I'm all for the new 4-foot safe passing buffer but the issue goes way beyond whether the police will enforce the 4-foot buffer law or not.

Consider the following:

Let's start with a road that has curbs on both sides and a double-yellow line down the center. Let's say that the double-yellow line takes up one foot of the road's surface. And let's have a bike rider riding some distance from the curb.

Some state DOTs and various cycling publications suggest that bike riders position themselves about 3 feet from the curb. Why is this? The argument is that the edge of the road is frequently where drainage grates are placed and also where debris collects. Also, bike riders need to have at least some space to move right if a car or truck is passing them too closely. Also, hitting a pedal on the curb when riding too close to the curb would be catastrophic.

So, there are some pretty good arguments for riding 3 feet from the curb. But let's be "good" cyclists and compromise a little. Let's say we ride 18 inches from the curb. Less than that is clearly dangerous.

Now, if our tires are 18 inches from the curb, how far from the curb would the closest-to-traffic part of our bike be? If you're riding a straight-handlebars bike (as opposed to drop bars), a typical total width is about 36 inches such that 1/2 of that width extends to the traffic-side of your tires. Thus, if you're tires are 18 inches (and they could be more) from the curb, the end of your traffic-side handlebar would be 3 feet from the curb.

Still with me?

Then add the 4-foot safe-passing buffer. That means that a passing car should be a minimum of 7 feet from the curb if the bike rider is only 18 inches from the curb.

Here's where the issue gets complicated for local cities and towns.

Large sedans (e.g. SUVs) and pickup trucks can be close to 7 feet wide. Larger commercial trucks and emergency vehicles can be much wider than that. Let's just use a width of 7 feet.

How wide would a road with a double-yellow line have to be, in total, to allow a vehicle to pass a bike rider without riding on or over the double-yellow line? This is the real issue here. Some some towns might need to implement laws to prohibit cars and trucks from passing a bike rider AT ANY DISTANCE on some roads because some roads are too narrow.

Why is this?

If we add all the stuff we have to fit on half the road, i.e., the rider's distance from the curb (1.5 feet), one-half the handlebars (1.5 feet), a 4-foot safety buffer, and a 7-foot car or pickup truck, we need a one-direction total of 14 feet. If the bike rider is more than 1.5 feet from the curb, we need even more than 14 feet. Now, double that because the road has one lane in each direction requiring a 28-foot width. And, finally, add one foot for the double yellow line area.

The bottom line is that roads with a double yellow line need to be a minimum of 29 feet wide. In my town, which is likely typical of many towns in Massachusetts, very few of our roads are this wide. The larger roads, i.e., those with a double yellow line down the center, are right around 29 and 30 feet wide.

The town could switch from a double yellow to a single yellow but this is not necessarily a safe thing to do. They could, as some have suggested they're likely to do, just choose to not enforce the law. Or, at least on some roads, they could make it illegal to pass a bike rider at all.

This new 4-foot buffer law is going to unleash some very interesting discussions. As the old saying goes, that which hits the fan, and it's about to, is not often evenly distributed. It looks like we're going to be in for a wild ride.