green times of the intersection instantaneously as a function of vehicle/pedestrian volume

on each approach. This detection comes in three main technologies, which include detector

loops, various types of cameras, and pedestrian push buttons. At the University corridor,

the only current detection devices in operation are pedestrian push-buttons at the Ped-walk.

and Knoles. These types of intersections use a circle with yielding at each approach in

order to circulate cars to their proper destinations without using any signalized equipment.

The negative of roundabouts is that they do not facilitate people with disabilities due to the

lack of any sound devices for the visually impaired.

their volume has no effect on the vehicle traffic of the corridor. This design could be used to

replace the Ped-walk on the University corridor of this project.

phases when a pedestrian waiting to cross the road is detected. When a pedestrian pushes

a typical pedestrian push button, the Hawk signal displays a yellow phase and then red

phase for both directions of vehicular traffic for a given set amount of time. Once this time

has passed and the pedestrian is crossing the intersection, the signal displays two

alternating flashing red lights to both directions of vehicular traffic so that vehicles may

proceed through the intersection after yielding to the pedestrian.

cars per second of green time through the entire corridor. Since the slight majority of the

traffic volume runs eastbound-westbound, through both intersections, a delayed

coordination between these signals may prove to reduce queue length and delay time.

Delayed or progression timing forces the intersection to have the same cycle length or half

cycle lengths, therefore, the Ped-walk would require a longer green time for the

eastbound/westbound traffic which only has vehicle traffic flow.

their timing plans. Having the signals utilize a longer green time in one or both directions

may decrease the length of time the average pedestrian or car is stationary at the

intersection. Most traffic comes from the eastbound-westbound and creates a longer green

time in the opposite direction could increase average vehicle and pedestrian delay

substantially and will provide a longer green time for the vehicles travelling through the Ped-

walk.

intersections to be preserved. These timing plans were collected directly from

the Econolite ASC/3 controllers at the site. The timing plans that were in use are the

minimum allowable times for the pedestrian walk times for the University and Knoles

intersection. The Ped-walk allows for a longer pedestrian time to factor in the platoon effect

of the pedestrian at the intersection of the Ped-walk and University.

Table 1-Design Matrix for Timing Alternatives

Table 2- Design Matrix for Geometric Alternatives

The above design matrices describe the decision processes that IDD Engineering followed to

provide the best design for the University corridor. Table 1 describes the timing alternatives and

their corresponding ranking on the four main requirements. Table 2 shows the same information

for the five geometric design alternatives.

Each criterion was ranked on a scale of 1 to 5, 5 being advantageous and 1 being unsatisfactory.

These rankings were then multiplied by their corresponding weight and displayed in these tables.

The second column on these tables shows the weight that each criterion was given. The individual

weights for each criterion describe the level of importance to the overall project.

These design matrices concluded that leaving the time plan as it stands now while adding detection

would be the most beneficial design for the University corridor.

provide the best design for the University corridor. Table 1 describes the timing alternatives and

their corresponding ranking on the four main requirements. Table 2 shows the same information

for the five geometric design alternatives.

Each criterion was ranked on a scale of 1 to 5, 5 being advantageous and 1 being unsatisfactory.

These rankings were then multiplied by their corresponding weight and displayed in these tables.

The second column on these tables shows the weight that each criterion was given. The individual

weights for each criterion describe the level of importance to the overall project.

These design matrices concluded that leaving the time plan as it stands now while adding detection

would be the most beneficial design for the University corridor.

Copyright Northern Arizona University, IDD Engineering

Last Modified: 4/28/11