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Paper No. 01-3118

PREPRINT

Duplication for publication or sale is strictly prohibited without

prior written permission of the Transportation Research Board

Title: Benefits Evaluation of Basic

Information Dissemination Services

Authors: Jean-Claude Thill, Galina Rogova

Transportation Research Board

80th

Annual Meeting

January 7-11, 2001

Washington, D.C.

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Benefits Evaluation of Basic Information Dissemination Services

Jean-Claude Thill, Professor, Department of Geography, SUNY at Buffalo, Amherst, NY 14261,

(716) 645-2722 ext 24, jcthill@acsu.buffalo.edu

Galina Rogova, Ph.D., Calspan University at Buffalo Research Center, Buffalo, NY 14225

Abstract. This paper reports on the design and development of a library of modeling tools dubbed "ITS

Options Analysis Model" (ITSOAM) to evaluate the merit of ITS deployment elements within a

benefits-cost framework. ITSOAM is designed as a sketch planning tool to meet the diversity of needs

of New York State ITS coordinators in their economic assessment of expected user and operational

benefits imputable to specific ITS elements in specific corridors. It is intended as a system assisting

engineers and planners in screening worthy ITS deployments. The paper presents the general modeling

philosophy and framework of ITSOAM, with a particular emphasis on the evaluation of basic

information dissemination by variable message signs.

INTRODUCTION

Many State Departments of Transportation have embraced Intelligent Transportation Systems (ITS)

technologies for offering alternative strategies to achieving their programmatic goals. As early as 1992,

the New York State Department of Transportation (NYSDOT) established a "Policy for the

Application of IVHS in New York State" (1). In this policy statement, NYSDOT pledges to

"encourage the development and implementation of technological solutions to known or predicted

transportation problems, provided these technological solutions are cost-effective and consistent with

the Department's program goals" (p. 2). The Department's policy was visionary in more ways than one.

It foresaw the need to "institutionalize IVHS thinking throughout the Department and to have

consideration of IVHS technologies become a fundamental project development activity" (p. 5). The

interweaving of ITS considerations into the transportation program development process is also the

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cornerstone of several FHWA-funded initiatives, including the ITS Planning Handbook (2), and the ITS

Deployment Analysis System (IDAS) (3, 4).

The ability to conduct options analysis regarding alternative capital investments in new lane

capacity versus more efficient use of existing lane capacity as a means of increasing throughput andenhance safety is limited by the benefits evaluation tools and models available to planners. Additionally,

there are equally limited tools and models available to conduct options analysis among different types of

ITS technologies. As the national ITS program transitions from the phase of operational tests to that of

field deployment, emphasis is shifting away from technological implementation issues toward market and

user acceptance, user benefits and integration of ITS approaches with a range of other strategies and

programs, and within the transportation planning process. Simultaneously, data on the outcome of

operational tests become available to perform analysis of user benefits of ITS services and to assist in

making program decisions among competing options.

In spite of a number of well-publicized studies (5, 6, 7, 8, 9) heralding the remarkable payoffs of

investments in ITS technology extrapolated from a handful of operational tests, ITS benefits assessment

is not a straightforward matter and poses significant challenges. Capital planning and programming

procedures at the New York State Department of Transportation require that projects with an ITS

content compete for scarce resources with projects whose approach is in line with the traditional

capacity-increase philosophy. The scarcity of good tools of benefits evaluation of ITS elements for use

at the program development and update stage is a known hindrance for ready programming and

deployment of new ITS user services.

This paper reports on a research effort lead by the Calspan University at Buffalo Research Center

(CUBRC) for the New York State Department of Transportation. This effort aims at developing a

library of modeling tools dubbed "ITS Options Analysis Model" (ITSOAM) to evaluate the merit of ITS

deployment elements within a benefits-cost framework. ITSOAM is developed as a sketch planning

tool to meet the diversity of needs of New York State ITS coordinators in their economic assessment of

expected user and operational benefits imputable to specific ITS elements in specific corridors. It is

intended as a system assisting engineers and planners in screening worthy ITS deployments. With this

objective in mind, fewer resources (data, time, and analyst expertise) need to be mobilized to conduct

economic evaluation at lower accuracy.

