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Tallaght to Ballyboden Walking and Cycling Scheme
Orlagh Roundabout Review Report
February 2020
Page 2 of 18
Table of Contents
A. Introduction
B. Description and Location
C. Roundabout Description as of 2015
D. Road Safety Audit (RSA) Stages 1/2/3/4
E. Traffic and Traffic Counts
F. Traffic Light Signalling
G. Junction Change Consideration
H. Comments Received
I. Summary
J. Conclusion
Reference List
1. Timeline of Events
2. Rathfarnham Templeogue Terenure Area Committee Meeting 12.09.17
3. Responses to RTT ACM
Page 3 of 18
A Introduction
This report has been prepared in response to queries raised by Councillors at the RT ACM and via
MembersNet. A site visit was held between Councillors and SDCC officers at the roundabout on
03.11.19 to more fully understand concerns.
B Description and Location
The R113 is a regional road, set in a suburban setting. It is of regional importance for the movement
of traffic while having an increased local function not only for vehicles but also for pedestrians and
cyclists. The R113 has numerous properties with frontage onto the road, which begin on the eastern
arm of Orlagh roundabout and include St Colmcilles Community College.
The R113 (including the Orlagh roundabout) at the junction of Scholarstown Road and St Colmcilles
Way, is used locally to access schools, the small retail premises on Orlagh Grove and the Knocklyon
Shopping Centre, it is also an entry/ exit road for the M50, which informs a wider regional use of this
road. It is a major distributor road within a regional context linking Knocklyon, Scholarstown and
Ballyboden areas to the wider road network.
The roundabout and the approach roads form part of the National Transport Authorities Greater
Dublin Area Cycle Network Plan acting as a feeder link between route SO5 and SO6. This scheme was
recognised as a critical link between SO5 and SO6 as it connects the schools with the surrounding
estates. There are a number of schools in the area including the largest primary school in the state, St
Colmcille’s National Primary School.
The scheme extends from the recently upgraded junction between Knocklyon Road and Scholarstown
Road to the approaches of the Orlagh Roundabout which is located approximately 300m from the
M50 Junction 12 diverging lane. The section of Scholarstown Road affected by the scheme is
approximately 300m in length with residential developments on both sides. It had a posted speed
limit of 50kph with a controlled pedestrian crossing on the southern end and bus stops located on the
northern end facilitating bus route 15 travelling between Clongriffin and Ballycullen Road (Stocking
C Roundabout Description as of 2015
In 2015, the Orlagh roundabout had three single-lane arms, and one two-lane arm which approached
from the east on R113. The southern arm facilitating Orlagh Grove has a posted speed limit of 30kph
with speed ramps located at the entrance to the housing estate. All other arms had a 50kph speed
limit. Bus stops are located on the eastern and western arms of the Orlagh roundabout facilitating bus
route 15 as described above and bus route 15-N travelling between D’Olier Street and Ellensborough.
Pedestrian Facilities
• Controlled pedestrian crossing exist on the following arms:
o Scholarstown Road (N) – Crossing located 25m back from traffic island
o R113 West (W) 0 Crossing located 20m back from traffic island
o R113 East (E)– Crossing located 14m back from traffic island
• All crossings are single stage crossings
• There are no controlled crossings on the Orlagh Grove Road. Uncontrolled crossing provided
through traffic island. No buff tactile provided.
Page 4 of 18
Cyclist Facilities
• Scholarstown Road (N) – Off-road northbound cycle track from the R113 West to the
pedestrian crossing, the lane does not extend up Scholarstown Road.
• R113 East (E) – Off-road cycle track westbound, 1.2m in width. This lane connects to the
uncontrolled crossing at Orlagh Grove. The eastbound cycle track commences 60m to the east
of the roundabout and is 1.25m in width. Both lanes are below the recommended cycle lane
widths as outlined in the National Cycle Manual.
• R113 West (W) – Off-road east and westbound cycle tracks of varying widths (0.75m to
0.90m). The cycle lanes west of the pedestrian crossing have been upgraded to 1.75m in
• No cycle facilities on Orlagh Grove.
• No cycle lanes through the roundabout or at crossings.
Traffic Lanes
• All movements permitted.
