Untangling the Triangle

Valuable lesson, quick construction helps MoDOT solve problems with its busiest interchange

Bill Wilson, Editor / February 21, 2003

If it's a weekday you can bet there are over 150,000 people
in Kansas City, Mo., barely moving on a couch.

The Grandview Triangle Interchange, where I-435, I-470 and
Highway 71 meet in a tangled mess, is perhaps the most outdated of its kind.
Containing three merging freeways and as many as 64 movements, the thoroughfare
is struggling to move its daily numbers, which could reach as high as a quarter
of a million in 10 years. The Missouri Department of Transportation recently
decided to give the Triangle a shapelier figure, but there was little room to
expand the waistline.

"One MoDOT official said the work involved is kind of
like somebody redoing your sofa and nobody has to get up," Bill Clarkson
Sr., president of Clarkson Construction, told Roads & Bridges.

Still, the mid-20th century look had to go, and in May of
2001 Clarkson Construction Co., Kansas City, Mo., started the first of a four-phased job. Work began, but the
traffic continued. The prime contractor could only close lanes during predetermined
off-peak hours or face up to a $6,000-an-hour fine. If certain milestones
weren't met by a certain date, the charge was $8,000 a day.

"In this area you can't slow down traffic, especially
during rush hour," Rich Markey, chief bridge engineer at Clarkson
Construction, told Roads & Bridges. "They wanted to maintain traffic
flow as best as they could."

"The reason why the Triangle is so extensively
complicated is because we have to find a way to keep functioning out
there," Steve Porter, senior public information specialist for MoDOT, told
Roads & Bridges.

There's also run-ins with the past, most of which have been
dug and cleaned up--some required an excavator, others a handshake.

It's their way--or no highway

Over 50 years ago, MoDOT thought it had the upper hand. The Kansas
City Planning Commission developed a concept to connect the south with the
north along 71 Highway. The South Midtown Freeway was a major element in the
city's highway master plan, and in the mid-60s Kansas City officials gained
support for the project and received approval of a corridor plan.

By 1970, properties on the south side of the project, from
Bannister Road to 63rd Street, were being acquired. Property owners in the path
of the project, however, soon followed with a lawsuit, and work was stalled for
more than a decade. Officials eventually went another way with the design, and
changed the corridor--now called the Bruce R. Watkins Drive--to a trafficway
with signalized intersections at several key points. Work was completed in

"We learned the hard way. When we had an alternative we
thought it was the best alternative and said, ?This is the way we're
going to do it,'" Steve Hamadi, MoDOT transportation proj-ect manager,
told Roads & Bridges. "That's the way highway departments used to operate."

Traffic has been known to function unpredictably, and during
the time of the Watkins debate congestion was starting to move in the wrong
direction. In the 1960s, city planners thought the growth pattern would go
south along 71 Highway and I-35. The Watkins was supposed to solve this
problem, but during the delay life and development began sprouting up in other
places. The Grandview Triangle Interchange was taking the brunt of the traffic
strike. Overland Park has turned into the fastest growing business district in
the state, and Lee's Summit is the fastest growing community.

"You draw a line between Lee's Summit and Overland Park
and it's basically I-435 and I-470 going through the Triangle," said
Porter. "When we designed the Triangle back in the early 70s we did not
figure on it being the main line through that section, but we designed the
movement as a ramp or two. The mainline traffic cannot handle just two lanes of

The original design concept called for a series of collector
ramps and some added lanes. Politicians heavily opposed the idea, which was
immediately scratched.

MoDOT then conducted a value engineering study. Officials
had a one-week meeting with community leaders and outside engineers and came up
with the following alternatives:

* Repairing and adding lanes;

* Adding a couple of collector ramps; and

* Grand redesign and rebuild.

It was decided to take the second alternative to the public,
which gave it lukewarm support at best (40% was in favor of the design). Still
not satisfied, MoDOT formed a Triangle Advisory Board, which contained some of
the harshest of critics, and hired a consulting firm, HNTB Corp., Kansas City.
After additional input, HNTB had six months to come up with a fourth design

HNTB was able to combine strong elements of all three of the
original alternatives, and public support shot from 40% to 97%.

"Their roadway design probably took well over 100,000
man-hours," added Hamadi.

Fast-acting medicine

MoDOT didn't want to see any more travel time go to waste
and immediately did some patch work--$5 million worth--on the Triangle to
loosen the flow.

A left-hand lane was installed on a previous project with
the idea that lanes would eventually be added to I-435. What it turned into was
a left-hand drop, where vehicles had to make a forced merge. Crews went in and
modified the configuration so the left-hand lane was continuous instead of
ending at the Triangle.

"That lane-drop configuration really helps the traffic
flow quite a bit," said Hamadi. "It didn't increase the capacity of
the roadways, but it decreased the number of lane changes, and lane changes
could have a bigger impact than the number of lanes that are built."

