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ICDN: Before we discuss IDAS, tell me about your background. Are you a computer scientist or a traffic engineer?

Lee: "Transportation analyst" is probably a good term. My degree is in geography and my interests are in transportation economics and planning.

ICDN: What research group are you in at Oak Ridge National Laboratory?

Lee: We have a lab-wide ITS program, which cuts across a lot of different divisions. Our research ranges from ITS human factors, to instrumentation and control, to modeling and simulation. My area of focus involves modeling and economic analysis/evaluation.

ICDN: How long has the IDAS project been underway?

Lee: We are undertaking it in a number of phases. The first phase, in which the project's vision was developed, took place in 1996 and early 1997. We arrived at a final scope of work in the summer of 1997. We began to actually develop IDAS late in ’97, with Cambridge Systematics as our prime contractor. So we’ve been at it for 15 months or so.

ICDN: And you have already had your first software deliverable, so-called "Build 1" of IDAS, right?

Lee: Right. Build 1 is what we are calling a prototype. It has somewhat limited functionality but it does consider several ITS elements. We saved the more difficult ones for the Build 2 version, but Build 1 is being tested and evaluated now by the Pima Association of Governments (PAG) in the Tucson area. So far, we’ve found some interesting results and have also identified some of the issues that will need to be addressed in Build 2.

ICDN: Is this "Build 1" software generally available?

Lee: Yes, it is available from our contractor, Cambridge Systematics.

ICDN: So any MPO or other transportation agency can acquire it?

Lee: Yes, we are encouraging that. Cambridge Systematics is charging a nominal fee of $40 to cover the cost of their cutting the CD and printing the documentation, which is fairly extensive.

ICDN: Is the ultimate goal of IDAS to have a planning tool that will let MPOs analyze the impact of adding various different ITS components?

Lee: That’s right, different ITS options, as well as combinations of ITS and more conventional transportation investments.

ICDN: What is the most common planning tool that MPOs use today?

Lee: The most common commercial packages are TRANPLAN, EMME 2, TRANSCAD, and MINUTP. They all fit within the genre of what people usually refer to as the"4-step planning models" or "travel demand models" that have been around for some time. Virtually all MPOs use these types of tools in one way or another.

ICDN: What activities do the "4 steps" encompass?

Lee: The 4 steps include: 1) trip generation (predicting trips from origin zones), 2) trip distribution (the prediction of destinations for those trips), 3) mode choice (transit, auto, etc.), and 4) trip assignment (prediction of actual routes).

ICDN: In its ultimate implementation -- beyond even "Build 2" -- is IDAS intended to be a stand-alone tool, or is it intended to integrate with these other existing tools that you mentioned?

Lee: Very much the latter -- it is designed to integrate with those existing tools. That is a very important notion: We do not want to replace those existing tools, we want to link with them and work with them. We want to augment the set of tools that MPOs can use when they consider ITS options. The idea is to use some of the outputs generated by any one of these other models, and to let IDAS go into a more detailed analysis of ITS-related effects.

ICDN: One of your early project tasks was to do a literature search of ITS benefits, is that right?

Lee: Right.

ICDN: Transportation planners and operations people often complain that much of the information about ITS benefits is anecdotal, "soft" as opposed to "hard." Did you find that to be the case?

Lee: It is fair to say that that still continues to a great extent. A number of ongoing efforts outside of our particular program are trying to address that shortcoming, including the Metropolitan Model Deployment Initiative (MMDI) evaluations, where studies will try to get a more quantitative basis for the benefits estimates. In reviewing the literature, we’ve tried to be as careful as possible to identify studies with strong empirical or model bases, rather than those based on anecdotal evidence.

ICDN: Let me ask a loaded question. The credibility of a tool like IDAS would seem to be vitally important -- are you concerned that some people may view IDAS as more of a promotional tool for ITS technologies than an objective analysis tool?

Lee: I think people will find that IDAS is a very objective tool in several respects. First of all, there is the documentation itself, where we try to be clear and explicit about the assumptions and calculations. We try to be transparent in terms of how each module works. Secondly, in terms of the actual implementation and use of the model, we allow the user to change virtually any of the inputs. As you are suggesting, a model’s results depend very much on the assumptions you make, and IDAS allows the user to change virtually all of those assumptions. A third aspect that is relevant to the point you are raising is a "benefits library" of previous studies of the benefits of ITS deployments. The user can go into this library, identify the basis of IDAS’s assumptions, look at some other studies that have come up with other estimates, and then go to the sources that are cited in that library to more closely investigate what underlies those results.

ICDN: It sounds like, in effect, there is some kind of data table with the assumptions and quantification that are applied to different ITS technologies, and that information can be adjusted over time by users. Is that what you are saying?

Lee: Right. There is a large database that reflects the various information and assumptions made on the benefits side. There is another one on the cost side, as well.