• Single lane approach on three arms, however it is acknowledged that the Scholarstown Road
(N) approach operated as a 2-lane approach.
• A 2-lane approach exists on the westbound approach from the R113 (E).
The needs of pedestrians and cyclists were not adequately catered for prior
D Road Safety Audit (RSA) Stages 1/2/3/4
CSEA produced an options report for the scheme in June 2015 entitled; Tallaght to Ballyboden Cycle
Route Scheme Phase 1, Preliminary Junction Appraisal and Traffic Analysis. This report identified 6
possible junction options for the upgrade of the Orlagh Roundabout.
Stage 1 and 2 RSA reports analysed the 6 options and provided the following comments only regarding
the Orlagh Roundabout:
• Option 1, to provide entry angles on all four arms of the Orlagh roundabout that passively
slows and aligns drivers approaching the roundabout, and to provide a signalised pedestrian
crossing on both arms of the Scholarstown Road (northern and eastern arms).
• The report recommends for Option 2 to remove the second lane approach on the eastern arm
of Orlagh roundabout to avoid side swipe collisions.
Following this report the preferred option was selected and on 12.09.17 a report was brought to the
RTT ACM under Section 38 of the Road Traffic Act 1994. This was approved.
Section 38 (7) states that ‘A traffic calming measure provided under this section shall be deemed to
be a structure forming part of the public road concerned and necessary for the safety of road users’.
This was deemed to be necessary and taking into regard the Stage 1 and 2 RSA Report, the second
lane approach was designed out.
RSA Stage 3 was issued in February 2019 having been prepared by CSEA Consultants, the following
comments were issued:
• Entry angles associated with straight splitter islands has been addressed.
• The proposed zebra crossings and two lanes on the eastern arm are not applicable, as they
were designed out.
Page 5 of 18
• The report also comments that the toucan crossings on the approaches to Orlagh roundabout
may result in excessive queues during peak times and recommends that the phases within the
toucan crossings do not occur so close together that excessive queues form on the approaches
(eg ensure an adequate minimum green time for vehicles between crossing phases during
peak periods).
The Stage 4 RSA report, dated June 2019, was prepared by Bruton Consulting Engineers Ltd to compare
and contrast the safety of the original roundabout facilities to the new roundabout facilities
considering pedestrians, cyclists and vehicular traffic.
The following conclusions were made by the authors:
• In conclusion the recent changes have increased the safety at the roundabout compared to
its original layout.
• In conclusion the current layout is an improvement in safety on the original layout for
• In conclusion the current layout is an improvement with regard to safety on the original layout
for cyclists.
• Overall the current layout improves safety for HGVs with the exception of a swept path issue
at Scholarstown Road (L4016).
• Key to this is the reduction of traffic speed through the use of tighter geometry and raised
• The greatest benefit has been to vulnerable road users and this is the correct priority given
the proximity of the local schools.
• It is important that capacity and safety are not confused. The capacity of the roundabout has
been reduced and journey times are longer however it is not believed to be to such an
extent that drivers would undertake dangerous manoeuvres from frustration.
• It is recommended that the tapers at the raised table and swept path of the buses be looked
at on Scholarstown Road (L4016) along with the items raised in Section 6.0.
Four road safety audits were conducted, and the reports compiled are in respect of matters that have
adverse effect on road safety and the perspective of all road users are considered. It must be noted
here that road safety is not the same as road capacity.
SDCC would be required to provide a written response to the auditors should any of the
recommendations with the road safety audit report be rejected, stating reasons for non-acceptance.
South Dublin County Council accepted all recommendations within the RSA reports.
E Traffic and Traffic Counts
The country nears full employment and with an increasing population and increased residential and
employment development taking place in Dublin, traffic across the entire Greater Dublin Area, and
including within the South Dublin functional area, has increased substantially over the last 5 to 10
years. This strong economic activity coupled with an underinvestment in public transport in those
areas of very high transport demand, results in high congestion levels.
A new report from the TomTom Traffic Index published on January 29th, 2020, shows that Dublin is
the 17th most congested city in the world, with motorists spending an average of 8 days and 21 hours
sitting in peak traffic, a year. The TomTom Traffic Index examined the traffic situation in 416 cities in
57 countries around the world. The report showed that congestion has risen across the country,
especially in Dublin where traffic queue waiting times have risen on average by 3% in the last year.
