NE2 asked: Why is 14 feet the accepted minimum for a “substandard-width” lane. Florida Statute 316.515(1) says that a vehicle may be 102 inches (8.5 feet) wide, not including safety devices (e.g. mirrors). I don’t know how far mirrors are allowed to stick out, but I would assume at least 6 inches on each side. With a 3 foot passing clearance, that leaves only 1.5 feet for the bike in a 14-foot lane, certainly not enough for safe operation.
You have correctly cited the applicable statute.
s. 316.515 – Maximum Width, Height, Length
(1) Width Limitation – The total outside width of any vehicle or the load thereon may not exceed 102 inches, exclusive of safety devices determined by the department to be necessary for the safe and efficient operation of motor vehicles.
Vehicles that are even wider may be encountered on the roadways. It is not realistic to try to define a substandard-width lane based on the widest vehicle that could possibly be on the road. Rather, it is defined based on the safety of the roadway users.
We must look at this question from the different perspectives of the cyclist and the overtaking driver.
A substandard width lane is defined in the bicycle regulations, and is one of the many conditions and circumstances that gives the cyclist the right to leave the right-most curb or edge of the roadway. I believe the intent of that provision is to allow a cyclist to control the lane and discourage unsafe passing within narrow lanes. Note that the statute does not specify the actual width of a substandard-width lane.
s. 316.2065 – Bicycle Regulations
(5)(a) 3. For the purposes of this subsection, a “substandard-width lane” is a lane too narrow for a bicycle and another vehicle to travel safely side by side within the lane.
Without regard to the width of the lane, the burden for safety when overtaking and passing a bicyclist lies entirely with the overtaking driver if the cyclist is otherwise obeying the law. The driver must pass at a safe distance, and no less than 3 feet.
s. 316.083 – Overtaking and Passing A Vehicle
(1) …. The driver of a vehicle overtaking a bicycle or other nonmotorized vehicle must pass the bicycle or other nonmotorized vehicle at a safe distance of not less than 3 feet between the vehicle and the bicycle or other nonmotorized vehicle.
The driver of the overtaking vehicle must make the determination that it is safe before passing. The driver of a Smart Car may be able to safely pass within a 12-foot wide lane if the cyclist is to the right. The driver of the vehicle you describe in the question will have to wait until it is safe to change lanes to pass a cyclist in a lane that is 14 feet or even wider.
The width of 14 feet is derived from Florida Department of Transportation planning and design guidelines. Note that they also indicate the 14 feet is the width that allows MOST motor vehicles to safely pass a cyclist while remaining within the lane. Drivers of wider vehicles must change lanes to pass.
Plans Preparation Manual
Chapter 8 – Bicycle Facilities
Section 8.4.3 Wide Curb Lanes
Wide outside curb lanes are through lanes which provide a minimum of 14 feet in width. This width allows most motor vehicles to pass cyclists within the travel lane, which is not possible in more typical 10-12 foot wide travel lanes.
Manual of Uniform Minimum Standards for Design, Construction and Maintenance for Streets and Highways (Florida Greenbook)
Chapter 9 – Bicycle Facilities
B.3 Curb Lanes
Fourteen feet is the recommended lane width for shared use in a wide curb lane, and is the minimum width that will allow passenger cars to safely pass bicyclists within a single lane.
More detail of the various rights and responsibilities of roadway users can be found in the post on Substandard-Width Lanes.