Comment

Representation ID: 15770

Received: 11/05/2016

Respondent: National Highways

We understand that modelling is currently being undertaken to determine what the impact of development could be on the highway network and therefore what measures may be required to mitigate these impacts. It is therefore unclear at this stage whether it will be possible to sufficiently mitigate the impact of the allocated development locations or whether the impact will be too great to feasibly ensure that the network operates within capacity at the end of the plan period.

Comment

Representation ID: 15771

Received: 11/05/2016

Respondent: National Highways

The Local Plan does not provide any details of infrastructure funding, which may be unknown at this stage if the specific infrastructure schemes that are required have not yet been identified. It is important that once the schemes are identified that the funding method for each is outlined, including any Central Government or Local Government funding that is available, the amount that could be collected from developers and any shortfall that could occur. It is recommended that an IDP is prepared to provide further details regarding the infrastructure provision and funding.

Comment

Representation ID: 15773

Received: 11/05/2016

Respondent: National Highways

PBA, on behalf of Brentwood Borough Council, have prepared an evidence base to support the development proposals within the LP. The intention of this modelling is to determine how many additional vehicles will be generated on the network as a result of the LP and where improvements may be required to ensure the network continues to operate effectively throughout the plan period. AECOM on behalf of Highways England have prepared a separate technical note detailing a review of this section of the evidence base.

Comment

Representation ID: 15782

Received: 11/05/2016

Respondent: National Highways

We consider that the trip generation and distribution assumed by PBA is broadly reasonable. Some concerns have been raised regarding the assignment of trips across the network, primarily the decision to assign all trips between two zones to the same route, whereas in reality we consider that a number of different routes may be used, particularly if routes become congested and users change to an alternative route to avoid the congestion. However, we consider that the current methodology could result in a robust impact on the Strategic Road Network and therefore may be reasonable to take forward. If, however, the local highway authority plans to deter drivers from making use of certain routes or congestion hotspots cause a significant change in route choice, the total development trips on the strategic road network could alter from that presented within the Highway Modelling Report. The assessment undertaken suggests very high impacts to the Strategic Road Network.

Comment

Representation ID: 15783

Received: 11/05/2016

Respondent: National Highways

Junction capacity assessments of the Strategic Road Network have not been presented within the Modelling Report, despite experiencing significant increases in trips at the junction as a result of development. It is recommended these are undertaken to determine the predicted operation of the junctions following LP development and to determine what measures may be required to mitigate the impact. Consideration may also need to be given to undertaking merge/diverge assessments at various locations to determine whether changes are required to support the LP development.

Comment

Representation ID: 15824

Received: 11/05/2016

Respondent: National Highways

Technical note provided by Highways England, written by AECOM to document a review of the Brentwood Draft Local Plan evidnce base (in the form of spreadsheet modelling). The technical note should be read in conjunction with the separate technical note entitled ' 'TN_Draft Brentwood Local Plan Review_v4' (dated March 2016).

Comment

Representation ID: 15827

Received: 11/05/2016

Respondent: National Highways

As there is no validated traffic model for Brentwood, PBA have adopted an alternative approach using available information. OmniTRANS has been used to build a simplified model of Brentwood Borough. The defined zoning system and an Integrated Transport Network (ITN) layer were imported. Additional zones were created to represent the proposed areas for major development sites. The mean link speeds from TrafficMaster (including junction delays) were added to the links. This model allowed skim times and distances to be calculated for each zone pair. A base year assignment was undertaken on the basis of census data and a synthetic distribution based on the trip lengths and the relative attractiveness (land use) of various zones. This was judged to be approximately correct but did not undergo any formal validation process. These time and distance skims were used to determine the distribution of development trips and also the assignment of those trips. In all of the assessed scenarios, the total level of trip growth resulting from planned developments was greater than the growth implied by TEMPro. Hence, there was no requirement to allow for additional developments. Indeed, the overall growth assessed was higher than that implied by national forecasts. he assigned turning movements of the development traffic at the assessed junctions were added to the observed turning movements To calculate future year scenarios. Hence, the future year assessments were not reliant on the base year assigned traffic flows.

Comment

Representation ID: 15838

Received: 11/05/2016

Respondent: National Highways

According to the modelling report the expected developments in the LP can be placed into three
categories:
Committed housing developments for all options (brownfield sites and urban extensions);
Committed employment developments; and
Various options for strategic housing developments.

Comment

Representation ID: 15839

Received: 11/05/2016

Respondent: National Highways

Committed Sites: Most of the committed housing sites (shown as yellow dots in Figure 1) are relatively small and will not have significant trip generation. There are a few places where sites (or combinations of sites) will have a significant impact. Three sites in West Horndon (south of the A127) are expected to include about 500 dwellings. A site close to the High Street in Brentwood is expected to include 200 dwellings.