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The functionality built into ITSOAM evolved from an extensive outreach effort by the study team

among ITS stakeholders within NYSDOT. It rests on the following principles:

Compatibility with evaluation tools and processes used for conventional capital projects at

NYSDOT and New York State Metropolitan Planning Organizations. With this in mind, only delay,safety, environmental (emission and fuel consumption), and for some ITS services, operational

benefits are quantified. No attempt is made at quantifying other types of benefits.

Compatibility with NYSDOT goals. When appropriate, four primary benefit groups are quantified:

delay, safety, emission, and fuel cost.

Evaluation centered on individual ITS market packages (10), or elements thereof, rather than on

ITS systems components.

Estimation of benefits at the scale best suited for the planning of ITS elements under consideration,

i.e., at the corridor, sub-region, or facility-level.

Low input data requirement. As a program development tool, ITSOAM must be self-contained and

implementable without resorting to a four-step planning model or a traffic simulation model.

Analysis of sensitivity to critical model parameters, such as rate of traffic diversion in response to

variable message signs or incident detection time. Dependence on local deployment conditions and

uncertainty regarding the effects of ITS elements can be captured by sensitivity analysis.

These guiding principles set ITSOAM apart from a few other sketch-planning level tools that are

currently operational or under development, particularly IDAS (3, 4), SCRITS (11), and QRBCAT

(12), the latter being basic sketch planning tools, while the former works in tandem with full-blown

network and demand analyses. ITSOAM does not account for mode shift, temporal diversion, or

induced demand.

This paper presents the general modeling philosophy and framework of ITSOAM, with a particular

emphasis on the evaluation of basic information dissemination by variable message signs. Many other

information dissemination services can be evaluated in a similar fashion. Within ITSOAM, the same

modeling strategy also serves to evaluate information collection elements. The reader will find detailed

description of ITSOAM in (13).

The paper is organized as follows. The second section describes the taxonomy of ITS elements for

which the ITSOAM benefits evaluation environment is developed. The next three sections present the

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modeling framework around which ITSOAM is built. For sake of brevity, the presentation focuses on

the case of VMS deployments. Inputs and outputs of a sample ITSOAM session evaluating the benefits

of VMS deployment during a single traffic-disrupting event (i.e., a traffic incident, a schedule and non-

recurrent event, etc.) are provided next. Conclusions on this design and development of ITSOAM aredrawn in the final section.

TAXONOMY OF ITS ELEMENTS TO BE EVALUATED

Interview Process

Interviews with NYSDOT regional ITS coordinators and selected transportation planners from

various parts of the state were conducted to establish the baseline situation of ITS deployment in each

NYSDOT Region as well as to elicit regional priorities for future ITS deployments. This outreach effort

identified the ITS elements most likely to be deployed in one or another region of the state, for which

the department may need an appropriate evaluation tool. Furthermore, only highway-oriented ITS

elements initiated and supported by the department were considered relevant to the objectives of the

project. As a result, all targeted ITS elements are consistent with strategies geared toward the

deployment of Advanced Traffic Management Systems (ATMS) or Advanced Traveler Information

Systems (ATIS). Vehicle-based ATIS market packages fall beyond the department's planning scope.

Information about traffic and travel conditions being the cornerstone of ITS, the benefits evaluation

system is articulated around the dominant informational functionality of each targeted ITS element, either

information dissemination or information collection.

Information Dissemination Elements

Variable message signs (VMS, including speed display boards and parking management systems),

highway advisory radio (HAR), non-subscription information services (world wide web, commercial

television and radio, fax reports, phone services), and information kiosks are the primary DOT-

supported information dissemination elements that provide information to motorists. These elements

directly enable motorists to change their travel behavior (whether, where, and when to go) in response

to travel conditions brought to their attention. The information content of these elements is provided by

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the information collection elements to the traffic management center (TMC) which, in turn, analyzes,

processes, and prepares the information for dissemination to actual and potential travelers. In some

instances, such as with speed display boards, the information is collected, stored and consumed locally,

without any intervention of the TMC.Only information dissemination elements put in place by the Department of Transportation are

evaluated. Dissemination elements that require a subscription or are established by private entities are

only considered in this modeling framework to the extent that they interact, or operate along with DOT-

established elements.

