Reasoned document of Technical Specifications for Self-Propelled Track and Turn out Monitoring Car (Specification No. TM/IM/457 of 2019)

Clause No.

RDSO Specification M/s MerMec Ltd M/s D.M.A M/s Graw, Poland

4.1 (i) Inertial principle of measurement

with laser contact-less sensors shall

be used for measurement of

vertical and lateral profiles of both

left & right rails with appropriate

correction for roll and yaw. Gauge

shall be measured with laser based

contact-less sensors.

3-point principle of measurement with laser contact-less sensors shall be used for measurement of vertical and lateral profiles of both left & right rails with appropriate correction for roll and yaw. Gauge shall be measured with laser based contact-less sensors.

Reason: This approach makes measurement at 0 kmh and low speeds possible (required in the points & crossings); moreover cost of such solution is lower.

RDSO Comments

With 3 point measurement system defects of irrelevant wavelengths are not filtered and techniques to measure from zero speed with inertial principle are also available. Thus this clause of specs remains unchanged.

4.1 (iii)

Sampling distance for recording shall be user selectable from 0.25 to 0.50 meter. The least count of the tachometer shall not be more than 1.0 mm.

Ok but user selection will be available before acquisition and applied for all systems.

RDSO Comments Yes selection will be available before start of acquisition of data but it may be different for different parameters e.g for turnout parameters.

4.1 (Vii)

System shall have facility to automatically pause the recording in case of STTMC’s movement in reverse direction. The system shall also be able to correctly measure the reverse movement and compensate for the same on forward movement of STTMC, so as to restart the recording from the point where recording was paused.

We suggest to change this way: System shall be able to filter out short movements in reverse direction, when the movement happens on the same track. The measurement of the stations and yards intrinsically requires continuous recording back and forth on the different tracks and the direction change shall be managed automatically.

RDSO Comments May be agreed. Clause will be suitably modified.

4.2 (i) The same LASER contact less sensors being used for recording of track geometry parameters shall be used in this sub system for measurement of rail profile and wear.

Similar LASER contact less sensors as being used for recording of track geometry parameters shall be used in this sub system for measurement of rail profile and wear. Reason: Rail profile can be measured by Track Parameters Recording System or System for Measurement of Various Parameters of Turnouts as well.

RDSO Comments Use of same system will result in reduction in numbers of LASER and camera and will give advantage in mounting of system underneath of coach or on bogie. However the firm is free to choose any hardware /sensors to fulfil the performance requirements of the specifications. Clause

will be modified accordingly.

4.2 (iv)

The system should have the facility for measurement of both rail profiles with an accuracy of 0.15 mm or better and storage of same in a format compatible with ORIAN 8GP rail profile measurement system of KLD installed in 72 stone LORAM Rail Grinding Machine of RGI series at user selectable interval in the range of 0.25m to 5.0m.

Compliant, assuming RDSO will provide the format required by grinding machines working in India, according to interval selection corresponding to multiple of the sampling step used on-board.

The system should have the facility for measurement of both rail profiles with a accuracy of 0.15 mm or better and storage of same in a format compatible with ORIAN 8 GP rail profile measurement system of KLD installed in 72 stone LORAM Rail grinding machine of RGI series at user selectable interval in the range of 0.25 m to 5.0m. Detailed description of ORIAN 8 GP rail profile measurement system of KLD installed in 72 stone LORAM Rail grinding machine of RGI series will be provided to the contractor by the Ordering Party.

Reason: We haven’t got

information about availability of the mentioned format for third parties.

RDSO Comments The format of data of ORIAN 8 GP profile measurement system will be provided after award of work.

The format of data of ORIAN 8 GP profile measurement system will be provided after award of work.

4.4 (i) System shall be capable to identify,

store and print image and

description of the defects in both

left and right Rail, Fastenings,

sleepers and Ballast.

System shall be capable to identify, store and print image and description of the defects in both left and right Rail, Fastenings, Sleepers and Ballast – this analysis will be done off- line during post processing of the acquired image data. Reason: Post processing of the acquired images off-line eliminates the high requirements connected with the computing power to be installed on board and carrying the complex analyses in real time, thus reducing the costs significantly, without

affecting the quality and accuracy of the inspection results.

RDSO Comments The report is to be generated on completion of measurement of individual turnouts at end of recording. The requirement has been included in clause 4.5 (V).

