The city finally released their Environmental Impact report
last week.
It is several hundred pages and I have been wading through
it as fast as I can. They say it will have no impact, but that is what we
expected them to say. So I will give my review so far.
First, my predictions…
Prediction #1
The rush hour traffic count will
come out higher than expected, and the parts of the plan the CTA won’t want to
talk about will include rush hour bans on all of Western and Damen (with loss
of bicycle lanes) and probably parts California,
Kedzie and Halsted.
True.
They didn’t make it easy, but the rush hour traffic counts
are there in
Appendix B-2: Level of Service Analysis
It’s labeled “Existing Volume Schematics” on pages 6-14 and
it is in the form of a bunch of intersectional counts for every intersection.
They’re confusing, but to get a count for, say, the south
side of any intersection, you add all
the vehicles in the north bound lane (inc turns) and the count in the south
bound lane that travels straight and the south bound turns from the cross
streets.
I did that and they showed that my seat of the pants AM rush
traffic counts were right on the money. They indicate that compared to IDOT’s
2010 counts, they are 25% higher in the phase 1 zone (Cortland
to 31st), 6% lower in the north section (Irving
Pk to Cortland)
and 13% higher in the south (31st to 95th). And when I
estimated they would have to divert 650 car per hour in the rush, the actual
number is more like 1000.
Even with these variations, IDOT’s counts were the closest
to current conditions.
I tried to figure out which counts they were using for their
planning. They show a map of what they thought it was at:
Page 12, (13 by screen count)
But it didn’t match any I had seen. They show traffic counts
on Damen where it jumps over the South Branch and Stevenson in the 40,000 range.
I can’t imagine that happening unless one of the other bridges was out.
It turns out that the numbers were based on CMAP’s Travel
Demand Model, which was based on counts from as far back as 2002. They crunch
the numbers and create a model that estimates the current conditions. Every so
often they check it against the real world to see if it is accurate. This works
well enough for the broad brush planning that CMAP does, but it falls apart when it comes to pin-striping
out what is going to happen at any one street.
I’ll get into that later. Right now, let’s go back to the
intersection schematics.
The complex nature of the counts has some advantages.
Because they counted every turn, on every intersection (down to alleys), you
can get a reasonably accurate measure of how many automobile trips are taken on
Ashland on the average rush hour. This number would be analogous to the CTA
boarding counts.
I added up the AM rush count
and found that 22002 vehicles enter Ashland Ave between Irving Pk and 95th each hour during the
typical AM rush. I cross checked this by adding up the number of vehicles
leaving. That total was 22342.
That is what you would expect. Roughly every vehicle that
enters the road leaves at some point.
I ran the same calculations on their projected “Build
Alternative Volume Schematics”. Those totals were 21666 vehicles entering and
only 11940 leaving.
I am not sure how that is supposed to work. The increase in
CTA ridership would only account for about 100 of the 1000 vehicles diverted
each hour. The only scenario I can imagine where that would work is if half of
the people who get on Ashland to
take a 1-2 mile trip get stuck in traffic for over an hour.
To be fair, I don’t think this is part of an evil plan to
turn Ashland into a 16.1 mile
parking lot. I think they didn’t check the numbers because they just didn’t
care. They were worried about what would happen when they magically cut the
traffic rate in half and got rid of the left hand turns. All they cared about
was whether CMAP’s model showed enough through lane capacity on the alternate
routes.
Nothing in their calculations show what will happen when the
52 cars that used to make a left hand turn, eastbound onto Augusta
are queuing up on Damen to make the same turn.
Prediction #2
If phase one gets built as planned,
the route of Elston to Ogden to California
will turn into an unintended bypass. This will piss off the people on Fry
St. to no end, because everyone will be using
their street to dodge the traffic snafu in the Elston-Milwaukee-Ogden
interchange.
True.
Go back to Appendix B-1: Regional Traffic Diversion Analysis
Down at the bottom they have (pgs 23- 28) they have maps of
projected diverted volumes. Ogden
has the second highest diverted counts. They blip over Elston and use Sacramento
instead of California. The reason
for these differences from my prediction is that they are using CMAP’s demand
model that thinks these streets are already saturated.
Look at Appendix B-1: Regional Traffic Diversion Analysis
page 11.
They have a chart called Table 1: Existing Conditions Results by North‐South Routes.
Here they show something called the VMT.
VMT or “vehicle miles traveled” is the daily traffic count
times the length of the road measured. It is simple enough. For roads of equal
lengths, the road with the higher VMT has the higher average traffic counts.
