April 3, 2013
‘Permitted’ Left Turns Pose Serious Danger For Pedestrians
Michael Harper for redOrbit.com — Your Universe Online
Executing a ℠permitted´ left turn while driving through your neighborhood can be a risky maneuver. These are different from the ℠protected´ left turns, which are indicated by a solid green arrow. Permitted left turns are allowed when there´s a break in oncoming traffic. This means drivers who attempt this tricky turn may only be focused on cars hurtling towards them and not other potential risks — like pedestrians.
A new study from Oregon State University (OSU) has shown that permitted left turns are particularly dangerous to pedestrians. According to their research, four to nine percent of the time, drivers don´t bother to check for bikers or walkers before they make their turn.
Assistant professor of transportation engineering at OSU David Hurwitz claims that crosswalks are already dangerous enough, but the sometimes confusing signals which permit a left turn make these pedestrian areas even more dangerous.
“There are far more pedestrian crashes in marked crosswalks than anywhere else on roads, and pedestrians already have a false sense of security,” said Hurwitz in a statement. “This study found that one key concern is permitted left turns.”
What´s worse, the study found that in particularly busy intersections, drivers in a left turn lane pay even less attention to cross-walking pedestrians compared to less-trafficked intersections.
Hurwitz and a team of engineers created a simulation in their labs to measure how frequently drivers check their surroundings before executing a permitted left turn.
The team created a full-scale driving simulator which monitored the eye movements of volunteer drivers. According to their results, drivers only check for pedestrians one time in ten or twenty turns. This presents a significant risk to pedestrians who, according to the researchers, believe that drivers are looking out for them before turning left.
Hurwitz and his team blame cities and states for implementing confusing and conflicting traffic signals which allow permitted left turns. According to the study, the government was urged as early as 2009 to create a consistent standard across the US, but the process of changing the millions of signals across the nation is a lengthy and expensive one. Washington County in Oregon recently prohibited these left turns, a move which Hurwitz hopes other pedestrian-friendly counties will follow.
“In traffic management you always have multiple goals, which sometimes conflict,” explained Hurwitz.
“You want to move traffic as efficiently as possible, because there´s a cost to making vehicles wait. You use more fuel, increase emissions and waste people´s time. The permitted left turn can help with efficiency.”
“But the safety of the traveling public is also critical,” continued Hurwitz. “Sometimes the goal of safety has to override the goal of efficiency, and we think this is one of those times.”
New traffic signals are equipped with four heads, one of which is used to indicate a permitted left turn. Yet the OSU study found that these new signals are an expensive option which do not change a driver´s behavior.
Cities pay upwards of $800 to install just one of these new signals, yet retrofitting the older three headed models to display a permitted left turn could end up saving US cities and states millions of dollars.