ICDN: Was the Pima Assoc. of Governments, or "PAG," involved in developing IDAS?

Lee: They are part of our eleven MPO Steering Committee. We want to make IDAS useful to the ultimate end-users, and certainly MPOs are among the primary end-users we have in mind, so we got them onboard very early in the process. In fact, the Steering Committee helped develop the overall Scope of Work as well as the top-level design. So PAG was one of those MPOs involved in the early stages of the project, and they continue to be involved. They are active participants in our meetings.

ICDN: In your presentation at the recent TRB Annual Meeting, PAG cited preliminary results in using IDAS Build 1, specifically in analyzing the possible impact of adding ramp meters to Tucson-area freeways. Have they used it so far in many different contexts, or is that the primary one?

Lee: That is one of the two primary test applications so far, the other application is Automated Vehicle Location.

ICDN: I presume you worked with them hand-in-hand to help them get IDAS Build 1 configured properly and to train their key people?

Lee: Very much so. As with any new software, there is a learning curve. In this particular case we are dealing with a prototype, which is bound to have some glitches. So there was a lot of interaction.

ICDN: One result cited in the TRB presentation was that in some cases the IDAS processing time was considerable. While some tasks only took a few minutes to run on the Pentium II/450, other tasks took considerably longer. For example, the "travel time/throughput module" took over 5 hours to run in one case. Wouldn't excessive run time be a problem in any kind of planning tool?

Lee: It is a problem, and something that we are very sensitive to. We don’t want IDAS to become an overly complicated piece of software that is difficult to use, understand, or run. And part of being ‘difficult to run’ means execution times which are prohibitively long for most planning applications. One of the challenges in Build 2 is to significantly decrease these run times.

ICDN: Walk us through the process of using IDAS, say a scenario to analyze the impact of adding ramp meters.

Lee: Let me take a step back and outline the overall process. The travel demand models generate trip tables and travel times, as well as information on the locations of the nodes and highway/transit links or segments. IDAS has a number of utility functions that help translate these output tables into IDAS input tables. Among these data will be information on the transportation network itself. One of the main windows in IDAS is a screen of that network. Of course, users can pan or zoom in on the particular ramp or segments or nodes of interest. It is a fairly straightforward process: the left window lists different ITS options or elements, and the user can then click and drag a particular ITS component over to the vicinity of where he/she wants that deployed on the network. Once that is accomplished, another screen in IDAS prompts the user to click on the specific locations where he/she wants to deploy that ITS component. IDAS provides some guidance to the user to do the appropriate thing. Let me illustrate what I mean by "appropriate." Let’s say you are going to deploy ramp meters. If you do, then you will affect, at least implicitly, the capacities on the freeway links associated with that ramp. IDAS will prompt the user to effectively increase the capacities of these links. So, depending on the kind of ITS deployment that’s done, there’s some guidance provided to the user to adjust other parameters.

ICDN: It sounds a bit like Turbo Tax, which gives the user hints on other things to do to save money at tax time.

Lee: We try to provide that kind of guidance so that the user makes changes appropriate for the particular kind of ITS deployment under consideration. IDAS has some expert-system aspects, but it doesn’t make things dummy proof.

ICDN: I’m sure you have heard the argument that for the transportation infrastructure, ITS must compete against concrete, that it’s often a matter of building more capacity vs. managing your existing network more effectively. Can IDAS ultimately help MPOs decide whether to add a freeway lane or, alternatively, to add greater traffic management capability with such things as ramp metering, lane-control signals, and variable message signs?

Lee: Yes, we certainly hope so. That is a major goal and I know you realize that no one solution fits or is best in all cases. The motivation for having tools like IDAS is to help planners and other analysts address those kinds of questions. In some cases, the best option might be a combination of the more traditional options together with ITS options.

ICDN: When you add ramp meters, you potentially back up traffic in ramp queues which, in turn, can impinge on nearby arterial traffic. Does IDAS take that effect into account?

Lee: It does. That is a good example where a particular solution is not a good idea in all cases. Certainly there are situations where those kinds of "disbenefits" exceed any benefits, so in these cases it's not a good way to go.

ICDN: In the benefits table that you presented at your TRB presentation, the benefit from adding ramp meters was shown to be around $2,000,000 annually, at an annual cost of around $200,000, for a benefits/cost ratio of 10:1. Right?

Lee: Yes, in that particular case.

ICDN: Would IDAS come up with cases where the benefit to cost is less than one-to-one.

Lee: Of course. There are going to be situations in which the benefits just don’t justify deployment, and we want to see those situations. Planners would obviously want to see those situations, and they certainly will come up.

ICDN: So, there might be some cases where IDAS could identify that putting ramp meters in these particular locations actually would detract from the system. It’s a possibility.

Lee: Yes it is.

