HomeMy WebLinkAbout04-14-2003 Study SessionDublin City Council
Study Session
Monday, April 14, 2003 -Council Chambers
Present: Absent:
Mayor McCash Mr. Kranstuber
Vice Mayor Boring Mr. Reiner
Mr. Lecklider
Ms. Salay
Ms. Chinnici-Zuercher (arrived 8:10 p.m.)
Ms. Brautigam
Mr. Hammersmith
Mr. Gunderman
Mayor McCash called the study session to order at 7:15 p.m
Historic Dublin Riverwalk
Mr. Gunderman presented background on the subject. In the City's Community Plan,
there is an area known as "Old Dublin," in which it is suggested that the City pursue a
system of pathways that would give both access to the river and connectivity to other
portions of the City. At the time the Community Plan was written, however, it was
understood that no one had looked at the practical aspects of such a connection; a
future study would be necessary. That is the subject of this discussion.
Mr. Gunderman introduced Mark Kline, of Kinzelman and Kline, who began work on this
study approximately a year ago. They began their study by initially meeting with
members of the Chamber of Commerce and individual business owners. Others were,
Dublin School Board members, members of the City's Natural Resources Advisory
Commission, Parks and Recreation Advisory Commission, Architectural Review Board,
a library representative, and individual homeowners.
Mark Kline, Kinzelman and Kline, stated that they started the process by dividing the
river or greenway into three study areas: the Scioto River corridor, the Historic District
corridor, the Shawan Falls/Indian Run corridor. Although they are interconnected, they
are also distinctly different with separate issues, which must be addressed in the design
process.
The Scioto River Corridor
This area runs from the I-270/Emerald Parkway bridge south to the Historic District.
Aerial photographs were taken of this area, and the entire river corridor was traveled and
photographed by boat from the water. There is much that can be seen from the water
that cannot be seen from the land. GIS maps identified City-owned property, public
lands, the existing bikeway, and the proposed bikeway. He noted that the "staging area"
for the Emerald Parkway bridge construction is public land. As such, could be a
parkland access point to the river for fishing, canoeing, kayaking, or viewing purposes.
The City has right-of-way along Emerald Parkway, and there is Federal property in the 1-
270 bridge overpass. In that location, there would be a means to access the river from
the opposite side. There are also the possibility of the City acquiring additional
greenspace along the river, which would provide additional linkage to the river.
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Monday, April 14, 2003
Page 2
There is a topography issue. From Dublin Road, dropping to the Scioto River, the grade
js steep; however, at the river, the land is fairly flat. There are flood zones, and they re
well-documented on all the plans. The Community Plan suggested that there be a river
access trail system along the Scioto River. However, there are existing residential lots
with existing structures in relatively close proximity to the edge of the river shoreline.
This presents achallenge -how can a trail easement be acquired without impacting the
homeowners in that particular area. The issues have been outlined
Mr. Kline stated that there are also problems with the existing structures, which are
situated close to the river. This could be better addressed by using a boardwalk system
along the river's edge. There are questions as to how the boardwalk could be
constructed and maintained. If the boardwalk were raised above the water, from a
safety standpoint, it would be desirable to have a railing. Railing is not functional,
though, with an undulating stream, which carries a lot of debris. It would destroy a
boardwalk. In addition, this is a navigable stream, so there are restrictions as to what is
permitted in and near the water in the flood zone. This is an area that identified for
potential, later development. In reality, due to the financial and physical impacts, the
feasibility of developing this area is minimal.
Indian Run Corridor
Mr. Kline noted that even if the section between the currently-owned City property down
to Indian Run is not feasible for connection today, there are other options for access to
the river. That could occur from the Dublin Road bikeway or from public properties that
are adjacent to Dublin Road. Perhaps such access could be designated as weekend
access, when the businesses are closed and the parking lots are empty. At Indian Run,
with the streamflowthat Domes out and underneath Dublin Road, a pedestrian bridge
would be necessary to access the other side.
In the "staging area" north of Emerald Parkway Bridge, northeast of the Scioto River, it
would be possible to construct a small parking lot with a trail switchback down to the
river, which could be connected to the existing sidewalk on the bridge. This could also
provide access to the bikeway. The bikeway runs along the road, but there are currently
no staging areas. This area could also provide schoolbus parking andlor a picnic table
or two.
In the area from the I-270 bridge to Indian Run, the slope and conditions are precarious.