MoDOT also decided to resurface 71 Highway and conduct some
bridge repairs. The 71 Highway was in such bad shape maintenance was being
conducted on a daily basis. As soon as Triangle work is complete, MoDOT will
tear up and apply a more permanent surface.

"We needed to get 71 Highway in good enough condition
so it would last five or seven years and take our maintenance crews off of
it," said Hamadi.

A motorist assist program was put in place, and emergency
zoning signs were installed. Each zone now carries a number a driver can use to
report accidents. Officials say the system has taken 15 minutes off emergency
response time.

"The police came to us and said they were having a hard
time locating incidents in the interchange and they came up with the idea of
dividing the Triangle up into zones," said Hamadi. "Emergency
services now has a chart that tells them not only where the incident is at but
the best way to get there."

A release valve to the south is being reconstructed. The
two-lane 150 Highway has expanded to a four-lane divided one.

"We've had people who have used the Triangle regularly
for a number of years and they come up to us and say, ?Is the Triangle
working better today than three or four years ago?'" said Porter.
"The fact is, it is operating better than before."

History hit MoDOT again during the early stages of the
Triangle. A creek that parallels 71 Highway between Red Bridge Road and I-470
had to be relocated 150 ft to the east so that additional ramps could be
installed. The creek rests on a flood plain, which for years was used as a dump

"When we went out there it looked like these tires were
just growing out of the stream bank, and you could see other construction
materials like brick and shingles," said Hamadi.

Fuel tanks and contaminated soil had to be removed, as well
as almost 200 tons of tires, some still attached to axles.

The landfill also was the resting place of two demolished
bridges. Several asbestos-contaminated buildings had to be torn down, and PCB
had to be removed along an old railroad route.

When the final truckload of garbage was removed, cleanup
costs ranged between $1-2 million.

Where's the money from?

Once preliminary work was complete, MoDOT rolled in for the
big show.

As mentioned before, the project has been cut into four stages.
Phase 1--the area carrying the highest risk for accidents--involved building a
two-lane, south-to-west mainline on I-435; reconfiguring south I-435 ramps to
south 71 Highway and east I-470 to create a separation from express traffic;
adding lanes to north I-435 and replacing bridges. There was an $8,000-a-day
incentive/disincentive, with the maximum award working out to 5%--or about $2.5
million--of the $48 million job. Clarkson completed work on Dec. 23, 2002, 10
months ahead of schedule, to receive full benefits.

Work on Phase 2 ($65 million) began in July 2002. Here the
focus is on west I-470 and ramps from north 71 Highway to I-470. The ramps will
allow merging traffic to join mainline traffic on parallel lanes, no longer
forcing motorists to immediately merge with high-speed traffic. The redesign
also shifts west I-470 to the right side of 71 Highway. The plan, when
completed, will more than triple capacity.

The third phase includes east I-435 to I-470, a section of
71 Highway and most of its ramps north of Red Bridge Road and ramps from south
I-435 to south 71 Highway and east I-470.

The final upgrade will consist of 71 Highway; its ramps and
collector roads south of Red Bridge Road; the relocation and reconstruction of
a new Red Bridge Road bridge; replacement of the Longview Road underpass with a
bridge over 71 Highway; and replacement of the Kansas City Southern railroad
bridge over 71 Highway just north of Blue Ridge Blvd.

Funding, however, could keep all work locked up in Phase 2.
Unlike other states, Missouri does not fund road and bridge work through a
sales or gas tax. A four-cent-per-gallon gas tax increase was on the ballot
this past November, but voters rejected it by a 71% margin.

Due to the lack of financial support, MoDOT has to rely on
bond financing. Between 2001-2006, MoDOT is allowed to issue up to $2 billion
in bond financing, but the downswing in the economy cut from what was
originally planned. So far almost $110 million in bonds has been used for
Triangle work.

"The last $30-50 million is probably up in the air
right now, but we'll get funded eventually," said Hamadi.

But if the cash flow is reduced to a trickle, MoDOT may have
to break the project up into smaller pieces. The original timetable called for
all work to be completed in 71?2 years. A lack of funding could stretch
it out to 12 years.

"We have kept I-435 and all of mainline I-470 on
schedule," said Hamadi. "That is probably about 65-70% of the traffic
congestion and the worst accident location. The problem is 71 Highway has to be
reconstructed last, and that has the biggest impact from the financial

Phasing right through

There are times when construction is the victim of delay.
Clarkson's suffering came soon after Phase 1 received the go-ahead, in the late
spring/early summer of 2001. The Kansas City area experienced one of its
wettest seasons in recent memory, and two miles of permanent median barrier had
to be installed along I-435. The Oct. 31 deadline for barrier work was closing

"We were running into late Oct., Nov. and early Dec.
(2001) trying to get the concrete extruded there," said Clarkson. "If
we got caught in the winter we were facing about a $250,000 a month

Throwing another twist into the deadline was the fact that
Missouri does not allow Superpave to be placed on concrete after Oct. 1. So the
completion date on the barrier job--which included a Superpave
overlay--was pushed up 30 days.

