M50 RED COW INTERCHANGE LUAS LIGHT RAIL SYSTEM GRADE SEPARATION FEASIBILITY REPORT

Transcription

1 M50 RED COW INTERCHANGE LUAS LIGHT RAIL SYSTEM GRADE SEPARATION FEASIBILITY REPORT PREPARED FOR: THE DEPARTMENT OF TRANSPORT KILDARE STREET DUBLIN 2. PROJECT T th AUGUST 2003 O CONNOR SUTTON CRONIN & ASSOCIATES CONSULTING CIVIL & STRUCTURAL ENGINEERS 9 PRUSSIA STREET DUBLIN 7 01)

2 O CONNOR SUTTON CRONIN & ASSOCIATES CONSULTING CIVIL & STRUCTURAL ENGINEERS REPORT ON OPTIONS FOR GRADE SEPARATION OF LUAS AT RED COW INTERCHANGE FOR DEPARTMENT OF TRANSPORT PROJECT T nd AUGUST 2003 INDEX PAGE 1. EXECUTIVE SUMMARY 1 2. INTRODUCTION 2 3. RED COW INTERCHANGE 3 4. CURRENT LUAS ALIGNMENT PROPOSALS 4 5. FUTURE ROAD PROPOSALS 5 6. LUAS ALIGNMENT GEOMETRIC CONSTRAINTS 6 7. LUAS GRADE SEPARATION OPTIONS 7 8. PREFERRED OPTION SUMMARY & RECOMMENDATIONS 11

3 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport O CONNOR SUTTON CRONIN & ASSOCIATES CONSULTING CIVIL & STRUCTURAL ENGINEERS REPORT ON OPTIONS FOR GRADE SEPARATION OF LUAS AT RED COW INTERCHANGE FOR DEPARTMENT OF TRANSPORT 1. EXECUTIVE SUMMARY PROJECT T nd AUGUST O Connor Sutton Cronin & Associates (OCSC) have been appointed by the Department of Transport (DoT) to carry out a review of the engineering feasibility of providing a grade separated crossing of the M50 Motorway and Red Cow interchange for the LUAS light rail system Line A Tallaght to Abbey Street Line. The OCSC brief is to review the present situation along with the various current infrastructural proposals for the immediate Red Cow area (LUAS at-grade, Park & Ride at-grade/grade separated access, National Roads Authority (NRA) interchange upgrade proposals) and to set out the feasibility of providing a separation between the LUAS line and the local road infrastructure. This separation may either be along the current LUAS alignment but be elevated or dropped relative to the road or alternatively, may involve a horizontal realignment away from the interchange to cross the M50 at a point removed from the roundabout where it would not interfere with traffic OCSC have consulted with a number of parties in the preparation of this report including the DoT, South Dublin County Council (SDCC), the Railway Procurement Agency (RPA), the National Roads Authority (NRA) and ARUP Consulting Engineers (ARUP). These consultations were undertaken for the following reasons: to advise the statutory bodies of the OCSC brief and to obtain all relevant background information necessary for a rigorous assessment of the issues; to better understand the means by which the present LUAS alignment was developed; to ascertain the geometric constraints to light rail alignment design; to garner all relevant information in relation to future road proposals in the area; 1.3. It is important that any proposals brought forward for LUAS alignment change take cognizance of and be compatible with the existing built environment, the current roads alignment and any future plans for road improvements in the area The report analyses the information received from the statutory bodies and considers a number of options for grade separation of the light rail system in the light of all current and known future constraints. These options are judged on engineering feasibility, effectiveness, impact on the built environment, land acquisition requirements, impact on current LUAS works and possible consequential delays to LUAS Line A opening which is currently planned for August The report concludes that the preferred grade separation option can be achieved by maintaining the bulk of the current horizontal alignment of the LUAS along the median of the R110 Regional Road (Naas Road) and elevating the vertical alignment to allow the rail line to cross the Red Cow interchange above current road levels The proposed alignment is compatible with NRA proposals for upgrading the Red Cow interchange and with the Ewbank Preece O heocha Mott McDonald proposals for a grade separated access to the LUAS depot at the south-western corner of the junction between the M50 and the N7 Naas Road. The cost of the proposed option is estimated to be in the order at 25 million. The adoption of the preferred option will mean a delay in the opening of the LUAS beyond August 2004 or alternatively an opening followed by a future closure to effect the necessary tie-in between the current and proposed alignment. Project No. T 79 1 Issue No. 1, 29 th August 2003