Page 6 of 18
Traffic volumes in the South Dublin’s functional area also display a steady increase year on year in
keeping with the results of the TomTom Traffic Index Report. This increase in traffic is evidenced in
the TII traffic count stations on the M50 in the vicinity of Kilnamanagh and Ballycullen which show the
following volume increases in the local area:
Year Kilnamanagh Ballycullen
2015 114431 106381
2016 118683 110213
2017 121605 113517
2018 122265 114021
2019 122729 114378
AADT – Annual Average Daily Traffic
The figures show a 7.2% increase at Kilnamanagh from 2015, and a 7.5% increase at Ballycullen for the
same time period.
In addition, more localised traffic counts, carried out by SDCC, on the Knocklyon Road at regular
intervals show the following results:
Year Knocklyon Road
2014 7783
2017 7012
2018 7706
2019 8276
These figures indicate that the traffic volumes dropped during the roadworks at the Scholarstown/
Knocklyon junctions but have since increased. With an increase of 6.33% from 2014, and a massive
increase of 7.3% in one year alone from 2018 to 2019.
The following results show traffic counts, carried out by SDCC, on the Ballycullen Road near
Year Ballycullen Road
2015 7102
2019 8089
These results show an increase of 13.9% from 2015 to 2019, almost double the increase shown by the
count results of on the M50, carried out by the TII and more than double the increase shown by the
count results of the Knocklyon Road, carried out by SDCC. The traffic counts for Knocklyon and
Ballycullen Roads were carried out mid-week during school term from 07:00 to 19:00 as
recommended. These are considered to be the busiest days of the week. In short all of this evidence
demonstrates that the number of vehicles passing through Orlagh Roundabout has increased
massively in last number of years. This increase in-and-of-itself is one of the primary reasons why there
is increased congestion at this roundabout at peak times.
Page 7 of 18
Comparison of Road Users November 2014 to February 2019
7am – 7pm General
Buses People on
Peds Cyclist
Tuesday 25.11.14 18,975 214 19,260 1,112 401
Thursday 28.02.19 20,137 259 23,310 2,522 562
Increase +6% +21% +21% +133% +40%
* assuming 90 people per bus as provided by NTA presentation 12.03.19
AM Peak Hour
General Traffic Buses Peds Cyclist
Tuesday 25.11.14 1899 17 222 169
Thursday 28.02.19 1694 22 937 184
Increase -11% +29% +322% +9%
Share of Modes using the Roundabout
2014 – mode share 2019 – mode share
General Traffic 2,468 (67%) 2,202 (49.5%)
Bus, Ped & Cycle 1,241 (33%) 2,221 (50.5%)
Total Capacity 3,709 4,422
*assuming 50 people per bus in this location and 1.3 per car (NTA approved assumptions)
Between November 2014 and February 2019 there was a decrease of general traffic by 11% at the
Orlagh Roundabout during the peak hour of 08:00 to 09:00. This decrease should not be mistaken as
implying an overall decrease in general traffic. In fact, and as set out in the preceding sections, there
has been a big increase in amount of traffic on the roads in the area.
The decrease in the general traffic passing through the roundabout at peak time (i.e. between 8am
and 9am) is for the following reasons
• Peak time has extended out beyond 8am to 9am.
• The number of buses passing through the junction at peak time has increased from 5 to 22
• Pedestrians moving through the junction during peak time has increased by over 700 people.
• The number of cyclists has increased by 15.
In total (as of Dec 2019) 4,442 people passed through this junction during the morning peak time,
compared to 3,709 people (as of November 2014), which equates to a 20% increase in the number of
people moving through the junction.
This 20% increase in people moving through the junction across a range of modes, serves to
demonstrate that the project has helped to unlock additional capacity in the junction for a broader
range of people. A project focused solely on improving capacity for vehicles would not provide such
capacity improvements.
