maidenhead station improvements modelling report: proposed

Maidenhead Station Improvements

Modelling Report:

Proposed at-grade crossing improvements

Date: October 2017

Created by

Jessica Cecchinell i [email protected]

mailto:[email protected]

© Project Centre Proposed at-grade crossing improvements 1

CONTENTS PAGE PAGE NO.

1. INTRODUCTION 2.

2. EXISTING SITUATION

2.1 Road Network

2.2 Traffic Volumes

2.3 Signal Timing and Timetable

3. BASE MODELLING 9

3.1 LinSig Structure

3.2 Saturation Flows

3.3 Signal Data

3.4 Demand Dependent Stages / Bonus Greens

3.5 Underutilised Green Times

3.5 Base model validation and conclusion

4. DESIGN AND MODELLING 19

4.1 Introduction

4.2 ‘MOVA Current Scenario’ & MOVA Proposed Scenarios

4.3 Proposed Design

4.4 Proposed Modelling

4.5 Traffic Reassignment

4.6 Proposed LinSig Structure

4.7 Signal Timings

4.8 Proposed Intergreen Periods


5. MODELLING RESULTS 31

6. CONCLUSIONS & RECOMMENDATIONS 42

APPENDIX A – BASE LINSIG MODEL RESULTS

APPENDIX B - PROPOSED LINSIG MODEL RESULTS

APPENDIX C – GENERAL ARRANGEMENTS

INFORMATION AVAILABLE ON REQUEST

MCC AND QL SURVEY DATA

EMAIL CORRESPONDENCE & RAW SIGNAL DATA

SATURATION FLOW DATA

ANALYSED SIGNAL DATA

OBSERVED DEGREE OF SATURATION DATA

QUALITY


1. INTRODUCTION

This report supports work undertaken to develop a business case for the

Maidenhead Station Access scheme.

Improvement proposals involve enhancements to pedestrian and cycling

facilities and improvements to the public realm that will notably enhance the

accessibility and functionality of the Station, reacting to planned growth in

passenger numbers and significant development activity within the Town centre

area.

One of the key outcomes of the scheme will be an improvement in crossing

facilities at the station. Current at-grade signalised road crossings that link the

town centre to the station are convoluted and there is limited public realm

space for large groups of pedestrians to wait.

Options have been developed to improve the at-grade crossings and

accommodate future growth in pedestrians, cyclists and motor vehicle traffic

associated with passenger growth at Maidenhead Station.

LinSig computer software has been used to simulate base (existing) traffic

conditions and predict how the junctions would operate with proposed layout

options in place.

This technical report describes the modelling, validation and option assessment

process and presents associated conclusions and recommendations.


2. EXISTING SITUATION

2.1 Road Network

The road network within the study area comprises of three signal controlled

junctions, which are listed below:

Grenfell Place / Grenfell Road;

Grenfell Road / Queen Street / King Street; and

King Street / Braywick Road / Shoppenhangers Road.

Figure 2.1 illustrates the extent of the study area (highlighted in red) and the

location of the signalised junctions within the network (highlighted with blue

circles / arrows) that this technical report provides information.

Figure 2.1 – Location Plan


Grenfell Place / Grenfell Road

The Grenfell Place / Grenfell Road junction is a signalised three-arm junction.

The junction, at the time of the traffic surveys, was running on CLF plans and the

signal stage sequence for the junction is shown in Figure 2.2.

Figure 2.2 – Signal Stage Sequence (Grenfell Place / Grenfell Road junction)

Grenfell Road / Queen Street / King Street

The Grenfell Road / Queen Street / King Street junction is a signalised six-arm

junction. The junction, at the time of the traffic surveys, was running on CLF

plans. The existing traffic signals operate a two stage sequence (in order of

stages 1, 3). The first stage is for traffic on Grenfell Road, King Street and Keys

Place and pedestrian movement across the westbound and southbound Queen

Street arms. Stage 3 is dedicated to traffic on the westbound and southbound

Queen Street approaching lanes together with pedestrian crossing movements

across Grenfell Road, King Street and Keys Place.

Figure 2.3 – Signal Stage Sequence (Grenfell Road / Queen Street / King Street junction)

King Street / Braywick Road / Shoppenhangers Road

The King Street / Braywick Road / Shoppenhangers Road junction is a signal

controlled three-arm junction. The junction, at the time of the traffic surveys,


was running on CLF plans and the traffic signals operate in three stages (in order

of stages 1, 2, 3). The first stage is for traffic on Braywick Road and King S treet

(ahead traffic flow only), and pedestrian movements across Shoppenhangers

Road (Phase I) and King Street Road right turn arm (Phase J). Stage 2 provides

an extended green to the ahead traffic flow on King Street (early cut -off to the

northbound approach) and allows the simultaneous discharge of the left turning

traffic flow on Shoppenhangers road and the right turning traffic fl ow from King

Street into Shoppenhangers Road. Pedestrians on Braywick Road approaching

lanes are also allowed to cross within this stage.

Figure 2.4 –

Signal

Stage

Sequence

(King

Street /

Braywick

Road /

Shoppenhangers Road junction)

2.2 Traffic Volume

Traffic surveys were required to review the volume, speed and mix of traffic on

the network between Grenfell Place / Grenfell Road and King Street / Braywick

Road / Shoppenhangers Road junctions.