Comment

Representation ID: 15842

Received: 11/05/2016

Respondent: National Highways

Committed Sites: Most of the committed housing sites (shown as yellow dots in Figure 1) are relatively small and will not have significant trip generation. There are a few places where sites (or combinations of sites) will have a significant impact. Three sites in West Horndon (south of the A127) are expected to include about 500 dwellings. A site close to the High Street in Brentwood is expected to include 200 dwellings.

Comment

Representation ID: 15844

Received: 11/05/2016

Respondent: National Highways

Urban extensions:
The most significant urban extension involves 500 dwellings at Shenfield close to the A12 junction. A further 250 dwellings are expected near Doddinghurst Road in North Brentwood. There is no easy access to the A12 from the sites in North Brentwood.

Comment

Representation ID: 15846

Received: 11/05/2016

Respondent: National Highways

Employment
The most significant employment site (shown as a purple dot in the south west of Figure 1) is Site 101A at Cobham Hall to the east of M25 Junction 29. The only access and egress is via Junction 29. The location of this site in the extreme south west of the borough and its proximity to the motorway means that many of the trips will originate from outside of the borough.

Comment

Representation ID: 15848

Received: 11/05/2016

Respondent: National Highways

Strategic housing:
2500 dwellings at Dunton Hills Garden Village (shown as a red dot in the extreme south east of Figure 1);
2500 dwellings at sites in West Horndon (shown as blue dots in the south of Figure 1);
1170 dwellings at sites in North Brentwood (shown as green dots in the north of Figure 1); or
1000 dwellings at Running Waters (shown as an orange dot in the centre of Figure 1).
The strategic sites involve significantly more concentrated development than the brownfield sites and are generally larger than the urban extensions. AECOM understand that Option 1 has been taken forward for inclusion within the LP.

Comment

Representation ID: 15849

Received: 11/05/2016

Respondent: National Highways

A total of 23 junction have been modelled. None of the Strategic Road Network junctions have been modelled. Base year turning counts have been undertaken at these junctions. Although modelling has not been undertaken at either of the motorway junctions, the forecast increase in traffic at these
junctions is higher than at any other junction. With the exception of the motorway junctions, nearly all of the significant junctions which are affected by forecast development flows are included. Notable exceptions are the two left-in left-out junctions located between junctions 14 and 19/20 on the A127.
Roundabouts and priority junctions have been modelled using JUNCTIONS 8 software. LINSIG has been used for modelling signalised junctions. With the exception of Junctions 15 and 16, which are treated as a double mini-roundabout, no consideration is taken of potential interference between the junctions. This is only likely to be an issue for those closely-spaced junctions in the centre of Brentwood.

Comment

Representation ID: 15850

Received: 11/05/2016

Respondent: National Highways

Trip generation: The residents per household and person trip rates were from acceptable sources although trip rates appeared to be "quite low".
Noted that TRICS will give trip rates for a typical not an average day , in terms of junction assessments, "a typical day may be more appropriate".

Comment

Representation ID: 15851

Received: 11/05/2016

Respondent: National Highways

Trip distribution: For work trips, a matrix of weights was calculated using distance weights derived from Census journey to work data. In principle, this is reasonable.
Education trips used a matrix of weights using schools as attractors. This is considered to be acceptable.

Comment

Representation ID: 15852

Received: 11/05/2016

Respondent: National Highways

Assignment:
It was recognised that this method of assigning development trips would result in one route being used between each zone pair. In addition, there should be no reassignment of existing trips to avoid increasing congestion resulting from the assignment of development trips. PBA considered that this would represent a worst case for congestion. This could be the case for the junctions on routes used by development traffic. It could underestimate traffic at junctions which would be affected by reassigning traffic and junctions on other routes which would be expected to be used between certain zone pairs.

Comment

Representation ID: 15853

Received: 11/05/2016

Respondent: National Highways

Strategic Housing Developments
Dunton Hills Garden Village
Plots are shown of flows from four development options in Appendices C and D of the PBA report. It is stated that these are exclusive of the baseline traffic flows. However, the plots appear to show more traffic on the M25 than that coming from the developments. The mechanism for excluding this traffic is not known. Hence, there is some doubt that the plots are entirely accurate.
AECOM therefore consider that the assessment of the impact of Option 1 on the M25 junctions could be considered broadly robust. However, if a higher proportion of trips travelling to destinations east on the A12 travelled through the town centre and accessed the A12 at Junction 12, there could be a greater number of turning movements at that junction than is predicted by PBA.