4.4 (ii)

System shall be capable to store image and description of defect with location in separate files for each component of track i.e. Rails, Fastenings, Sleepers and Ballast

Compliance, user can generate separate reports for each defect type.

System shall be capable to ... store ... in separate files for each component" As managing multiple files is inconvenient, we propose to change to: "System shall be capable to ... store all defects in a file where every defect is identified by type. The same record also contains the name of the full defect report file ... A utility allows exporting the defects in separate files for each component". Equivalent techniques are allowed, provided at least these functions are delivered.

RDSO Comments The para deals with storage of image report and not generation & printing of report.

All defects of particular item i.e. rails, fastening, and sleeper to be stored in separate files, as

keeping all details in one file will make file size too large and shall be difficult to handle .

4.5 Added new clause To limit the amount of space and weight required by measuring systems, the hardware adopted for optical measurement of turnout parameters shall be shared with Track Geometry Measurement System.

We suggest adding this requirement in order to optimize the space for installation under the train. Our switch geometry system integrates the possibility to measure switch parameter when it passes on the switch and track geometry parameters in line.

RDSO Comments The specifications are performance specification. Firms are free to design the hardware & software of systems. New clause is not required to be added.

4.6 Added new clause Spatial sampling step in longitudinal direction (pitch) in switch area shall be maximum20 mm at the maximum measurement speed.

We suggest to change the sampling step for the switch area and reduce it at 20mm. This is affecting error in positioning the switch points and frog along the track.

RDSO Comments Agreed. New clause will be added

4.5 (i)

System shall be capable of recording turnout parameters on following types of turnouts prevalent on IR

1 in 20 turnout on concrete

sleepers

1 in 16 turnout on concrete

sleepers

1 in 12 turnout on concrete

sleepers

1 in 8.5 turnout on concrete

sleepers System should be capable to be

We need detailed drawings of those switches

upgraded for inclusion of any new type of switch/crossing body/turnout at later stage.

RDSO Comments These will be uploaded along with the tender document. Any additional Turnout drawing will also be uploaded. Clause is being amended accordingly.

4.5 (V)

The turnout inspection report shall be printed and the measured values of various parameters shall be stored in ASCII/database format. It shall be feasible to upload the data in IR track management system to generate the inspection report in TMS.

We need detailed specification of format required by IR track management system

The turnout inspection report shall be printed and the measured values of various parameters shall be stored in ASCII/database format-this analysis will be done off-line during post processing of the acquired profile data. It shall be feasible to upload the data in IR track management system to generate the inspection report in TMS. Reason: Post processing of the profile and finding turnout layout orientation off-line eliminates the high

requirements connected with the computing power to be installed on board and carrying the complex analyses in real time, thus reducing the costs significantly, without affecting the quality and accuracy of the inspection results.

RDSO Comments No specific format is required by TMS. The data stored in ASCII (CSV format) or in data base will be suitable for uploading on TMS.

This may be agreed and report is to be generated and printed on completion of measurement of individual turnouts at end of any session. The clause will be modified accordingly

5.1-A(i)

Absolute vertical profile of left and

right rail on two user selectable

band pass filters in the range of 3 m

to 100 m in steps of 1m.

Absolute vertical profile of left and right rail on two user selectable band pass filters in the range of 3 m to 100 m in steps of 1 m – as Longitudinal Level and Alignment defined in EN13848-1 standard. Reason: Mentioned EN 13848 standards contain detailed parameters definitions and accuracy requirements.

RDSO Comments

It’s not necessary that the measurements will be done on the band pass filters defined in EN-13848-1 standard. Thus mention of code is not necessary. However the accuracy will be verified on the band pass filters given in EN-13848-1.

5.1-B The accuracy of measured track parameters in terms of repeatability and reproducibility shall be in accordance with the limits laid down in European code EN 13848-2. The reproducibility shall be tested and confirmed in the speed band of 20 to 110Kmph as per the limits laid down in European code EN 13848-2.

The accuracy of measured track parameters, defined in the standard EN13848-1, in terms of repeatability and reproducibility shall be in accordance with the limits laid down in European code EN13848-2. The reproducibility shall be tested and confirmed in the speed band of 20 to 110 Kmph as per the limits laid down in European code EN 13848-2. Reason: EN 13848-2 standard provides accuracy requirements

only for the parameters defined in the EN 13848-1 standard.

