Some of the most common types of accidents on the road are collisions involving left turns. In previous posts, we’ve discussed how left turns are relatively complex maneuvers and how driver behaviors and distractions play a large role in these collisions. In this post, we will focus on how intersection design can also play a role in left turn accidents. We will discuss what makes certain intersections more dangerous and how this infrastructure can be improved to prevent left turn collisions.
- Uncontrolled or Poorly Marked Intersections
The absence of clear markings or control devices at intersections can be large contributing factors to left turn collisions. Unmarked intersections have no stop signs, yield signs, or traffic lights. This design can cause confusion among drivers about who has the right of way. Left turning drivers must be able to clearly signal their intentions to oncoming traffic and other drivers. At uncontrolled intersections, it is good practice to attempt to make eye contact with other drivers to confirm that they see you.
- Lacking Left Turn Lanes
Intersections without dedicated left turn lanes can be more complicated for left turning drivers. Drivers who are attempting to execute a left turn must wait for a safe gap in oncoming traffic. While waiting, they may feel pressured by other drivers behind them waiting to proceed straight through the intersection. Even under pressure, drivers should never attempt to make a hasty left turn and should always wait for a safe gap in traffic.
- Poor Visibility
Some intersections have better visibility than others. Obstacles like buildings, trees, miscellaneous infrastructure and even large vehicles can block the views of left-turning drivers. It is always important to proceed with caution prior to making a left turn, but this is especially important in a low visibility scenario. Never try and complete a left turn if you do not have a clear view on oncoming traffic, the traffic signals, or obstacles in the crosswalk.
- Complicated Signals
Often times, busy intersections will employ a combination of signals such as dedicated left turn signals, pedestrian crossing signals, advanced green signals and signals directed at multiple left turn lanes. When signaling is more complex, drivers attempting to make a left turn may become distracted or confused. If possible, it is best to familiarize yourself with complex intersections in advance or make your left turn at an alternate intersection.
- Geometry and Traffic Flow
The traffic flow of an intersection can plays a large role in the likelihood of an accident. One example of this would be intersections designed to compel left-turning drivers to make tight left turns, leaving little room for error. Multiple left turn lanes may be very close to each other, and drivers must be careful not to turn too wide when executing a left turn. For left-turning drivers, it is important to maintain awareness of intersections markings to avoid encroaching on another lane.
- Bicycles and Pedestrians
Some intersections have heavier pedestrian traffic flow than others. It is common to see very heavy pedestrian traffic at urban intersections, and it is vital that left-turning drivers have a clear view of the crosswalks they will need to pass. It is important never to rely on traffic signals alone, and drivers should still scan the intersections even if pedestrians do not have the walk sign.
Engineering Solutions for Safer Intersections:
There are various innovative engineering solutions intended to mitigate preventable left turn collisions:
- Roundabouts: Roundabouts allow for continuous traffic flow and more predictability in terms of traffic direction.
- Protected Left Turn Phases: Intersections with designated green arrows for left-turning drivers eliminates the need to wait for a gap in oncoming traffic.
- Improved Sight Lines: Maintenance is key when it comes to traffic infrastructure, including trimming vegetation and removing obstacles to improve visibility.
- Traffic Calming Measures: Speed bumps and slower speed limits afford drivers more time to react to unexpected situations.
The Role of Advanced Technology in Intersection Design:
It is important to mention that technological advancements may eventually play a crucial role in reducing left turn accidents. In previous posts, we’ve discussed the roles of artificial intelligence, autonomous vehicles and algorithmic infrastructure in improving traffic safety. New intersections should be designed with these advancements in mind.
Intersection design can play a huge role in the likelihood of left turn accidents. Municipalities should be keenly aware of these factors so that they can make necessary improvements to high-risk intersections. As drivers, it is important to recognize when an intersection is potentially dangerous for left turns. If you feel uncomfortable completing a left turn at a particular intersection, it may be best to proceed straight through the intersection and make your left turn at a safer point.