Closing two lanes of traffic on I-435 during every dry
night, Clarkson was able to meet the rush delivery. The median barrier
construction included laying a 4-in. aggregate base, which was covered with 14
in. of concrete and a 5-in. Superpave overlay. Clarkson used a Rexcon Town
& Country to pave the 14-in.-thick concrete section. Producing the overlay
was a Blaw Knox 5510 asphalt paver (Circle 932). Three vibratory
rollers--two Hypac 766s (Circle 933) and a Hypac 778 (Circle
934)--and a Bomag 180 pneumatic roller (Circle 935) handled compaction. A
Gomaco 6400 (Circle 936) formed the 51-in. barrier wall.

Five structural-steel bridges were erected in phase 1, and
most of the steel was set at night. A total of 42 bridge deck pours, with the
assistance of a Gomaco C450 deck finisher (Circle 937), also were done during
twilight hours. Two of the spans--one 781 ft long, one 1,199 ft
long--stand on north I-435. South I-435 holds the other three, which
measure 275, 1,781 and 2,452 ft long.

Drilled shafts 5 in. in diam. were placed 50 ft deep for the
120 bridge columns in Phase 1.

All new bridges in the Triangle are designed to have
hammerhead-type caps. An ashler stone form liner is used when pouring the
columns for aesthetic purposes.

Also unique to Missouri bridge building is the use of
prestressed concrete panels in the bridge deck. Instead of wood forms, a pad of
Styrofoam is placed on top of the girders. Then comes the 3-in. prestressed
concrete panel, and a 51/2-in. full-depth riding surface is placed on
top. A seven-day wet cure has produced strengths as high as 6,000-7,000 psi.
The MoDOT requirement is 4,500 psi.

Clarkson also dropped 80,000 sq yd of pavement during phase
1, and most was of the 14-in.-thick concrete variety.

Plant location has played a key role in the quick
production. LaFarge North America is the ready-mix supplier and has a plant
located two miles from the center of the jobsite. Using a CS Johnson dual-drum
wet batch plant set up adjacent to the Triangle, Clarkson has been able to
batch its own product for the concrete paving portion of the job.

Mid America Precast, Jefferson City, Mo., supplied over
50,000 sq ft of mechanically stabilized earth (MSE) retaining walls in phase 1.

Work on I-470--Phase 2--has been in full swing for
weeks. At press time, about 40 of the 64 bridge columns were in place and
progress had been made on four bridges. All substructure work must be complete
by July 4.

Two of the bridges, currently being worked on adjacent to
existing traffic on I-470, are 2,000-ft-long overhead structures over Hickman
Hills Drive and Hickman Hills Creek. A 500-ft-long temporary bridge is being
installed to tie into west I-470, and the fourth span (300 ft) is an on-ramp,
which will take traffic from Red Bridge Road to 71 Highway north.

When complete, Phase 2 will have eight new bridges. The
drilled shafts--8-9 ft in diam., 40 ft deep--are the only real change
in bridge construction specs from phase 1.

Phase 2 will contain over a million yd of
embankment-in-place, which couldn't start until the massive environmental
cleanup and the creek relocation were complete.

The design calls for over 90,000 sq ft of MSE retaining

Clarkson expects to start concrete paving in the spring, and
all traffic must be driving on the new west I-470 by March 24, 2004.

About the Author

Bill Wilson is editor of Roads & Bridges.

Related Articles

The $5 million renovation of the Atlantic Boulevard Bridge in Pompano Beach has turned a 65-year-old functional structure into a local icon for…
October 07, 2019
The Milwaukee County Zoo is home to over 2,100 living creatures, and sees over 1 million visitors of the human variety on an annual basis. Those…
October 02, 2019
Skyward’s airspace intelligence
Before a pilot can operate a drone in the field, they need to make sure their operations will be safe. Skyward’s airspace intelligence gives pilots more situational awareness than they would otherwise have, helping reduce risk and minimize unforeseen snags while in the field.
There’s no way around it—infrastructure inspection is as risky and dangerous as it is vital. According to OSHA, sending workers up towers or on top…
September 16, 2019
Crews working off a 3D BrIM model; image courtesy of Zenith Survey
Crews working off a 3D BrIM model; image courtesy of Zenith Survey
Government agencies are under pressure to optimize limited resources while also responding to increasing demands for better performance. Across the…
September 12, 2019