RDSO Comments This can be agreed as accuracy is to be verified for the parameters given in EN-13848-1. The para will be modified accordingly.

5.2 (ii) Vertical and lateral rail wear of both

rails (Left & right) for different type

of rails being used on Indian

Railways.

What is the difference between lateral rail wear mentioned in the 5.2 (ii) and horizontal rail wear mentioned in point 5.2 (iii). It looks lateral were mentioned in the 5.2 (ii) is redundant.

Horizontal rail wear of both rails

(Left & right) for different type of

rails being used on Indian Railways

RDSO Comments Lateral and horizontal wear are not same. Lateral wear is measured on gauge face at a depth of 13 mm from rail top w.r.t gauge face of new rail. The horizontal wear is difference in width of

head of new and worn out rail at a depth of 13 mm from rail top.

5.2 (x)

The accuracy of wear in terms of repeatability and reproducibility shall be measured in terms of SD of sample to sample variation for a block of 200 m and the 95 percentile values shall be within the limits given below

a. Lateral wear (Horizontal gauge side wear)0.2 mm

b. Vertical wear 0.2 mm

c. 450 internal rail profile wear 0.2 mm

d. Rail roll over + 0.250

e. Lip flow 0.3mm

Compliance, assuming the rail completely visible from the head to the foot.

The accuracy of wear in terms of repeatability and reproducibility shall be measured in terms of SD of sample to sample variation for a block of 200 m and the 95 percentile values shall be within the limits given below.

a. Lateral wear (Horizontal gauge side wear) - 0.3mm

b. Vertical wear - 0.3mm

c. 450 internal rail profile wear - 0.45mm

d. Rail roll over ±0.30 e. Lip flow = 0.3mm

Reason: It should be pointed out that all the mentioned parameters can be measured after alignment of the recorded profile with nominal rail profile. Such operation is source of an additional error,

therefore, we are suggesting use of less demanding limits.

RDSO Comments It is clarified that the accuracy of system will be tested with fully visible rails.

The system giving the specified accuracy are available provided full rail is visible. Thus no change in accuracy is acceptable. However accuracy will be verified with fully visible rails only.

5.4 System shall be capable of identifying and reporting defects in rails, sleepers, fastenings and ballast. Following defects shall be identified in each track component.

Please consider the changes suggested

RDSO Comments Clause to be modified as per TIMS specifications

5.5 System for measurement of Turnout parameters

The system shall be capable of measuring following parameters of turnouts

We suggest adding the automatic detection of the switch in order to reduce operator activities and related human error

RDSO Comments Agreed, New clause will be added

A. Parameters to be measured on complete turnout

i) Condition of sleepers

similar to straight track

given in para 5.4 (ii)

Our system is able to automatically identify the zones of the turnouts in which it is possible to provide the inspections requested in points i) and ii)

The automatic analysis can only identify macroscopic defects, due to the turnout components hiding parts of the sleepers, thus making the automatic analysis incomplete. We suggest an interactive analysis, by browsing the images

RDSO Comments Interactive analysis may be agreed. The clause will be modified suitably

ii) Excess/Deficiency of ballast

similar to straight track

given in para 5.4 (iv)

This is an additional set of quite expensive sensors An alternative is the operator evaluation, by browsing the images

RDSO Comments Operator evaluation may be agreed.

B. Parameters to be measured at Switch assembly and lead Portion

It is not clear what the parameters to be monitored are. We need the drawings of the turnouts to be inspected to better analyse these specifications. We need drawings of each parameters do you want to monitor in order to evaluate the feasibility for implement these custom measurement and the extra costs related. We suggest to provide the following measurements with the reproducibility indicated that usually we provide for our customers:

Parameter Resolution Reproducibility

Guard Check Gauge Guard Face

< 0.1 mm + 0.6 mm

The tongue profile measurement, compared with the design profile, e.g. every 20 mm, shows also the local damage. This condition can probably be unified with II 4 d)Normally defined as tongue to stock rail distance. This distance should be almost 0. This way something measurable is defined

Annex 5 does not contain definitions of parameters mentioned in clause 5.5

Reason: Detailed definitions of parameters mentioned in clause 5.5 B, 5.5 C, and 5.5 D are needed for system design.