To further test the traffic numbers a further traffic count was carried out at the request of the Council
in December 2019 show similar numbers to that of February 2019, they are as follows:
Page 8 of 18
Comparison of 2019 Traffic Counts 7am – 7pm
7am – 7pm General
Buses People on
Peds Cyclist
Thursday 28.02.19 20,137 259 23,310 2,522 562
Tuesday 03.12.19 19,674 251 22,590 2,212 355
Wednesday 04.12.19 20,019 271 24,390 2,460 397
*An average of 90 people per bus
Over the course of the day the numbers of general traffic remain broadly consistent across the year,
the number of buses has increased, the number of pedestrians has remained broadly consistent, but
the number of cyclists has fallen.
Comparison of 2019 Traffic Counts AM Peak 8am – 9am
AM Peak Hour
General Traffic Buses Peds Cyclist
Thursday 28.02.19 1694 22 937 184
Tuesday 03.12.19 911 23 652 120
Wednesday 04.12.19 1785 21 386 94
The figure for general traffic is significantly lower on Tuesday 03.12.19 than the other dates.
Pedestrian and cyclist numbers differ considerably with just less than half the number of pedestrians
counted on Tuesday 03.12.19 when compared to Wednesday 04.12.19. The difference between the
number of pedestrians counted on Thursday 28.02.19 to Wednesday 04.12.19 is a staggering
difference of 551 less pedestrians. This is reflected similarly when considering the number of cyclists
on these dates with a difference of 90, almost half the number of cyclists travelled through the
junction on Wednesday 04.12.19 than on Thursday 28.02.19. This may be due to adverse weather
conditions and cold temperatures.
No 15 Bus comparison September 2017 to September 2019
AVL data from Dublin Bus
Page 9 of 18
Sept 2017* Sept 2019 Sept 2017 Sept 2019
Route 15 Am peak Am peak PM peak PM Peak
From B To A 1.5mins 2mins 1.5mins 1.5mins
From A To B 1 min 1.5min 1m 1min
Route 175
From C To A NA** 6.5mins NA** 2min
From A To C NA** 1 min NA** 1min
* Junction under construction 2018
** Bus only started operating in Sept 2018
Unfortunately bus no 15 only began operating in September 2018 and therefore there is no historic
data. Reviewing historical data as provided on the Google maps traffic information platform, which is
uncertified, it shows that the queuing time from C to A is coloured red and dark red, indicating
between 4-7 minutes during the AM peak hour on all Tuesdays, Wednesdays and Thursdays during
September 2017. With the increase in traffic in this area it is of no surprise that the queue time for
Route 175 reflects this in its AVL data as supplied by Dublin Bus, in September 2019 the queue time
was 6.5 minutes during the peak am hour.
F Traffic Light Signalling
In December 2019, SDCC carried out further queue and traffic counts, the council proceeded to change
the pedestrian signals to increase the wait time for pedestrians, which should result in a decrease of
queue time for vehicles, and again carried out queue and traffic counts following the change to assess
the impact. These counts and traffic light amendments took place on the 03/ 04.12.19, while the
pedestrian signals were reset before the 7am count took place on 04.12.19.
All pedestrian signal timings on the three existing crossings prior to the change were set at a minimum
of 7 sec and a maximum of 40 sec.
Before 7am on 04.12.19 (and from then until the writing of this report) the pedestrian signal timings
were reset to provide the following timings:
• Scholarstown Road (N): min 7 sec; max 40 sec
• St Colmcilles Way R113 (W): min 10 sec; max 60 sec
• Scholarstown Road R113 (E): min 10 sec; max 60 sec
Page 10 of 18
Comparing the number of vehicles passing through each arm of the Orlagh roundabout junction, of
the traffic counts taken during the December 2019 count, considering the AM peak hour of this count
to be 08:30-09:30, pre and post-implementation of the pedestrian signal change, the count showed
an increase of capacity of 3.2%. Additional capacity was noted on Scholarstown Road R113 (E), Orlagh
Grove, St Colmcilles Way R113 (W) approaches. Percentage gains were +0.7%, +17% and +20.6%
The 20.6% increase in capacity on St Colmcilles Way R113 (W) approach is significant given that it
connects to the on and off ramps of the M50 at J12. Any increase in capacity on this link will have a
positive impact on the Strategic Road Network.
A reduction in capacity of 13.7% was recorded on Scholarstown Road (N). Effectively, changing the
signal timing at the junction had the effect of increasing the overall capacity of the junction by 3.2%
and reallocating time to the main traffic stream, east – west movement.
