1 ITS specification Ramp meter site layout (ITS-05-01) NZ Transport Agency Effective from September 2011
2 Copyright information This publication is copyright NZ Transport Agency (NZTA). Material in it may be reproduced for personal or inhouse use without formal permission or charge, provided suitable acknowledgement is made to this publication and the NZTA as the source. Requests and enquiries about the reproduction of material in this publication for any other purpose should be made to: NZ Transport Agency Private Bag 6995 Wellington 6141 The permission to reproduce material in this publication does not extend to any material for which the copyright is identified as being held by a third party. Authorisation to reproduce material belonging to a third party must be obtained from the copyright holder(s) concerned. Disclaimer The NZTA has endeavoured to ensure material in this document is technically accurate and reflects legal requirements. However, the document does not override governing legislation. The NZTA does not accept liability for any consequences arising from the use of this document. If the user of this document is unsure whether the material is correct, they should refer directly to the relevant legislation and contact the NZTA. More information Published September 2011 If you have further queries, call our contact centre on or write to us: NZ Transport Agency Private Bag 6995 Wellington 6141 This document is available on the NZTA s website at
3 Page i Document management plan 1) Purpose The purpose of this document is to specify the general requirements for Ramp Meter site layout design. 2) Document information Document name Document number Document status Document availability ITS specification: Ramp meter site layout ITS Final This document is located in electronic form on the NZ Transport Agency s website at Document author Waterview ITS Requirements Working Group: Jamie French (09) Tom Harris (09) Document owner Henry Pretorius 3) Key words ITS Ramp Meter Site Layout requirements.
4 Page ii Record of amendments Amendment number Section amended Description of change Updated by Effective date Draft R0 All ITS Draft Specifications Issue JF/TLH 23/9/2010 Draft R1 All AMA Specifications Review JF & TLH 26/1/2011
5 Page iii Contents Document management plan Record of amendments i ii 1.0 Ramp meter system site layout Scope Design assumptions Standard drawings Layout design requirements Stop line Loop types General Count and mainline loops Queue loops Count loop configuration and locations Configuration Mainline loop configuration, ramp merge Mainline loop configuration, lane gain On-ramp count loops Motorway off-ramps Ramp signal by-pass lanes Queue loop configuration and locations Configuration First on-ramp queue loop Additional queue loops Arterial queue loops Ramp signal loop identification General Primary queue loop identification Primary count loop numbering Mainline loops Secondary loop identification Signal controller location General 10
6 Page iv Controller identification Advance warning signs General Type A AWS Type B AWS Advanced warning sign identification Ramp signals Static signage Ramp signal signage Regulatory speed signs PW 43-1 special signage, road narrows both sides PW 3 traffic signal sign Priority bypass lanes Line markings Motorway to motorway ramp signalling Journey time information, type D sign 15
7 Page Ramp meter system site layout 1.1 Scope The purpose of this document is to identify the design requirements for the equipment layouts at a Ramp Meter Site in order for a detailed ITS design to be undertaken. In general each Ramp Meter Site will consist of: a. A Ramp Meter Controller used to manage the operation of the lights and advanced warning signs; b. Mainline and Ramp Count and Occupancy Detector Loops monitoring the flow rates on the motorway for the RMS to determine the best operating conditions; c. Queue Detector Loops to monitor queue lengths on the on-ramp and arterial road; d. Ramp Meter Signals to limit the traffic on the on-ramp to control the flow on traffic onto the motorway; e. Type A Advanced Warning Signs giving motorists prior warning of Ramp Signal Operation; f. Type B Advanced Warning Signs warning motorists to stop at the Ramp Signals; g. Power supply; h. Roadside Communications cabinet, plinth and apron; i. Communications interfacing equipment; j. Guardrail protection and other accessories as necessary. This document also outlines the details for the Journey Time Information Variable Message Signs (VMS Type D) and their location and connectivity. This specification should be used as guidance as to the following: a. Stop Line Positioning b. Loop Positioning c. Signal Controller Location d. AWS Location including e. Traffic Signal Location f. Static Signage g. Line Markings. This document should be read in conjunction with the NZ Transport Agency s (NZTA) ITS specification: Ramp meter supply and installation (ITS-05-02). 1.2 Design assumptions The Ramp Metering System is a traffic management technique, which manages the number of vehicles joining a motorway at peak periods. The fundamental purpose of the RMS is to prevent or delay the onset of flow breakdown on the main carriageway by a combination of: a. Managing the flow on the entry slip road to avoid large platoons of vehicles entering the main carriageway and causing flow breakdown; and
8 Page 2 b. Restricting the flow onto the motorway of additional traffic that, if unrestricted would trigger flow breakdown. By preventing or delaying this flow breakdown, the system provides the following benefits: a. Less congestion and improved traffic flows on the main carriageway; b. Higher throughput during peak periods on the main carriageway; and, c. Smoother and more reliable journey times on the main carriageway. For the ramp meter equipment layout design it is assumed that the associated road layout has been designed and the road geometry requirements for the Ramp Meter System have been met. Note: This document is intended as a design guideline and any design created using this document must be audited and approved prior to construction. 1.3 Standard drawings The standard drawings for Ramp Meter System layouts are attached in the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). The standard drawings are provided for information to provide a basis for design. The contractor shall provide site specific detailed design drawings for all structures and foundations associated with the project for review prior to commencement of fabrication. The drawings attached in the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03) should be used as guidance only.
