Saturday, June 5, 2010

Why it's no surprise a bike and car collided at Beacon and Grant

We also have (thanks to Nathan) the police report for the 5/27 car/bike crash at Beacon and Grant. As I suspected, it involved a car catching a gap in car traffic to turn left, in this case from Beacon eastbound to Grant northbound, and missing that there was no gap in bike traffic.

This one's not so simple.

A cyclist on Beacon heading to Newton Centre will frequently find a car in his lane stopped short of the intersection, because a) traffic is backed up from Langley to Grant, so it would block the box to continue or b) the driver is just being kind and creating a gap for an eastbound driver looking to turn left (north) onto Grant or a southbound driver on Grant looking to turn left or right on Beacon. Whether with express intent or not, the driver has created a gap for turning traffic. Call the westbound, gap-creating driver WBS (westbound Beacon straight), the eastbound driver B2GL (Beacon to Grant left), and the southbound drivers G2BR and G2BL (Grant to Beacon right and left).

But, the gap-creating rationale doesn't necessarily apply to the biker. Even if there are cars backed up from Langley, there's plenty of space to ride legally to the right, so a bike is not going to block the box. Or, the biker was not privy to the decision to informally yield the right-of-way to turning traffic. But, the gap-creating decision on the driver G's part is going to induce any of three different drivers -- B2GL, G2BL, or G2BR -- to make the turn. And, there is a potential conflict between B2GL and G2BL. However created, when there's a gap, the biker is basically riding into a gauntlet.

According to the crash report, what happened on 5/27 was pretty much the back-up scenario. One or more WBS cars stopped short of Grant. Two B2GLs caught the break in traffic and turned left from a stop. The cyclist was riding westbound, passed the stopped WBSs, realized he was going to hit the first B2GL, slammed on the brakes, and went over the handlebars. The first B2GL stopped short and the cyclist hit the car.

The B2GL should not have been across the bikers path. But, it doesn't absolve the driver to recognize that the rider showed poor judgment. Obscured by westbound traffic, he proceeded into the intersection despite the fact that the WBS cars in his lane had created a turn-inducing gap.

Contrary to my friend Nathan's suggestion, this isn't principally a striping issue. There should be (and I am confident there will be) more bike-appropriate striping through intersections on Beacon Street. But, stripes aren't armor. A bad crash happened last fall at an intersection on Beacon that is striped properly. There is no break in the shoulder stripe where the driver swerved abruptly and rode over a bicylist on Comm. Ave. the same day. And, who's to say that better through striping wouldn't induce more bicyclists to proceed injudiciously than cause motorists to proceed more judiciously.

Bigger things are necessary to reduce the stress and risk of the Beacon/Grant intersection. The intersection needs better, safer gap-making. A roundabout would be ideal. Loathe as I am to say it, if not a roundabout, maybe it's time to put a full signal at the intersection. Having ridden many, many times through all the intersections where there have been recent bike/auto crashes, this strikes me as the likeliest to have another one.


Nathan Phillips said...

Sean, I agree this particular intersection is not one where straight-through striping would have helped. This intersection is too complicated for that to be effective by itself, and the roundabout approach sounds best.
My striping concern is focused on the numerous, smaller 3-way intersections along Beacon. The striping just doesn't make sense: we are taught from day one of driving school the principles that a) one should not cross a solid line parallel to one's direction of travel, and its corollary b) that solid lines demarcate unimpeded travel paths. Here the striping violates both of those fundamental principles (from the cyclist's perspective if not the motorist's). At best it is an inconsistent application of road paint; at worst misleading to motorists and dangerous to cyclists. To defend this kind of striping would require that language be put in driver's manuals declaring this to be an exception to the general principle.

Sean Roche said...

Oh, I'm not defending this kind of striping. It's sub-optimal and I doubt we'll see the city do any of this kind of striping going forward. The issue is how high a priority should fixing these stripes compared to adding bike accommodations generally.

Mark said...

A very similar situation led to the death of a cyclist a few years ago on Commonwealth Ave in Newton. The cyclist was riding westbound to the right of a line of stopped cars. One driver made a gap to let an oncoming driver make a left turn. The cyclist did not see the turning car, the stopped cars making it difficult to see, and collided with it. This was in the vicinity of Morton Street. There is a memorial bench there today.

Nathan Phillips said...

Sean, call it a pet peeve of mine, a small daily insult as I (we) cross multiple solid lines.

Mark, I feel that motorists, with good intention, often induce dangerous actions in others. Creating the gap to allow left turning cars is one example. Stopping to wave pedestrians across when they don't have the right-of-way is another example - it is an invitation to get hit by other cars that have not cooperated in this unusual decision.

Charlie said...

The bicyclist was definitely not at fault here. It's the responsibility of the turning vehicle to yield to through vehicles.