In ITSOAM, we consider three distinct types of information provided through these elements:

Road condition information, such as traffic density, expected delay, incident or hazardous driving

conditions downstream. This information is disseminated primarily by VMS, HAR, and non-

subscription information services.

Information about facilities (e.g. parking lots), which are disseminated by VMS.

Travel services information, which is available through kiosks and may also include elements of road

condition information.

From an informational perspective, the major difference between kiosks and the other information

dissemination elements resides in kiosks usually providing non-real-time information or wide area real-

time information (e.g., weather condition in a multi-county region) and being used by motorists with

limited familiarity with the area (non-commuters). On the other hand, information provided by VMS and

HAR is typically real time. It is also received and used by all motorists, irrespective of their travel

purpose. Non-subscription information services are also used by all travelers, but often prior to the start

of a trip.1 The pre-trip information received may lead the traveler to reconsider the decision to travel, or

to adjust departure time, mode of transportation, or the route followed.

Information Collection Elements

Information collection elements provide information to the TMC, which is then disseminated to

travelers, traffic control and emergency management officers, and others. The evaluated elements

1Cellular phone services are a notable exception in this matter.

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include closed circuit television (CCTV), vehicle probes, inductive loops and other traffic detection

devices (sonic systems, magnetic systems, etc.), incident detection algorithms, weather sensors, and

highway emergency local patrols (HELP).

Other Elements

Several targeted elements build on the functionality of information collection and dissemination

elements to enhance systems performance and efficiency. Ramp metering and adaptive traffic control

systems incorporate real-time traffic condition information for traffic management on freeway and

arterial systems. HELP services play a more complex role in the overall system: while roving HELP

response vehicles are a key component of an incident management strategy and, by detecting incidents,

serve as information collection units, they also receive information captured by others sources and

processed by the emergency management center; in addition, HELP directly impacts system efficiency

by reducing the duration of traffic disruptions. Finally, weigh-in-motion scales operate rather

independently from other ITS elements.

System Structure

The information flow diagram for the elements to be evaluated is presented in Figure 1. Each of the

ITS elements mentioned above generates benefits. While benefits evaluation is aimed at supporting

decisions to deploy systems consisting of multiple elements (say, an incident management system or a

traffic management center), it is desirable to consider the case of each ITS elements separately, and

evaluate its benefits independently of other elements. With a clear understanding of the relationship

between all the elements to be affected by this particular deployment, interactions between elements can

be captured and double-counting errors minimized. ITSOAM implements the heuristic model proposed

in (14) to statistically estimate the combined benefits of a system deployment.

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Figure 1. Information Flow Diagram.

GENERIC BENEFITS EVALUATION MODEL

The generic benefits evaluation model on which ITSOAM is built is presented in Figure 2. There are

three types of input information required for benefits models:

1. Domain knowledge information. Domain knowledge information contains data related to institutional

(i.e., DOT) databases and standard DOT notions such as road network, historical data about

parameters of travel on the network. The latter include travel time, average number of incidents,

traffic composition (commuters, non-commuters, commercial vehicles), roadway capacity, number

of lanes, characteristics of different categories of delay, information on different categories of

incidents, etc.

EMC

HELPTraffic controlsystem

VMS

HAR

Inductive loops

and other sensors

Infokiosks

Weather sensors /

RWIS

CCTVCommuters

Noncommuters

TMCVehicle probes

Non-subscription

information

services

WIM

Ramp metering

Traffic signal

coordination

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Figure 2. Benefits Evaluation Model Information Flow.