9 Page Layout design requirements 2.1 Stop line The stop line will be the point at which the vehicles are brought to a halt on the on-ramp prior to release onto the motorway. It is from this starting point of stop line placement that will facilitate the remainder of the design. The stop line will typically be located m upstream of the physical nose as detailed in NZTA M2 Standard Ramp Metered Entrance Details drawing attached within section 1 Layout Drawings of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). Upon placement of the stop line the positioning of loops can commence. 2.2 Loop types General The supply and installation of any inductive loop for the purpose of ramp signalling shall be done in accordance with the National Traffic Signal Specification attached within the appendices of the NZTA s ITS specification: Ramp meter supply and installation (ITS-05-02) and the NZTA s ITS specification: Inductive loops and feeder cables (ITS-03-01). There are two types of detector loops required for ramp signaling: Count and mainline loops Count and Occupancy Detector Loops (referred to as Count Loop), these are installed in the following locations: a. On the on-ramp after the stop line; b. On the mainline motorway; c. On off-ramps Queue loops Queue Detector Loops (referred to as Queue Loops), these are installed in the following locations: a. At the beginning and along the on-ramps; b. In adjoining arterial roads.
10 Page Count loop configuration and locations Configuration The typical configuration of a Count Loop is detailed in Figure 1. Figure 1 To Controller 2m 3m 2m 0.7m 0.7m Count Loop Edge Line Edge Line The loops shall be physically installed in line with the NZTA s ITS specification: Inductive loops and feeder cables (ITS-03-01). Where required a pair of Count Loops shall be installed in each lane. Ramp Signalling Count Loops shall be located as per the following configuration scenarios:
11 Page Mainline loop configuration, ramp merge For merge on-ramps two sets of mainline loops are required, one set to be located 20m beyond the end of the marked ramp, and the other set is to be located within 20m of the end of merge taper, as detailed in Figure 2. Figure 2: Mainline count loops, ramp merge Mainline loop configuration, lane gain For lane gain on-ramps the mainline loops are required to be located 50m beyond the physical nose as detailed in figure 3. Figure 3: Mainline count loop, lane gain
12 Page On-ramp count loops The on-ramp count loops shall be located in such a way that ensures that only one vehicle is detected at any one time, for example In a dual lane on-ramp the loops will need to be positioned after the vehicles have merged Typically an on-ramp count loop shall be located adjacent to the physical nose as detailed in figure 4, the exception to this is where the lane merge is completed downstream of point Z, in this case the count loop shall be located just after the completion of the merge. Figure 4: On-ramp count loop Motorway off-ramps For motorway off-ramps the mainline and off-ramp count loops will be installed, where practical, adjacent to the physical nose, as detailed in figure 5. Figure 5: Off-ramp count loop
13 Page Ramp signal by-pass lanes Ramp Signals sites that are installed with a priority/by-pass lane will have count loops positioned at the end of the by-pass lane, as detailed in figure 6. Figure 6: Bypass lane 2.4 Queue loop configuration and locations Configuration The number of queue loops required shall be dependent on the number of lanes and the length of lanes before the stop line. Within a dual lane on-ramp the queue loops shall be installed adjacent to each other. Queue loop shall be installed in pairs; typical configuration of a queue loop is detailed in figure 7. Figure 7: Queue loop