Take another look at that chart. Particularly these three
(the three highest)
Western Ave. VMT
306,429
Damen Ave. VMT
322,336
Ashland Ave. VMT
264,626
They are operating with a model that shows Damen has a
higher ADT than either Western or Ashland.
Damen is actually a couple of miles shorter then the others
and this translates to Damen having a daily traffic count in excess of 22000
for its entire length. Damen only approaches 20000 in a few places. For the
most part it is below 15000 and for a third of its length (Back of the yards)
it is below 10000.
On page 12 they say:
“In reviewing the existing conditions travel demand model
outputs, the VMT for Damen
Avenue appears to be higher than
expected when compared with other parallel routes in the study area. However, the modeled VMT value is not used in the analysis, rather the relative change between Existing and Build Conditions
is used, which is the best indicator for regional traffic diversion.”
So they noticed and ignored it. The VMT is the product of
two numbers, one of which (the road length) is literally set in concrete. It
didn't occur to them that the other (the modeled daily traffic count) is the
very number they used to analyze the impact on every other route. It is a sad
day when you hire a room full of engineers and not one of them has the good
sense god gave a turnip.
Remember those maps at the bottom of “Appendix B-1: Regional
Traffic Diversion Analysis”, well take another look. Damen at North
Ave (based on IDOT’s counts) has excess rush hour
capacity of around 375 vehicles an hour. They predict that it will only get 12
of the diverted vehicles during the AM rush. Western which has an excess rush
hour capacity of less than 200, will see an increase of 348.
Why such a difference? Because of CMAP’s model they think
Damen is way over capacity and Western is way under. They also think that
Elston and California are over
run with autos and that Sacramento Blvd
is a good alternate despite the fact that a third of the phase 1 section winds
its way through two huge parks.
Except for the actual time spent counting cars, the 7000
hours they spent modeling the traffic effects was a waste of time. It was based
on data that was too coarse to be used in this way.
There are
only three basic truths about the impacts on other streets
1, Starting with the closest, all alternates will fill to
capacity until all the traffic displaced from Ashland
is absorbed.
2, In as much
as the average trip on Ashland is
less than 2 miles, those alternates less than 1 mile away, will be under the
highest pressure to exceed capacity. Increases on California
and Kedzie will mostly be people who would normally take Western but have been
diverted because of the congestion.
3, The level of
service, particularly on the two lane alternates, will decline in proportion to
number of new left turn maneuvers in excess of available queuing capacity.
Prediction #3
If phase one ever gets built, phase
two will be the southern portion. Traffic on Ashland
and Western are 10% lower down there and shouldn’t present a problem.
Remains to be seen…
They are still referring to both the north and south segments,
collectively, as phase two. However they always mention the south segment
first.
Prediction #4
Phase three, will be from Clybourn
to Irving Park and it will never be built. Traffic on Ashland
is 25% higher up there and all the alternates are near capacity.
Remains to be seen…
The traffic rate is still higher up there. There is one
possibility though. Reviewing the intersection schematics, I noticed something.
The traffic rates spike between Belmont and Armitage. This leads me to believe
that these are the result of people accessing the Kennedy. Around 1000 cars turn onto or out of Webster
and Armitage each rush hour. If a full time snafu at the Cortland
lane reduction backs up into these two intersections, enough traffic may switch
to an alternate ramp and lower the count to a more attractive number.
I am still holding to my prediction though.
So far I have two confirmed predictions and two pending, that’s a better
batting average than Jeanne Dixon.
I feel emboldened to make a fifth prediction.
CMAP’s projections say that the building the BRT will result in
2% of the corridor wide VMT disappearing. A whopping 34000 Vehicle miles
traveled. Don’t get worked up though, it works out to about 16 cars per typical
rush hour on each of the 8 primary alternates.
Prediction #5
Geography and traffic lead me to suspect that the people
accessing the Kennedy at Armitage and Webster are mostly from the east side of Ashland.
Their access routes to the alternate ramps at Division pretty much suck.
Elston is on the wrong side of the river, Racine
doesn't go through and, Clybourn and Halsted squeeze them through a nasty choke
point caused by the all the shopping at North Ave.
These people represent 25% of the disappearing traffic and they will not disappear.
Instead they will reroute outside of the corridor by using Clark
and the Drive.
Paul K. Dickman
Coming soon
Ashland Ave BRT 3, The route we left behind.
