Narrowing Lanes -
Why Toronto's Traffic Department Couldn't Be More Wrong
|The City of Toronto
plans to narrow
lane widths to improve traffic safety. However,
believe that narrow
lane widths are associated with higher
source Huff Post
||Buses are 10.5 feet wide when counting
mirror-to-mirror width. That gives bus drivers a cushion of 3 inches on
either side of the bus in an 11-foot
lane on Sir Francis Drake
Pray they are awesome drivers through the curves.
While John Tory, the mayor-elect, has already
endorsed the City's plans, he and the traffic
experts at the City must review traffic safety
studies that conclude otherwise.
A front-page story in the
Globe and Mail reported that the city is exploring
options to reduce road
lane widths to improve traffic safety. City's
traffic department believes that narrow
lane widths will result in reduced speeds, which
they think will improve traffic safety. Stephen Buckley, the
general manager of the City's Transportation services
department, told the Globe that
lane widths in the downtown core in
American cities are already down to 10-feet.
While the City's traffic department sounds confident in its assertions, its
recommended guidelines on
lane widths are in stark contradiction to what we
know from traffic engineering and safety
lane widths by default have higher
accident rates. Even more disconcerting is
the City's backgrounder on
lane width guidelines, which states that traffic
"throughput is independent of speed." Nothing could be
more wrong about traffic flow than this statement.
I had the privilege of studying under Professor Emeritus Ezra Hauer, who is a
world-renowned expert on traffic safety. In a
lane widths, Prof. Hauer wrote: "under identical
traffic conditions, roads with:
- 10 foot
lanes have 5% more
- 12 foot
lanes have 1% more crashes than
- 11 foot
He further explained that while 3-metre wide
roads had more crashes than 3.75-metre wide roads,
the difference between 3.65-metre and 3.75-metre roads was not significant.
Professor Hauer is not alone in raising concerns about narrow
lane widths. Most
traffic-engineering experts have concluded the same. In a paper published
in 2014 in the journal Safety Science, the
University of Alberta's academics found a
statistically significant and negative correlation between
lane widths and
accident rates. They explain the reasons why wider
lanes are safer than
lanes. "Basic engineering knowledge suggests that
lanes contribute to safer transportation facilities"
because "any action that makes a task easier to perform will make that task
safer to perform." Remember, wider
lanes make it easier to drive and hence improve
There are even gender dimensions to this issue.
study published in
Accident Analysis and Prevention
women were likely to experience more
accidents than male drivers in "heavy traffic
reduced median widths, narrow
lane widths, and large number of
It is important to note that some published research concluded that wider
Individuals, who are not traffic engineering experts, have usually authored such
studies. Consider, for example, a
study by Prof. Reid Ewing and Eric Dumbaugh in which
they argue that
lanes exceed 11 feet in width." The authors,
unfortunately, have misread and misquoted Prof. Ezra Hauer's research that
concluded exactly the opposite.
traffic services department plans to exempt bus and
transit routes from
lane width reduction.
The exemption is motivated by a concern about buses
being wider than cars and hence the need for wider
Just like public transit buses,
fire engines, ambulances, and
school buses are also wide-body vehicles,
which are not restricted to operate on designated routes.
lane widths will influence the ambulatory response
times in the downtown core.
It is important to recognize that downtown
Toronto is not merely an employment hub,
but also a hub for health care facilities.
Most advanced trauma centres, birthing centres, specialized hospitals for women
and children are located in downtown Toronto.
lane widths in and around downtown Toronto will
worsen travel times
increase access and egress times to and from the
primary health care facilities.
The backgrounder on
lane with guidelines states that traffic flow is
independent of speed or
lane widths. This is in
contradiction of the fundamental equation of traffic flow, which states
that throughput (traffic flow) is essentially a function of two variables, i.e.
traffic density and speed. Narrow
lane widths will lead to lower traffic
speeds, which will reduce the traffic flow through
the urban core.
The City's backgrounder on
lane widths further states that regardless of their
speed, cars maintain two second spacing between them.
Again, the fundamental equation of traffic flow states that the spacing between
increases with speed.
What concerns me even more is that the City's
guidelines claim that reducing
lane widths will not reduce traffic speeds or
However, the City's traffic department gives a different message to the
newspapers revealing that
the purpose of
lane width reduction is primarily to reduced traffic
What is the logic behind issuing contradictory statements?
Traffic engineering offers a whole host of traffic calming solutions to lower
speed on urban arterials.
Accidents occurring at lower speeds have lower fatality rates than
those at higher speeds.
However, system-wide narrowing of
lane widths is likely to worsen traffic safety in
the City and not improve it.
Remember, the road to hell is paved with good intentions. Let us not be