Fully classified (junction) turning counts (MCC) and queue length (QL) surveys

were carried out on Tuesday 29th August 2017 (weekday AM and PM peak

periods). The MCC data has been analysed by PCL to establish the peak hours

as follows:

Weekday morning peak hour (AM) – 08:00 - 09:00; and

Weekday evening peak hour (PM) – 17:00 - 18:00.

The traffic and signal data associated with these peak hours have been used to

develop the validated base LinSig models. The peak hour traffic flows, in

passenger car units (PCUs), are presented graphically in the traffic flow

diagrams (Figures 2.5 – 2.6) below. Comprehensive MCC survey and Queue

Length data is contained in Appendix A of this report.


Figure 2.5 – AM Peak hour Traffic Flows (in PCUs)


Figure 2.6 – PM Peak hour Traffic Flows (in PCUs)


In addition, video surveys have been completed on the same day and time periods as

the classified junction turning counts and queue length surveys. The video surveys were

set to capture traffic signal heads and traffic discharge at stop lines on each approach

of the signalised junctions.

2.3 Signal Timing and Timetable

The CLF plans signal timing and timetables have been derived from the controller

specifications provided by RBWM.

The relevant signal information and the email correspondence with RBWM are

contained in Appendix B of this report.


3. BASE MODELLING

3.1 LinSig Structure

Base LinSig modelling of the junctions has been undertaken, as agreed RBWM, for the

morning (AM) and evening (PM) peak periods on a neutral weekday.

The base LinSig models were built using information from the OS map, site visit and

traffic behaviour observed from the video survey footage.

The LinSig structure has been developed to represent the layout of the junctions within

the study area, taking into account all allowed movements at each junction. Figure 3.1

below shows the LinSig link structure that has been developed and used to model the

junctions within the study area between Grenfell Place / Grenfell Road and King

Street / Braywick Road / Shoppenhangers Road junctions.

Figure 3.1 – Link Structure for Base Model


As can be seen from Figure 3.1, the offside southbound King Street approach to the

Shoppenhangers Road / King Street / Braywick Road junction which is a lane

dedicated to the right turning traffic, has been modelled as a long lane instead of a

flare. The video observations have revealed that there are times in which the traffic

queue extends from the upstream junction. More so, the modelling of the offside lane

as flare in LinSig means that there is a mutual interaction between traffic in the middle

lane and offside flare whilst the video footage has confirmed that the operation of this

lane does not affect the traffic queue and discharge of the middle one.

In addition, the southbound offside Queen Street lane (right traffic flow) has been

modelled as long lane due to the traffic and queuing conditions which makes this lane

largely used during the peak hours. However, the southbound offside Queen Street lane

(middle lane) in which it has been observed a lower traffic flow, has not been modelled

as a flare due to LinSig limitations.


Link saturation flows were measured using video recordings where possible. The

saturation flow for each lane has been derived as an average of 5 measurements.

During the saturation flow measurements, it was observed that some lanes experience

exit blocking which inhibits free flow conditions whilst other lanes have low traffic

demand. For these lanes, the RR67 formula (based on lane geometry) was used to

estimate the saturation flows.

A summary of the saturation flows used in the base models are listed in Table 3.1 below.

The full saturation flow data is provided in Appendix C.


Table 3.1 – Measured / Calculated Saturation Flows

Link Saturation Flow Measured or

Calculated

Grenfell Road / Green Place

Grenfell Place SB Approach- N/S 2003 Measured

Grenfell Place SB Approach- O/S 2016 Measured

Grenfell Road EB Approach- N/S 2049 Measured

Grenfell Road WB Approach- N/S 1992 Measured

Grenfell Road WB Approach- O/S 2009 Measured

Grenfell Road / Queen Street / King Street / Keys Place

Grenfell Road EB Approach- N/S 1999 Measured

Grenfell Road EB Approach- O/S 1920 Measured

King Street NB Approach- N/S 1968 Measured

King Street NB Approach- O/S 1968 Measured

Queen Street SB Approach- N/S 2003 Measured

Queen Street SB Approach- O/S (middle lane) 2015 Calculated

Queen Street SB Approach- O/S (RT) 1995 Measured

Queen Street WB Approach- N/S 1944 Measured

Queen Street WB Approach- O/S 1903 Measured

Keys Place SB Approach- N/S 2065 Calculated


Braywick Road NB Approach- N/S 1872 Measured

Braywick Road NB Approach- O/S 1982 Measured

King Street SB Approach- N/S 1981 Measured

King Street SB Approach- O/S (middle lane) 2015 Measured

King Street SB Approach- O/S (LT) 1944 Measured

Shoppenhangers Road EB Approach- N/S 1937 Measured


3.3 Signal Data

The signalised junctions, at the time of survey were running on CLF plans. The controller

specifications provided by RBWM have been analysed to obtain the stage durations

and cycle times for each junction during the assessed peak hours. However, the video

footage analysis has evidenced that the cycle time values on the Grenfell Road /

Grenfell Place and Grenfell Road / Queen Street / King Street junctions are lower than

the CTs indicated in the CLF plans (90s in the AM peak and 86s in the PM peak).

Therefore, further video analysis has been carried out to determine the green time

allocated to each lane and the accurate cycle times at these two junctions. Table 3.2

shows a summary of the cycle times and stage durations for each junction during the

peak periods.