Comment

Representation ID: 15861

Received: 11/05/2016

Respondent: National Highways

North of Brentwood strategic option
Whilst AECOM recognise that the assignment of trips via the M25 rather than the A128 may underestimate the number of trips on the local highway network, AECOM consider that by assigning a significant proportion of traffic via the M25, this should result in a robust assessment of the impact of options three on Junction 28. However, if traffic routed via A1023, for access to the SRN for trips travelling along the A12 to / from the east the first point of contact could be at A12 Junction 12. Therefore, by assigning the majority of these trips via M25 Junction 28 the modelling could be underestimating the impact of turning movements at A12 Junction 12.

Comment

Representation ID: 15864

Received: 11/05/2016

Respondent: National Highways

Strategic option - East of running waters
This site is at a greater distance from the major roads than the other alternative options considered. Trips disperse via the A128, The Avenue and Running Waters. The choice of road used to travel to and from the A127 in the AM and PM peak differs. The choice of route makes a significant difference to the junctions used. In reality, there is likely to be a split with some relief for the most congested junctions but increases at less congested junctions.
Despite the distance of the strategic site option four from the SRN, there is predicted to be an increase in trips at both M25 Junction 28 and 29, the extent of which is outlined within the table below. The development is located in closer proximity to the A12 than Strategic Options 1 and 2 and is therefore likely to have a greater impact at Junction 12, while the impact at M25 Junction 29 may be less than Options 1 and 2. It should be noted that due to a lack of clarity on the flow diagrams in Appendix C, it has not been possible to calculate the increase at A12 Junction 12. It is recommended that this information is provided by BBC.

Comment

Representation ID: 15872

Received: 11/05/2016

Respondent: National Highways

An assessment of the operation of the SRN junctions has not been undertaken within the Highway Modelling Report. Therefore it is not possible for AECOM to speculate on the potential operation of these junctions following Local Plan development.
Junction 17 (A1023 / Mascalls Lane / Spital Lane) and Junction 19/20 (A127 / B186) are located close to M25 Junctions 28 and 29 respectively and AECOM consider that any queuing back from
these junctions towards the motorway could compromise the effective operation of these junctions. AECOM have primarily considered the operation of the junctions for Option 1, as this is the preferred option that has been taken forward for implementation in the LP.
At Junction 17 the A1023 approach to the junction (the approach of concern to HE) is predicted to operate over capacity in the AM peak, with Mean Max Queues (MMQ) expected to reach approximately 300m back from the junction. Whilst M25 Junction 28 is approximately 500m away, as the approach is over capacity it is likely that the full extent of the queue will be approximately 600m at the end of the peak hour. This could reach back to, and through, M25 Junction 28 and could therefore affect the operation of the junction and the M25 offslips.
At Junction 19 the A127 Eastbound offslip is predicted to operate significantly over-capacity in the AM peak, with queues predicted to reach approximately 1km, which could stretch back to M25 Junction 29.

Comment

Representation ID: 15873

Received: 11/05/2016

Respondent: National Highways

Additional issues:
Appear to be mistakes in the reporting. In Tables 11-1 and 11-2, the description of junction 15 (Priority left-in left-out) is not consistent with the description in Table 2-1 (double mini-roundabout). Further descriptions that the operation of this junction is very much influenced by the level of mainline traffic suggests that this is not the junction described as Junction 15 in Section 2. Hence, it is unclear whether the reported values are meaningful. Some investigation is required as to what has been modelled as Junction 15. Junction 21 is labelled as not applicable (N/A) for options 2 and 3. While this is correct for option 2 as the junction would be closed, there should be a value for option 3. The appropriate values
should be inserted into Tables 11-1 and 11-2.

Comment

Representation ID: 15874

Received: 11/05/2016

Respondent: National Highways

Additional issues. Appear to be mistakes in reporting. Some through trips on the motorway appear to be designated as development trips. This is clear from the plots in Appendix D where there are more trips on the M25 passing northbound through Junction 29 than leave at the exit at Junction 28. Hence, there must be some trips which pass through both junctions with neither trip end in the Brentwood area. It is not clear whether this has any significance for the assessment.

Comment

Representation ID: 15875

Received: 11/05/2016

Respondent: National Highways

Additional issues. Appear to be mistakes in reporting. It is reported that there seems to be some traffic reassignment within the option tests when the development traffic is added to the baseline traffic. According to the described methodology, this should not happen. The only reason why this may happen is if routes are closed as in Thorndon Avenue in Option 2. Some investigation is recommended as to why this happens.

