Kevin Flynn's Inside Lane » seattle http://www.inside-lane.com News and commentary about Colorado transportation Fri, 23 Apr 2010 15:04:54 +0000 http://wordpress.org/?v=2.9.2 en hourly 1 Seattle suburban cities try new pavement markings to help bicycles trigger traffic signals http://www.inside-lane.com/2009/09/03/seattle-suburban-cities-try-new-pavement-markings-to-help-bicycles-trigger-traffic-signals/ http://www.inside-lane.com/2009/09/03/seattle-suburban-cities-try-new-pavement-markings-to-help-bicycles-trigger-traffic-signals/#comments Thu, 03 Sep 2009 11:05:23 +0000 Kevin Flynn http://www.inside-lane.com/?p=784 Redmond and Kirkland, two cities east of Seattle, are experimenting with new pavement markings designed to show bicyclists exactly where to stop in order to trigger the embedded detection system that will give them the green light. One of the frustrations of bike riding in the city can be the failure of traffic signals’ inductive loops buried in the street at intersections to be sensitive enough to detect the relatively lightweight bicycles. The markings help strike a balance between increasing the system’s sensitivity, which could cause the loops to falsely detect traffic by picking up large vehicles in adjacent lanes, and having cyclists wait longer periods for their green signal. ]]> Traffic signals that are demand responsive to automobiles, through electromagnetic sensor loops embedded in the street, are great tools for moving traffic. They control the signal to give green time where it’s most needed, determine whether a motorist is waiting in the turn lane for the left arrow or sitting at a side street waiting to get out onto a busy highway.

But they’re not so great for bicyclists.

A cyclist waits for a green signal on top of the new pavement markings being tested in Redmond and Kirkland, Wash. The marking shows cyclists the best place to stop in order to trigger the signal.

A cyclist waits for a green signal on top of the new pavement markings being tested in Redmond and Kirkland, Wash. The marking shows cyclists the best place to stop in order to trigger the signal.


The lighter weight and relatively smaller scale of the metal in bicycle tire rims and frames sometimes present problems for cyclists trying to maneuver through city streets. The electromagnetic loops generated by the embedded wires have to be set at a level that will detect an automobile idling above it, but not so sensitive that it will also detect a large vehicle waiting in an adjacent lane. Getting false readings of where the traffic is located disrupts the signal phasing and traffic flow.

As many American cities, including Denver, move toward making the streets more bicycle-friendly, traffic engineers are tweaking the system so that cyclists can trigger green lights.

And in the Seattle suburbs of Redmond and Kirkland, they’re coming up with new pavement markings to help cyclists.

Close-up shows the detail of the new pavement marking, next to the embedded inductive loop that triggers the green signal.

Close-up shows the detail of the new pavement marking, next to the embedded inductive loop that triggers the green signal.

The new pavement marking shows a bicycle symbol with white blocks behind and ahead of it. Engineers place it on the asphalt in the optimum location for a bicycle to be detected. In the examples in those two cities, the markings have been painted just beyond the intersection stop bar.

The best place for a bicycle to be detected is near the embedded wire rather than in the middle of the loop.

Kirkland traffic engineers have placed the new markings at seven intersections. In Redmond, they are on 150th Avenue NE, along with shared-lane markings called sharrows showing bicyclists where they are to ride. The shared lane means cyclists can ride in mixed traffic with autos rather than marking a separate bicycle lane near the shoulder.

If cyclists stop on the markings, traffic engineers say they electromagnetic loop will detect it and give them their place in the signal cycle.

]]> http://www.inside-lane.com/2009/09/03/seattle-suburban-cities-try-new-pavement-markings-to-help-bicycles-trigger-traffic-signals/feed/ 0 Seattle light rail passenger counting system on the blink http://www.inside-lane.com/2009/08/26/seattle-light-rail-passenger-counting-system-on-the-blink/ http://www.inside-lane.com/2009/08/26/seattle-light-rail-passenger-counting-system-on-the-blink/#comments Thu, 27 Aug 2009 02:28:43 +0000 Kevin Flynn http://www.inside-lane.com/?p=672 reports SeattlePI.com. Sound Transit spokesman Geoff Patrick said Tuesday the system began malfunctioning in the last few weeks and shouldn't affect the accuracy of previous reports on ridership numbers.]]> A technical glitch is hindering Sound Transit’s ability to count riders on the month-old Link light rail line, reports SeattlePI.com.

Sound Transit spokesman Geoff Patrick said Tuesday the system began malfunctioning in the last few weeks and shouldn’t affect the accuracy of previous reports on ridership numbers.

Ten light rail vehicles are equipped with an Automatic Passenger Counter — an infrared sensor that counts passengers boarding on and off at stations. Once per day, the system is supposed to wirelessly download the data to Sound Transit’s operations center. Recently, it hasn’t been working properly, Patrick said.

Read the entire story at SeattlePI.com.

]]> http://www.inside-lane.com/2009/08/26/seattle-light-rail-passenger-counting-system-on-the-blink/feed/ 0 Seattle light rail system opens http://www.inside-lane.com/2009/07/28/seattle-light-rail-system-opens/ http://www.inside-lane.com/2009/07/28/seattle-light-rail-system-opens/#comments Tue, 28 Jul 2009 06:19:10 +0000 Kevin Flynn http://www.inside-lane.com/?p=34 Seattle’s new Link light rail line operated by Sound Transit opened July 20 to light first-day ridership. The agency projects 26,600 boardings a day by next year. Read more about it in the Seattle Times and at Sound Transit.

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