If Each of the roads has 250 street lights on each opposite side, the total number of street lights on one road is 250*2 = <<250*2=500>>500
Since each neighborhood has four roads passing through it, the total number of street lights in one neighborhood is 500*4 = <<500*4=2000>>2000 street lights.
The town has ten neighborhoods, and since each neighborhood has 2000 street lights on all its roads, there are 2000*10 = <<2000*10=20000>>20000 street lights in the town.
#### 20000