CrossJurisdictional

Signal

Coordination

In Phoenix

And Seattle

Removing Barriers to 

Seamless Travel on 

Arterial Streets

Lessons Learned From 

The Metropolitan Model

Deployment Initiative
1

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Project Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

What Was Done in Phoenix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Institutional Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Deployment Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Results from Phoenix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Findings from a Similar Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Figures

Figure 1. Road Study Corridor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Figure 2. Phoenix Metropolitan Model Deployment Initiative Smart Corridors . . . . . . .4

Figure 3. AZTech Smart Corridors Integration . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Figure 4. Northbound Speed Profile Comparison . . . . . . . . . . . . . . . . . . . . . . . . .7

Figure 5. Southbound Speed Profile Comparison . . . . . . . . . . . . . . . . . . . . . . . . .7

Figure 6. Average Measure of Efficiency Comparison . . . . . . . . . . . . . . . . . . . . .8

Figure 7. Comparison of Means . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Tables

Table 1. Development Costs of Scottsdale/Rural Road Corridor . . . . . . . . . . . . . . .6
2

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

Preface

In 1996, the Secretary of Transportation

announced the Operation TimeSaver goal

to deploy integrated Intelligent Transportation

Systems (ITS) infrastructure in 75 of the

nation’s largest metropolitan areas. That

year, the U.S. Department of Transportation

also established the Metropolitan Model

Deployment Initiative (MMDI). The purpose

of this effort was to 

create model deployments

that represent integrated 

transportation management systems. The 

objectives of the initiative

include determining the

effects of increased

deployment on traffic characteristics and

operations and documenting the benefits

that enabled the specific sites to be selected.

The Metropolitan Model Deployment 

Initiative in Phoenix is called “AZTech”.

Integration is one of the factors in successful

ITS deployment. An integrated system is

often more effective than one in which all

components function separately. This case

study is one of a series documenting the

level of ITS integration in several major

metropolitan areas. This study also provides

transportation professionals with an example

of how to integrate ITS components and 

systems, including related costs and other

details.

Background

The Phoenix area, as with many metropolitan

areas, is made up of several separate

jurisdictions. If all trips were made within

the same jurisdiction and no boundaries

were ever crossed, traffic signals could be

coordinated within those respective boundaries and efficient progression achieved.

However, this is never actually the case. 

Early on, the jurisdictions located in the

East Valley of Phoenix operated their own

traffic signal systems with some interjurisdictional coordination. These cities include

Chandler, Gilbert, Scottsdale, Tempe, and

Mesa. Regional signal coordination brought

along “Smart Corridors,” or corridors that

allow smooth progression from one jurisdiction to the next. A Smart Corridor is a

corridor in which all transportation facilities

are used at their maximum efficiency 

during both an incident and normal periods

of congestion.

The use of regional traffic signal coordination

has made commuting through several 

jurisdictions in Arizona easier and more

economical. Many municipalities across

the country use similar traffic signal cycle

lengths and background cycles along 

arterials to help achieve smooth travel 

progression. A cycle length can be defined

as the green, yellow, and all-red times

combined for each approach. Traffic signal

progression prevents unnecessary delays

for motorists. Similar cycle lengths along

an arterial help achieve smooth progression.
3

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

The Scottsdale/Rural Road Corridor

(Figure 1) is a major north/south arterial

corridor in Arizona that connects

Scottsdale and Tempe. Along the route

there are 21 traffic signals within two 

jurisdictions (five located in Scottsdale and

16 located in Tempe). Prior to this project,

the jurisdictional separation was a boundary

for traffic signal coordination, delaying

drivers with an unnecessary stop between

cities. The Smart Corridor project relocated

the jurisdictional boundary to a more 

functional setting (Loop 202), allowing the

signal coordination to continue through the

adjacent town. This case study reports the

benefits achieved from the regional signal

coordination efforts in Phoenix.

Detector stations were placed at several

mid-block locations along this route to

relay traffic flow and congestion information to the Traffic Management Centers in

Tempe and Scottsdale. Operations personnel in each jurisdiction use this real-time

information to coordinate traffic signals

and provide smooth progression across

jurisdictional boundaries (Figure 2).

Tempe, however, is the only city that feeds

vehicle count and speed data into the

AZTech network.

Project Description

Figure 1. Road Study Corridor
4

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

The traffic signals along the Scottsdale/

Rural Road Corridor were operating at 

different background cycles, creating a

break in progression. If all the signals along

the corridor operated at similar background

cycles, progression would improve. Motorists

would travel through the green phase at

each signal after the initial red light. The

traffic signals in Tempe and Scottsdale

were operating at cycle lengths of 110

and 102 seconds, respectively. Adjusting

the timing of the signals to a common

cycle length helped achieve smooth 

progression. To create the Smart Corridor,

several signals along the arterial were

retimed to a common background cycle

and appropriate offsets were determined.

