	0.183	0.183	0.183
light truck		3.48	0.482	0.419	0.419	0.419	0.419
small truck		0.63	1.417	1.093	0.850	0.850	0.850
vans		2.79	0.561	0.463	0.380	0.380	0.380
special truck		0.02	3.007	2.326	1.863	1.799	1.799
LPG car		4.96	0.161	0.161	0.161	0.161	0.161
	Total (%)	39.16 (76%)
	Model Mean		0.254	0.236	0.226	0.226	0.226
Diesel
bus		0.37	5.857	4.510	3.601	3.366	3.366
regular car		2.53	0.183	0.183	0.183	0.183	0.183
small truck		2.87	1.417	1.093	0.850	0.850	0.850
vans		2.20	0.561	0.463	0.380	0.380	0.380
regular truck		3.83	4.257	3.264	2.661	2.590	2.590
special truck		0.59	3.007	2.326	1.863	1.799	1.799
	Total (%)	12.39 (24%)
	Model Mean		2.099	1.627	1.321	1.228	1.228
*based data from BEP-TMG (1996)

Fig. 2. Potential growth in the number of HZEVs in the Tokyo vehicle fleet.

Fig. 3. Potential reduction in NO_x emission as a function of HZEV growth rate.

Fig. 4. Forecast of NO_x concentration at roadside monitoring stations.