4 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 2. INTRODUCTION 2.1. O Connor Sutton Cronin & Associates (OCSC) have been appointed by the Department of Transport (DoT) to carry out a review of the feasibility of providing a grade separated crossing of the M50 Motorway and Red Cow interchange for the LUAS light rail system Line A Tallaght to Abbey Street Line The current alignment proposals for the light rail system ( see Section 3 following) shows the trams running along the central median of the R110 Naas Road through the Long Mile Road/Nangor Road hamburger junction, before crossing the Red Cow junction at-grade via a new M50 overbridge which has been constructed to the immediate south of the current rotary interchange layout The matter of LUAS and the Red Cow interchange has been topical for some time now and the Department of Transport is anxious to consider options to allow for a grade separation of the light rail trams from the road network local to the interchange In undertaking this review OCSC, as earlier noted have had discussions with the following statutory bodies and Consulting Engineers representatives: National Roads Authority (NRA), Mr. Tim Aherne; Railway Procurement Agency (RPA), Mr. Michael Sheedy; South Dublin County Council (SDCC), Mr. Frank Coffey; ARUP Consulting Engineers, Mr. Colin Salter The purpose of these meetings was to garner the necessary information to allow for a rigorous assessment of the issues and to consult as widely as possible in relation to previous alignment designs, design constraints and any future infrastructure proposals for the immediate area The Red Cow interchange is the junction of the M50 Motorway with the N7 National Primary Road and the R110 Regional Road. The junction is located between two exceptionally busy at-grade junctions at Newlands Cross and at the Nangor Road/Long Mile Road and is probably the busiest interchange in the country Traffic levels through the junction would be of the order of 70,000 vehicle per day with very strong tidal movements in the a.m. and p.m. peak hours. Indeed the junction tends to have extended peaks and to be congested throughout the day. The strongest movements in the a.m. peak is the left turn off the N7 inbound continuing northbound along the M50 and the straight eastbound movement along the R110, with the reverse movements being strongest in the p.m. peak There is a perception that the addition of the LUAS, as currently designed, to the currently heavily loaded junction will be the straw which breaks the camel s back and it is in this context that this review has been commissioned in order to protect the significant investment in both the light rail system and the local and national road infrastructure, and to ensure insofar as possible the most effective and efficient outcome to the benefit of all transport modes. Project No. T 79 2 Issue No. 1, 29 th August 2003

5 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 3. RED COW INTERCHANGE 3.1. The Red Cow interchange is a grade separated large diameter signalised rotary interchange located at the junction of the M50 Motorway, the N7 National Primary (Dublin Limerick) Road and the R110 Regional Road which is one of the main radial routes into the centre of Dublin see Site Location Map overleaf The interchange is as noted one of the busiest in the country with AADT 1 traffic volumes in the high tens of thousands and with a relatively high volume of heavy goods vehicles The area immediately surrounding the interchange is quite densely build out with the Fox & Geese industrial complex south east, the proposed LUAS depot and Park & Ride facility to the south west and the Clondalkin residential area to the north west see Figure 1 following In addition to the foregoing there are a number of live planning applications for further developments in the area all of which militate against the selection of alternative alignment options for either the light rail system or the local road infrastructure The NRA has already undertaken a measure of improvements to the junction. These include the construction of capacity enhancement measures to the on and off slips at the interchange. In particular new freeflow slips have been provided from the N7 northbound and from the R110 southbound onto the Motorway which allows this traffic to avoid some of the daily congestion at the interchange The eastbound off ramp from the southbound lane of the motorway onto the R110 has also been improved to allow for a further level of freeflow in the area The situation at the junction is not helped by the presence of the two at-grade junctions to the immediate east and west at Newlands Cross and at Nangor Road/Long Mile Road. The Nangor Road junction has recently been redesigned and is now a hamburger arrangement The NRA has already commissioned studies into further grade-separated and freeflow design options at a number of the M50 interchanges including the Red Cow. Early versions of these designs have been the subject of some public consultation and ongoing design work has continued in the interim The NRA has also brought forward proposals for an upgrade of the M50 to a 2*3 facility and the new West Link toll bridge has recently been opened immediately north of the M50/N4 interchange to the north of the Red Cow. These future road proposals are discussed further in Section 5 following and it is likely that some at least of the proposals will be implemented in the short to medium term. to the north east, the Ballymount Industrial complex to the 3.7. The above measures have helped the current situation but the ongoing rise in traffic levels over the 1990 s has meant that the situation continues to disimprove. This ongoing disimprovement will in all likelihood continue to be the pattern as traffic levels continue to rise at least until 2006, after which time the Dublin Transportation Office (DTO) traffic model shows a decline in traffic levels as public transport improvements take effect It is important in the context of this report, that cognizance is taken of all of these proposed road upgrades and that any options for realignment and grade-separation of the light rail system be compatible with NRA road proposals and other planned developments in the immediate area. 1 Annual Average Daily Traffic Project No. T 79 3 Issue No. 1, 29 th August 2003

