Leading Bicycle Interval

We arrived in Amsterdam and the first thing I did upon arriving is visit the closest traffic signal to our hotel. I was interested to compare the experiences in Denmark with the Dutch practices. This was a minor street connecting with a more significant street adjacent to the Rijksmuseum. The first thing noticeable about this signal was that the indications for the bicycle are nearside. The second is that there are two separate indications (a large head mounted at around 3 meters) and a 10 cm (4 inches) indication. My guess is that the redundant signal head is used for the same reason we use multiple displays, but can't be sure. The third and most interesting from an operations perspective is the leading bicycle interval. I tried to take as many pictures as I could one after another to guess at how much time the intervals was for the bikes (it was about five seconds based on my camera time stamp). It seems that the reason for a Leading Bicycle Interval (LBI) is that the crosswalk is very large and it would be a nice thing to allow people on bicycles to establish themselves in the intersection across the crosswalk and to make the turn if they were so inclined. This might reduce the potential conflict point at the intersections which you can see just past the crosswalk and out of the shade of the curb tight building. The fourth application which we have used very sparingly in the U.S. is mirrors. In this application, I am guessing it helps freight and other motor vehicles determine if there are pedestrians coming up along the sidewalk and bikes approaching. It's another cue for encouraging the safe movement of traffic. I can already hear the complaints of maintenance staff if we proposed these at intersections.

Assuming that a community only wants to spend so much for a traffic signal (I doubt the Dutch love their signals any more than we do), in the U.S. (and in Portland), I would like to do an assessment of what elements of traffic signals cost us the most money (foundations for signal poles and the mast arm signal poles themselves) and what yields the highest safety benefits. There are distinct costs for traffic signals that require to be mounted over the lane lines and that is a function of the assumed speed of traffic and reaction times and so many human factors issues that it would be very helpful to know the tradeoffs between actually safety elements we design at intersections and their cost. I would be willing to wager a strong cup of coffee at Water Avenue that we could save ourselves a lot of money if we traded the costs of foundations and invested in better detection, marking on the pavement, and maintenance resources.