14 Page First on-ramp queue loop To facilitate the design process and to determine the length of the on-ramp, a set of queue loops will need to be located near the top of the on-ramp. Typically the first set of queue loops to be installed on an on-ramp, whether the installation is for a single lane or a dual lane ramp, shall be located a minimum of 20m downstream from the start of the ramp or at the point all arterial merging has taken place as detailed in figure 8. Figure 8: First set of queue loops Additional queue loops Depending on the length of the on-ramp additional queue loops may be required to facilitate in the operation of ramp signals, if the distance between the stop line and the first set of loops on the on-ramp is greater than 130m an additional set of queue loops may be needed. However it is not advisable to have a set of count loops within 70m of the stop line. Figure 9: Single queue loop The location of the additional loops shall be positioned at a distance of 60% of the distance between the stop line and the required loops installed near the top of the on-ramp. For example: The stop line is located 100m upstream of the physical nose of the on-ramp To Controller 1.75m The Primary set of loops at the top of the on-ramp is installed 20m from the arterial road. The measured distance between the stop line and the first set of loops is 160m, the additional set of queue loops shall be installed upstream of the stop line at 60% of the distance, thus being: 160/100x60 = 96m The additional set of loops shall be installed 96m upstream of the stop line 64m from the primary set of queue loops. Additional queue loops shall be installed as a single loop as per figure 9. Toby Box Edge Line 1m 1.75m 0.7m 0.7m Single Queue Loop Edge Line
15 Page Arterial queue loops Additional queue loops may be required on arterial roads dependent on the calculated length of the on-ramp. If the on-ramp is long enough to require additional on-ramp loops generally there would be no need for the installation of arterial loops. Ramps that have only one set of queue loops and have less than 130m between the stop line and the first queue loops may require additional queue loops installed on the left merge lanes and right turn lanes of the arterial road. The location of these loops will be dependent on local conditions. For an example of arterial loops refer to M2 Standard Ramp Metered Entrance Details drawing attached within section 1 Layout drawings of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). 2.5 Ramp signal loop identification General In order for a Signal Controller personality to be created the loops must be identified. Currently the existing Ramp Metering System is only able to operate with a maximum of 24 inductive loops connected into the ramp meter controller at the site. Only double Queue loops require both their primary and secondary loops to be connected and operational, where a single queue loop is installed no secondary queue loop exists, all secondary Count and secondary Mainline Loops are installed but not connected, this is for resilience purpose only in the event of primary loop failure. No secondary Queue Loop will operate with an identification higher than 24. All loops within the installation, regardless of their connection status shall be assigned a number following this numbering methodology. The primary loop in a pair of loops is the leading loop in the pair. The secondary loop in a pair of loops is the second loop of the pair. For a graphical representation of loop numbering refer to section 2 Loop identification of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). The following process shall be followed to identify the loops Primary queue loop identification The primary loop of the first set of queue loops on an on-ramp (or left turn lane in dual lane on-ramp configuration) shall be numbered Q1. All other primary queue loops installed for the site shall be numbered in an anticlockwise direction around Q1 until all the primary queue loops are identified. Loops in multi lane ramps shall be numbered closest to the left hand kerb first. The arc of the anti-clockwise numbering shall be continued to extend to incorporate all primary queue loops in the arterial road. Any queue loops that have been installed as a single queue loop shall be classed a primary loop, for example: On-ramp primary queue loops are identified as Q1 (LH Lane), Q2 (RH Lane), and Q3 (LH Lane), Q4 (RH Lane), then arterial road primary queue loops are identified as Q5 and Q6.