Table 3.2 – Stage Durations and Cycle Time, seconds (s)

Stage AM Peak PM Peak


1 60 59

2 20 18

Cycle Time 80 77


1 50 45

3 24 34

Cycle Time 74 79


1 46 46

2 30 26

3 14 14

Cycle Time 90 86

3.4 Demand Dependent Stages / Bonus Greens

The controller specifications indicates that Stage 2 of the Grenfell Road / Grenfell Place

junction and Stages 2 and 3 of the King Street / Braywick Road / Shoppenhangers Road

junction are demand dependent and can be called in if there is demand for traffic

phase. The video analysis has confirmed that these stages are called in all the times

during the assessed peak hours. Therefore, no bonus greens have been accounted for

in the modelling.


3.5 Underutilised Green Times

The video survey footage has been analysed to determine the parameters for

calculating the observed degrees of saturation (DoS) on all approach lanes to the

junctions during the peak hours.

The analysis of the observed DoS established that there is currently underutilised green

time (UGT) on some of the approach lanes to the junctions. The UGT was observed to

be as a result of exit blocking and slow moving vehicles (high HGV proportion, at times).

Figure 3.2 below shows examples of issues causing UGT occurrences at the junctions.

Figure 3.2 – Exit blocking on King Street NB and Braywick Road NB; AM peak

As can be seen in Figures 3.2, exit blocking occurs during the AM peak period on

Braywick Road and King Street approaches heading northbound from the King Street /

Braywick Road / Shoppenhangers Road junction due to traffic queues extending from

the Grenfell Place / Grenfell Road signalised junction.

Table 3.3 below shows all the UGT included in the base modelling for all approach lanes

to the junction.


Table 3.3 – UGT included in Base Model, seconds (s)

3.6 Base model validation and conclusion

The video survey footage has been analysed to derive the observed Degree of

Saturation (DoS) for each of the lane approaches of the junctions. The DoS has been

obtained for all of the modelled peak hours.

Approach Link

UGT applied (s)

AM PM


Grenfell Place SB Approach- N/S J1: 1/1 -4 -11

Grenfell Place SB Approach- O/S J1:1/2 -1 -1

Grenfell Road EB Approach- N/S J1:2/1 -1 –

Grenfell Road WB Approach- N/S J1:8/1 -5 -3

Grenfell Road WB Approach- O/S J1:8/2 -4 -2


Grenfell Road EB Approach- N/S J2:2/1 -1 -3

Grenfell Road EB Approach- O/S J2:2/2 -1 -2

King Street NB Approach- N/S J2:3/1 -10 -6

King Street NB Approach- O/S J2:3/2 -2 -5

Queen Street SB Approach- N/S J2:1/1 – -1

Queen Street SB Approach- O/S (middle

lane) J2:1/2 – –

Queen Street SB Approach- O/S (RT) J2:1/3 – -3

Queen Street WB Approach- N/S J2:4/1 – -4

Queen Street WB Approach- O/S J2:4/2 – -2

Keys Place SB Approach- N/S J2:5/1 – -3


Braywick Road NB Approach- N/S J3:3/2 -11 -10

Braywick Road NB Approach- O/S J3:3/3 -6 -6

King Street SB Approach- N/S J3:1/1 – -6

King Street SB Approach- O/S (middle lane) J3:1/2 -1 -3

King Street SB Approach- O/S (LT) J3:1/3 – -2

Shoppenhangers Road EB Approach- N/S J3:4/1 -6 -2


The observed values and base model results for the DoS at all approaches, during all

peak periods, are summarised in Table 3.5. Appendix E provides the base LinSig models

and results and Appendix F has a comprehensive observed DoS data.

Table 3.4 - Comparison of Observed and Modelled Degrees of Saturation (DoS)

Degree of Saturation (%)

AM PM

Observed Modelled Diff Observed Modelled Diff


Grenfell Place SB Approach- N/S 39% 38% 1% 44% 44% 0%

Grenfell Place SB Approach- O/S 37% 33% 4% 31% 32% -1%

Grenfell Road EB Approach- N/S 80% 77% 3% 87% 87% 0%

Grenfell Road WB Approach- N/S 60% 62% -2% 62% 66% -4%

Grenfell Road WB Approach- O/S 66% 66% 0% 56% 55% 1%

Cycle Time 80 77


Grenfell Road EB Approach- N/S 42% 42% 0% 70% 72% -2%

Grenfell Road EB Approach- O/S 54% 54% 0% 55% 52% 3%

King Street NB Approach- N/S 88% 91% -3% 82% 82% 0%

King Street NB Approach- O/S 82% 78% 4% 79% 80% -1%

Queen Street SB Approach- N/S 35% 34% 1% 63% 64% -1%


lane) 15% 13% 2% 18% 13% 5%

Queen Street SB Approach- O/S (RT) 34% 29% 5% 60% 55% 5%

Queen Street WB Approach- N/S 40% 37% 4% 68% 64% 4%

Queen Street WB Approach- O/S 37% 39% -2% 71% 70% 1%

Keys Place SB Approach- N/S 9% 8% 1% 26% 22% 4%

Cycle Time 74 79


Braywick Road NB Approach- N/S 79% 83% -4% 69% 66% 3%

Braywick Road NB Approach- O/S 60% 56% 4% 43% 40% 3%

King Street SB Approach- N/S 38% 37% 1% 60% 61% -1%

King Street SB Approach- O/S (middle 34% 29% 5% 41% 38% 3%


Table 3.5 - Comparison of Observed and Modelled Mean Maximum Queue (MMQ)

lane)