Shawan Fallsllndian Run Corridor
Mr. Kline noted that five years ago, the City purchased two parcels of land near Shawan
Falls. The plan was for a passive park areas, trail access, and viewing opportunities for
Shawan Falls in a controlled, environmentally sensitive area. They designed a small
parking lot with safe pedestrian and handicapped accessibility to an amazing area.
Shawan Falls is a controlled trail access. Presently, there are severe rock cliff drop-off
areas. Walking along the edge is a safety hazard; however, the public is entering the
area. They suggest a rim trail be constructed, pulled back and away from the top of the
edge, with an occasional overlook created at select safe paints, perhaps deck overlooks.
The City can choose where the overlooks are to eliminate risk, maintain the beauty, and
provide accessibility. There is presently a crossing, but it does not have the capacity for
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Monday, April 14, 2003
Page 3
two-way traffic. Another site could be chosen, which would be more safe and yet not
diminish the visual impact of the waterfalls. There is a bikeway along S.R. 161, and the
bridge at Shawan Falls and S.R. 161 will be replaced. It is very narrow, and presently
there is no pedestrian access. They have suggested to Engineering that if the bridge is
replaced that it accommodate one pedestrian lane.
Mr. Kline indicated that they have met with school officials and they have shared their
concerns regarding potential impact to school property. He suggested to the school
that the trail would be created on the backside of the fence. There are options for either
a higher or lower trail with site-specific observation areas. There is a historic cemetery
behind the Library. The bikepath comes down and breaks away before entering the
Library property, thus avoiding adding traffic congestion to the Library circulation area. It
is desirable to keep the pedestrian traffic separate from Library vehicular traffic. The
parking lot recently developed on school properly is located adjacent to this area. The
path would be on the opposite side from the Library. A minimum-width sidewalk could
connect the trail to the downtown Historic Dublin business district. There will also be a
pedestrian-activated warning signal, which will provide a safe crossing where there is
presently not a traffic signal. He noted that they had considered bringing the pedestrian
traffic down on N. Riverview Street in the area where a wood staircase leads to the S. R.
161 bikepath which leads under Dublin Road bridge. However, this is a vehicle-
dominatedarea, and it is not practical to consider emphasizing pedestrian traffic without
making significant changes. Because those changes did not appear feasible, they did
not pursue that direction. The property lines are very tight in the Riverview Street area,
and it includes an historic stone wall. Although there is significant pedestrian traffic, the
sidewalk system works very well.
Historic Downtown District
Most of the properties are low-lying. There is the possibility far a trail system to link the
area to the river. North Riverview goes down to the bridge at 161. After going down a
staircase, and crossing under the bridge, another flight of stairs leads up to South
Riverview. Or, it is possible to go down another flight of stairs and back under the bridge
to Kiwanis Park. The park can also be accessed by a drive lane. At the river level,
Kiwanis park and the City-owned land are connected.
Consideration was given to connecting the various islands in the river. After learning
from the residents, that the islands are occasionally submerged during the year, the idea
was abandoned.
He noted that the nature of a river is to leave behind debris along the banks as it rises
and falls, therefore, the parkland along the river is not meant to be pristine park space.
The riverbank environment cannot be mowed and manicured.
There is an existing staircase to South Riverview. As this is City-owned land, it is
possible to make a connection between the business district and the river. The comp
plan shows a pedestrian trail system south from South Riverview down to Short Street.
However, the setback of the homes on South Riverview is minimal. Putting in a sidewalk
system would significantly impact those properties. They now believe that putting a
walkway down South Riverview is not feasible.
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Page 4
One suggestion in the comp plan may have some potential, depending on Council's
prioritization of a river access from the business district to the riverl. An access from
Blacksmith Lane is not feasible. Because of its narrowness and steepness, if Spring Hill
were used by pedestrians, it could not be used by vehicular traffic. A pedestrian re-
circulation to Blacksmith Lane was also determined to be unfeasible. They propose that
South Riverview and Blacksmith Lane remain the same two-way circulation, and that the
circulation be made pedestrian-only.
Another issue was a home on Spring Hill that has such a small setback, that it is
impossible to squeeze in a four-foot sidewalk. One section of the house may extend into
the right-of-way or under the road.
Because there are only three lots on that section of the road, it would not be a problem
to make the connection pedestrian only. There is no through traffic. There is some
through traffic on Blacksmith Lane, used by those looking for a shortcut to bypass the
traffic light.