2. Constants. Parameters characterize the ITS elements to be deployed, their use, market penetration,

and perception by travelers as well as their interaction with the rest of the transportation system. In

many cases, due to the absence of real simulation efforts, ITSOAM uses average values compiled

from the relevant literature on simulation and operational test results. Such constants include the

number of travelers willing to divert as a result of information obtained from VMS and/or HAR, the

reduction in incident detection, response, an clearance times, among others. Transferability of these

values to other settings may be questionable and, therefore, it is necessary to secure data pertaining

to circumstances similar to those of the planned deployment. Because of the uncertainty inherent to

a number of constants (questionable reliability of information sources, inconsistencies among

information sources), an analysis of sensitivity of the model results to the assumed values is

recommended.

3. Variables. Variables are defined interactively by the user of the model during the evaluation session.

This type of model input contains the technical specifications of the ITS element being evaluated

(control parameters, hereafter). Variables may include others baseline information that may be

BENEFITS

EVALUATION

MODEL

Variables

Domain knowledge

information

Constants

Benefits

Parameters

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available from any data collection elements, type of information transmitted by information

dissemination elements, etc.

The benefits evaluation model is a modular Windows-based application programmed in Visual

Basic. Data inputs are either default values stored in the applications database or information suppliedinteractively by the user through dialog boxes. The rest of this paper will provide a brief overview of the

model design for a specific deployment of VMS elements, followed by a demonstration of a sample

evaluation session with ITSOAM.

EVALUATION OF VMS ELEMENTS

Taxonomy of VMS Activation Circumstances

Variable message signs may be used in a variety of situations, all of which involve the display of

real-time information for the benefit of motorists. Six main instances can be identified, each one with its

own control parameter I:

Non-recurrent events related to incidents on or around the roadway ( I = 1). Incidents may

include breakdowns, vehicle disablements or crashes, hazardous material spill, etc;

Scheduled non-recurrent events with capacity reduction (short road constructions): I = 2;

Scheduled non-recurrent events with no capacity reduction (special event traffic --fair, football

game, etc.): I = 3;

Environmental problems due to hazardous weather conditions (heavy fog, lake effect snow, etc):

I = 4;

Scheduled recurrent event (major road construction): I = 5;

Facilities related VMS (automated parking management system, speed display boards, notification

of approach to toll gates, ramp metering, parking facilities, truck inspection and weigh stations, lanecontrol signs): I = 6. Only automated parking management systems and speed display boards

are explicitly evaluated in ITSOAM. All other facility-related VMSs primarily generate safety

benefits by alerting motorists that they are in the vicinity of a facility that changes traffic conditions.

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These benefits are hard to quantify, and are best treated as qualitative elements in a benefit-cost

evaluation.

Some of these VMS elements can create benefits by diverting motorists to alternate routes and

easing congestion. Primary benefits are then expected to involve a reduction of delay, which in turnsmay generate safety, emission and fuel consumption benefits. Others (e.g., VMS associated with ramp

metering or weigh stations, speed display boards) can create benefits through incident reduction by

alerting drivers or improving conditions of commercial vehicles (CV).

Traffic conditions developing in connection with non-recurrent events are captured by instance 1 in

the above list. Conditions created by non-recurrent and unscheduled events are represented by

instances 2-4. Instance 5 describes scheduled, recurrent traffic disturbances. Advanced parking

management systems and speed display boards are the two types of facility-related VMSs evaluated in

this study. An overview of measured benefits of field operational tests and other ITS deployments

entailing VMS elements is available in (6, 7, 8, 15).

Interestingly from an operational perspective, the first four instances are very similar. They boil

down to variations of the same core modeling framework outlined below. The information content of

messages displayed on VMSs (particularly, expected length of delay) has been found to influence

drivers' en route diversion behavior (16, 17, 18, 19), which is one of the key mechanisms through which

user benefits are materialize. Accordingly, each version of the VMS evaluation algorithm incorporates

the control parameter T defining the information content of the VMS messages: T = 1 to 5. The

control parameters are interpreted as follows.

T = 1: VMSs provide limited descriptive information on traffic congestion (e.g., incident ahead,

congestion ahead, etc.). Message of this sort may be displayed in the case of non-recurrent

congestion caused by an incident or a planned event, e.g. road construction or special event.