King Street SB Approach- O/S (LT) 35% 39% -4% 86% 84% 2%

Shoppenhangers Road EB Approach- N/S 89% 93% -4% 76% 73% 3%

Cycle Time 90 86

Mean Maximum Queue (PCUs)

AM PM

Observed Modelled Diff Observed Modelled Diff


Grenfell Place SB Approach- N/S 3 6 -3 5 7 -2

Grenfell Place SB Approach- O/S 2 5 -3 5 4 1

Grenfell Road EB Approach- N/S 6 7 -1 6 9 -3

Grenfell Road WB Approach- N/S 5 11 -6 7 12 -5

Grenfell Road WB Approach- O/S 7 13 -6 6 9 -3

Cycle Time 80 77


Grenfell Road EB Approach- N/S 5 6 -1 7 13 -6

Grenfell Road EB Approach- O/S 5 8 -3 7 8 -1

King Street NB Approach- N/S 10 19 -9 13 14 -1

King Street NB Approach- O/S 11 15 -4 10 14 -4

Queen Street SB Approach- N/S 2 1 1 3 11 -8


lane) 1 1 0 2 0 2

Queen Street SB Approach- O/S (RT) 1 1 0 3 3 0

Queen Street WB Approach- N/S 3 3 0 7 8 -1

Queen Street WB Approach- O/S 3 3 0 0 9 -9

Keys Place SB Approach- N/S 2 1 1 3 3 0

Cycle Time 74 79


Braywick Road NB Approach- N/S 7 18 -11 8 12 -4

Braywick Road NB Approach- O/S 6 10 -4 5 6 -1

King Street SB Approach- N/S 3 5 -2 3 11 -8


As shown in Tables 3.5 and 3.6, the base LinSig model results compare reasonably well

with the observed values (DoS and MMQ), which suggest an accurate simulation of the

existing traffic conditions. In Table 3.5, the difference between the observed DoS and

modelled values for each link is +/-5% or less.

All arms of the Grenfell Road / Grenfell Place junction operate significantly below the

maximum desired practical capacity of 90% DoS during the observed peak hours. The

highest DoS (of 87% for the observed and modelled) were experienced on Grenfell

Road (eastbound) during the PM peak period.

The King Street northbound approach (nearside lane) is operating slightly over the

desired maximum practical capacity of 90% DoS during the AM peak hour. The lane

also operates at high capacity, close to but less than 90%, during the PM peak hours.

This is evident in both the modelled and the observed DoS values in Table 3.5. This is

observed to be caused by the high volume of traffic and the occurrence of exit

blocking on this approach.

Similarly, Shoppenhangers Road (eastbound) approach of the King Street / Braywick

Road / Shoppenhangers Road junction is currently operating at high capacity during

the AM peak period with modelled value of 93% (slightly above than 90%) but

operating below the desired maximum practical capacity of 90% during the PM peak

hour.

All other approach lanes operate below the desired maximum practical capacity of

90% during all peak hours.

The modelled MMQ compares very well with the observed MMQ on all the approach

lanes of the junction (during all peak hours). The capacity issues identified through the

DoS values are reflected very well in the MMQ of those approaches.

The base LinSig model is found to be robust and representative of the existing traffic

conditions during the time of the surveys at the signalised junction for the assessed peak

hours. It is therefore concluded that the validated base model can be used to assess

the impact of proposed schemes in terms of lane capacities and queue lengths.

King Street SB Approach- O/S (middle

lane) 3 4 -1 3 5 -2

King Street SB Approach- O/S (LT) 4 4 0 8 10 -2

Shoppenhangers Road EB Approach- N/S 13 14 -1 10 8 2

Cycle Time 90 86


4. DESIGN AND MODELLING

4.1 Introduction

Two options have been developed for improving the existing at-grade crossings at

Grenfell Road / Queen Street / King Street signalised junction. Outcomes of the

modelling work undertaken are described below.

4.2 ‘MOVA Current Scenario’ & MOVA Proposed Scenario

The linked Microprocessor Optimised Vehicle Actuation (MOVA) system is

proposed to be implemented at Grenfell Road / Queen Street / King Street,

Grenfell Road / Green Place and King Street / Braywick Road / Shoppenhangers

Road junctions.

As mentioned previously, the traffic control strategy MOVA will be implemented in the

proposed network to maximise the operational efficiency of the junctions. The process

of MOVA is based on two modes of operation which depend on the road conditions –

congested and uncongested (free flowing). In free flowing mode the aim of MOVA is to

disperse any queues which have built up on a red signal, it then assesses the traffic

flows approaching on each arm of the junction and calculates if extending the current

green would be beneficial. If it is beneficial then the current green is extended and the

calculation is repeated.

When the network is congested MOVA operates in capacity maximising mode. This

assesses which approaches are overloaded and how efficiently the green is being used

and seeks to determine a set of signal timings which will maximise the throughput of the

junction under the current conditions.

As described in paragraph 3.3, the modelled network was operating on CLF plans at

the time of the traffic surveys. Therefore, the proposed MOVA timing data have been

applied to the validated base for comparison with the proposed options. In order to

replicate the operation of this traffic control system in LinSig software, the signal timings

of each junction have been optimised and higher cycle time values have been used in

the models ensuring the entire network running within capacity.

The analogous methodology has been applied in the modelling of the proposed

options.

4.3 Proposed Design

PCL has developed two at-grade crossing options. These proposed designs involve

some changes to the existing layout of the Grenfell road / Queen Street / King Street

junction which are briefly described below and shown in Appendix H:


Option 1

Removal of right turn from Queen Street to A308 to provide wider pavements

and new public space;

Footways would be re-paved in area to create consistent and legible route

between town centre and Station; and

Two-stage crossing over A308.