Some citizens have also informed them that the S.R. 161 bridge is unsafe for
pedestrians. It is too narrow with high curbs. The suggestion has been made for a
pedestrian bridge over the river to connect with the trail system on the other side.
However, that is not practical. It could be feasible, if there is a way of suspending a
pedestrian bridge off the existing superstructure of the bridge, and it was not necessary
to erect piles into the riverbed, or piles could be lined up with the existing support
structure, it would have less impact on the river and construction costs. Dayton is
constructing two similar bridges to provide a pedestrian connection from a large park
area to the downtown area.
Mayor McCash inquired if Kiwanis has a master plan far this park area.
Staff response is that there is such a plan.
Ms. Salay inquired if the feasibility of a pedestrian suspension from an existing bridge
has been studied at all.
Mr. Kline indicated it has nat. Yet, his previous experience indicates to him that it is a
viable option.
Ms. Boring inquired how adding that element would aesthetically impact the bridge.
Mr. Kline stated that it would be necessary to set the elevation of the bridge. This was
included in the study undertaken during the planning of the Emerald Parkway bridge.
The hydraulic information related to this stream is available in that report. This is an
attractive bridge, and it would be desirable not to add something that would detract from
its appearance. Presently, he is unaware of the elevation that may be required.
Additional research would be necessary before it could be presented as a feasible
project.
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Page 5
Mr. Kline stated that coming down South Riverview, there is a stairway that leads down
under the bridge, then back up. The original bridge contained a stairway on both sides.
A later bridge replaced them with a single wood staircase, which serves only one side.
The suggestion is to add a vertical elevation staircase on one side. That, along with an
additional sidewalk should meet the citizens' needs. This would eliminate the necessity
of going down into a neighborhood that is not part of the intended destination before
going back up to the business district.
He showed a concept for Spring Hill of a pedestrian circulation. The parking lot would
have access on a good slope. It would be loaded from Blacksmith Lane. There would
still be good two-way circulation, leading down one street then back up to High Street.
He noted that the original comp plan called for a second pedestrian conncection with an
overlook on Pinney Hill. However, because of the dense vegetation, a view of the river
is not possible from that location. Therefore, they have removed that component from
their plan.
Finally, their plan calls for a sidewalk along the north side of Short Street. They
recommend that the City also purchase a couple of vacant parcels. Although linear
access up and down the river may not be feasible, the suggestion is to provide overlooks
or access at key points along the river. The justification for this location is that it is at the
terminus of a large residential area, and could provide the community great long views of
the river.
The study covers construction details for trails, path systems and a boardwalk. This
includes a bikeway boardwalk at Shawan Falls along S. R. 161. He also shared
information on a floating system, which can be done in a very wet area. It has been
done at a couple of private Dublin residences. It is a minimal impact construction. Piles
are run into the river, support beams are added, and the boardwalk is run on top of the
structure. It does not disturb anything except the area the foundation is in. There is a
similar boardwalk system in the Quarry area.
Mr. Gunderman stated a good portion of the comp plan attempts to make connections all
along the river. In the northern section, that is not practical. In Old Dublin, South
Riverview was originally thought to be an obvious location, but due to the configuration
of South Riverview, that is also not practical. That leaves a lack of pedestrian access
from High Street to the river. At this point, it has become important to evaluate the
priority of a pedestrian connection in this area. This could work in the Spring Hill area
better, next to the Kiwanis Park. They had this project on hold for awhile, pending the
stormwater project, thinking it better to consolidate efforts that would disrupt the ground.
However, that project did not occur, but vital surveys were performed.
Ms. Salay inquired if the City were to make Spring Hill pedestrian only, what impact
would that have on the area traffic? Are two-way alleys an option? The one-way signs
in that area are often not respected.
Mr. Gunderman stated that one of the reasons a sidewalk on South Riverview was not
practical was that it almost demanded acne-way street system. Converting Spring Hill
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Page 6
to pedestrian traffic would not demand any changes in the adjoining streets. They can
retain atwo-way system. There may be a segment of a street or two that would need to
be changed to one-way, but this would have less impact than a pedestrian connection
on South Riverview.
Ms. Salay inquired if this would be up from South Riverview to High Street.
Ms. Gunderman responded that was the most practical solution.
Mrs. Boring inquired if the proposal would also redo the street to make it more inviting.
