[CANUFNET] trees on high speed right-of-ways

Thu Apr 1 14:40:38 EDT 2010

Hi, we're very interested in trying more native species, but there's
really nothing "native" to highway medians.  It's an extremely
inhospitable environment and our best performers have been exotic
species where the risk of spread is low because we choose a non-seeding
cultivar.

We have had some success with some blue fescues and grasses which again
are not native but tough.  On some of the wider medians and slower
streets we have successfully used a few native species.  Many of the
native species are very difficult to find from a reliable commercial
source.

Thanks, Ian

From: Meagher, Michael [mailto:Michael.Meagher at NRCan-RNCan.gc.ca] 
Sent: Thursday, April 01, 2010 11:31 AM
To: Canadian Urban Forest Network
Cc: Ian Wilson
Subject: RE: [CANUFNET] trees on high speed right-of-ways

Mr.. Wilson: Why not try native species, such as sagebrush, antelope
brush OR cactus? Maybe also Potentilla species?

All should be well suited climatically, remain small, thus no major
pruning in future, not generate a safety issue re crashing cars, require
less water and be long lived. Should be cheaper to replace, also.

They may need maintenance to remove flying/lodged plastic bags and cups,
but that should be faster (cheaper) than water truck spraying and
pruning.

Regards

M. Meagher, R.P.F. (Ret.)

Victoria, BC.

________________________________

From: canufnet-bounces at list.web.net
[mailto:canufnet-bounces at list.web.net] On Behalf Of Ian Wilson
Sent: Monday, February 22, 2010 8:11 AM
To: Canadian Urban Forest Network
Subject: Re: [CANUFNET] trees on high speed right-of-ways

Hi Martha,

We have some medians on Highway 97 in Kelowna, where the posted speeds
reach 80 km/hr (and many people drive 100 km/hr).  These were originally
planted in 1998.  At the time, the transportation engineers originally
objected to the trees in the centre median as possible hazards, however
our parks manager at the time pointed out that it would be preferable
for a vehicle to hit these trees rather than to drive into on-coming
traffic.

The medians are not very wide - they are only the width of a lane of
traffic (about 4.2 metres I think).  They have a slightly sloped brick
apron around the edges, with a planting strip in the middle, planted
with trees shrubs and irrigation.  If you have the space, I would
definitely recommend going wider because the narrow width causes some
issues with sand, salt, and worker safety.  We are now in the process of
renovating some of our highway medians to include safety curbs as you
mentioned, we are converting the spray irrigation to drip (spray
irrigation is higher maintenance and creates runoff onto the road), and
we are also going to construct a flat spot at the end of each median
where a maintenance vehicle can park.

Many of our medians have shrub roses which seem to do fine with the
salts and look good but they catch all the flying garbage.  We are
replacing the roses with more xeriscape type plants such as low growing
fescues.

We have found species selection to be quite challenging due to road
salts and constant wind due to traffic which seems to dry out the leaves
in the heat of summer.  Norway maple is quite tolerant of the salts but
suffers from leaf scorch in late summer.  Red oak and Austrian pine
generally do pretty well.  London plane does well except that the salt
spray tends to kill the buds on the lower portion of the tree and you
get a lot of 'witches brooms' forming.  We're going to try some elms.
Something really tough and weedy like "Tree of Heaven" might even be
worth trying if you can plant males that don't go to seed.

We were concerned that the London planes would get too large but because
of the very limited soil volume they have only reached about an 8 inch
caliper and now grow very slowly.  The good news is they require very
little pruning and don't create much of a hazard for vehicles that run
them over, but in the long term they may start to decline due to the
limited soil volume.  Theoretically they may be able to access some
additional native soils through the bottom of the planter but they are
probably poor quality and compacted.

Good luck,

Ian 

Ian Wilson, Park Services Manager

Civic Operations

TEL 250 469-8842 

FAX 250 862-3335

City of Kelowna 1359 KLO road, Kelowna, BC  V1W 3N8  kelowna.ca
<http://www.kelowna.ca> 

From: canufnet-bounces at list.web.net
[mailto:canufnet-bounces at list.web.net] On Behalf Of Barwinsky, Martha
Sent: Saturday, February 20, 2010 9:45 AM
To: canufnet at list.web.net
Subject: [CANUFNET] trees on high speed right-of-ways

I have some questions for city arborists/foresters related to trees in
centre medians in higher speed zones:

1. Does anyone have a situation with trees, especially mature trees,
currently growing on centre medians of higher speed right-of-ways i.e.
80 km/hr? If so, how do you manage this with transportation engineers,
i.e. that their view is the trees are a hazard to driver safety?

2. Are you planting in these centre medians provided that the median is
a certain width, safety curbs are constructed, and/or the trees are in
raised planters, etc - barring concerns with de-icing salt impact on
tree health? 

3. Do you have guidelines in place in cooperation with transportation in
that you do or do not plant trees in these centre medians?

Thanks in advance for your feedback!

Martha Barwinsky

City Forester

City of Winnipeg

105-1155 Pacific Ave

Winnipeg, MB R3E 3P1

ph: (204) 986-3701

fax: (204) 986-3860

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