6 Department of Transport PROJECT: LUAS - RED COW GRADE SEPARATION REPORT. DRAWING: SITE LOCATION MAP CLIENT: Department of Transport Kildare Street Dublin 2. Drawn By: Checked By: Designed By: Scale: P. Corrigan T. Horan N/A N.T.S. O'Connor Sutton Cronin & Associates Consulting Civil & Structural Engineers 9 Prussia Street Dublin 7 R.C.D. 023 ISSUE 1 R.C.D. 0 PROJECT NO. T 79 Ordnance Survey Ireland Licence No. EN Government of Ireland.

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8 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 4. CURRENT LUAS DESIGN PROPOSALS 4.1. Current LUAS alignment design proposals for the area envisage outbound Luas trams crossing the R110/Nangor Road hamburger junction and travelling westbound along the central median of the R110 Naas Road as far as the Red Cow interchange The horizontal alignment consists of a straight or almost straight section along the central median followed by a series of reverse horizontal curves some quite close to design minimum standards in particular the turn adjacent the Alfa Romeo site at the R110 entry to the interchange. The vertical alignment is essentially at-grade but there is a separation of approximately a metre to the R110 close to the interchange The LUAS trams have free movement along the median as far as the Red Cow interchange but then cede priority to traffic at the interchange. They then wait until signalled before travelling across the Naas Road entry arm of the roundabout and the M50 southbound on-ramp before coming to rest on a newly provided overbridge to the immediate south of the interchange. The trams then await further signalling before crossing the northbound off-ramp of the M50 and continuing on into the Red Cow depot. The LUAS does not cross the R110 freeflow slip southbound onto the M50.The reverse procedure applies for inbound trams see Figure 2 overleaf The trams can cross the R110 entry to the interchange when signals are red both to this arm (R110 traffic heading southbound onto the M50 is unaffected by the trams) and to the N7 Naas Road inbound. During this window, the southbound on slip to the M50 is rarely used as traffic entering the interchange is coming off the M50 southbound and move predominantly eastbound to the R110 or westbound to the N As noted, the trams come to rest on the LUAS M50 overbridge before waiting to cross the northbound off slip into the new LUAS depot and Park & Ride site. This off ramp receives only 10 seconds of green time during any cycle and it is therefore relatively easy for the LUAS to cross the ramp in normal conditions The current signal cycle timings at the Red Cow vary between 60 and 70 seconds in the a.m. and p.m. peaks and it is envisaged that the trams will at worse effect the crossing within a single cycle and indeed in a shorter time in many instances. The current arrangement and phasing of signals at the interchange means that it will be possible for the LUAS trams to cross the interchange without interference to traffic and without taking signal green time from any traffic movement Traffic modelling of the junction by the DTO has shown that the LUAS trams can effect the crossing of the interchange without impact on traffic in normal conditions and in most cases will be able to effect the crossing within a single signal cycle Notwithstanding the above however it is evident that the imposition of extra movements and conflicts at the Red Cow interchange, which is currently heavily saturated and subject to frequent congestion events, has at least the potential for greater and more frequent problems. The potential is exacerbated by the fact that the interchange is not a freeflow junction but has a number of at-grade conflicts between very heavy traffic movements In particular there is the possibility that the trams may get caught up in at least some of these events and that rather than being a cause of conflict may become a victim of same. It is in this context that the DoT have requested this review to be carried out. Project No. T 79 4 Issue No. 1, 29 th August 2003

