A Modified 𝑝-Median Model for the Emergency Facilities Location Problem and Its Variable Neighbourhood Search-Based Algorithm

Table 1

The computational results for the ORLIB pmed1–40 instances.

Number	𝑛	𝑝	Opt.	Result	Error (%)	Iterations
pmed1	100	5	5819	5819	0	28
pmed2	100	10	4093	4093	0	311
pmed3	100	10	4250	4250	0	355
pmed4	100	20	3034	3034	0	59691
pmed5	100	33	1355	1355	0	520295
pmed6	200	5	7824	7824	0	46
pmed7	200	10	5631	5631	0	364
pmed8	200	20	4445	4445	0	172840
pmed9	200	40	2734	2734	0	5851762
pmed10	200	67	1255	1255	0	19672781
pmed11	300	5	7696	7696	0	335
pmed12	300	10	6634	6634	0	9216
pmed13	300	30	4374	4374	0	1329065
pmed14	300	60	2968	2968	0	12960824
pmed15	300	100	1729	1729	0	1121054
pmed16	400	5	8162	8162	0	246
pmed17	400	10	6999	6999	0	5761
pmed18	400	40	4809	4809	0	5767360
pmed19	400	80	2845	2845	0	489788
pmed20	400	133	1789	1789	0	750728
pmed21	500	5	9138	9138	0	85
pmed22	500	10	8579	8579	0	7461
pmed23	500	50	4619	4619	0	36678
pmed24	500	100	2961	2961	0	32685
pmed25	500	167	1828	1828	0	3725367
pmed26	600	5	9917	9917	0	159
pmed27	600	10	8307	8307	0	2551
pmed28	600	60	4498	4498	0	36304
pmed29	600	120	3033	3033	0	5343570
pmed30	600	200	1989	1989	0	2146715
pmed31	700	5	10086	10086	0	57
pmed32	700	10	9297	9297	0	20694
pmed33	700	70	4700	4700	0	568705
pmed34	700	140	3013	3013	0	61781
pmed35	800	5	10400	10400	0	296
pmed36	800	10	9934	9934	0	15857
pmed37	800	80	5057	5057	0	1162436
pmed38	900	5	11060	11060	0	2430
pmed39	900	10	9423	9423	0	642
pmed40	900	90	5128	5129	0.019501	1149577
Average	—	—	—	—	0.0005	1575673