Comment

Representation ID: 15876

Received: 11/05/2016

Respondent: National Highways

Additional issues. Consequences of the adopted process. There are some zone pairs where there are at least two alternative routes. The choice of route will affect the junctions through which development traffic passes. Small changes in the assignment assumptions may result in significant differences in junction loading. The distribution and assignment has been based on certain assumptions for the values of time and distance. Some of the routes used by development trips in the model may not be considered to be suitable by the local highway authority. In these cases, they may take action to prohibit or deter the movement. This would have the consequence of increasing the loading on the junctions of alternative routes. In some cases, this may result in other junctions being assessed as critical. Sensitivity tests could be undertaken which apply a penalty to unsuitable routes thereby encouraging development trips onto more major roads.

Comment

Representation ID: 15877

Received: 11/05/2016

Respondent: National Highways

Additional isues. Consequences of the adopted process.
As discussed earlier in this note, no assessment is made of M25 junctions. The increase in the number of trips at M25 Junctions 28 and 29 is higher than at any of the junctions modelled. AECOM recommend that capcity tests are undertaken to determine the resultant operation performance at these junctions. This type of assessment could have used a full highway assignment model had one been available. The assignment from such a model would differ in several important ways:
The extent of increasing junction delays would affect route choice. (This has two consequences: Several routes will be used by development trips between zone pairs; and existing trips may change route as a result of congestion caused by development trips).
Increasing congestion may result in interference (blocking back) between junctions.

Comment

Representation ID: 15878

Received: 11/05/2016

Respondent: National Highways

While the methodology used would show a worst case at some junctions, allowing for reassignment of trips may indicate a worst case at other junctions. Ultimately, this may depend
on the level of mitigation. If full mitigation is provided, then the routes assigned may be used by all traffic. In reality, it is unlikely that full mitigation will be possible at these junctions with consequence reassignment to sub optimal routes. This may require mitigation measures at other junctions.
It is probable that the optimum strategy for Brentwood Borough Council would be to install some mitigation measures at the junctions assessed as being most congested but accept that it is not possible to achieve nil detriment by this method alone. Actions to reduce congestion on other routes could result in a reassignment of traffic away from the more congested routes which may be a more cost effective strategy depending on the relative costs and constraints of improvements.

Comment

Representation ID: 15879

Received: 11/05/2016

Respondent: National Highways

Conclusion
This technical note has been prepared to review the Highway Modelling approach used to support the preparation of the Brentwood Local Plan. The review was intended to establish whether PBA's (Brentwood BC's consultants) approach to transport modelling will reasonably reflect the potential
impact the Local Plan development could have on the strategic road network over the plan period. AECOM has made a number of comments and recommendations throughout the note.

Comment

Representation ID: 15880

Received: 11/05/2016

Respondent: National Highways

Conclusion (2)
In summary AECOM consider that the trip generation and distribution assumed by PBA can be considered reasonable. Some concerns have been raised regarding the assignment of trips across the network, primarily the decision to assign all trips between two zones to the same route, whereas in reality AECOM consider that a number of different routes may be used, particularly if routes become congested and users change to an alternative route to avoid the congestion.
However, AECOM consider that the current methodology could result in a robust impact at the strategic road network and therefore may be reasonable to take forward. If, however, the local highway authority plans to deter drivers from making use of certain routes or congestion hotspots cause a significant change in route choice, the total development trips on the strategic road network could alter from that presented within the Highway Modelling Report. The assessment undertaken suggests very high impacts to the SRN.
Junction capacity assessments of the strategic road network have not been presented within the Modelling Report, despite experiencing significant increases in trips at the junction as a result of development. It is recommended these are undertaken to determine the predicted operation of the junctions following Local Plan development and to determine what measures may be required to mitigate the impact. Consideration may also need to be given to undertaking merge/diverge assessments at various locations to determine whether changes are required to support the Local Plan development.

Object

Representation ID: 15902

Received: 12/05/2016

Respondent: Kitewood

Agent: Kitewood

The SHMAA considers the housing market for Brentwood is self-contained. Brentwood Borough has strong inter-connectivity with London and Essex and therefore could not be considered a self-contained Borough. There appears to be strong commuting flows with Basildon and Chelmsford, and the construction of Crossrail (strategic objective S07) will only increase this connectivity with London and Essex. On that basis, we consider that Brentwood should consider a joint-SHMA with Basildon, Chelmsford and Epping Forest to establish the overall OAN for the HMA and how the overall OAN can be collectively met.

It is not clear from the draft Local Plan and the supporting evidence base whether or not the Council has fully considered London migration and this is therefore contrary to NPPF.