Option 2

Queen Street amended to join A308 at new junction;

Footways re-paved to create consistent and legible route between town

centre and Station;

Pedestrian / cycle route amended to east side of A308; and

Two-stage crossing over A308.

Appendix H contains the General Arrangement (GA) of the proposed designs

described above.

4.4 Proposed Modelling

The models for the two proposed options have been modelled from the calibrated /

validated base LinSig models with changes made to the base models described below:

Option 1

The proposed option has been modelled with the cycle times used in the

‘MOVA current scenario’ (96s and 72s in the AM and PM peak hours

respectively) and higher cycle time values (104s and 88s in the AM and PM

peaks);

Intergreen re-measured (calculated to TfL SQA-645 standard);

Method of Control (MoC) has not been altered; and

Reassignment of traffic flow due to closure of right turning traffic on Queen

Street.

Option 2

The proposed option has been modelled with the cycle times used in the

‘MOVA current scenario’ (96s and 72s in the AM and PM peak hours


respectively) and higher cycle time values (104s and 120s in the AM and PM

peaks);

Intergreen re-measured (calculated to TfL SQA-645 standard); and

Method of Control amended to include pedestrian stream for the pedestrian

crossing across the southbound A308 exit lane.

4.5 Traffic Reassignment

The closure of Queen Street right turning traffic to A308 has involved the diversion of the

traffic exiting town centre through the entire network. However, to reduce the diversion

route length, there is potential to make a section of Broadway two-way between

Nicholson’s and A308. Therefore, two different scenarios have been modelled for

Option 1.

The peak hours re-assigned traffic flow used in the proposed Option 1 are shown

graphically, in passenger car units (PCUs), in the traffic flow diagrams (Figure 4.1– 4.2)

below.


Figure 4.1 a) – AM Peak hour - Reassigned Traffic Flows (in PCUs) through the network


Figure 4.1 b) – PM Peak hour - Reassigned Traffic Flows (in PCUs) through the network


Figure 4.2 a) – AM Peak hour - Reassigned Traffic Flows (in PCUs) through Broadway


Figure 4.2 b) – PM Peak hour - Reassigned Traffic Flows (in PCUs) through Broadway

A

4.6 Proposed LinSig Structure

As can be seen in Figure 4.3, the LinSig structure for Option 1 has remained the same as

the base model with the exception of the southbound Queen Street right turn

approach to the Grenfell Road / Queen Street / King Street junction which has been

removed. In addition the pedestrian crossing facility across this lane has been also

removed.

Figure 4.3 – Link Structure for Proposed Model – Option 1

B

Figure 4.4 shows the LinSig structure used for Option 2. The southbound Queen Street

arm has been amended and two internal links of 1 PCU length have been provided on

the southbound A308.

Figure 4.4 – Link Structure for Proposed Model – Option 2

C

4.7 Signal Timings

The proposed methods of control for the two modelled options are shown below in

Figure 4.5 – 4.6.

Figure 4.5 – Proposed Method of Control – Option 1

The signal stage sequence for the Grenfell Road / Queen Street / King Street junction

will continue to operate a two stage sequence.

Figure 4.6 – Proposed Method of Control – Option 2

The proposed junction is proposed to operate a two stage signal sequence and will

largely be unchanged, with the exception of a separate stream for the pedestrian

D

crossing across the southbound A308 exit lane. This stream (Stream 2) is necessary to

control southbound traffic leaving the junction and the signalised pedestrian crossing

facility.

4.8 Proposed Intergreen Periods

Proposed Option 1

The proposed intergreens for the proposed Option 1 are illustrated in Figure 4.7 below.

Figure 4.7– Proposed Intergreen periods (seconds) – Option 1

A B C D E F G H I J K L

A - - - - 6 - - - - 5 3

B - 5 - - - 6 - - - 8 3

C - 5 - - - - 6 - - - 3

D - - - 5 - - - 6 - 5 3

E - - - 5 - - - - 6 - 3

F 9 - - - - - - - - - 3

G - 8 - - - - - - - - 3

H - - 9 - - - - - - - 3

I - - - 9 - - - - - - 3

J - - - - 8 - - - - 6 3

K - - - - - - - - - - -

L 2 2 2 2 2 2 2 2 2 2 -

Proposed Option 2

The LinSig model of the proposed option 2 has been prepared to include new phase /

stage intergreens illustrated in Figure 4.8. The intergreen values have been obtained to

TfL specifications using the method prescribed in TAL 01/06 and referenced in the SQA-

0645.

Figure 4.8– Proposed Intergreen periods (seconds) – Option 2

A B C D E F G H I J K L M

A - - - - 6 - - - - 5 3 -

E

B - 6 - - - - - - - 8 3 -

C - 5 - - - - 6 - - - 3 -

D - - - 5 - - - 6 - - 3 -

E - - - 5 - - - - 6 - 3 -

F 9 - - - - - - - - - 3 -

G - - - - - - - - - - - 8

H - - 10 - - - - - - - 3 -

I - - - 9 - - - - - - 3 -

J - - - - 8 - - - - 6 3 -

K - - - - - - - - - - - -

L 2 2 2 2 2 2 - 2 2 2 - -

M - - - - - - 6 - - - - -


As the proposed design of the Grenfell Road / Queen Street / King Street junction alters

the existing geometry, in particular the lane widths and radii, the existing saturation

flows would change and cannot be use for the proposed modelling. Hence, the

saturation flows at Queen Street approaching lanes used in the proposed models have

been calculated using the RR67.