ICDN: How accurate do you think these benefits and cost numbers are?

Lee: They are very much ballpark numbers and I think that’s fine. Users recognize that these tools provide just ballpark estimates because they do hinge on a lot of assumptions that are reflected in the data inputs. Uncertainty can obviously lead to imprecision in the results. Notwithstanding their imprecision, ballpark numbers still provide a useful basis for comparisons and planning.

ICDN: To your knowledge, are any other MPOs using IDAS Build 1 at this time?

Lee: A number of MPOs on our Steering Committee are starting to gear up. Officially, they are going to be helping out in terms of evaluating the Build 2 version, but part of that preparation is to familiarize themselves with Build 1. We expect to have a preliminary version of Build 2 available for testing in the May 1999 timeframe.

ICDN: Let’s talk about Build 2 vs. Build 1. I understand that the ATIS components were not included in Build 1 but will be in Build 2. Is that correct?

Lee: Yes, that’s right.

ICDN: What other significant differences, in functionality or user friendliness, will there be between Build 2 and Build 1?

Lee: There will be a number of improvements. First, the run times will improve so that they are acceptable. Second, the system will be more user-friendly. Third, Build 2 will have enhanced output capabilities. One of the things we have in mind is to allow the user to view the performance differences between an ITS option and a baseline option on a link-by-link basis. Right now we just have tabular summaries. In terms of functionality, we are targeting the traffic assignment module, a key part of IDAS, for improvement. We also plan to incorporate some non-traditional benefits, such as enhanced time reliability, which is not usually considered in travel demand models. Traditional travel demand models emphasize average travel times. We think that some ITS elements provide improved travel time reliability, not just improved speeds or improved travel times. Build 1 provides estimates of travel time reliability, but we’re still testing that module. There are other non-traditional benefits as well, such as the value of information -- for example, just knowing that you will delayed 10 minutes in a traffic jam rather than sitting there and wondering how long it will take to clear it. The value of enhanced safety and security in transit systems is yet another example of non-traditional benefits which ITS aims to provide.

ICDN: Are any other similar tools available to MPOs today that try to evaluate the impact of new ITS deployments?

Lee: No, there aren’t. That was the motivation for developing IDAS.

ICDN: Are any other research organizations, including university ITS research centers, currently working on a tool that would potentially compete against IDAS, as far as you know?

Lee: There are certainly other tools under development, but IDAS is unique in terms of coupling with models that the MPOs are using now and trying to become part of that existing process. However, there are some other very interesting efforts underway. Most transportation people have probably heard about TRANSIMS, which is being developed for FHWA by Los Alamos National Laboratory. They are beginning to turn their attention to incorporating some ITS aspects within that model. From the discussions and briefs on that project which I've attended, they are looking at the effect of ATIS on traveler or driver decisions, and driving behavior. TRANSIMS is a so-called "micro-simulation model," so they are looking at the effect of the quality and type of information on the decisions that trip makers make. It’s really the next generation of travel demand models: many hope that it will replace the 4-step process in time.

ICDN: Any other projects of that type?

Lee: Another effort involves work being done in the Seattle area by Mitretek. They have developed a process for linking various models, including the INTEGRATION model. Mitretek’s value-added is in developing software to link these models to focus on ITS deployments; their emphasis has been on major corridors in the Seattle area. A third effort is Mike Van Aerde's work at Virginia Tech. Mike is getting some of the ITS aspects into his INTEGRATION model. This project is at a fairly early stage, but has some very interesting features.

ICDN: Are you directly working with any of these 3 efforts in the IDAS project?

Lee: One of the key people involved in the Mitretek effort, Karl Wunderlich, is on our Advisory Panel, so we have the benefit of his insights. And Mike Van Aerde is part of our IDAS team.

ICDN: What do you think will encourage MPOs to use IDAS once Build 2 is out?

Lee: I think it is both a push and a pull process. We are already seeing great interest in IDAS among MPOs in particular and state DOT’s, as well. They are waiting with some anticipation to have a tool to help them. I think they recognize that it’s not going to be a silver bullet, but it’s going to be useful. Right now they are limited in the tools they can use to address ITS-specific questions, so there is certainly great interest. That is the "pull" part. The "push" part involves our getting the word out -- not trying to force anyone to use it, but just making people aware of it, and having an efficient way of distributing it

ICDN: Do you plan to make any presentations about IDAS at ITS America's upcoming Annual Meeting in April?

Lee: Yes, in fact, one session will be devoted just to IDAS and will include a panel of several of the MPOs that I’ve mentioned.

Would IDAS help you make transportation infrastructure deployment choices? What issues might factor into your own choice to adopt such a tool? What functions or features seem to be missing (if any)? Share your views in the ITS Forum. Click on the "note" icon (or click here) to share your thoughts with others on the front lines of ITS deployment.