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Approved-By:  Steve & Mary Marsh <[log in to unmask]>
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Date:         Mon, 7 Jun 1999 13:07:49 -0400
Reply-To: Sierra Club Forum on Transportation Issues
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Sender: Sierra Club Forum on Transportation Issues
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From: Steve & Mary Marsh <[log in to unmask]>
Subject:      Re: TLCNet: Bikeways and Impervious surfaces.
To: [log in to unmask]

This issue is the heat under the collar in many different projects here in
Maryland.  From my understanding the difference is the closeness to the
sentivive area and the width of the trail.  Some of these new trails are
becoming the superhighways of  bikedom.  How wide were the trails your study in
based upon?

Mary Marsh
__________

Todd Litman wrote:

> At 10:26 AM 6/6/99 -0400, Robert B. Bennett wrote:
> >There is a plan afoot in my area (Newark, Delaware) to construct a new
> >bikeway, which for all its positive features, raises the spectre of more
> >impervious surfacing in our local watersheds that are already stressed.
> >Also, there has been a lot of so-called "Greenways" construction elsewhere
> >in our general area, that has blacktopped a lot of open space. Has anyone
> >addressed this problem elsewhere and does anyone know of a bikable
> >surfacing that is made of pervious material?
>
> I think that it is good to raise the issue because paving land for roads
> and parking facilities has significant environmental impacts that should be
> considered in transport planning, but I don't think that paved trails cause
> nearly as much problem because they are narrow and because of their use.
> Our report "Land Use Impact Costs of Transportation" describes these
> impacts and "Pavement Busters Guide" discusses how to reduce them (both are
> available free at our website: http://www.islandnet.com/~litman). For more
> detailed information on motor vehicle water quality impact see our report
> "Transportation Cost Analysis".
>
> Let's compare the differences between parking/roads and trails with respect
> to these impacts:
>
> * Reduced stormwater recharge.
> When large areas of land are paved it becomes necessary to channel
> stormwater into drains in order to avoid flooding. Trails are narrow and
> stormwater is usually allowed to drain off onto the side where it soaks
> into the soil.
>
> * Reduced water quality.
> Stormwater from roads tends to be contaminated by dripping vehicle fluids
> (crankcase oil, gasoline, coolant, etc.) and particulates (tire and brake
> lining wear, road dust, etc) which can degrade surface and groundwater
> (think of the oily sheen that usually develops on roadway puddles).
> Non-motorized travel does not produce such harmful waste. You may have the
> odd dropped ice cream cone or leaking water bottles, but impacts on water
> quality should be minimal.
>
> * "Heat Island" effect.
> Dark pavement, such as asphalt, gains heat under the sun, resulting in
> excessive temperatures in areas that have lots of pavement. This is both
> uncomfortable and increases cooling costs during the summer in many cities.
> Trails are often made of concrete, which causes much less heat gain, and
> they are frequently located in areas that are shaded by trees.
>
> * Loss of greenspace.
> Of course, any type of human development tends to displace existing
> greenspace, but there would be no difference between a paved and an unpaved
> trail surface.
>
> * Encourages low density urban expansion ("sprawl").
> Roads, particularly increased highway capacity and parking facilities, tend
> to encourage urban sprawl by degrading the urban environment (Who wants to
> live next to heavy traffic?) and by accommodating longer vehicle trips.
> Trails don't tend to do this because non-motorized transport has minimal
> pollution or accident risk impacts and there is a natural limit to walking
> and bicycling distances.
>
> My conclusion is that most of the concerns raised about increased roads and
> parking facilities do not apply very much to trails, and that negative
> impacts are generally more than offset by the reducions in motor vehicle
> use that can result. For more information see our report "Quantifying the
> Benefits of Non-Motorized Travel
> for Achieving TDM Objectives," also available at our website.
>
> There ARE alternative surfaces that may be appropriate for relatively
> light-use recreational trails, but I would not recommend them for heavy-use
> trails that serve urban transportation purposes since they are unsuitable
> for narrow tire bicycles. These include gravel, cinder, and a type of
> pavement blocks that has gaps for soil that cover about half of the
> surface. There is a picture of these blocks in "Pavement Busters Guide".
> They are ideal for light-duty parking surfaces and a few communities
> encourage this use in zoning codes. I don't think that they are used nearly
> as frequently as they should be. However, they produce a "washboard"
> surface that would be uncomfortable for bicycling.
>
> I think that you could achieve the most environmental benefit by paving
> trails for bicycling and encouraging a reduction in pavement for parking
> and roads, and the use of alternative pavement surfaces that are not
> entirely impervious to water for light use parking facilities and alleys.
>
> For more information on impervious surface impacts you may want to visit
> the NEMO Project (www.canr.uconn.edu/ces/nemo) and the Center for Watershed
> Protection (www.pipeline.com/~mrrunoff). Other sources of information are
> listed at the end of our papers.
>
> Sincerely,
>
> Todd Litman, Director
> Victoria Transport Policy Institute
> "Efficiency - Equity - Clarity"
> 1250 Rudlin Street
> Victoria, BC, V8V 3R7, Canada
> Phone & Fax: 250-360-1560
> E-mail:  [log in to unmask]
> Website: http://www.islandnet.com/~litman
>
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