RDSO Comments

i) Condition of switch assembly as per details given in table of annexure-V (4,5,6 of II)

RDSO Comments Assessment of switch assembly condition is being defined more specifically. Clause is being amended suitably

ii) Throw of switch at ATS Also defined as the opening of the open tongue; minimum distance in between stock rail and open tongue.

RDSO Comments Gauge

Switch passage width ( open blade and check rail

< 0.1 mm +0.6 mm

Check Rail Height

<0.1 mm +0.6 mm

Frog flangeway gap width and depth

<0.1 mm +0.6 MM

Yes, Interpretation is correct

iii) Divergence at heel block Should be done by the operator, by browsing the images.

RDSO Comments Parameter measurement is reviewed and modified suitably.

v) Gap between top edge of stretcher bar and bottom of rail foot as per details given in annexure-V (19 of II)

We need a drawing to better understand this definition (a cross section).

RDSO Comments It is being uploaded with Annexure -5.

vi) Distance between gauge faces of stock rail at JOH

Better to define JOH as the distance from the tongue edge (can be different for every turnout type).

RDSO Comments Parameter measurement is reviewed and modified suitably.

vii) Clearance at JOH as per

details given in annexure-V

(20 of II)

Should be done by the operator, by browsing the images.

RDSO Comments Parameter measurement is reviewed and modified suitably.

xi) Housing of stock and tongue rails as per details given in annexure-V (13 of II)

Need a drawing to better understand what should be measured.

RDSO Comments It will be uploaded along with pre bid minutes.

xii) Seating of tongue rail on slide chairs as per details given in annexure-V (14 of II)

Should be done by the operator, by browsing the images.

RDSO Comments Parameter measurement is reviewed and modified suitably.

Annexure 05 gives definition of all required parameters, however any specific clarification can be provided.

C. Parameters to be measured on Crossing Portion

Annex 5 does not contain definitions of parameters mentioned in clause 5.5 C

RDSO Comments

i) Gap at heel and toe of crossing on main line and turnout

Will need a tighter definition, but it is enough to start with

RDSO Comments Parameter measurement is reviewed and modified suitably.

iii) Condition of crossing as per details given in annexure-V (21 of III)

The system can automatically evaluate big defects, but the operator shall browse the images for a complete analysis.

RDSO Comments Can be agreed. Parameter measurement is reviewed and modified suitably.

vi) Condition of check rail fitting as per details given in annexure-V (26 of III)

Should be done by the operator, by browsing the images.

RDSO Comments Can be agreed. Parameter measurement is reviewed and modified suitably.

Annexure 05 gives definition of all required parameters, however any specific clarification can be provided.

D. Turn in Curve as per details given in annexure-V (28 & 29 of IV)

Shall be defined in the data base describing the infrastructure

Annex 5 does not contain definitions of parameters mentioned in clause 5.5 D

See also the notes added aside every item in Annexure V (annexe to the end of this document)

Reason: Detailed definitions of parameters mentioned in clause 5.5 B, 5.5 C, and 5.5 D are needed for system design.

RDSO Comments Parameter measurement is reviewed and more specific definition of parameters to be measured along with drawings of turnouts showing parameter details is being uploaded along with Annexure-05.

Can be agreed. Parameter measurement is reviewed and modified suitably.

Annexure 05 is reviewed and revised annexure with more specific definition of parameters along with drawings of turnouts is uploaded with pre bid minutes

5.6 B Route feature information and synchronization

ITMS should be changed to STTMC

RDSO Comments Agreed. Clause will e modified

New Clause Added

OPERATING MODES

The data acquisition is completely automatic. The system works unattended and acquires all localization and measurement data without any operator intervention other than START at the session beginning and STOP at the session end. A session is composed by any number of consecutive runs up and down, all the way in a station (end to end) via different itineraries, in order to explore all the tracks and

turnouts in the sequence most suited to run. It does not matter if different branches of the turnouts are taken in different runs or even different sessions: the system automatically recomposes the turnouts, via automatic localization. The system can work similarly on main track, but can also work based on the standard route files of the IR, as every Track Geometry Measurement Train or as the TIMS. When the session ends, the system shall be capable of automatically delivering a measurement coverage analysis in a reasonable time (no more than two hours after the session end). The analysis result shall be shown on the station map, highlighting measured and non measured tracks and turnouts in different colours.