Mr. Gunderman stated that it would. Sketches in the plan suggest how the street would
look. These designs have been shared with the public in the meetings on this topic.
Mrs. Boring stated that she is concerned with the degree of difficulty for senior citizens to
use it. It should be made attractive and inviting. It could be a positive addition to the
community, if done right.
Mr. Gunderman stated that the issue which has been discussed thoroughly is what is the
priority or goal. Is it to provide access to the river for this community, which is primarily
residential? Or is it to retain the character of the residential area as it is and not add
pathways that would bring in outside elements, thereby changing the community. This is
a policy issue. If the priority is to provide pedestrian access into that area, staff's
recommendation is that Spring Hill is the best option. The priority has not yet been
clearly defined.
Mrs. Boring inquired how the Community Plan defined it.
Mr. Gunderman responded that the Community Plan suggested pathways in this location
as well as others that staff has determined impractical.
Mrs. Boring stated that the Community Plan stated that the river is the drawing) point of
the community, and should be emphasized accordingly, so is staff wanting this Council's
confirmation of that policy?
Mr. Gunderman responded that staff would like that confirmation, ar other direction, in
view of the type of constraints presented here, for instance, the fact that, although it is
the best choice, Spring Hill is a very steep hill.
Ms. Salay stated that she has attended many of the public meetings during which the
residents have discussed the feasibility of the rivennralk. While everyone agrees with the
Community Plan -they want access to the river. However, studies show that at certain
points along the river, it is impractical to try to achieve that access. On South Riverview
Street, the river cannot be seen due to the neighbors' backyards. If the riverwalk is
made on Riverview Street, the street is so narrow and the setbacks so small that it would
be necessary for the City to take one homeowner's front yard entirely to put in the
necessary sidewalk. That is not really necessary. It is not that the residents do not want
people to walk on their streets, but that they do not want to lose their yards to the
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Page 7
sidewalks. In that case, it makes mare sense to take the formal rivenivalk up the street
to the business district on South High Street, to benefit those businesses. She
envisions that the river walk would be where there is a river access. This report will
relieve the concerns of the residents of South Riverview. The traffic on that street is
slow and light. It is possible far pedestrians to walk down the street without a formal
sidewalk.
Mrs. Boring stated that this does not address the policy question raised by Mr.
Gunderman.
Ms. Salay stated that he has pointed out that the Community Plan states that the river is
one of the City's primary assets, and access to the community should be provided
wherever possible. Mr. Kline and staff agree with that direction and have indicated that
in many locations, it is possible to do that. However, they have also pointed out that an
S. Riverview Street it is not impractical. On the backside, the walk along the riverwalk is
too steep. The next option is having the riverwalk on South Spring Street.
Mrs. Boring inquired if that was the question.
Mr. Kline stated, as a community, is a physical connection in the Historic Business
District essential? There are other connections possible within the community, for
instance, the Emerald Parkway connection at the I-270 bridge. There are other points of
access to the river, outside the historic business district. There is more flexibility in the
unbuilt environments along the river. The built environment of the historic business and
neighboring residential area are less flexible. It is feasible, but requires the elimination
of vehicular traffic. Also, n the business district there is no other starting point for this
connection than the Kiwanis Park area.
Mr. Lecklider referred to page 20 of the plan. He asked if the path along the riverbank
has been concluded impractical due to its close proximity to the river. There is no
possibility for a boardwalk?
Ms. Salay responded that it disappears in bad weather.
Mr. Gunderman stated that a boardwalk would be too wet/slick, and a railing would not
be sufficiently effective on a boardwalk right next to the river.
Mr. Kline stated that the hillside from the backs of the homes to the river is extremely
steep. Something would have to be done further north.
Mrs. Boring stated that making Spring Hill a pedestrian walkway would give a connection
to the City-owned land on the river.
Mr. Gunderman stated that after it became obvious that a connection was not possible
from South Riverview that we really departing from the Community Plan spirit. Spring
Hill was at least in the Plan, and the best option available.
Mr. Lecklider inquired if feedback has been received from residents regarding the
suggestion to close Spring Hill to vehicular traffic.
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Monday, April 14, 2003
Page 8
Mr. Gunderman responded that although discussions with the residents included the
probability of pedestrian traffic on Spring Hill, it was only recently that it was concluded
that the street would not accommodate both vehicular and pedestrian - it had to be one
or the other..