16 Page Primary count loop numbering The primary off-ramp count loop (or loops) shall be the starting point for numbering the Count Loops. The number assigned to the first count loop will depend on the number of queue loops, for example: If the last queue loop was identified as Q6, then the primary off-ramp Count Loop shall be identified as C7. Typically there will be one set of off-ramp count loops and one set of on-ramp count loops and the primary onramp count loop shall be numbered next in the sequence, for example: The primary off-ramp count loop is identified as C7; the primary on-ramp count loop is identified as C8. Where there are two off-ramp lanes the primary off-ramp Count Loop will be C7 and C8 and the primary on-ramp count loop would be C9. Ramps installed with a by-pass lane will have two sets of count loops with the primary on-ramp count loop that is closest to the left hand kerb numbered first Mainline loops The first mainline primary loop to be numbered shall be the primary loop in lane 1 adjacent to the off-ramp count loops, the other mainline primary loops shall be numbered across the carriageway and in the direction of travel, for example: Where the last primary count loop was identified as C9, the primary mainline loops adjacent to the off-ramp count loops will be numbered M11 in Lane 1, M12 in Lane 2 and M12 in lane 3. Moving in the direction of travel the next primary mainline loops encountered shall be the next loop to be identified, for example: The previous primary mainline loop was located in lane 3 and identified as M12, the next primary mainline loop encountered will be the lane 1 loop adjacent to the on-ramp count loop, this loop will be identified as M13, repeating the process across the carriageway and moving in the direction of travel until all primary mainline loops have been numbered Secondary loop identification Once all the primary loops have been identified the numbering returns to the first set of queue loops on the onramp and the secondary loops are numbered sequentially in the same order as the primary loops. Refer to Loop identification example in section 2 of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). 2.6 Signal controller location General The signal controller is responsible for the monitoring and performance of the ramp signal and associated loops, traffic signals and advanced warning signs. Ideally the controller cabinet shall be located adjacent to a network communications cabinet to facilitate in the connection to the fibre network and be easily accessible for maintenance without the need for Traffic Management, where practical. Ideally the controller shall be in such a location that would allow a ramp signal engineer to clearly see the operation of the traffic signals and be of easy access for a maintenance vehicle. All ramp meter system loop feeder cables shall be connected to the loop detector card within the controller, where practical no loops should extend more than 500m from the controller.
17 Page Controller identification Ramp Signals Controllers shall be identified by the SCATS identifier number assigned to the Ramp Meter Site with the cabinet identified as per ITS Roadside Cabinet Specification. The SCATS identifier number assigned shall be in the identifying numbers for all the ramp meter equipment connected to the controller in accordance with Section and the identifying number of the ramp signal controller cabinet in accordance and section of the NZTA s ITS specification: General requirements (ITS-01-01). 2.7 Advance warning signs General Advanced warning signs (AWS) are used to notify road users of the current status of the ramp signals; they come in two types and operate as follows: a. Type A. Advise motorist that ramp signals are in operation; b. Type B. Advise motorist of an impending stop or that the Ramp Signals are not operating Type A AWS Type A sign shall be located on all arterial roads that feed into the on-ramp and in a position that is clear to all motorists intending to use the ramp that sign is feeding. The AWS shall be installed as per specification in the NZTA s ITS specification: Ramp meter supply and installation (ITS-05-02) and will ideally not be more than 75m from the start of the on-ramp but at a point that still enables a motorist to make a choice of whether to enter the on-ramp or remain on the arterial road. In installations where a congestion of Type A signs are present the direction the sign feeds shall be attached to the AWS pole via a metal cardinal plate, refer to drawing C-007 in section 4 Static signs of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03) Type B AWS The number of lanes associated with the on-ramp shall determine the number of Type B signs. For a single lane on-ramp one Type B sign shall be located on the left hand side of the on-ramp For a dual lane on-ramp two Type B signs shall be installed one on the left of the left on-ramp lane and one on the right of the right on-ramp lane. For an on-ramp that has been installed with a priority by-pass lane one Type B shall be located on the right hand side. The Type B signs shall be located at a distance of 90% of the distance from the stop line to the primary set of queue loops at the start of the on-ramp, for example: The stop line is located 100m upstream of the physical nose of the on-ramp The Primary sets of loops at the top of the on-ramp are installed 20m from the arterial road. The measured distance between the stop line and the first set of loops is 160m, the Type B Sign shall be installed upstream of the stop line at 90% of this distance, thus being: 160/100x90 = 144m Therefore the Type B Sign shall be installed 144m upstream of the stop line.