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10 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 5. FUTURE ROAD PROPOSALS junction. The construction of the complete scheme will also involve significant local land acquisition The NRA through ARUP Consulting Engineers have prepared proposals for further grade separation of the Red Cow interchange. These proposals allow for the grade separation of a number of heavy traffic movements and will alleviate congestion at the interchange It is likely however that some measures will be implemented to facilitate the heaviest traffic movements at the junction. These would include in particular the northbound movement from the N7 onto the M50 and the westbound movement off the M50 onto the N Work on a number of design options has been ongoing for some time now and a number of different options have been developed The estimated cost for the complete scheme has been estimated at close to 100 million and it is uncertain as to whether the complete scheme will go ahead in the medium term. It is uncertain also what the overall benefits of the complete scheme would be in the context of the two atgrade junctions either side of the interchange at Newlands Cross and at the R110/Nangor Road/Long Mile Road 5.5. In addition to the above the NRA have also prepared proposals for an upgrade of the M50 to a 2*3 arrangement by the construction of a third lane in each direction in the space currently occupied by the central median. It is again uncertain as to when these proposals will be implemented but it is likely that priority would be given to that section of the motorway between the N7 and N4 interchanges The complete Red Cow grade separation scheme is shown in Figure 3 overleaf and the proposal can be seen in the context of the current LUAS alignment design at the interchange The scheme essentially involves the construction of a third tier at the interchange. The M50 mainline proper remains unaltered but the straight through movement from the N7 to the R110 is accommodated by a newly constructed overbridge across the motorway close to the east-west diameter of the current rotary The westbound movement off the M50 onto the N7 is accommodated by a third tier over the new east-west link and across the M50 close to and north of the current southern bridge of the rotary The existing southern bridge of the rotary is used in the design to accommodate westbound traffic exiting the Turnpike Road to the west of the Red Cow Hotel. The scheme is better presented graphically as shown in Figure 4 following It is likely that a reduced form of the scheme, to cater for the heaviest of movements at the junction, can be constructed with a cost in the region of million It is notable however that the design still incorporates the LUAS trams effecting some crossings atgrade. Project No. T 79 5 Issue No. 1, 29 th August 2003

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12 RED COW LUAS GRADE SEPARATION FEASIBILITY REPORT FIGURE 4 GRAPHICAL REPRESENTATION OF PROPOSED RED COW INTERCHANGE UPGRADING BY ARUP CONSULTING ENGINEERS

13 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 6. LUAS ALIGNMENT GEOMETRIC CONSTRAINTS & VEHICLE CHARACTERISTICS In order to conceive of alternative alignment options for the light rail system it is necessary to have knowledge of the horizontal and vertical geometric alignment constraints under which the trams can safely and comfortably operate The geometric alignment constraints for the light rail system are set out in the RPA document Track Alignments Tramway Clearances Design Criteria and is based on the Alsom Citadis vehicle characteristics. A copy of this document has been provided to OCSC by the RPA At its proposed normal operating speed of 70 kilometres per hour, the light rail system requires a minimum design radius of 544 metres approximately As this horizontal radius decreases so to must the safe operating speed of the tram. The absolute minimum specified horizontal radius specified is 25 metres at which radius the trams can only travel at 15 kilometres per hour In the vertical plane the absolute minimum summit (crest) curve length is 700 metres and the absolute minimum sag curve specified is 350 metres The maximum vertical gradient at which the trams are permitted to travel is 6% In addition to the above there are particular horizontal and vertical alignment constraints at those locations where passenger stops are to be provided. In such instances the horizontal radius is limited to a minimum of 300 metres and the vertical gradient limited to 2% (rising to 4% in exceptional situations). SE 2.70 m DKE 2.40 m 6.2 m SCHEMATIC DIAGRAM OF LUAS ROLLING STOCK GUAGES 6.8. The length of a tram will be either 30 metres or 41 metres depending on the type of vehicle and the width of a tram is 2.40 metres The height of a vehicle is 3.35 metres but this is added to by the pantograph which links the tram to the overhead power transmission network The maximum loaded weight of the 30 metre and 41 metre trams is 590 and 774 kilonewtons respectively. The design specification also details the hypothesis of loads for structural design purposes In conjunction with the foregoing, cognisance needs to be taken of both the static and kinematic envelopes of the trams. The static envelope of a tram on a level straight track is 2.40 metres. The kinematic envelope of the vehicle takes account a number of dynamic elements which arise from the motion of the vehicle including lateral movement and is 2.70 metres on level straight track The swept path of two trams running side by side is as shown in the schematic diagram below. There is some widening of this envelope required with horizontal curvature but the diagram is offered as an indication of the width requirements of the system The design criteria also offers information in relation to minimum lateral clearances between the trams and other light rail infrastructure, continuous obstacles, footpaths, cycleways etc The above requirements have been borne in mind by OCSC in developing possible alternative alignment options for the light rail in the vicinity of the Red Cow interchange. Project No. T 79 6 Issue No. 1, 29 th August 2003