Traffic detection equipment relayed 

information, such as traffic speed and 

volume, for use in signal timing updates. 

Institutional integration had to precede 

integrating the components of each technical

system in the East Valley of Phoenix. The

AZTech Technical Oversight Committee

provided an interagency model approach

to regional traffic issues for this effort.

Transportation specialists from each of the

five cities form the East Valley Task Force,

which is responsible for identifying areas

for improvement. Standards were established

for interagency coordination, and solutions

were developed to increase coordination

between jurisdictions. For this particular

study, the task force’s goal was to 

synchronize the last traffic signal in one

jurisdiction with the first signal in the 

adjacent jurisdiction.

What Was Done in Phoenix Institutional Issues

Figure 2. Phoenix Metropolitan Model Deployment Initiative Smart Corridors
5

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

“AZTech has built a lot of

positive working relationships

and rapport between these

municipalities so that you

look at the big picture rather

than just what your own

needs might be.”

– Brian Latte

Signal Systems Engineer 

City of Chandler

To achieve full technical integration, some

Smart Corridor components were linked to

the AZTech server to facilitate data exchange

(Figure 3). Implementing a communications

infrastructure allowed information flow

between jurisdictions. Also, traffic signal

controllers, surveillance equipment, and

detection devices were installed or upgraded

to collect information. Workstations were

installed at the Traffic Operations Centers

(TOCs) in each jurisdiction to allow 

sharing of the traffic information, which in

turn provided each jurisdiction with the

opportunity to update signal-timing plans

to reflect real-time changes in traffic patterns.

Developing a regional traffic control and

management plan was also a factor in

integration. This plan includes traffic signal

timing plans for some of the Smart Corridors,

as well as procedures for coordinating 

traffic management activities between 

jurisdictions. The integration of these 

components played a key role in interagency

communication and coordination.

Integration

Figure 3. AZTech Smart Corridors Integration
6

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

The main capital cost for this project

involved the purchase of traffic detection

equipment (Table 1). Other costs included

the jurisdictional share of the Traffic

Operations Center planning, development

and implementation, staffing, and hardware maintenance. Each of eight regions

involved with implementing cross-jurisdictional signal coordination is responsible for

12.5 percent of the operating costs of the

Traffic Operations Center. Annual operations and maintenance costs for the project

have been estimated to equal 5 percent 

of the initial non-labor deployment costs.

Table 1 illustrates a breakdown of the

costs associated with the Scottsdale/Rural

Road project. 

Two data collection efforts were conducted

for this evaluation in January and February

1999. One effort involved collecting traffic

counts and turning-movement data at 

several traffic signals both before and after

the signal timings were changed. The 

second effort involved the use of Global

Positioning System (GPS) satellite receivers

in vehicles that traveled along the arterial,

also before and after the timing changes.

Variables such as vehicle location and

speed were recorded on a real-time basis,

and the data were used to calculate travel

time, delay, and vehicle accelerations.

Table 1. Development Costs of Scottsdale/Rural Road Corridor

Equipment Description Fixed Costs Annual Costs

Detection devices (6 x 6 Loops) $65,625

Maricopa County Department of Transportation 

planning (.33 full-time employee) 41,250

Loop maintenance @ 10% of capital cost 5,381

Camera maintenance @ 2% of capital cost 984

12.5% Share of Traffic Operations Center’s 

development, acquisition, and installation 84,527

4% Share of AZTech hardware and software 2,734

4% Share of Wide Area Network/Codec 14,594

4% Share of video switch expansion 810

4% Share of TRW systems engineering and 

project management 46,666

4% Share of Traffic Operations Center operator training 2,891

12.5% Share of Traffic Operations Center’s 

communications costs 15,686

4% Share of AZTech server equipment replacement 4,281

4% Share of AZTech server operations and 

maintenance staff (1 full-time employee) 4,100

Totals $259,097 $30,432

Deployment Costs Data Collection
7

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

Several operational benefits were

observed through the large-scale signal

coordination effort, including increases in

average travel speed (Figures 4 and 5).

The afternoon peak period (southbound)

experienced a more substantial increase in

average travel speed at the three retimed

intersections (shown by the dashed red

lines). The large gaps between the two

southbound speed profile curves show an

increase in speed at the intersections 

with retimed signals. McKellips Road

experienced an increase in average

speed of almost 10 miles per hour. 

The green dashed line shows the 

location of a railroad grade crossing.

The previously mentioned variables were

used to determine the overall effects of the

signal timing changes in terms of throughput

Figure 4. Northbound Speed Profile Comparison

Figure 5. Southbound Speed Profile Comparison

Results from Phoenix
8

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

Figure 6. Average Measure of Efficiency Comparison

and efficiency. Figures 6 and 7 show the

effects of signal coordination with respect

to Global Positioning System data analysis.

