Untested highway software not used anywhere else in Mass.

Comments by the Federal Highway Administration that have delayed the reconstruction of Mass. Ave. are based on a new and untested computer tool that “hasn’t been widely reviewed” or “been used in this state by other traffic engineers and state agencies,” according to the Massachusetts Department of Transportation.

The agency, in a February 14 reply to a January 23 letter from the Federal Highway Administration, contrasts the Urban Streets Analysis Package promoted by Federal Highway with the Synchro model, which it says is “commonly used” and accepted.

The software is used to model traffic metrics under different assumptions and road designs. According to the reply:

Since the Urban Street analysis package is very new and hasn’t been fully reviewed by the traffic/transportation industry, FST [Arlington’s engineers] cautioned MassDOT and the FHWA that the analysis and the results could give inaccurate and/or unreliable results, and may be confusing to reviewers as well as the public.

This is especially true since this analysis and methodology is new and as far as we can determine has not been used in this state by other traffic engineers and state agencies. In fact, to the best of our knowledge, this is the only project that has been required by FHWA to use this multi-modal analysis software program.

…The analysis that was previously presented in the Functional Design Report was based on an analysis package (Synchro) that is commonly used and has been fully reviewed and accepted by MassDOT. (Feb 14 letter pp. 12–13, emphasis added.)

Urban Streets is not included in MassDOT’s list of approved software tools, where it is listed as “HCS 2010” (see note below).

Elsewhere in its February 14 reply, MassDOT notes other limitations of the Urban Streets “multi-modal analysis” that call into question its fitness to be used for some purposes.

There are a number of improvements of which the Urban Streets analysis does not take into consideration. (p. 2)

[Some] proposed improvements that will benefit traffic flow/safety…are not reflected by the multimodal analysis. (p. 3)

The Urban Streets Model software…is less appropriate for evaluating proposed signal timing. (p. 8)

The Urban Streets Model does not account for the impact of bus stops in the operation since this analysis is built to provide a comparison of the four modes of travel (vehicles, bicycles, pedestrians and transit). (p 6)

Few if any highway-planning software claims to be good for every purpose. MassDOT’s 5-page “Guide on Traffic Analysis Tools” (October 2012, p. 2) draws distinctions by use among 8 different software tools.

For instance, Synchro is approved for “signalized analysis” (and some other purposes) but not “roundabout analysis.”  Something called “TSIS-CORSIM” is good for “network analysis” and “simulation” but nothing else.

Urban Streets is not listed for “network analysis.”

Update: “Urban Streets” in this context is a module of HCS 2010. In light of the anonymous comment below, I have edited this report, though I did not completely rewrite it.

I appreciate this information, and regret the error. It’s not so easy to make sense of these documents, none of which were written with the interested public in mind.

MassDOT’s characterization of Streets as not widely reviewed and not used in Massachusetts remain of concern in this context.


2 comments so far

  1. McTrans on

    What is reported here as “Urban Streets” or “Urban Streets analysis package” actually refers to “Streets”, a module of HCS 2010 (http://mctrans.ce.ufl.edu/hcs/). HCS 2010 _is_ a traffic capacity analysis software package listed on MassDOT’s Approved List of Traffic Analysis Tools, approved for unsignalized and signalized intersection capacity analysis and for signal optimization, but not yet approved for network analysis.

    • Adam Auster on

      Thanks for clearing this up. I will change my report to reflect this.

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