RDSO Comments The proposed requirement is reasonable and has been included in para 5.5 of the specifications.

6.0 Hardware The on board computer shall

allow the complete analysis of the data, after the end of the acquisition session. The data analysis includes the ability to browse the images, for the operators to identify the defects the system cannot detect automatically. Therefore the on board computer is equipped with 3 high resolution monitors a the relevant software environment where the images from all cameras can be browsed in dynamically configurable sizes and resolution, in dynamically configurable layout, at variable speed, allowing the operator to jump to every turnout or defect by selecting it in a list.

RDSO Comments The specifications are performance specifications, thus firms are free to choose any hardware. However the requirement of browsing the image by operator is logical and is included in para 5.5

6.10 The system shall be provided with

good quality UPS of proper rating

and reputed make. The entire

system will be powered via this

The system shall be provided with good quality UPS of proper rating and reputed make. The system

UPS, with back up time of at least

60 minutes.

processing part (computers) will be powered via this UPS, with a backup time sufficient for spare power source connection.

Reason: We do not know why such a long sustain period. If to wait for a power outage, a much cheaper and better solution is an additional generator turned on as needed. In this case, a back time of up to 10 minutes is sufficient for the period of switching power sources. On the other hand, after a power outage, the vehicle will not go anywhere so there is no reason for the system to remain on. May be it is enough to guarantee a quick system restart? In addition, the

operation of an additional generator is much cheaper than a high-power UPS. Leading UPS manufacturers recommend replacing batteries every year if they are used in harsh environments including elevated temperatures. The cost of replacing battery packs needed to support the entire system (and not just computers) will be much higher than the cost of operating an additional generator.

RDSO Comments 01 hour backup is required to avoid loss of data, if DG set have a minor problem, which can be rectified quickly.

7.1.4 (iii)

The software shall have capability

to store and print track parameter

value in peak form on short chord

at track feature location

Meaning of the requirement is unclear. We would like to ask for clarification.

RDSO Comments The example Track features are SEJ, P&C, Curves, Bridges and Level Crossing etc and track defect values measured on short chord on these features are to be stored and print.

7.2 Post Processing of data As every vehicle is assigned to a zone, and considering India dimensions, it seems advisable to provide one server in the back office of every zone. Thus a server is associated to every vehicle. Data transfer from the vehicle to the back office server is via a removable solid state disk, due to the huge volume of data. This server shall provide the data to the operators in the zone. The operators shall connect to the server using a standard browser as Firefox or Chrome, via the IR Intranet. The web client shall provide a graphical interface allowing to browse strip charts, images, defects reports, turnout reports, etc., everything synchronized in space

It is suggested to put more detailed specification of the additional reports especially section wise summaries which allows for realistic workload estimation.

(browsing on one window lets the others follow automatically. Two dedicate windows show the geographical map with the tracks and turnouts superposed and the track schematic model (signalling style). The user can select what windows shall be active at any time. Every user can store and recall multiple windows configurations. The server stores a data base completely describing the infrastructure in terms of arcs and nodes, superposed to the geographical map (free of license: e.g. open street map). Also the schematic map can be represented. An embedded and dedicated CAD (only enabled users can access it) allows creating the maps and adding the relevant metadata (turnout id, turnout type, turnout category to select the thresholds set). An environment to browse the high resolution images shall be provided on each server in the

back office. The server is equipped with 3 high resolution monitors (4k) and the relevant software environment where the images from all cameras can be browsed in dynamically configurable sizes and resolution, in dynamically configurable layout, at variable speed, allowing the operator to jump to every turnout or defect by selecting it in a list. Generally speaking: the operator shall browse the images to add the evaluation of number of parameters, create defects manually, validate or invalidate the automatically detected defects. The software allows "jumping" to the data of the area where a defect has been detected, by simply clicking on the defect in the text list. The server software can generate 3 main types of reports: - Single turnout: all parameters are shown in a table, showing in different colours different levels of defect - Itinerary: the user can create

an itinerary defining the list of turnouts it goes through. Typically, these itineraries are the ones the passenger trains run in the stations. It is very important to have an overall and comprehensive report of the status of these itineraries, which have a higher importance than the branches only used for shunting. - Line: in the very same way the IR Track Geometry and/or video inspection cars do it. The server shall be able to show a historical view of the data (strip charts of measurements taken at different times superposed: at least 3 measurement sessions)

RDSO Comments The system should have capability to generate reports on the completion of recording of a particular TO. The system should have facility for storage of data on portable HDD for record. The system should have facility for uploading the processed data and reports on IR TMS server.

