Expert says plenty of factors to consider when widening highways
'Researchers have found if there are more lanes, crash frequency could increase or decrease'
The debate continues over whether widening all of Highway 3, from Windsor to Leamington, will make it safer.
Politicians say four lanes are needed to make it safer. At least one transit expert claims it won't make a difference. And the Ministry of Transportation's most up-to-date statistics show that the collision rate was virtually unchanged in a five-kilometre stretch that was widened from two to four lanes in 2009.
So, CBC Windsor wanted an expert's opinion. Amy Dodge interviewed University of Windsor engineering professor Chris Lee, an expert on traffic safety and road design.
Here's what he had to say:
1. Generally speaking, are four lanes better than two?
It's hard to say that more lanes increase safety.- Chris Lee, University of Windsor engineering professor
The number of lanes has mixed effects. An increased number of lanes can increase the speed. In the meantime, more lanes can avoid the conflict with other vehicles. It's hard to say more lanes increase safety. It depends on the type of vehicles. If there are more trucks and heavy vehicles, more lanes should help.
2. So, what does the scientific evidence and statistics show when it comes to four-lanes versus two lanes?
Using historical crash records we can develop statistical models. In the past, researchers have found if there are more lanes, crash frequency could increase or decrease. It depends on the vehicle mix. If most vehicles are passenger cars, if there are more lanes, they travel at higher speed. If there are more heavy vehicles and slow-moving vehicles, more lanes should help. You improve safety, eventually.
3. What effect do barriers and/or medians — or the lack thereof — have on the safety of a highway?
If there are physical or raised medians, it can help prevent cross-media crashes and head-on collisions. Although, it increases the chance of hitting the barrier. Relatively speaking, hitting the barrier is less severe than hitting a vehicle coming from an opposite direction.
4. If overpasses and on and off ramps aren't part of four-lane highway, how important are stoplights and traffic signals? What role do they play?
If there are traffic lights, vehicles are more likely to stop and go. This can potentially increase the chance of rear-end collisions. In the meantime, if there are traffic lights, the drivers should [end up being] more careful because they are more cautious when they approach an intersection.
5. What, if anything, does research show about driver behaviour on two- and four-lane highways?
Psychologically, drivers should be more comfortable if there are more lanes. So, they'll probably travel at higher speeds. If they find any slow moving vehicles ahead, they're more likely to change lanes and take the faster lane.
6. What other options are there to make a highway safer, other than widening the road to four lanes?
Lane width. If the lane is wider, drivers have more space for manouvering their vehicle. Drivers also feel more comfortable because the space between two vehicles in adjacent lanes is larger. Most research in the past found a wider lane is safer than a narrow lane.
Rumble strips obviously help, particularly when the drivers are tired and not cautious after long drives. When they're alerted, they can easily take their proper position on the roadway and avoid a potential collision.
With files from Amy Dodge and Greg Layson