Why a Shorter Route Can Take Longer
On a typical U.S. street, a driver making a left turn must cross the paths of vehicles coming the other way. In busy traffic, that can mean waiting for a gap or sitting through a signal cycle. A delivery truck may also need more room to swing through the turn, so the maneuver can be slower and less predictable than following the road around a block and turning right.
Route planners weigh more than distance. They estimate how long each road segment and intersection is likely to take, then choose a sequence of stops that can keep the vehicle moving. If a left turn is expected to cause a long wait, a slightly longer route with easier turns may get the driver to the next stop sooner.
Fewer Difficult Crossings, Not No Left Turns
Avoiding a left turn can also reduce the time a truck spends exposed in an intersection, where it must cross oncoming lanes. That matters for safety, but routing systems cannot remove every such turn: street layouts, one-way roads, traffic conditions, and the locations of deliveries all constrain the choices. A detour also uses extra road distance, so the best route is a tradeoff rather than a blanket ban.
The practical payoff is cumulative. A few minutes saved at several difficult intersections can make a delivery route more reliable, even when the truck travels farther. The long way around can be the faster—and less exposed—way through the day.