Ms. Salay stated that there are many property owners along the river who cannot be
heard tonight in this forum. It is important that Council not came to any decisions without
having their input.
Mrs. Boring stated that it is important to provide public access to the city only and to
provide it from some other area than 161, which has heavy vehicular traffic.
Mayor McCash inquired, if Spring Hill is closed, how would the traffic flow for Blacksmith
Alley be handled?
Mr. Kline stated that it would be necessary to study the traffic patterns as they exist
before making a recommendation.
Ms. Salay noted that Blacksmith Alley is an escape route when High Street backs up, so
it will be important to take traffic counts and determine vehicle designations.
Mayor McCash stated that he believes the option of closing Spring Hill as an alleyway
and turning it into a pedestrian connection makes sense. The vision of the Community
Plan was to connect North and South Riverview and north and south business district
and provide different connections other than the Bridge/High Street intersection. The
stairway connection at S.R. 161 and providing something at Spring Hill ties the two sides
of the district together. It gives a more pedestrian environment and provides access to
the City-owned property an the river. The residents and the Historic Dublin Association
had requested the City to purchase river-front property, preserve it, not develop it. It is a
scenic amenity which makes sense to share with the community. In addition, eliminating
that alley should help the traffic flow in the business district. He believes the Spring Hill
proposal is a good approach to the situation.
Mrs. Boring inquired if there would be parking designated areas available for visitors to
the Kiwanis park?
Mr. Kline stated that according to their observations, there is a significant amount of
pedestrian traffic on S. Riverview and na real vehicular conflict on S. Riverview. The
residents indicated that there are people who park down on that block. That likely will be
an enforcement problem far a limited time. It could also be controlled by changing the
road environment. For instance, the flat pavement, could be replaced with a curb
sections.
Ms. Salay inquired about ADA requirements. Is it sufficient for the City to make the trail
or sidewalk accessible except where the topography prohibits.
Mr. Kline indicated that the City is required only to make the best effort possible to
provide handicap accessibility.
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Monday, April 14, 2003
Page 9
Mayor McCash inquired about the "reasonable access" presently provided for the City-
owned property south of Bridge Street. The majority of visitors park up at the City-
owned lot by Dublin Village Tavern. What if the City provided two parallel parking places
on S. Riverview for this purpose? Could a handicapped individual gain access to the
City-owned property.
Mr. Kline stated that there is a small plateau area. They could research the possibility of
providing handicapped parking there. An overlook could be provide an opportunity for
some type of overlook, similar to those considered for Shawan Fallls and Indian Run.
The same thing could occur on the south end at Short Street. Those opportunities are
limited.
Mrs. Boring inquired if there was a timeline involved for getting this finalized and then for
scheduling it in the CIP.
Mr. Kline stated that part of their task is to test those elements that are part of the
Community Plan and determine those that are feasible. Once those are identified for a
modified plan, the next step will be to develop an estimate of costs for the CIP.
Mrs. Boring suggested that if there is a block of the project that is prepared in advance of
the rest of the plan, that it be submitted for CIP approval on its own.
Ms. Salay agreed and expressed her opinion that the Shawan Falls project should be
fast-tracked ahead of the remainder of the project.
Mr. Lecklider referred to page four. He stated that access makes sens from a vehicular
perspective. However, at some point it would be necessary to cross Dublin Road or
Emerald Parkway. That is a dangerous crossing.
Mr. Kline stated that it is a signalized crossing.
Ms. Salay inquired if it is possible to cross under the bridge.
Mr. Kline stated that there with the sidewalk along the bridge, the tunnels, and the
bikeway along Dublin Road, there shouldn't be a problem. On the east side, however,
there could be difficult. There is a signal, so perhaps a modification could be made, if
the Columbus permits. Columbus has property along Riverside Drive, and they have
planned a bikeway interface with the City of Dublin's bikeway.
Mr. Hammersmith stated that when the next phase of Emerald Parkway, which will run to
the east, this project will be considered. Although it will be a large section of highway, it
will continue the present configuration, which includes a bikepath and sidewalk.
Mr. Kline stated that would present the opportunity for a tunnel under Riverside Drive.
He inquired if it is Council's desire for staff to evaluate the traffic patterns in Historic
Dublin.
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Page 10
Council consensus was that Mr. Kline proceed with the evaluation.
Mrs. Boring inquired about maintenance of Kiwanis Park.