The table below shows the AM peak, 08:30-09:30, approach volumes at the Orlagh Roundabout pre
and post signal change implementation:
Approach Arm Pedestrian
Number of Vehicles % Change
Road (E)
Yes 556 560 + 0.7%
Orlagh Grove No Signals 147 172 + 17%
St Colmcilles Way
R113 (W)
Yes 510 615 + 20.6%
Road (N)
No 562 485 -13.7%
Total Vehicles Passing Through
1775 1832 +3.2%
A queue of traffic is defined as those vehicles at a junction which are stationary or which have slowed
down to walking speed or less.
Queue length information was recorded during the traffic count on 03.12.19 and 04.12.19.
Wednesday 04.12.19 corresponds to post implementation of the reconfiguration of the pedestrian
traffic signals at the Orlagh Roundabout.
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The information in the table below shows the longest queue lengths recorded on each arm of the
Orlagh Roundabout junction during the AM peak hour and during the 2 and a half hour morning period
for which the signal change was made (07:00-09:30) pre-implementation on Tuesday 03.12.19, and
post-implementation on Wednesday 04.12.19 of the pedestrian signal change.
Approach Arm Period Longest Queue
Length 03.12.19 (m)
Longest Queue
Length 04.12.19 (m)
Scholarstown Road
R113 (E)
AM Peak Hour (08:30 –
72.5+ 70+
Across Signal Change
Period (07:00-09:30)
72.5+ 75+
Orlagh Grove AM Peak Hour (08:30 –
15 15
Across Signal Change
Period (07:00-09:30)
40 40
St Colmcilles Way
R113 (W)
AM Peak Hour (08:30 –
15 0
Across Signal Change
Period (07:00-09:30)
15 5
Scholarstown Road
AM Peak Hour (08:30 –
20 35
Across Signal Change
Period (07:00-09:30)
25 45
The “+” figures in the queue data represent the longest queue that can be accurately seen.
The table below shows that the queue lengths recorded on Scholarstown Road R113 (E) and Orlagh
Grove are similar pre and post-implementation. Comparing pre and post-implementation results, a
reduction can be noted in the queue lengths on St Colmcilles Way R113 (W) approach following the
change in the pedestrian signal timings. An increase can be seen in the queue lengths recorded on the
Scholarstown Road (N) approach following the change in the pedestrian signal timings. A reduction in
the queue lengths on St Colmcilles Way R113 (W) approach is significant given that it connects to the
on and off ramps of the M50 at J12. Reduced queues on this link will have a positive impact on the
Strategic Road Network.
G Junction Change Consideration
Option 1 Signalisied Roundabout
Signalising the Orlagh roundabout has been considered, the outcome of this consideration is that the
Orlagh roundabout due to its lack of capacity is not suitable for this change. Vehicles waiting on the
roundabout would block the carriageway for the vehicles with a green light.
Option 2 Full Signalised Crossroads
Removing the roundabout and having a full signalised crossroads junction has been considered. The
outcome of this consideration is that the queue lengths would increase considerably, due to the
requirement of adequate green time given to each major arm of the crossroads, Orlagh Grove is
considered the only minor arm, including the contribution of added green time afforded to
pedestrians and cyclists.
Page 12 of 18
Option 3 Revert back to Two Lanes In, One Out
The consideration of reverting back to the original layout of the roundabout of two lanes in from the
eastern arm (R113, Scholarstowns Road) and one lane out on the western arm (R113, St Colmcilles
Way) is interdict. RSA 1 and 2 Report clearly states that this arrangement is unsafe for drivers,
pedestrians and cyclists asit is reasonable to suggest that drivers may expect two lanes on the western
exit of the roundabout, which may result in side swipe collisions where the available width on the exit
is not sufficient to cater for parallel vehicle entry, circulation and exit.
