The Right Side of a Turning Tractor-Trailer with a Cyclist in the Bike Lane
You are stopped in the right-hand lane of a four-lane arterial in Dartmouth, waiting at a red light. Directly ahead is a 16-metre tractor-trailer loaded with gravel, with a "Caution - Wide Turns" placard on the back. A marked bike lane runs along your right, separated from the traffic lane by a solid white line. A cyclist has ridden up beside you and is now level with your right rear door, one foot on the pavement. The truck's right turn signal begins to flash, and the cab edges left, angling toward the left side of its lane while the trailer wheels stay straight. The light turns green, the cyclist begins to pedal forward along the bike lane, and your passenger tells you to move up so you don't lose your place.
1. What is the truck driver doing, and why is the space on its right about to disappear?
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The driver is setting up a wide right turn. A long wheelbase trailer cannot follow the cab around a tight corner without the rear wheels tracking inside the cab's path - over the curb, a sign pole, or a cyclist. So the driver swings left first, then turns right, and the trailer's rear wheels cut the corner.
That means the cab angling left does not mean the truck is turning left; the right signal tells you the real intention, and you should believe the signal plus the placard. As the turn develops, the space along the truck's right side closes like a door. That space is exactly where the cyclist is and where your car would be if you moved up. Large vehicles also have a deep blind spot along the right side and directly behind the trailer; a good working rule is that if you cannot see the driver's mirrors, the driver cannot see you. Never enter the gap on the right of a turning heavy vehicle, even on a green light, even if the gap looks wide enough.
2. What do you do about the cyclist, and what do you deliberately avoid doing?
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You cannot steer the cyclist, but you can avoid becoming part of the hazard. Hold your position: do not creep forward, and do not swing right into the bike lane, which would either strike the cyclist or squeeze them toward the trailer. Leave the bike lane completely clear so the rider has somewhere to go.
If the cyclist is clearly about to ride into the trailer's path, a short tap of the horn may be justified - the alternative is a fatal crush - but do not lean on it, and do not expect a startled rider to react predictably. Give them room to stop or to swerve left into your lane if they must; that is another reason to stay back rather than nose forward. Your passenger's concern about losing your place in traffic is worth nothing against a collision between a bicycle and a loaded trailer. Wait until the truck has completed the turn and the bike lane is clear.
3. Once the truck is moving, how closely should you follow, and how would you pass it?
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Leave at least three to four seconds, and more in rain or at highway speed. The truck blocks your view of the road two or three vehicles ahead, so you cannot anticipate the braking that will reach you a second late. Gravel loads shed stones, heavy tires throw spray, and a sudden stop by a loaded trailer is not something you want to discover at a one-second gap.
When you pass, do it on the left, decisively: signal, mirror and shoulder check, then move through the truck's blind spot rather than pacing alongside it. On a multi-lane road, confirm the lane is clear ahead before you commit, because being trapped beside a truck that begins to change lanes is a bad place to be. Do not pass on the right, where the blind spot is largest and where the driver may be positioning for a turn. Once past, do not cut back in front - leave enough room that the truck can stop without your bumper in the way.