However, this just highlights the importance of using a large dose of caution in situations like this, when a queue of cars continues through an intersection. Leaving a gap for turning traffic was the right thing for the motorists to do, as to not block the intersection. However, the visibility of bicyclists to the right of those cars is probably pretty poor for motorists turning from the opposite direction.

As a bicyclist and a motorist, I often hate it when people are "nice" and wave me on when I don't have the right of way. I fear that others who aren't paying attention may not realize what's going on. I much prefer that when people have the right of way that they take it. I'd rather wait and be safe.

gmc said...
This comment has been removed by a blog administrator.
Steve R said...

What I can't yet figure out, and I've read the accident report, is why the bicyclist was invisible to the left-turning driver.

If he was blocked by a line of cars, what was the line of cars doing there? There's no earthly reason for traffic to have stopped, unless it was backed up all the way from the light ahead at Langley, or unless (as we seem to be implying here) some nice driver stopped to let waiting drivers turn left.

Charlie, I'm with you about drivers who stop to wave me through. I'm just waiting for a rear-end collision.

Why would straight-through striping not have helped? How about a green path moving from the shoulder to the left of the right turn lane? At least then cars might also know to watch for bikes.

Would it have guaranteed safety? Of course not, but it might have triggered a second look.

We all have to remember that any engineering change might not prevent any single accident--but if handled correctly, it likely will reduce the frequency and severity of accidents, and that's all we can hope for.

Sean Roche said...


Traffic regularly backs up to Grant from the Langley light. A gap for left-turning traffic (to or from Grant) is created when westbound traffic stops so as not to block the box. Westbound traffic also stops as a courtesy, but that is -- in my experience -- less the case. Keep in mind also that it's a flashing light. Stopping to let turning traffic through is more consistent with the flashing signal than with an unsignalized intersection.

Why didn't the car see the biker?Besides the obvious -- on the right, he was tucked behind the stopped westbound traffic -- it's a stressful intersection and the driver was probably focused on taking advantage of his opportunity to get across traffic.

My contention is that, given the stress created by the traffic patterns and the intersection design, bikes are going to be off drivers radar. You're surprised that the driver didn't see the biker. If a driver doesn't see a grown man on a bike, what's the likelihood that he's going to see, pay attention to, and change his behavior as a result of stripes on the roadway?

Don't get me wrong. Stripes are always going to be better than no stripes or badly done stripes. But, the dangers to bikers in this intersection are much bigger than stripes or no stripes.

Steve R said...


You're right. My post was unwisely pre-caffeinated & I didn't read your entry carefully, nor was I recalling the many times I've seen traffic backed up from Langley.

I'm all for a roundabout there, plus some bike lane striping that instructs bikers how to take the roundabout.

We do need to think carefully about how lane markings interact with intersections, and also how they might transition into more congested village centers. And in so doing, open up conversations about how intersections are designed from the ground up. Many intersections in Newton strike me less as "designed" than as agglomerations of hodgepodge fixes. (e.g., Beacon and Hammond Pond Pkwy)

The accident map shows a lot of bike-car accidents are at intersections. No surprise there.

One proposal we might take up with city officials is to see if we can "borrow" some design work from the firm designing bike accomodations for Boston, in the interests of contiguous & safe routes into the city. (Could MAPC help fund that?) And/or send city engineers to some workshops or conferences on bike/ped-friendly design, with especial attention to options for intersections.

We've already got some interesting ideas for specific adaptations along Comm. Ave. & Washington, proposed by Northeastern students and a Tufts grad student. Can we arrange some meetings between P. Furth and our engineers?

Anonymous said...

"I feel that motorists, with good intention, often induce dangerous actions in others. Creating the gap to allow left turning cars is one example. Stopping to wave pedestrians across when they don't have the right-of-way is another example - it is an invitation to get hit by other cars that have not cooperated in this unusual decision."

Not that what you're saying is untrue, but keep in mind that cars are required to stop so as not to block an intersection, which, from what I've read, was the case in the Beacon and Grant accident.

Charlie said...

One way that striping COULD help is if there were a bike lane between the through lane and right turn only lane that then continued dashed through the intersection, similar to the bike lanes along Comm Ave in Boston by the BU Bridge. The bike lanes are dashed and painted green through the intersection. This would at least give a cue to motorists to expect bicyclists to be riding through the intersection there, to the right of the through motor-vehicle traffic.

Herzog said...


As much as I hate cycling around the BU bridge, I think that the green bicycle lane is HUGE help to all road users!

Eric said...

This strikes, no pun intended, me as another situation where through bike traffic might be better suited, as someone on this blog posted, by moving left of stopped traffic.

There's a long downhill for westbound cyclists, allowing them to merge comfortably at whatever speed they like, as the westbound cars decelerate for the oncoming traffic. Bikers would be much more visible to turning traffic left of the stopped cars.

With all the posts about being doored, or right hooked, and sharing the road, this strikes me as the one thing, that experienced regular cyclists could do to increase driver's awareness of them and increase their own safety. I can't remeber the last time I read about a cyclist head-on with an auto crash....