Option 4 Two Lanes In, Two Out
The introduction of two lanes in from the eastern arm (R113, Scholarstowns Road) and two lanes out
on the western arm (R113, St Colmcilles Way) was considered and rejected on the grounds that
• The engineering advice (informed by traffic counts of 20,137 on Thursday 28.02.19) is that a
single lane roundabout is adequate
• Segregation of cyclists is necessary and recommended above 6,000 vehicles per day and
specific design features must be introduced to ensure the safety of cyclists and space is
required to provide this segregated cycle infrastructure The Cycle Manual informs that double
or multiple gyratory lanes are not cycle friendly due to traffic weaving and the risk of side
• Improved and safer crossings for vulnerable road users is needed in this location in particular
given the location of nearby schools and housing developments
Option 5 Keep Existing Roundabout
The RSA Stage 4 Report concluded that the current layout of the Orlagh roundabout in comparison
with its original is best for safety for all road users except for buses.
The existing layout of the Orlagh roundabout allows for vehicular entry onto the roundabout between
gaps in the traffic, this ensures that traffic moves slowly but flows consistently. The tight edged radii
and tighter geometry design of roundabout in general ensures that traffic speeds are reduced. Slower
traffic is safer for all road users, especially vulnerable road users.
The use of the roundabout by pedestrians and cyclists has increased dramatically, aligned with this
the volumes of traffic has increased considerably over time also. The purpose of this scheme was to
encourage use of walking and cycling to school for children and shorter journeys by foot or bicycle for
all, and not to increase the capacity of the roundabout.
Keeping the existing roundabout and continually monitoring the pedestrian signals is the preferred
H Comments Received from traffic warden, local school and Dublin cycle campaign
Traffic Warden
On 31.01.19 the traffic warden, at the Orlagh roundabout reported the following positive feedback on
the new roundabout layout:
• Safety in general is much better
• Speed has been significantly reduced
• The ramp adjacent to her crossing has greatly improved operations at her crossing
Page 13 of 18
• Some children that would normally have been accompanied by their parent are now making their
way to school on their own
• There are delays at peak times, but otherwise ok
• As she lives locally, she says people are not seeing the benefits of the new layout and are still very
On 29.10.19 the traffic warden, at the Orlagh roundabout reported the following positive feedback on
the new roundabout layout:
• The works have made the junction a lot safer. The new position of the roundabout has reduced
speeds on the Scholarstown Rd (E) arm
• Vehicles breaking pedestrian lights remains an issue
• Speed remains an issue from the M50 arm (W) and the Orlagh Grove (S) arm
• Queue times and lengths appear marginally higher. Peak time is 8:20-9:20am. Traffic was always
an issue here and does not appear to be significantly worse. Traffic was traditionally backed up to
Santa Maria on the Scholarstown Rd (E) arm but not anymore
• Clears at 9:20am and from then on speeds creep up
• Visible increase in walkers and cyclists to the junction
Cycling Campaign to MMA, on 10.03.19;
Our view is that we are pleased with the improvements to the cycling infrastructure and the fact that
it has reduced traffic dominance. The increase in walking and cycling numbers is very welcome, and
these numbers are likely to increase further as more people see it as an easier way to get around…
Headmaster, Colmcille Community College
The Councils Road Safety Officer met with Principal who is fully supportive of the improved safety at
Orlagh for their students – who claimed over 90% of them walk/cycle to school. However, the Principal
did mention challenges exiting the school for staff due to traffic volume and due to the increasing
number of cyclists – there is a conflict between the design of their entrance intersecting the shared
use path. He suggested that this needs to be improved as there have been a number of accidents. A
cycle track along Scholarstown Road and Ballyboden Way is needed.
Vice Principal and Green School Coordinator, St. Colmcille’s SNS, Idrone Avenue, Knocklyon
RSO met with Vice-Principal (VP) and Green-Schools Coordinator (GSC). The VP and GSC discussed the
background to their needs in improving facilities for pedestrians and cyclists as a consequence of their
temporary relocation to Sancta Maria during the building works at their current site on Idrone Avenue.
The VP and GSC were in agreement that after the works were complete at Orlagh they believed that
more people were walking and scooting, however, they both felt that they could not promote cycling
to school due to the lack of connectedness to the improved facilities on Knocklyon Road/Scholarstown
Road. The VP/GSC would welcome a count on pedestrians/cyclists that they could disseminate
through the wider school community i.e. School Newsletter.
Page 14 of 18
I Summary
Stage 1 through to stage 4 of the Road Safety Audit has been carried out by consultants and considered
by the Council. The reports compiled by the road safety auditors are in respect of matters that have
adverse effect on road safety and the perspective of all road users are considered.