The results show a 6 percent increase in

the average speed between the before

and after conditions, which is deemed 

statistically significant. As a result, vehicles

stopped 4.3 percent less. The results from

a microscopic simulation model were 

similar in nature and were in accordance

with these results.

Figure 7 illustrates the small environmental

and pollution-related effects of the project.

However, the project positively affected

travel speeds, number of stops, and crash

risk. Travel speeds increased by approximately 3 miles per hour, and the number of

stops decreased significantly. Crash risk

also decreased by 6.7 percent.

The mean value of each variable did not

significantly change from the before period

to the after period. However, over the

three analysis periods (A.M., P.M., and

HC=Hydrocarbons CO=Carbon Monoxide NOx=Nitrous Oxides VMT=Vehicle Miles Traveled

Crashes 

(per 106 VMT)
9

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

Figure 7. Comparison of Means

*Based on assumptions made by researchers at Virginia Polytechnic Institute.

midday), the mainline throughput increased

by 13 percent. Throughput is defined as

the number of trips per unit time, or the

number of person trips processed by the

system. This increase suggests that the 

system is more efficient due to the signal

timing changes.

Reduced fuel consumption was 

another benefit of this project. In fact, 

fuel consumption was reduced by 1.6

percent, resulting in fuel savings of more

than 260,000 liters per year.*

The Seattle Smart Trek ITS Deployment

involved a similar study to determine the

benefits that could be achieved through

cross-jurisdictional signal coordination.

However, only simulation modeling was

used to analyze the proposed signal 

timing changes. None of the signals in

Seattle was physically retimed in the field.

The evaluation examined the potential

effects of retiming signals using a coordinated fixed timing plan along two major

arterials (SR 99 and SR 522) in North

Seattle. As in the study in Phoenix, several

measures of effectiveness were evaluated

Findings from a 

Similar Deployment

HC=Hydrocarbons CO=Carbon Monoxide NOx=Nitrous Oxides VMT=Vehicle Miles Traveled

Avg. crash 

risk

(per 106 VMT)
10

CrossJurisdictional 

Signal

Coordination 

In Phoenix 

And Seattle

“Signal integration will

always be an ongoing

process. We’ve made many

improvements already, but

it’s a continual process,

because traffic is always

changing.”

– Jan Siedler

Signal Systems Supervisor

City of Mesa Chairperson

East Valley Task Force

to determine the effects that the new timing

plans would have on traffic flow.

The results from the modeling effort were

consistent with those from Phoenix. The

model predicted a 7 percent reduction in

average vehicle delay during morning

peak conditions. The results also showed

a 2.5 percent decrease in crash risk, as

well as negligible changes in throughput.

No adverse impacts were predicted for

perpendicular streets crossing SR 99 and

SR 522, primarily because the cross

streets would have the same phase split

using both baseline and coordinated plans.

Large-scale signal coordination efforts can

not only provide traveler benefits, but can

also substantially increase levels of interagency communication. A communications

infrastructure links jurisdictions in the

Phoenix Area, allowing them to share 

real-time traffic operations information and

update signal plans accordingly. The idea

of a multijurisdictional system allows regional

goals to be initiated and achieved.

Signal coordination requires careful planning

for maximum efficiency. In the Scottsdale/

Tempe Area, the boundary for coordination

previously existed at a jurisdictional 

separation. Moving this coordination

boundary to a more functional boundary

(Loop 202) has provided a seamless 

commute from one jurisdiction to the next.

A functional boundary is an area at which

traffic signal coordination is less of an

issue. For the Phoenix area, regional traffic

signal coordination has been achieved

through careful planning and increased

coordination efforts.

Local participants predict that careful

coordination and cooperation will have a

long-range impact on traffic operations in

the East Valley, and that maintaining and

updating coordination and communication

efforts will provide increased benefits in the

future. Ideas such as this can provide

municipalities with the framework needed

to deploy similar Smart Corridor systems.

Lessons Learned
U.S. Department of Transportation

400 7th Street, SW

Washington, DC 20590

FHWA-OP-01-035 EDL #13221

Intelligent 

Transportation 

Systems

ITS Web Resources

ITS Joint Program Office:

www.its.dot.gov

ITS Cooperative Deployment Network:

www.nawgits.com/icdn.html

ITS Electronic Document Library (EDL):

www.its.dot.gov/itsweb/welcome.htm

ITS Professional Capacity Building Program:

www.pcb.its.dot.gov

Federal Transit Administration

Transit ITS Program:

www.fta.dot.gov/research/fleet/its/its.htm