ENOUGH KILLING: How to Make Bike-Car Collisions Less Deadly

It’s important to know that the huge increase in bicycling in Boston has been accompanied by a much small increase in bike-car collisions, meaning that the accident rate has gone down.  It’s yet another validation of the “Safety In Numbers” principle.  It’s not that the new cyclists are more skilled than the previous ones, or that a higher percentage of them are wearing helmets. It’s simply that the more people on bikes the more that drivers become aware and accepting of their presence, leading to a lower rate of collisions and injuries. But that doesn’t make it any less upsetting to learn that yet another bicyclist has been killed by a motor vehicle. The fifth this year. Yet another ghost haunting our streets. The police haven’t issued a final report on this latest tragedy, so the following is based on what has been available in the newspapers and on-line.  But here is my best guess of what happened, and some suggestions about how to make it less likely to happen again.


Twenty-three year old BU graduate student, Christopher Weigl was cycling down Commonwealth Avenue on his way to class.  It’s a down-hill grade in that area and the light ahead of him was green.  If he did what most people (including myself) do in that stretch of road, noticing that none of the cars in the lane immediately to his left had their right-turn blinkers on, he sped up as he approached the intersection.

The tractor-trailer driver, working for an out-of-town firm, was also coming down Commonwealth and getting ready to make a right turn on to St. Paul street.  He was in the far-left lane because the size of his vehicle required a large turning radius.  Knowing that his turn would block both car lanes, and noticing a break in the traffic, he pulled a sharp and quick right.

Even if the truck had its turn blinkers on, it’s unlikely that Weigl could see the truck coming from two lanes to his left.  Even if he thought to look (and could see) over the cars on his right  it would also be difficult for the truck driver to notice a fast-moving cyclist who probably was still a  hundred feet or more before the intersection when he turned his wheel and hit the gas.

By the time Weigl saw the truck in front of him it was too late.   News reports say that we was wearing a helmet, but it wouldn’t have mattered – it seldom matters in a collision drastic enough to kill.  It’s not clear if Weigl was instantly killed by the impact or fell under a wheel before the driver could stop, which is the usual cause of death when someone is doored and is then thrown outwards into the street – which is what happened a couple years ago to a young women in Cambridge’s Central Square and may be what happened to the cyclist killed earlier this year in South Boston.


There are a couple of possible preventive lessons in this.  Yes, cyclists should be very careful when approaching intersections – you may be dead right, but you’re still dead.  But that’s not the real issue here – no one was acting illegally or irresponsibly or stupidly.  Everyone was doing what they were supposed to;  and someone died.

First, the city and state should enforce the law forbidding two-lane right turns.  They’re simply too dangerous – accidents waiting to happen.  If the intersection isn’t big enough for a tractor-trailer to make a one-lane turn, then they shouldn’t do it – and neither should car drivers no matter what their turning radius.  (And this is yet another good reason to start installing intersection cameras!)   A more drastic approach would be to ban 18 wheelers from the city either all the time or during certain hours. Deliveries should be done with smaller box trucks. They are not only safer when moving but take up less curbside space. This is what they do in bike friendly cities in Europe.

Second, to prevent under-wheel killings, the state should require all large trucks, tractor-trailers, and buses to have “side guards.”   These are railings or flat sheets between the wheels that both save fuel by making the truck more aerodynamic and save lives by preventing bicyclists, motorcyclists, scooter-riders, and pedestrians from sliding under the wheels.   They’re expensive,  costing $800 to $2,000 to install.  On the other hand, they work:  side guards have been mandatory in Europe since 1989;  after Britain adopted a side-guard requirement one study found that fatalities dropped 61% in cases where bikes collided with the side of the truck.  It all depends on your priorities.

Portland, Oregon now puts side guards on all municipal trucks.  Since the purpose is to prevent people from getting swept under the wheels, something that almost exclusively happens when the driver is turning right (partly because the driver is less able to see what’s approaching from the right than from the left) , the city only places them on the right side of the truck.  In Canada, Newfoundland and Quebec have put side guards on their government-owned truck fleets.  (British sites provide technical details about fitting side guards on various types of trucks, including retractable side guards for trucks that get tipped,  e.g. dump trucks, or those that drive over extremely uneven surfaces, e.g. logging trucks.

Third, we have to lower speed limits and build our new expectation into the very structure of the road.  A car going 40 mph has an 80% chance of killing anyone it hits.  Reducing the speed by half decreases the likelihood of death to 5%.   Dense commercial and residential areas should have a default limit of 20 mph – or less.  Walk Boston and other advocacy groups are working on a bill to do this on a state-wide basis.  Defining the street segments to be affected and how to measure speed violations turns out to be very difficult, but when the final wording is determined we all need to support it.  In addition, we need to give municipalities the right to create “Safety Zones” around not only schools but also parks, playgrounds, senior centers, and health care facilities with speed bumps that make it uncomfortable to drive faster than 15 miles per hour.

Fourth, Complete Streets are not enough – unless the program mandates more protected bike lanes along major roads or turns certain streets into “bicycle boulevards” with special bike-prioritizing traffic signals at intersections.   This would not only provide a lower level of traffic stress, thereby inviting lots of additional people to try bikes and playing into the Safety In Numbers dynamic, but make it more likely that right-turning car (and truck) drivers would actually see cyclists.

Even better would be the creation of a cross-town series of bike “corridors.”  These would be composed of off-road paths through our parks (like the ones in the Emerald Necklace) or along our waterways (like the ones along the Charles and Neponset rivers).   They would include separated-from-traffic protected bike lanes – set up using painted lines, flexible buffers, or well-placed parked cars (as already exists on Western Avenue heading towards the Charles River), or even curb-separated cycle tracks (such as those being proposed for Melnea Cass and Malcolm X Boulevards).  The Corridors could also include low-traffic, usually residential “neighborways” which have been specially signed and shaped to keep cars at a low, child-safe speed.  And they could have some sections of “Bicycle Boulevards” which are larger, longer stretches of road that have been restructured to prioritize bicycle travel (such as might be possible along one side of upper Commonwealth Avenue).

At a minimum, all of DCR’s Parkways should be restriped to create buffered bike lanes.  This would also be fitting because, in the best of all possible futures, the Corridors would be treated like extensions of our parks into our neighborhoods – tree-lined, with water-runoff catchments, and occasional play spaces for local children to use, which is why those of us working for this vision describe it as a Green Routes system.

None of this will bring back Weigl or the other four cyclists killed by cars, trucks, and buses.  But it may reduce the number of future deaths.   We’ve got enough white bicycles.


Thanks to Alex Epstein for the side guard idea and Charlie Denison for suggesting the truck ban.


Related Previous Postings:

VULNERABLE ROAD USERS (VRU) PROTECTION LAWS: “Whoever Can Do The Most Damage Has To Be The Most Careful”


GREEN ROUTES TO THE FUTURE: Combining Regional Vision and Local Initiative to Revitalize Urban Transportation and Well-Being

PARKS, GREENWAYS, AND TRANSPORTATION: Increasing Usefulness By Combining Visions

SAFE CYCLING:  Actual, Subjective, Social; Solo or Group

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