T = 2: The informational content of the posted message is enhanced with a more detailed

description of the magnitude of the traffic disruption downstream (e.g., incident ahead, one lane is

blocked, incident ahead, 1 hour delay, incident ahead, alternative route time is T minutes).

T = 3: The VMS message consists in detailed prescriptive information on traffic congestion (e.g.,

possible alternative routes available, take next exit).

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T = 4: Speed advisory messages are displayed on the VMS to bring motorists to adjust their

speed to the local traffic conditions. These messages may be personalized to increase response and

compliance.

T = 5: Other traffic operations information is posted on the VMS, such parking spaceavailability.

As indicated in Table 1, various combinations of control parameters I and T produce multiple

cases that are treated in ITSOAM.

T

I 1 2 3 4 5

1 4 4 4 - -

2 4 4 4 4 -

3 4 4 4 - -

4 - - - 4 -

5 - - - 4 -

6 - - - 4 4

Table 1. VMS Deployments Evaluated in ITSOAM, by Control Parameters I and T.

MODEL DESIGN FOR INFORMATION DISSEMINATION ELEMENTS

Overall Design

In this section, the model design for benefits evaluation of VMS deployments such that I = 1 to 3

and T = 1 to 3 is outlined. Other deployment cases from Table 1 require rather different models that

are described in (13).

In ITSOAM, benefits are first estimated for a single event responsible for the disruption of normal

traffic operations. This event is an incident when I = 1, short-term roadway work when I = 2, or

a special event when I = 3. Forecast of benefits over an extended planning horizon can be obtained

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by applying the proper expansion factors to the single-event estimates. Expansion factors are estimated

from the historical database of parameters and constants (20). This allows for the derivation of annual

benefits from event-based estimates.

For the sake of consistency with established NYSDOT programming goals and procedures, delay,safety, and environmental (emission and fuel consumption) benefits are quantified. No attempt is made

at quantifying other types of benefits. This approach is in line with other evaluation modeling efforts (for

instance (11)), with the National ITS Architecture Benefits Study (21), and with field evaluations of

VMS deployments (5, 6, 7, 8, 9). The logical sequence of the three evaluation models is reported in

Figure 3. The role of the delay model in ITSOAM is twofold: it estimates a delay-related measure of

effectiveness; in addition, this model serves to predict key measures of traffic operation before and after

deployment (speed and volume) for input in the safety and environmental models. Each model compares

the before and after deployment situations and imputes to the VMS being evaluated any changes that

may be predicted. Specific measures of effectiveness are built into each model.

Figure 3. Logical Links between Delay, Safety, and Environmental Models.

Delay Model

Emission and Fuel

Consumption

Models

Safety Model

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Delay Model

The benefit metric selected to quantify the performance of VMS deployment on the congestion

reduction and mobility goal is the change in overall user delay on the impacted corridor before and

after VMS deployment. Overall delay is defined as the aggregate increase in travel time resulting from

the capacity reduction and/or flow increase. Individual travel time in the impacted corridor is modeled

with the following four components:

The traversal time on the portion of the freeway with reduced capacity and/or flow increase,

A delay associated with the merging of traffic on blocked lanes (if any) with traffic traveling on free

lanes (merge delay),

A delay associated with the dissipation of vehicle queues formed upstream of the incident location

(queue delay), and

A delay associated with the decision to exit the highway corridor upstream of the incident location

and to divert to an alternate route (diversion time).

This framework is sketched in Figure 4. A critical parameter of the model is the rate at which motorists

exit the impacted freeway ahead of the traffic disruption and follow an alternate route. By varying this

diversion rate upward to represent a stronger response of motorists to posted messages, the first three

components of delay are adjusted down, while aggregate diversion time goes up.

The delay model is discussed in full detail in (21). A brief overview is provided here. The traversal

time of motorists over the affected freeway section is described by a standard, non-linear, travel time-

traffic flow relationship. Similarly for the travel time of diverted traffic on alternate routes. The

computation of the merge delay is based on the model developed for ramp design (23, 24). This delay

is calculated as a function of the current traffic flow on the freeway and of the merging capacity. Queue

delay is computed with a deterministic queue model similar to queuing diagrams used in many incident

delay studies and evaluations of incident management programs (26, 27, 28, 29).

