For the past few weeks, I have had the opportunity to experience Philadelphia on two wheels, since a friend with a bicycle took up residence here. Besides good exercise, it's given me an opportunity to roam a little further beyond my home neighborhood and see just how easy--or difficult--it is for bicycles and motor vehicles to co-exist.
My first observation on that latter topic is this: Bicyclists have a built-in advantage in much of the city, thanks to the narrowness of the streets--a legacy of the original 1682 city plan, which was extended into much of North and South Philadelphia. Narrow streets--especially when they have parked cars on both sides, as they do almost everywhere outside Center City--force motorists to slow down and be more cognizant of the environment through which they are driving. On some of the most crowded streets in Center City, I find I can actually keep pace with the cars and trucks.
My second observation is this: Bike lanes provide a false sense of security. Even though motorists do observe lane discipline, and by and large stay out of the marked bike lanes, there are inevitable conflicts by dint of their traditional location at the right edge of the travel space. If there is a parking lane to the right, bicyclists still run the risk of running into car doors that open suddenly. Motorists attempting to turn right must cross the lane to do so, and often, they will not look to see if they are cutting off a bike in the bike lane; if a bicyclist is traveling in a mixed traffic lane, this does not happen, as the motorist must pay attention to the bike just ahead of him in the same lane. And what happens when it's time for the bicyclist to make a left turn? There is still at least one lane--and usually more than one--of mixed traffic to cross. If motorists are not used to encountering bicyclists in the regular lanes, they will soon completely forget to pay attention to them.
Philadelphia's Streets Department has been very good about posting "Share the Road" signs on city thoroughfares, even those with marked bike lanes. Judging from the behavior of the drivers around me as I travel through the city, the message must have soaked in. Education, not segregation, is the key to making sure two- and four-wheeled conveyances can get along together on city streets.