A written response is required to the auditors should any of the recommendations within the road
safety audit report be rejected, stating reasons for non-acceptance. South Dublin County Council
accepted all recommendations within the RSA reports, having designed out all safety concerns.
The stage 4 report concluded that the recent changes have increased the safety at the roundabout
compared to its original layout for all road users.
Traffic reports and traffic counts prove that there has been a significant increase in the amount of
traffic accessing our roads at all times, and this is reflected in the traffic counts taken at the Orlagh
roundabout junction.
The counts show that there is a considerable increase in the number of pedestrians and cyclists using
this junction, which demonstrates that safety has improved for these road users.
The changes made to the pedestrian signal timings on Wednesday 04.12.19, have shown improved
capacity on three approaches to the roundabout, but a reduction in capacity on Scholarstown Road
(N). The junction capacity improved by 3.2% overall reallocating time to the main traffic stream of east
– west. This has a positive impact on the Strategic Road Network. Queue length data reaffirmed this.
A reduction of queue lengths was recorded on St Colmcilles Way R113 (W) approach, no change was
made on the Orlagh Grove or Scholarstown Road (E) approaches, while an increase was recorded on
the Scholarstown Road (N) approach. Again, producing a positive impact on the Strategic Road
The consideration of reverting back to the original layout of the roundabout of two lanes in from the
eastern arm (R113, Scholarstown Road) and one lane out on the western arm (R113, St Colmcilles
Way) is interdict, having regard for the four road safety audits and the numerous traffic counts.
J Conclusion
Whilst it is acknowledged that queue times have grown worse at this roundabout a lot of this has been
caused because of general background traffic and overall congestion on the road network is getting
worse. It is the Councils decision that the Orlagh roundabout in its current format is;
• the safest design as supported by the road safety audit reports
• has facilitated an increase in the overall number of people being able to pass through the
junction in the AM peak from 3,709 people in 2014 to 4,422 in 2019
• has resulted in a mode share shift weighted towards public bus, pedestrians and cyclists with
an increase from 33% to 50% of people using the roundabout
On these grounds Council officers are not proposing to make any further changes to the roundabout.
Page 15 of 18
Reference List
Minutes of past Rathfarnham Templeogue Terenure ACM’s
Minutes of past Rathfarnham Templeogue Firhouse Bohernabreena ACM’s
Tallaght to Ballyboden Cycle Route Scheme Phase 1, Preliminary Junction Appraisal and Traffic
Analysis, CSEA, June 2015
Stage 1 and 2 Road Safety Audit, Scholarstown Road and Orlagh Roundabout Urban Improvement
Works, CSEA, July 2017
Stage 3 Road Safety Audit, Scholarstown Road/ Orlagh Roundabout Improvements, CSEA, February
Stage 4 Road Safety Audit, Comparative Safety Report Scholarstown Roundabout, Bruton Consulting
Engineers, June 2019
Traffic Implications of changing Pedestrian Signals at Orlagh Roundabout Scholarstown Road, CSEA,
February 2019
Presentation made by NTA to RTT ACM dated 12.03.19
TomTom Traffic Index Report dated 29.01.20
Page 16 of 18
1 Timeline of Events
Timeline Of Events
Date Action Description
25 November 2014 Traffic Counts Traffic counts on Orlagh RAB
June 2015 CSEA Options Report
May 2017 Dwg No 12_098_00_2010 Drawing attached to S38 Report, show
2 lane entry (E)
July 2017 Stage 1/ 2 RSA
July 2017 Dwg No 12_098_00_2010 Amended drawing, same no, shows
one lane entry all entries
12 September 2017 S38 report to RTT ACM Approved
23 May 2018 DMM Letter of Acceptance issued
July 2018 DMM on site
November 2018 DMM leave site
February 2019 Stage 3 RSA
June 2019 RSA 4
28 February 2019 Traffic Counts Traffic counts on Orlagh RAB
28 February 2019 Pedestrian Crossing Lights tweaked Lights tweaked following traffic count
August 2019 Assessment of Orlagh RAB
promised to RTT ACM
03 November 2019 Site visit to Orlagh RAB Unofficial traffic counts outcome is to
carry out new official traffic counts &
signal tweaking
04 December 2019 Traffic Counts 03/04.12.19 traffic counts occurred,
wait time for peds increased
10 December 2019 Report to RTT ACM
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2 Rathfarnham Templeogue Terenure Area Committee Meeting
RTT ACM 12.09.17
Under Section 38 of the Road Traffic Act 1994, as amended, the report regarding the public
consultation for the Scholarstown Road Improvements Works was brought before this committee.