F

5. PROPOSED MODELLING RESULTS

To assess the impact of the proposed schemes on traffic conditions at the modelled

network, the proposed modelling results have been compared with base model results

with the implementation of MOVA traffic control system. The traffic impacts on the

operation of the junctions due to the implementation of the proposed schemes are

assessed through two fundamental parameters, the Degree of Saturation (DoS) and

Mean Maximum Queue (MMQ).

Proposed Option 1 - TRAFFIC FLOW DIVERTED THROUGH THE NETWORK

Table 5.1a) – Comparison of MOVA base and Proposed Modelled Degrees of Saturation (DoS) –

Option 1 (96s AM & 72s PM)

ink Description


AM PM

Base (MOVA)

Option1 Diff Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 37% 38% -1% 50% 50% 0%

Grenfell Place SB Approach- O/S 32% 32% -1% 35% 35% 0%


Grenfell Road WB Approach- N/S 60% 56% 4% 72% 63% 8%

Grenfell Road WB Approach- O/S 66% 68% -2% 59% 62% -3%




King Street NB Approach- N/S 65% 70% -4% 81% 89% -8%

King Street NB Approach- O/S 63% 68% -5% 78% 86% -8%

Queen Street SB Approach- N/S 52% 49% 3% 70% 79% -

10%


lane) 20%

60% 14%

85%

Queen Street SB Approach- O/S (RT) 43% 60%


Queen Street WB Approach- O/S 61% 47% 14% 80% 80% 0%



Braywick Road NB Approach- N/S 85% 87% -2% 78% 93% -

G

15%

Braywick Road NB Approach- O/S 57% 61% -3% 46% 60% -

14%

King Street SB Approach- N/S 45% 42% 4% 66% 66% 0%


lane) 36% 33% 3% 40% 70%

-

30%

King Street SB Approach- O/S (LT) 35% 40% -4% 74% 90% -

16%

Shoppenhangers Road EB Approach- N/S 81% 85% -4% 65% 69% -4%

Cycle Time 96 72

Table 5.1 b) - Comparison of MOVA base and Proposed Mean Maximum Queue (MMQ) – Option

1 (96s AM & 72s PM)

Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 6 7 0 7 7 0

Grenfell Place SB Approach- O/S 5 5 0 5 5 0

Grenfell Road EB Approach- N/S 8 7 6 6

Grenfell Road WB Approach- N/S 4 1 3 7 1 6

Grenfell Road WB Approach- O/S 3 1 2 3 1 2


Grenfell Road EB Approach- N/S 1 1 0 11 9 2

Grenfell Road EB Approach- O/S 6 6 0 8 7 1

King Street NB Approach- N/S 6 6 0 12 19 -6




lane) 1

7

0

10

-10

Queen Street SB Approach- O/S (RT) 2 3 3

Queen Street WB Approach- N/S 5 4 0 8 8 0

H

As can be seen in Table 5.1a), the proposed modelling results suggest that Option1 (with

banned right turn traffic assumed to divert through the network), with the cycle times of 96s

in the AM and 72s in the PM peak hours, would not be feasible for the PM peak period. The

King Street / Braywick Road / Shoppenhangers Road junction is predicted to operate above

the maximum desired capacity (90%) with the highest DoS value of 93% predicted on the

nearside Braywick Road (northbound) during the evening peak.

Table 5.2 a) – Comparison of MOVA base and Proposed Modelled Degrees of Saturation (DoS) –


Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 37% 36% 1% 45% 46% -1%

Grenfell Place SB Approach- O/S 32% 32% 0% 34% 34% -1%

Grenfell Road EB Approach- N/S 65% 68% -3% 67% 63% 4%


Grenfell Road WB Approach- O/S 66% 66% 0% 57% 61% -4%


Grenfell Road EB Approach- N/S 33% 32% 2% 49% 57% -8%


Queen Street WB Approach- O/S 5 4 1 10 10 0





King Street SB Approach- N/S 9 3 7 10 10 0


lane) 8 5 3 4 16 -13


Shoppenhangers Road EB Approach- N/S 11 12 -1 6 7 0

Cycle Time 96 72

I

King Street NB Approach- N/S 64% 66% -2% 74% 84% -9%

King Street NB Approach- O/S 62% 66% -3% 73% 82% -9%

Queen Street SB Approach- N/S 51% 53% -3% 67% 76% -

10%


lane) 20%

65%

13%

81%


Queen Street WB Approach- N/S 55% 48% 6% 66% 69% -3%

Queen Street WB Approach- O/S 58% 51% 6% 73% 75% -3%



Braywick Road NB Approach- N/S 81% 84% -3% 74% 85% -

11%

Braywick Road NB Approach- O/S 56% 59% -3% 45% 56% -

11%

King Street SB Approach- N/S 35% 49% -

13% 60% 60% 0%


lane) 28% 39%

-

11% 37% 64%

-

28%

King Street SB Approach- O/S (LT) 36% 40% -4% 64% 86% -

22%

Shoppenhangers Road EB Approach-

N/S 81% 84% -3% 56% 68%

-

11%

Cycle Time 104 88


1 (104s AM & 88s PM)

Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff





J

The results reveal the benefit of considering higher cycle times (104s in the AM and 88s

in the PM) with all the predicted capacities below 90%. Increasing the cycle time (to

88s) in the PM peak hour improves the operating capacities of the nearside Braywick

Road (northbound) and the offside King Street (southbound) with DoS values of 85%

and 86% respectively.

