Possibly Dark is the Sun by Philip Jose Farmer:
Fifteen billion years from now, Earth is a dying planet, its skies darkened by the ashes of burned-out galaxies, its molten core long cooled. The sunless planet is nearing the day of final gravitational collapse in the surrounding galaxy. Mutations and evolution have led to a great disparity of life-forms, while civilization has resorted to the primitive.
Young Deyv of the Turtle Tribe knew nothing of his world's history or its fate. He lived only to track down the wretched Yawtl who had stolen his precious Soul Egg. Joined by other victims of the same thief - the feisty Vana and the plant-man Sloosh - the group sets off across a nightmare landscape of monster-haunted jungle and wetland. Their search leads them ultimately to the jewelled wasteland of the Shemibob, an ageless being from another star who knows Earth's end is near and holds the only key to escape.
The novel has already been asked about several times over the years. The description of the roads is:
The ancients had had great powers, though not enough to keep them from dying out. This highway, for instance, had existed long before Deyv's great-great-great-great-grandfather was born, and probably many generations before that. But it was not overgrown with plants, nor had trees been able to tear it apart. The green life, except for a short grass, encroached but withered when within sixty feet of the
road. Floods sometimes washed out the earth beneath it here and there. By some magical means, earth sifted back under it and packed down. Earthquakes twisted it, but as time went on, it straightened out.
And the traffic lights:
He also looked at, but did not go close to, the strange objects at the junction. There were four tall metallic posts, each bearing a round box with four round eyes. Deyv had never heard of these. Though they seemed to be inanimate, he did not care to investigate an unknown work of the ancients. If the posts were their totem poles, it was dangerous to get too close to them. As everybody knew, totem poles were charged with magic: good magic for those who came under their protection, bad magic for their enemies.
When Deyv was about a hundred yards from the junction, the poles clanged, and the top eyes of the two poles facing him gleamed bright with a green light. Startled, Deyv gave a little leap and gasped. Turn barked once and was silent. Aejip growled. For a long time, Deyv stood still, his eyes on the glowing green lights. Then, slowly, he backed away. Suddenly, the eyes went dead, and three clangs came from the two poles.
The traffic lights are not exactly worshipped, but more propitiated. The party meet a woman Vana who has found a way to control the lights:
Near sleep-time they came to another junction. Deyv started to detour around the poles, fearing a recurrence of the shocking incident, but he stopped when he saw Vana's curious behavior. She had boldly walked up to the poles. Before reaching the intersection, however, she sank to her knees. After bowing deeply three times and chanting at the same time, she rose and walked between the poles.
Deyv was amazed. He had thought that these clanging, light-flashing things were strange animals. It had not occurred to him they might be gods of some sort. They'd accepted her prayers and let her through.