14 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 7. LUAS GRADE SEPARATION OPTIONS Option 2: Southwards Horizontal Displacement 7.1. OCSC have considered a number of options for grade separation of Luas at the Red Cow. There are two main options for separation as follows: a horizontal alignment displacement to the north or south of the Red Cow interchange; a vertical alignment displacement to take the light rail either under or over the interchange Horizontal Realignment Options Option 1: Northwards Horizontal Displacement 7.2. As noted earlier in the report, the area in and around the Red Cow interchange is heavily developed and the options for realignment off the R110 east of the interchange are limited A horizontal displacement of the alignment to the north side of the R110 seems impracticable from even a superficial consideration. The displacement would require the LUAS to cross the R110 to the east of the Red Cow and run along the northern edge of the Regional Road The realignment would allow for a grade separated crossing of the M50 north of the existing rotary to the south of Holly Road before crossing the N7 to the west of the interchange to enter the LUAS depot see Figure 5 overleaf There are significant drawbacks to a consideration of this alignment as follows: the alignment would bring the LUAS into conflict with a number of existing premises located on the north side of the R110 to the detriment of travel times; the alignment requires the LUAS to cross the R110 atgrade between the Nangor Road junction and the Red Cow; the alignment leaves significant elements of the current LUAS alignment redundant; this option may pose difficulties with the current layout of the LUAS depot and Park & Ride facility; the option would not be compatible with proposals for upgrading the Red Cow interchange Considering all of the foregoing this horizontal realignment is not considered to be a viable option The second horizontal realignment option is to move the LUAS to the south of the R110. However this option seems equally unattractive as Option 1 from a number of viewpoints This area is equally as developed if not more so than the north side of the R110. There are a number of significant road junctions and business accesses on this side of the road and the introduction of a tram line here would lead to significant conflicts between the light rail system and other road users These conflicts would be to the detriment of both modes of transport and be much less efficient than the current proposals In addition to the above, the south side of the R110 immediately adjacent the Red Cow interchange is much more significantly built out than the corresponding area to the south of the R110. This makes a realignment design of the LUAS particularly difficult In order to avoid the interchange and impact with the on and off ramps of the motorway it would be desirable to cross the M50 some distance south of the rotary where the down gradient of the ramps would allow the LUAS to overbridge both with sufficient vertical clearance see Figure 6 following. Project No. T 79 7 Issue No. 1, 29 th August 2003

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17 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport This southwards movement of the alignment brings the LUAS into significant conflict with the built environment to the extent that land acquisition costs would be very significant This alignment would also require a significant redesign of the layout of the LUAS depot and Park & Ride facility Considering the foregoing, this realignment option is not recommended. Vertical Realignment Options Option 3: Vertical Realignment at Red Cow As an alternative to horizontal displacements of the current alignment, it would be possible to maintain the bulk of the current horizontal alignment and to vertically alter the light rail alignment in the vicinity of the Red Cow interchange There are a number of possible alternative alignment arrangements which could be provided in order to provide the requisite grade separation. Two possible alignments are shown in Figures 7 & 8 following. The designs will require the elevation of the line for approximately 200 metres east of the interchange along the R110 median in order to gain sufficient headroom at the interchange The deciding criteria between these alignments will be the degree to which they allow for the retention of existing LUAS civil works, including the depot and Park & Ride facility and the degree to which they are compatible with the NRA s proposals for further grade separation at the interchange The relative benefits of these vertical realignment options would be significant compared to the horizontal realignment options presented earlier These benefits would include, inter alia, the following: The current alignment along the R110 median could be retained with the undoubted benefits of segregation and travel time savings that it offers; There would be a minimal requirement if any for further land acquisition; There would be a minimum redundancy of LUAS civil engineering work undertaken to date; The overall cost of provision would be less than for other options particularly when land acquisition costs are taken into account; The alignment can be made compatible with current NRA proposals for an upgrade of the Red Cow road infrastructure and it may be possible to utilise the current LUAS bridge as part of that upgrade; The alignment design and construction could be fast tracked and constructed earlier than other realignment options given that land acquisition will be minimal if required There will be some disbenefits of the proposed alignment however. These will chiefly be related to further construction disruption to road traffic and possible disruption to LUAS operations It is currently expected that the LUAS Line A will be in operation and carrying passengers in August 2004 which is only 12 months away. It would be difficult to effect the necessary design, planning and construction work of a LUAS realignment within this relatively short period In this context there are then two options open to the Department of Transport and the RPA as follows: Project No. T 79 8 Issue No. 1, 29 th August 2003