Proposed Option 1 - TRAFFIC FLOW DIVERTED THROUGH BROADWAY








King Street NB Approach- N/S 6 6 0 9 13 -5

King Street NB Approach- O/S 10 9 1 14 12 2



lane) 1

8

0

13

Queen Street SB Approach- O/S (RT) 2 4







King Street SB Approach- N/S 1 11 -10 12 5 7


lane) 6 6 -1 3 17 -14


Shoppenhangers Road EB Approach- N/S 12 12 -1 7 8 -1

Cycle Time 104 88

K

Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 37% 38% -1% 50% 55% -5%

Grenfell Place SB Approach- O/S 32% 32% -1% 35% 38% -3%







King Street NB Approach- N/S 65% 60% 5% 81% 64% 16%

King Street NB Approach- O/S 63% 59% 5% 78% 63% 15%

Queen Street SB Approach- N/S 52% 49% 3% 70% 37% 33%


lane) 20%

31%

14%

65%






Braywick Road NB Approach- N/S 85% 76% 9% 78% 78% 0%




lane) 36% 29% 8% 40% 40% 0%


Shoppenhangers Road EB Approach- N/S 81% 78% 3% 65% 65% 0%

Cycle Time 96 72

L


1 (96s AM & 72s PM)

Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 6 7 0 7 8 -1

Grenfell Place SB Approach- O/S 5 5 0 5 5 -1







King Street NB Approach- N/S 6 5 0 12 5 7

King Street NB Approach- O/S 7 7 0 11 5 6

Queen Street SB Approach- N/S 1 1 1 10 0 10


lane) 1

3

0

8

-8






Braywick Road NB Approach- N/S 20 17 3 12 12 0

Braywick Road NB Approach- O/S 11 10 1 6 6 0



lane) 8 3 5 4 5 -1

King Street SB Approach- O/S (LT) 6 6 0 8 8 0

Shoppenhangers Road EB Approach- N/S 11 11 1 6 6 0

M

Table 5.3 a) above suggest that Option 1 (with banned right turn traffic assumed to

divert through Broadway) with cycle time of 96s and 72s in the AM and PM peak

periods respectively, would run more efficiently during the assessed peak hours with all

approaches well below 90% of the modelled network.

As expected, the queues on the approaching lanes are predicted to reduce in the

proposed modelling results. The decreases in MMQs are shown to be consistent with

their respective DoS on the approaching lanes.

Proposed Option 2



Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 37% 38% -1% 50% 52% -2%

Grenfell Place SB Approach- O/S 32% 33% -1% 35% 36% -1%





Grenfell Road EB Approach- N/S 34% 35% -1% 70% 66% 4%

Grenfell Road EB Approach- O/S 44% 45% -1% 51% 49% 2%

King Street NB Approach- N/S 65% 73% -8% 81% 94% -

13%

King Street NB Approach- O/S 63% 70% -7% 78% 90% -

13%

Queen Street SB Approach- N/S 52% 78% -

26% 70% 96%

-

26%

Queen Street SB Approach- O/S (middle 20% 43% 14% 59%

Cycle Time 96 72

N

lane)




Keys Place SB Approach- N/S 7% 8% -1% 21% 24% -3%






lane) 36% 29% 8% 40% 39% 1%



N/S 81% 78% 3% 65% 55% 10%

Cycle Time 96 72


2 (96s AM & 72s PM)

Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff











King Street NB Approach- O/S 7 19 11 16

O

The results from Table 5.4a) indicate a significant increase in DoS on the northbound

King Street and the nearside Queen Street (southbound) approaching lanes during the

evening peak following the implementation of the proposed scheme (Option 2). The

highest DoS is predicted on the southbound Queen Street approach (96%) during the

PM peak hour.

Proposed Option 2



Queen Street SB Approach- N/S 1 9 10 19


lane) 1

5

0

8

-8






Braywick Road NB Approach- N/S 20 19 1 12 12 0

Braywick Road NB Approach- O/S 11 11 1 6 6 0



lane) 8 2 6 4 4 0

King Street SB Approach- O/S (LT) 6 6 0 8 8 0

Shoppenhangers Road EB Approach- N/S 11 11 1 6 6 1

Cycle Time 96 72

P

Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 37% 37% 0% 45% 40% 6%

Grenfell Place SB Approach- O/S 32% 32% 0% 34% 32% 2%





Grenfell Road EB Approach- N/S 33% 34% -1% 49% 60% -

12%

Grenfell Road EB Approach- O/S 44% 45% -1% 67% 45% 22%

King Street NB Approach- N/S 64% 71% -7% 74% 72% 2%

King Street NB Approach- O/S 62% 68% -6% 73% 71% 2%

Queen Street SB Approach- N/S 51% 76% -

26% 67% 89%

-

22%


lane) 20%

42%

13%

55%




Keys Place SB Approach- N/S 7% 8% -1% 21% 21% 0%






lane) 28% 28% 0% 37% 34% 3%



N/S 81% 78% 3% 56% 47% 9%

Cycle Time 104 120

Q


2 (104s AM & 120s PM)