7.1.6 Added new clause We suggest to add this SW

Possibility to set up a SW feature that simulates a measurement by a manual tools

functionality.

RDSO Comments Simulation a measurement by a manual tool is good suggestion for validation and calibration of system. Thus it can be agreed.

10.5 Source code of processing and

exception report generation part of

online software and post processing

software shall be supplied along

with flow charts and algorithms.

Source code and executable files of

the software shall also be supplied

on CD/DVD as well as in hard copy.

Source codes will be deposited under an Escrow agreement whereby Indian Railways could obtain source codes in the event that the supplier declares bankruptcy or cannot be contacted after a certain period of time. Executable files of the software shall also be supplied on CD/DVD as well as in hard copy.

Reason: We can agree to this. Transferring source codes and algorithms without restrictions is equivalent to transferring know-how which is not in GRAW interest. In addition, any changes allow interference in the operation

of the system which results in blurring of responsibility.

RDSO Comments This is not agreed as we have not sought proprietary part of software. We have asked to provide the source code of processing software for generation of reports specifically developed for Indian Railway.

DESCRIPTION IN ANNEXURE–IV

3. Rails

a) Linear longitudinal defect (Crack on rail top) with minimum width of 1.0 mm and minimum length of 10.0 mm and Gauge corner defect with minimum size of 0.1mm x 0.9 mm. The Gauge corner defects needs to be reported when they are more than 10 in 1 metre.

We strongly suggest to increase thresholds in order to avoid high proliferation of defects. We suggest to change the minimum size for the gauge corner defect from 0.1mm x 0.9 mm to 0.3mm x 0.9 mm

RDSO Comments Minimum size of gauge corner defects is not 0.1x0.9 , it is 0.2 x 0.9 and equal to values given in ITMS specs and remain unchanged.

b) Area defect (Squat & wheel burn etc.) with minimum area of 10mm2.

Area defect (Squat & wheel burn etc.) with minimum resolution of 10mm^2 is provided. we suggest to set up thresholds starting from 100mm^2 for better and fast validation performances

RDSO Comments 10mm2 is not the threshold for exception report. It is the capability of system to measure.

d) Misaligned and cupped weld detection & measurement with minimum value of 1.0 mm

We strongly suggest to increase thresholds in order to avoid high proliferation of defects. We suggest to change the minimum value from 1.0 mm to 3.0

RDSO Comments The limits given are as per the values given in IRPWM, thus can not be changed.

4. Ballast

a) Excess/ Deficiency of ballast in terms of area with minimum identifiable area of 0.5m2

We strongly suggest to increase thresholds in order to avoid high proliferation of defects. We suggest to change the minimum value from 0.5 m2 to 1 m2

The ballast deficiency

measurement resolution is

defined as 5x5 com, thus the

ballast level shall be measured,

at every 5 cm max

transversally (Y) and every 5

cm max longitudinally, at max

operating speed.

0.5 m2 = 71 cm x 71 cm

5 cm x 5 + cm = 25 cm2

resolution

A reasonable vertical accuracy

is ±5 mm

RDSO Comments 0.5 m2 is not the threshold for reporting exception. This is the capability/accuracy of system to measure. However only area cannot determine excess or deficiency of ballast. It shall be linked with height also. Thus the 0.5m2 area with height more than

Yes, only area cannot determine excess or deficiency of ballast. It shall be linked with height also. Thus the 0.5m2 area with height more than +/- 35 mm w.r.t. theoretical profile is to be

+/- 35 mm w.r.t. theoretical profile is to be reported as excess or deficiency of ballast. Clause will be modified accordingly

reported as excess or deficiency of ballast. The clause will be modified accordingly.

b) Level of ballast w.r.t centre of sleeper with minimum value of 25.0 mm

we suggest to modify the threshold value to 35 mm in order to avoid too many unnecessary alarms

RDSO Comments The provided value of 25mm is not the threshold value for exception report. It is the accuracy of system for measurement. Thus no change in para is essential