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20 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport Delay the opening of this line or at least that part of the line which would be affected by the realignment works until such time as the works have been completed; Open the line and then put a closure in place whilst the realignment work takes place Each of the above options is quite unpalatable but the former seems the most sensible if the design and planning of the scheme can be fast tracked. Project No. T 79 9 Issue No. 1, 29 th August 2003

21 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 8. PREFERRED OPTION 8.1. The Preferred Option for grade separation of the light rail system at the Red Cow interchange is to maintain insofar as possible the current horizontal alignment along the R110 central median and to vertically elevate the tram line in the vicinity of the interchange as noted in Figures 7 & 8 earlier The further design of these options needs to be more rigorously fleshed out with better topographical information and to be examined in the context of maximum compatibility with the already completed LUAS works and the NRA proposals for the interchange The vertical realignment option however does allow 8.4. Any at-grade horizontal alignment of the track along either side of the R110 or even further displaced away from this road, will serve only to increase the travel time of the LUAS due to tram-vehicle conflicts and will more than offset the potential time losses at the Red Cow The use of the R110 central median for the LUAS is considered to be the most efficient alignment option possible. Under this arrangement, the trams have unimpeded flow from the Nangor Road junction as far as the Red Cow roundabout without having to cede priority to or take priority from road traffic Any other alignment option will increase the number conflicts between the LUAS and road traffic to the detriment of both modes of transport It is difficult to be precise in relation to the potential cost of the recommended vertical realignment options set out above, at this early stage. However the cost is likely to be of the order of million These figures are however to be considered in the context of the overall project cost of 750 million, the projected cost of the Red Cow upgrade at 100 million and the potential for travel time savings which they carry. maximum use to be made of existing tracking, minimises or avoids the need for new land acquisition and is the most efficient in terms of tram travel times It is recommended that further work be carried out on the detailed design of the vertical realignment options set out herein in consultation with both the RPA and the NRA and that the compatibility of the preferred realignment option be analysed with respect to the requirements of each body. Project No. T Issue No. 1, 29 th August 2003

22 O Connor Sutton Cronin & Associates LUAS Red Cow Grade Separation Report Consulting Civil & Structural Engineers Department of Transport 9. SUMMARY & RECOMMENDATIONS 9.1. Current RPA proposals for the LUAS alignment at the Red Cow interchange involve at grade crossings of the R110, and the on and off ramps of the M Although traffic modelling has shown that the LUAS can, in normal circumstances, negotiate the interchange with minimal impact on traffic, given the current signalling arrangement at the junction, there is concern that this may not always be the case The authors of this report have consulted with the various interested bodies charged with both road and LUAS proposals for the area, including the NRA, the RPA and the local Roads Authority, South Dublin County Council The authors have examined the NRA proposals for further grade separation at the Red Cow and have also considered the LUAS alignment design manuals Options for a horizontal realignment of the light rail system away from the Red Cow (in order to achieve separation at the interchange) have been examined but have been dismissed on the basis that they will not lead to reduced LUAS travel time but rather to more conflict between the rail and road systems It is accepted that the current horizontal alignment for the LUAS along the central median of the R110 is the most efficient alignment possible up to the point at which it crosses the interchange at grade. separation across the Red Cow interchange, as shown in the two sample options put forward This vertical alignment is achievable within the current median width and will maintain full segregation between the light rail line and road traffic on the R It will be necessary to take up and relay a certain amount of rail track which has been laid and it may also be necessary to alter the layout of the depot and Park & Ride. However further detailed design may allow for a minimisation of impact particularly within the depot and Park & Ride If the realignment as set out in this report is to proceed, it will impact on the current proposed opening time for the LUAS or alternatively require a closure of the line following opening in order to execute the tie-in works between the current and proposed alignment There is particular concern also that rather than being the cause of further congestion at the interchange, the LUAS may become a victim of the ongoing congestion in the area given the less disciplined characteristics of road as opposed to rail vehicles and respective driver behaviours There is a significant body of civil engineering work already completed by the RPA s contractors in this area including track laying and depot/park & Ride construction. It is important in a cost context that as much as possible of this work should be maintained It is recommended that grade separation at the junction be provided by maintaining in as far as possible, the current horizontal alignment along the central median of the R110 and then elevating the alignment to provide a vertical Tony Horan Chief Civil Engineer O Connor Sutton Cronin & Associates Project No. T Issue No. 1, 29 th August 2003