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Figure 4. VMS Delay Modeling Framework.

Safety Model

Safety benefits produced by VMS deployment are measured by the economic value imputable to

the reduction of the number of secondary and/or primary accidents on the impacted corridor. Because

accidents are traffic-related events, key inputs of the safety model are estimated by the delay model.

Many studies have been conducted to establish the relationship between accident occurrence and

roadway parameters. It has been found that traffic volume is a significant factor in predicting accident

rates (30, 31). The form of the relationship between accident rate and traffic volume is different for

freeways and arterials; it depends on the road characteristics (e.g., number of lanes, geometry, number

Overall Travel Time

without Capacity

reduction (TTNb)

Overall Travel Time

without VMS (TTb)

traversal time

merge delay

queue delay

diversion time

Benefits:

Value of time saved

Overall Travel Time

without Capacity

reduction (TTNvms)

Overall Travel Time

without VMS (TTvms)

traversal time

merge delay

queue delay

diversion time

B

AS

E

L

I

N

E

D

E

PL

O

Y

M

E

N

T

V

M

S

Overall Delay (TTb) Overall Delay (TTvms)

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of traffic lights, road surface, etc.). Since the accident rate depends directly on the traffic flow

characteristics, every ITS element that can reduce traffic concentration, VMT, or duration of hazardous

road conditions can provide safety benefits.

Reduction of the number of accidents occurring during an event disrupting traffic operations may bedue to:

reduction of accident rate

reduction of accident duration

reduction of VMT.

Table 2 summarizes the processes triggering changes in the number of accidents.

Accident Rate

- reduced congestion at the incident site (secondary accidents)

- reduced congestion at the construction/planned event site

- increased congestion on alternate roads

- switch to the lower class alternatives

Accident Duration

- reduced congestion at the incident site due to faster dissipation of residual queues

(secondary accidents)

- reduced congestion at the construction/planned event site due to faster dissipation of

residual queues

Vehicle Miles Traveled

- increased VMT due to switch to longer travel on alternate routes

Table 2. Sources of Reduction in the Number of Accidents in Presence of Information Dissemination

Services.

The framework of the model is depicted in Figure 5. With traffic volumes on main and alternate routes

generated by the delay model, the safety benefits model estimates the expected number of

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Environmental Benefits Model

Emission and fuel consumption benefits produced by the deployment of information dissemination

elements are measured by:

Reduction of VOC emission,

Reduction of NOx emission,

Reduction of CO emission,

Reduction of fuel consumption

among users and would-be users of the highway facility on which VMS deployment is evaluated. The

first three metrics correspond to the DOT goal of reduction of the environmental impacts of surface

transportation. The last metric is consistent with the objective of fuel waste reduction.

Reduction of harmful vehicle emission and fuel consumption can be linked in any of several causes,

including change of traffic speed mean and speed variation, and change of VMT.

Emission and fuel consumption of a vehicle are highly dependent on its mode of operation on a given

trip. Stop-and-go conditions typical of unsteady, congested or slowed traffic leads to higher levels of

emissions and higher fuel consumption. VMS is expected to reduce congestion and unsteady traffic, and

consequently to bring a reduction in vehicle emission and fuel consumption.

In addition, VMS may result in an increase in VMT because of the traffic diversion that is induced

by delay-related advisory messages. This effect runs contrary to that of traffic speed. VMS deployment

may therefore result in a net increase in vehicle emission and fuel consumption under certain conditions.

Since vehicle emission and fuel consumption are directly related to traffic conditions, speed

characteristics and congestion, the environmental benefits model follows the general structure of the

delay model. The framework of the model is depicted in Figure 6. It is consistent with the general

principles outlined in (32).

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Figure 6. Framework of the Environmental Benefits Model.