Mr. Gunderman stated that he has spoken with Mr. Hahn several times. Mr. Hahn has
indicated that the maintenance is satisfactory. As indicated earlier, this park is not and
will not be kept in pristine condition. The change in river elevation makes it difficult to
keep in perfect condition.
Meeting recess at 8:35 p.m.
Brand Road/Dublin Road Roundabout
Meeting resumes at 8:45 p.m.
Mr. Hammersmith stated that in December 2002, Council authorized staff to evaluate the
Dublin and Brand Road intersection. Initially, staff had suggested the consideration of a
roundabout for this intersection in the CIP hearings last year. Some of the reasons
were
- the scenic characteristics of both Dublin and Brand Roads. There was concern
regarding the impact of signalization on the aesthetic qualities of the intersection.
-the overall function of a signalized intersection.
The staff of DLZ of Ohio was engaged to conduct the study, which is now complete.
They evaluated the intersection in terms of a no-build alternative, an evaluation of the
signal that was programmed to be constructed this year, a signal to accommodate 2025
traffic, and lastly, evaluated that signal against the roundabout alternative.
He introduced Steve Metzer, DLZ of Ohio, Manager of Planning and Ecological
Services.
Mr. Metzer stated that the Powerpoint presentation covers:
- background/need for the study
- intersection alternatives evaluated
- results of evaluation
- aesthetic enhancements
- DLZ recommendation
Problem:
The existing intersection of Dublin and Brand roads particularly during the peak hour
exhibits congestion and delays. DLZ was to study that problem and develop a
recommendation to address those problems.
The existing intersection is stop controlled on Brand Road; Dublin Road is free-flow
traffic. That introduces a problem far traffic turning left (north) from Brand Road onto
Dublin Road. It is difficult to find an adequate gap in traffic to turn.
Methodology:
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Page 11
They looked at existing traffic counts and turning movements and projected those
numbers up to year 2025. They used an annual growth rate of two percent, consistent
with what the City's traffic engineer presented. All the traffic information presented will
be for 20 years worth of growth in the corridor. For the different alternatives, they used
two different modeling softwares. For the traffic signal alternative, the highway capacity
software, and far the modern roundabout alternative, the united kingdom model RODEL.
They developed conceptual alternatives, cost estimates, comparative evaluation matrix
comparing the recommended signal to the roundabout, prepared a final report for
Council.
Traffic Signal:
The City has programmed and originally anticipated constructing a signalized
intersection, adding left-turn lanes, at a cost of $500,000. During the analysis, however,
it was determined that method would only give about five years of adequate traffic
operation at that intersection. The large southbound movement in the AM peak period is
mare than a single through lane can provide. Two through lanes are needed on
southbound Dublin Road to accommodate the projected AM peak hour volume.
Dedicated left-turn lanes will be required on all three legs. Because we will then drop
from those two lanes to one on the southbound Dublin Road, there is an extensive taper
to achieve the merge. It is anticipated that with that configuration, however, this traffic
light will yield a level C. With level D being the goal, that is acceptable for year 2025
traffic. This is the only alternative for that light that will achieve that level of service.
Without two through lanes, the intersection will fail in year 2009.
Modern Roundabout Alternative
This utilizes the United Kingdom methodologies for design with the Rodel model. There
are significant differences between modern roundabouts and traffic circles.
Roundabouts can have significant benefits to City residents, including:
- improved traffic capacity (no loss of "green time,"}
- improved safety compared to signals (eliminate high-impact and both head-on and
front-to-side crashes,
-traffic calming benefits (for this reason, used in residential neighborhoods), greater
- aesthetic opportunities, perhaps as gateway to City,
-and lower maintenance costs than signals.
Mr. Kline stated that the analysis looked at two different roundabouts: one, asingle-lane
entry roundabout and two, adual-lane roundabout. The single lane roundabout would
work for approximately ten years. There is the option of initially constructing the
roundabout as a single lane, and later easily converted to a two-lane roundabout when
the service level begins to suffer.
Two-lane Modern Roundabout
With the two-lane model, two lanes exit the roundabout and taper to one lane. The
primary reason for the difference in taper lengths in the signal and the roundabout is that
the vehicles in the roundabout are going much slower, approximately 18 mileslhour.
The geometry of the roundabout is such that with the curve and the flare, it cannot be
driven faster. The roundabout is a one-way counterclockwise circle.
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Page 12
The curbs are six-inch and there is a deflector island. Vehicles approaching the
roundabout have to yield.
