The land of Israel is very hilly and thus difficult to traverse efficiently. Without a highway the pilgrims travelling to the three required feasts yearly would either have to travel over the hills and valleys in a straight line to Jerusalem or, conversely, follow the meanders of valleys on a relatively level area. Neither option was ideal especially when traveling with the elderly or very young along with their flocks and herds, the pack animals and wagons.
Two main highways existed in Israel from ancient times: the Via Maris that was near the coast of the Mediterranean and the Kings Highway in the TransJordan region. A feature of the ancient highways was a built up roadway with a ditch in either side for drainage of the winter rains. The Bible draws upon this imagery to teach lessons about the spiritual life: Go not to the right or the left, turn your foot from evil (Pr. 4.27).
Don Carson at the Gospel Coalition Blog has posted a devotional on Dt. 9 that shows two opposite extremes to avoid: paralyzing fear and haughty self-reliance. In this case the highway of walking with God would be humble obedience:
IF DEUTERONOMY 8 REMINDS THE Israelites that God is the One who gave them all their material blessings, not least the ability to work and produce wealth, Deuteronomy 9 insists he is also the One who will enable them to take over the Promised Land and vanquish their opponents. Before the struggle, the Israelites are still fighting their fears. God is the one who goes across ahead of you like a devouring fire. He will destroy them; he will subdue them before you” (Deut. 9:3). But after the struggle, the temptation of the Israelites will be quite different. Then they will be tempted to think that, whatever their fears before the event, it was their own intrinsic superiority that enabled them to accomplish the feat. So Moses warns them:
After the Lord your God has driven them out before you do not say to yourself,
“The Lord has brought me here to take possession of this land because of my
righteousness.” No, it is on account of the wickedness of these nations that the
Lord is going to drive them out before you. It is not because of your righteous-
ness or your integrity that you are going in to take possession of their land; but
on account of the wickedness of these nations . . . to accomplish what he swore
to your fathers, to Abraham, Isaac and Jacob. Understand, then, that it is not
because of your righteousness that the Lord your God is giving you this good
land to possess, for you are a stiff-necked people (Deut. 9:4-6).
And the evidence for this last point? Moses reminds them of their sorry rebellions during the wilderness years, starting from the wretched incident of the golden calf (Deut. 9:4-29).
What shall we learn? (1) Although the annihilation of the Canaanites fills us with embarrassed horror, there is a sense in which (dare I say it?) we had better get used to it. It is of a piece with the Flood, with the destruction of several empires, with hell itself. The proper response is Luke 13:1-5: unless we repent, we shall all likewise perish. (2) It may be true to say that the Israelites won because the Canaanites were so evil. It does not follow that the Canaanites lost because the Israelites were so good. God was working to improve the Israelites out of his own covenantal faithfulness. But they were extremely foolish if they thought, after the event, that they had earned their triumph. (3) Our temptations, like Israel’s vary with our circumstances: faithless fear in one circumstance, arrogant pride in another. Only the closest walk with God affords us the self-criticism that abominates both.