The modeling framework used in ITSOAM is sensitive to the type of technology implemented through

several parameters, but also to the response of motorists to ITS deployment. As indicated in the delay

reduction model, motorist response to VMS devices is evidenced through the rate at which motorists

exit the main corridor to follow an alternate route. The diversion rate serves to capture the route choice

effects of VMS. The macro structure of the model does not allow for change in this rate in response to

Emission and Fuel

Consumption Models

VOC, NOx, CO emissions

Fuel consumption

Environmental Constants

VOC, NOx, CO emission

factors Fuel consumption factors

Infrastructure and BehavioralParameters

Length of main corridor

Length of diversion route

Diversion rate

Etc.

Delay Model Components

Traversal time

Merge delay

Queue delay

Diversion time

Delay Model By-products

Traffic speed on main corridor

Traffic speed at merging point

Queue delay

Traffic speed on diversion route

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changing traffic conditions, however. Simulation of each individual vehicle is also beyond the capability

of this model, so that transition between modes of vehicle operation and their impact on emission and

fuel consumption cannot be apprehended in detail.

As indicated in Figure 6, the modeling approach requires inputs pertaining to emission factorsand fuel consumption rates. Emission factors are estimated as a function of average traffic speed by

county and facility type. These factors are generated by a customized version of EPA's MOBILE 5B

model for NYSDOT's Environmental Analysis Bureau.

SAMPLE ITSOAM EVALUATION SESSION

Let us consider the deployment of VMS on a freeway corridor and assess the delay, safety, and

environmental benefits accrued as a result of this deployment in case of an incident on the freeway. A

hypothetical scenario is set up here to illustrate the functionality of the ITSOAM evaluation tool. Figure

7 depicts the four windows in which the user may interactively specify the scenario to be evaluated.

ITSOAM contains many recommended default values, but the user is free to override them to better

capture the local situation under evaluation. The user may choose to evaluate benefits for a single value

of the diversion rate or to conduct an analysis of sensitivity of the results of the model to the value

assumed for this critical parameter. The latter option is illustrated here. It produces a series of curves

displaying benefits as a function of the diversion rate. See Figures 8 and 9.

A standard output of ITSOAM is a text file reproducing all the input data of the evaluation session,

as well as the estimated benefits for a single value of the diversion rate or for values within the range

specified by the user, if a comparative analysis is performed.

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Figure 7. Sample Data Input Screens of ITSOAM for modeling benefits during a Single Non-Recurrent

Event.

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Figure 8. Sample Output of ITSOAM: Delay Reduction Benefits for a Single Incident Event.

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Figure 9. Sample Output of ITSOAM: Safety, Emission and Fuel Consumption Benefits for a Single

Incident Event.

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CONCLUSION

This paper reported on the design and development of a library of modeling tools dubbed "ITS Options

Analysis Model" (ITSOAM) for evaluation of the merit of ITS deployment elements within a benefits-

cost framework. ITSOAM is designed as a sketch planning tool to meet the diversity of needs of New

York State ITS coordinators in their economic assessment of expected user and operational benefits

imputable to specific ITS elements in specific corridors. It is intended as a system assisting engineers

and planners in screening worthy ITS deployments. The paper presented the general modeling

philosophy and framework of ITSOAM, with a particular emphasis on the evaluation of basic

information dissemination by variable message signs.

ITSOAM is expected to enhance the capability of NYSDOT engineers in selecting the ITS

elements with the highest return on investment in each NYSDOT region. This planning tool will also help

in creating a leveled plain field between conventional capital improvement projects and projects

involving ITS deployment by enabling a more solid justification of expected benefits within the current

goal-oriented decision process of the department.

The ITSOAM approach combines user-friendliness and limited data requirements with a robust

modular modeling environment. It emphasizes the quantitative evaluation of delay, safety and

environmental benefits of ITS services for the sake of compatibility with current NYSDOT evaluation

procedures.

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Transportation, Albany, NY, 1992.

2. TransCORE.Integrating Intelligent Transportation Systems within the Transportation

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98-048, 1998.

3. Lee, Russell. IDAS-Planning ITS into the Mainstream, Traffic Technology International, 1998,

August/September, 44-48.

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