Saturday, July 24, 2010

What Passes for a Traffic Study at Riverside

In the world of simulation modeling, analysts routinely conduct what is called a sensitivity analysis. For a variable of interest (say vehicle trips in a traffic study), modelers tweak the value of an independent variable (say # of parking spaces) - increasing/decreasing it by some fraction, and evaluate how sensitively the output variable (traffic) responds.

The "Traffic Impact and Access Study" prepared by Vanasse Hangen Brustlin, Inc. for the developers of Riverside, has a glaring, fundamental flaw: it does not study the impact of number of parking spaces on traffic. This should be one of the FIRST things produced by a traffic study for a proposed development.

The study takes, as a given, the number of prescribed parking spots (2,720), and then estimates vehicle trips (and estimates that they will more than triple the current number of daily vehicle trips!).

Thus, probably the single most direct determinant of traffic is not studied in the traffic study.

At a minimum, this study should be extended to evaluate how the number of daily vehicle trips would change if the number of parking spaces were decreased by, say 1/3rd or 1/2, or increased by those fractions.

Going one step further, involving a glimmer of enlightened thinking about "transit oriented development", the analysis could then estimate how restricted parking would drive more use of the D line, the Commuter Rail from the western suburbs, and buses.

When this study is done, it will show clearly that more parking = more traffic. The number of parking spaces is currently prescribed to almost triple, from 960 to 2720. The number of daily vehicle trips is estimated to more than triple (3.25X, to be exact). This alone paints a picture of the tight relationship between parking and traffic.

In their original statement on the proposed development, the Auburndale Community Association stated as a precondition that no additional traffic could be generated from this development. Today we are facing more than a tripling. The question is whether we meant what we said.

Riverside neighbors need to understand that parking is the key lever on traffic. This is a far more effective focus than to focus on complicated freeway ramps and yet more pavement. More parking does not alleviate the traffic problem; it exacerbates it. The current plan allocates the most space to parking (748,000 sq ft), more than the office space and retail space combined. For "transit oriented development" this makes no sense.

Some Riverside neighbors are concerned that reducing parking in the development increases parking on residential streets. The straightforward solution is to restrict parking on residential streets by time period or to residents only, like they do in Boston.

9 comments:

Anonymous said...

for some reason you seem to think that the term "transit oriented development" can only be applicable for an outcome that you desire. If it gets more people to take the T, it's transit oriented. It seems as if you should let the folks who live around Riverside deal with this.

Nathan Phillips said...

I live very close to Riverside.

Nathan Phillips said...

Furthermore, how does tripling the parking space - primarily for people to terminate their car travel at Riverside to work there - get more people to take the T? You have it the wrong way around. If you don't put as many parking spaces there for car commuting workers, you select for T and commuter rail workers - and there are thousands of qualified workers with D line access.
The outcome I desire is for traffic less than the 3.25X that the traffic analysis estimates. How about you?

Ted Hess-Mahan said...

This is kind of a moot point. The MBTA, which controls the site, has made replacing the existing number of commuter parking spaces a sine qua non for development. So, I am not quite sure what would be accomplished by studying a reduced number of spaces.

Anonymous said...

Sorry, I would defer to anyone who lives in the area. It's your neighborhood, and if you can organize to get what you want. Go for it. Unless there is a time limit on the spots, I don't see why they wouldn't be used by commuters. Of course, Ted Hess-Mahan has a point.

Nathan Phillips said...

Ted - Sorry to hear your sense of helplessness. I like to think that government agencies can be persuaded to do the right thing - like the state recently did in reversing its regressive plan for Mass. Ave reconstruction in Boston to make it a complete street, even though it was not legally bound to do so.

So let's leave the commuter parking alone. That is the current 960 spaces. What about the additional 1800 parking spaces for the development? Do you think that is a moot point? Is 3.25X the current number of daily vehicle trips a done deal? If so, then the ACA statement on traffic was meaningless and not worth drafting. As a resident of Auburndale, if we cannot exert pressure to control parking and traffic, I want the MBTA to at least admit that this is not true to the principal of Transit Oriented Development. Note by the way that the MBTA does not list Riverside among its many examples on its web site of Transit Oriented Development.

Anonymous said...

Ridership out of riverside (and other suburb termini) cannot grow if there is no parking available.

Yes, TOD can exist with 2,000 parking spaces. Folks in Brookline (for example) could take the T to Riverside to work in the new offices. Meanwhile, folks in suburbia can park at riverside to take the T into the city.

If you want TOD at Riverside without more parking, then you need riverside to no longer be the terminus. Extend the green line 2 miles, and the parking lots will follow.

Nathan Phillips said...

The 1800 space development parking is not going to grow T ridership - quite the reverse. Do you see future car commuters driving to their place of work at Riverside, then riding the T for some other reason? They are already at work! But by putting in those 1800 spots, you've just dis-incentivized future hires from locating/relocating inside I95 and using public transit to access Riverside, and incentivized them to contribute to exurban sprawl and traffic by providing parking and enhanced access to I95.

So let's preserve ridership "out of" Riverside as you word it (i.e. toward Boston) by existing commuters, and grow ridership INTO Riverside by future reverse commuters (i.e. the young urban professionals yet to be hired) who will find it attractive to take the T to the development (along with those from the western suburbs - Natick, Framingham, Worcester - using the commuter rail). There are two MBTA bus lines too. We won't even throw in the possibility of bike commuting, which is gaining hugely in popularity. Do you think in this economy there won't be enough transit commuting workers to fill the few hundred jobs for the development?
You are on the mark to note that the parking lever can induce Brookline commuters to Riverside - along with, among other areas, Allston/Brighton, and a town full of highly educated and technically trained people - Newton.

Jo-Anne said...

While I live in Newton Centre, I work at Riverside Center, right beside this proposed development. My employer (and I believe many others in this buidling) subsidizes a T pass to encourage employees to ride the T. That could be done at the new development. There is no requirement to drive to work, especially when public transit drops one directly at the office. I agree with Nathan that this study was flawed and did not even take into account that any of the anticipated employees who will work at this site will take public transit or perhaps even ride a bike to work (both of which I do with ease to the building next door). I highly encourage our elected officials to require that the developer complete a new traffic impact study that looks at both how many parking spaces really are needed and the impact to those who currently live and work along Grove Street, which is ill equipped to handle an additional 1800+ vehicles each day.