18 Page Advanced warning sign identification Ramp Signal AWS shall be identified in accordance with section of the NZTA s ITS specification: General requirements (ITS-01-01). 2.8 Ramp signals The Ramp Signal LED Traffic Signals Heads shall either be pole mounted or attached on an overhead gantry, typically for single and dual lane on-ramps, without any priority by-pass lanes shall have post mounted signal heads installed. Three lane on-ramps and on-ramps installed with priority by-pass priority lanes shall be installed on an overhead gantry. Regardless of the ramp configuration the ramp signal Traffic Signals Heads shall be located 10m downstream of the stop line. For pole, gantry and the required installation details please refer to NZTA s ITS specification: Ramp meter supply and installation (ITS-05-02). 2.9 Static signage The static signage used within Ramp Signal installations will be dependent on the configuration of the on-ramp but all installations will typically consist of the following: Ramp signal signage Static Signage associated with the ramp signal traffic signal head shall be installed with the following message: One Vehicle per Green In a dual lane configuration this sign will be supplemented by an additional sign: Each Lane The location of these signs shall be dependent on the installation method of the traffic signal itself, for details of pole mounted signs refer to: Typical Entry Ramp Meter System 2 Lanes Metered Side Mount Option, drawing attached in section 1 Layout drawings of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). For details of gantry mounted signs refer to: Typical Entry Ramp Meter System 2 Lanes Metered Side Gantry Option, drawing attached in section 1 Layout drawings of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). For static sign details refer to section 4 Static signs of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03) Regulatory speed signs The NZTA s Manual of traffic signs and markings (MOTSAM) policy: Either RG-2 (100 km/h) signs or the alternative RG-2.1 DE-RESTRICTION sign must be installed at locations where a lesser speed limit (either temporary or permanent) changes to the general maximum speed limit, ie.100 km/h. RG-2 100kmph Regulatory Road Signs shall be installed 50m downstream of the stop line on either side of the lane.
19 Page 13 Refer to Typical Entry Ramp Meter System 2 Lanes Metered Side Mount Option, drawing attached in section 1 Layout drawings of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03) for RG-2 location. For details of the signs refer to PW 43-1 special signage, road narrows both sides Any on-ramp other than single lane ramps will narrow into one lane prior to motorway merging occurs. A PW Special road narrow sign shall be used at all locations that involve lane merging. Each sign shall be located beyond the stop line and prior to the merge point into one lane. For details of the sign refer to PW 3 traffic signal sign A PW-3 sign shall be used to notify motorists of the presence of traffic signals, these shall be installed on-top of each Type B AWS sign. For details of the sign refer to Priority bypass lanes Any site that is configured with a priority by-pass lane shall use static signage detailing the requirements of that lane; the information displayed on those signs shall be dependent on the vehicles that are allowed to use that lane. The location of these signs shall be dependent on the message each sign displays but will typically conform to drawing: Ramp Meter System 2 Lanes Metered plus Bypass attached in section 1 Layout drawings the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). For individual sign details refer to section 4 Static signs of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). Note that these sign guides are provided as a point of reference, and information displayed on the sign will be site specific and as per the detailed design Line markings All line markings shall be accordance with: MOTSAM Part 3 Section 12: Road Markings and Delineation. Stop Lines shall be in accordance with part 2, section 3.06 of the NZTA s MOTSAM. Centre lines installed on dual lane on-ramps from the stop line shall be in accordance with part 2, section 3.02 of MOTSAM.
20 Page Motorway to motorway ramp signalling In certain circumstances and where traffic volumes dictate, ramp metering may be used on motorway to motorway intersection. The location of the stop line and traffic signals follows the same methodology already detailed in this document. Queue loops will be set back from the stop line in 100m intervals until the previous merge point, detailed in drawing Entry Ramp Meter System Motorway to Motorway attached in section 1 layout drawings of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). Enlarged Advanced Warning Signs will be used, details of which can be found in appendix D, to inform motorist of ramp signal operation. The Type A sign shall be located on the previous motorway in a location prior to the lane split in order for road users to make an informed decision on the route they take. As with standard Ramp Signal installations the Type B sign shall be located on the ramp itself, depending on the length of the motorway to motorway ramp the Type B sign shall not be located any more than 150m upstream of the stop line. All rules regarding static signage and road marking still apply.
21 Page Journey time information, type D sign In addition to the advanced warning signs each ramp signal installation shall be complimented with additional message signs detailing estimated journey times in minutes via the motorway. The Type D signs are Variable Message Signs controlled independently of the ramp signal system and shall comply with the technical requirements of the NZTA s ITS specification: Variable message sign supply and installation (ITS-06-02). Type D VMS shall be located on the arterial roads that lead directly to the motorway on-ramps; they shall be located in a manner that clearly defines the direction they feed. In installations where a congestion of Type D signs are present the direction the sign feeds shall be attached to the VMS pole via a metal cardinal plate, refer to drawing C-007 in section 4 Static signs of the NZTA s ITS specification: Ramp meter system standard drawings (ITS-05-03). All Type D signs shall communicate with the NZTA Journey Time Information System, MACCA. Connections will be via multimode fibre cable as detailed in the NZTA s ITS specification: Variable message sign supply and installation (ITS-06-02). If direct connection the NZTA fibre network is not possible ADSL or other suitable methods of communications may be considered.