Does the capacity of the road influence how many agents can travel down it simultaneously?

Does the capacity of the road influence how many agents can travel down it simultaneously?

No. Number of lanes and whether there are stop signs or traffic lights only affect traffic agents. They do not affect non-traffic agents.

• Traffic agents include police, fire, ambulance, garbage trucks, delivery trucks, moving trucks and of course sims driving their cars.
• Non-traffic agents include power, water, sewage and of course pedestrian sims.

Power and water agents are absorbed as they pass buildings with available capacity. While the agents aren't affected by road capacity, they can be depleted by passing many buildings. If you layout your city with a powerplant at position 1, it is unlikely that agents will reach buildings at position 2.

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Update: There was a sewage issue fixed in patch 1.8.

Fixed a clog in the pipes where sewage would sometimes get backed up and act jittery.