Link Description


AM PM

Base

(MOVA) Option1 Diff

Base

(MOVA) Option1 Diff


Grenfell Place SB Approach- N/S 7 7 0 8 9 -1

Grenfell Place SB Approach- O/S 6 6 0 5 6 -1


Grenfell Road WB Approach- N/S 5 4 1 8 10 -2

Grenfell Road WB Approach- O/S 3 3 1 4 5 -1


Grenfell Road EB Approach- N/S 1 1 0 13 15 -3

Grenfell Road EB Approach- O/S 6 6 0 9 12 -3



Queen Street SB Approach- N/S 1 9 -8 12 23 -11


lane) 1

5

0

12

Queen Street SB Approach- O/S (RT) 2 4

Queen Street WB Approach- N/S 5 4 1 9 10 -1

Queen Street WB Approach- O/S 5 4 1 11 12 -1

Keys Place SB Approach- N/S 1 1 0 3 4 -1


Braywick Road NB Approach- N/S 20 19 1 14 17 -3

Braywick Road NB Approach- O/S 12 11 1 7 9 -2

R

With increased cycle times (104s in the AM and 120s in the PM), the model results

suggest that the junction would operate better with the predicted capacities on all

approaching lanes below 90% DoS during the AM and PM peak hours.

King Street SB Approach- N/S 1 8 -7 12 2 10


lane) 6 2 4 3 0 3


Shoppenhangers Road EB Approach- N/S 12 11 0 7 8 -2

Cycle Time 104 120

S

6. CONCLUSION

6.1.1 Base LinSig models have been developed and validated to simulate

existing traffic conditions for weekday morning peaks (AM) and evening

(PM) peak hours.

6.1.2 Base modelling indicates that the network currently operates within

capacity during peak hours, except for the northbound A308 movement

past the station, and the Shoppenhangers Road traffic signal approach.

Both movements exceed 90% capacity during peak hours.

6.1.3 Two at-grade crossing options at the Grenfell Road / Queen Street / King

Street junction have been developed for assessment.

6.1.4 Option1 involves removal of right turning traffic from Queen Street to A308 .

Right turners may either continue to travel to A308 south and then pass

around Stafferton Way roundabout to continue north, or potentially be

diverted from Nicholson’s car park via a two-way Broadway, thereby

avoiding the junction altogether. The latter option may not be taken

forward, therefore both scenarios have been tested.

6.1.5 Option 2 involves amendments to Queen Street arm (southbound) with a

two-stage crossing over A308. Right turning movements would be retained

in this scenario.

6.1.6 MOVA traffic control is being implemented at these signals. therefore, a

‘MOVA Current Scenario’ has been developed from the calibrated and

validate base model for option assessment purposes.

6.1.7 Option1, with banned right turn traffic assumed to divert via Stafferton

Way, would require cycle times to be amended to 104s in the AM peak

and 88s in the PM peak hours. With these amended cycle times, the

degree of saturation predicted on all approach lanes would be below

90%, leading to an improvement in conditions.

6.1.8 Option 1 with right turn traffic diverted away from the junction via

Broadway would be able to operate on cycle times of 96s and 72s in the

AM and PM peak periods respectively. This option is predictably shown to

operate more efficiently during the peak hours as it removes traffic from

the network.

T

6.1.9 Option 2 modelling has indicated that the layout proposed would cause

significant queuing on A308 approach lanes, and on Queen Street. The

signal operation is not optimum and would not be practical in this

location.

6.1.10 Option 1 with Broadway two-way would provide an optimum solution.

However, if this change did not occur and current right turners were

diverted through the network via Stafferton Way roundabout, the network

would still see operational improvements, albeit with a need to increase

cycle times to better reflect peak flow demands.

6.1.11 It is noted that the Stafferton Way diversion assumes that all current right

turners would divert via Stafferton Way, but the numbers would be

significantly less as there are alternative routes that could be used by

traffic leaving the town centre area. The approach taken is therefore

robust and “worst case”.

6.1.12 It is recommended to progress with Option 1 with banned right turn traffic

from Queen Street.

U

Document Control

Project: Maidenhead Station Business Case Job No: 1000004054

Subject: LinSig Modelling Issue: 01

Prepared by: J. Cecchinelli Date: 25/09/2017

Approved by: Paul Chandler Date: 02/10/2017

V

Quality

It is the policy of Project Centre to supply Services that meet or exceed our clients’

expectations of Quality and Service. To this end, the Company's Quality

Management System (QMS) has been structured to encompass all aspects of the

Company's activities including such areas as Sales, Design and Client Service.

By adopting our QMS on all aspects of the Company, Project Centre aims to achieve

the following objectives:

Ensure a clear understanding of customer requirements;

Ensure projects are completed to programme and within budget;

Improve productivity by having consistent procedures;

Increase flexibility of staff and systems through the adoption of a common

approach to staff appraisal and training;

Continually improve the standard of service we provide internally and

externally;

Achieve continuous and appropriate improvement in all aspects of the

company;

Our Quality Management Manual is supported by detailed operational

documentation. These relate to codes of practice, technical specifications, work

instructions, Key Performance Indicators, and other relevant documentation to form

a working set of documents governing the required work practices throughout the

Company.

All employees are trained to understand and discharge their individual responsibilities

to ensure the effective operation of the Quality Management System.

W

Appendix A – BASE LINSIG MODELS AND RESULTS

X

Appendix B – PROPOSED LINSIG MODEL AND RESULTS

Y

Appendix C – GENERAL ARRANGEMENTS (GA)

maidenhead station improvements modelling report: proposed

Documents