Mr. Kline noted that because of the proximity of adjacent properties, they have been
asked to look at the extreme opposite - a west rounabout. No encroachment in the
right-of-way occurs on the east side, but the tapers for the roadway and the pedestrian
safety path do begin to encroach on both properties.
Mrs. Boring inquired where the existing bikepath is.
Mr. Kline stated that it is just outside the existing roadway.
Mrs. Boring inquired if it would be possible to leave the roadway as it is and the
roundabout where it is.
Mr. Kline responded that it creates am unsafe condition called "see through."
Approaching traffic can see straight thorugh and will go through the one-way on the
wrong side. Drivers approaching the roundabout need visual indicators of what is
ahead. They can, however, construct the roundabout withjn the two options shown. It is
either right-of-way on one side or the other.
Discussion continued regarding proximity to the house.
Ms. Boring stated that she likes the roundabout, but she does not like the negative
impact on the neighborhood.
Ms. Salay inquired if the signalized intersection would have substantially longer tapers
than the roundabout.
Mr. Hammersmith responded that they would be triple the length.
Mr. Kline responded that the area of pavement required for the roundabout is only about
one-half that needed for the signalization.
Summary
The consultants recommend construction of the roundabout versus the signalization,
although both are acceptable. The roundabout would be much safer, its oust is slightly
over half the cost of the signalization, the aesthetics of the roundabout are better,
pedestrians and bicycles are accommodated equally well by either choice.
He noted that a couple of issues would need to be addressed with either alternative.
The most critical issue is the vertical stopping point distance on the north leg of the road.
Coming down the hill on Dublin Road, there is a view problem. There are ways to
alleviate the problem, such as by lowering the posted speed. The impact could be
reduced slightly by shifting the alignment east or west. It is important to maintain the
access of the residence to the east. Finally, the decision would have to be made
whether to construct the roundabout as one-lane or two-lane.
Study Session
Monday, April 14, 2003
Page 13
Mr. Kline showed a video of a pedestrian interaction with a roundabout on the campus of
Michigan State. It is an example of high volume pedestrian exchange.
In response to Ms. Chinnici-Zuercher's inquiry, Mr. Hammersmith noted that the
roundabout would greatly improve the existing conditions. There would be safe
pedestrian passage over Dublin Road.
Mr. Kline showed slides depicting examples of other roundabouts. He discussed the
psychological aspect of driving, which roundabouts accommodate in their structure.
Discussion continued regarding the amount and types of signage that would be needed
for the roundabout.
Mr. Hammersmith stated that when the project progressed to detail design, that the
residents would be involved in the discussion of aesthetics and landscaping.
Ms. Chinnici-Zuercher stated that the primary issue for her is the location in relationship
to the houses. Staff has indicated that "something in between" would be the actual
design -she would need to see that. The neighbors want to be, and should be, involved
in the final design. They are not unrealistic; they realize the traffic issue must be
addressed. However, many of those homes have shallow setbacks, and the design of
the roundabout placement must accommodate that situation. When the final design is
ready for Council's review, she would like Council to visit the actual site as a group in
order to envision the project on-site.
Ms. Salay requested comparative studies on the noise levels for adjacent residents from
roundabouts.
Ms. Salay inquired if there is are roundabouts on Rings Road and Ballantrae
Mr. Hammersmith responded that those are traffic circle. There are no roundabouts in
Dublin, nor in the State of Ohio.
Ms. Salay inquired if the traffic circle in Ballantrae would be of a comparative size to the
one suggested in this study.
Mr. Kline responded that the roundabout would be much smaller, approximately one-half
the size.
Ms. Salay expressed concern regarding the use of flashing lights at night at signalized
intersections.
Mr. Hammersmith stated that the it has been acity-wide policy. Many of the traffic
signals are programmed to begin flashing at 11:00 a.m. It has been done city-wide, and
he has had concerns about those intersections.
Ms. Salay inquired if staff/the consultant had studied the posssible impact of a bridge
across Memorial Drive.
Study Session
Monday, April 14, 2003
Page 14
Mr. Hammersmith stated that Mr. Kline has indicated that asingle-lane roundabout at
the location would work for 10 years. Actually, it should work for 20-25 years.
Mr. Kline stated that they have conducted noise level analyses for similar projects. He
will fonnrard copies to Council
Ms. Salay inquired about the possibility of shifting the roundabout
Mr. Hammersmith