The report noted that details of the proposed scheme was advertised in the Tallaght Echo on 01.06.17
and the closing date for submissions was 17:00 on Saturday 01.07.17. Fourteen submissions were
received and responded to within the report.
Additional to the Section 38 Report a Drawing (CSEA Dwg No: 12_098_00_2010) was submitted, this
drawing detailed a two lane entry onto the Orlagh roundabout from Scholarstown Rd eastern arm
heading west.
All submissions received were in favour of the scheme, including two councillors. Only submissions,
numbers 3, 9 and 12, made reference to the Orlagh roundabout.
The roads section presented the scheme and described the proposals as follows;
1. The provision of almost 0.5km of off-road shared cycle and pedestrian space from the
Knocklyon Road Junction to and around the Orlagh Grove Roundabout.
2. Improved crossing facilities at the entrances to Beverley Drive and the Rookery housing
3. Improved crossing facilities on all four arms of the Orlagh Grove roundabout.
4. Upgraded public lighting using efficient LED lighting.
5. Bus stop improvements with Real Time Passenger Information (RTPI) and improved set-down
6. Removal of numerous existing ESB and Eir overhead cables that span throughout the scheme.
7. Additional landscaping works throughout the scheme.
8. Provision of new and improved drainage.
9. Provision of new public lighting, road markings and cycle route signage.
The minutes of this meeting referenced a short description of the scheme and a summary of the works
as listed above. Queries were raised by Councillors E Murphy, D O’Donovan and P Donovan, were
responded and the report was noted.
RTT ACM 12.03.19
The NTA made a presentation to the RT ACM on 12.03.19 following a request from councillors, the
presentation provided the councillors and spectators with;
• An overview of the remit of the NTA
• Highlighting effective management of transport demand
• The hierarchy of road users
• Informing on National, Regional and Local Policy
• Informing of the reasons for this scheme, catering for the largest national primary school and
other nearby schools
• Highlighting accidents
• Informing on how roundabouts work well for pedestrians and cyclists only if designed to
specifically address their needs and expectations, where the key is slower speeds and a 90
degree entry
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3 Responses to RTT ACM
Date Of ACM Query by Response
08.07.19 Councillor D. S.
Crowe, TD
Reinstatement of original RAB will not be considered. Overall
increase in vehicles moving through RAB.
Dramatic increase in pedestrians and cyclists moving through
09.04.19 Councillor D.
Stage 4 RSA, auditor to be appointed.
12.03.19 Councillor D.
No plan to reinstate two entry lanes at Orlagh RAB, these
were removed due to independent RSA which determined
that there was a risk of side swiping accidents on the
Scholarstown Rd eastern arm heading west.
12.02.19 Councillor E.
Additional time provided to contractor due various reasons.
NTA to attend next RT ACM.
12.02.19 Councillor D.
Synopsis of works at the Orlagh RAB provided, detailing
planning and construction stages, and stating that the Stage
2 RSA determined the change at the RAB from two to one
lane entry at the detailed design stage.
12.02.19 HEADED ITEM: M.
Report on the objectives of the scheme, construction stage,
cost, and that the NTA will attend RT ACM 12.03.19.
08.01.19 HEADED ITEM: J.
Report on the objectives of the scheme and construction
stage and monitoring plans post construction.
08.01.19 Councillor D.
To invite the NTA to the February RT ACM, due to traffic
chaos at the Orlagh RAB.
11.12.18 Councillor E.
Delays at the RAB causing public disquiet, the construction is
not yet complete, contractor still on site, delays to be
expected until completion.
11.12.18 Councillor P. Foley Delays at the RAB causing public disquiet, the construction is
not yet complete, contractor still on site, delays to be
expected until completion.