News

August 2013

Economy, Transport & Environment Department

Palace Lane, Beaulieu: impact of temporary traffic signals on shuttle working

1.              Purpose and introduction

1.1            There are ongoing concerns about the use of B3054 Palace Lane by HGVs through Beaulieu. The road is not particularly suitable for such vehicles because it has tight bends, narrow footways and historic buildings located close to the edge of the road. However, it is the only route available for many HGVs due to the low railway bridge at Ampress in Lymington on the A337, which would otherwise be more appropriate for such traffic.

1.2            Banning HGVs through Beaulieu has been ruled out for the time being because it is not currently feasible to provide an alternative route. The possibility of using traffic signals on a shuttle working arrangement at the tightest bend in the village by the Montagu Arms Hotel has therefore been considered as a possible means of keeping HGVs away from a building particularly close to the edge of the road (Northern Cottages, which has been struck in the past) and to prevent HGVs from overrunning footways.

1.3            This paper summaries how the use of signals has been considered and what the impact of traffic could be were such an arrangement introduced permanently.

2.             Use of temporary traffic signals

2.1            If permanent traffic signals were to be installed on a shuttle working basis on the bend by the Montagu Arms Hotel, so that only one direction of traffic can proceed at a time, the impact on traffic would need to be investigated first. Since works had been planned to install new “bell” bollards in Palace Lane and that this would need to be undertaken using temporary traffic signals, it presented an opportunity to study the effects of traffic signals.  

2.2            Temporary signals were installed either side of the bend, as shown in the attached drawing (no. C.J006847.01) and were in operation from Tuesday 7 May to Friday 10 May 2013. Automatic survey equipment was used to measure traffic flow during this period and also in the week beforehand for comparison purposes. CCTV was used to monitor queue lengths and record any traffic incidents that occurred.

2.3            The signal heads and “wait here for signal” signs had to be set back from the bend at the positions shown on the drawing to allow an articulated HGV to negotiate the bend and straighten up on the correct side of the road.

 

3.              Traffic flow and queue length

3.1            The number of vehicles passing through Palace Lane were counted at several locations and in one location in High Street. Comparing the Tuesday to Friday in the week before, and the Tuesday to Friday in the following week when temporary signals were in use, traffic flow in general decreased. This varied at each location surveyed in Palace Lane, but flows dropped by 2% to 13%. Table 1 in Appendix 1 gives further information.

3.2            It cannot be stated with certainty that the use of temporary signals was the cause of the drop because traffic volumes can vary from week to week due to a number of factors, but it is likely that they did have some impact on traffic flow. It is possible that they deterred some people from using the road. The decrease in flow was greater on the Wednesday, Thursday and Friday compared to the Tuesday, the first day the signals were in use, which could suggest frequent users of the road changed their route once they had encountered the signals.

3.3            Traffic flow in High Street increased by 29% and 17% on the Thursday and Friday respectively. It is difficult to explain as to why this could have happened and whether such marked increases were due to the presence of the signals. It was noted on a number of occasions that when Palace Lane became blocked due to animals in the road or HGVs passing each other, traffic diverted up High Street, therefore this could partly explain an increase on these two days.

3.4            Whilst potentially reducing overall traffic flow could be seen positively, the signals did cause traffic to queue in the village. CCTV was used to monitor queues for eastbound traffic (traffic coming from B3056 Hatchett Lane) in order to find out if traffic would queue back from Palace Lane onto Hatchett Lane. The opposite direction was not monitored because traffic would not affect other junctions. Table 2 in Appendix 2 gives some selected times of the day and details of queue lengths.

3.5            If a vehicle reached the “wait here” sign (that is, the stop line) as the signal went red, it would have to wait 68 seconds for the green signal. For most of the day vehicles would not have wait more than 68 seconds to go through because the green time was generally long enough to clear the queue apart from one or two vehicles. Vehicles at the back of the queue that did not get through first time though would have to wait for 136 seconds.

3.6            At the evening peak time, at 5pm, queues were much longer and did back on Hatchett Lane. At this time most drivers in the queue had to wait two cycles of the signals to get through. It is of more concern that traffic had to wait in Hatchett Lane because of the queue in Palace Lane. This resulted in some delay to southbound traffic in Hatchett Lane.

3.7            An important consideration is that the temporary signals were used outside of the holiday season, and therefore during the summer peak period traffic flows are likely to be higher, meaning delays and queues caused by signals would be longer.

4.              Other impacts on traffic

  1.               Ability of HGVs to pass each other

4.1            One of the main factors that determine where the traffic signal heads and stop lines can be located is the width of the carriageway, since there are only certain points where traffic can queue without obstructing vehicles passing in the opposite direction. The temporary signals were located as close to the corner by the Montagu Arms Hotel as possible, but also so that traffic would not block access to the fire station. However, north of this bend the road narrows as it approaches the bridge. If there is an HGV in the queue and an HGV coming in the opposite direction a blockage can occur unless one of the HGVs mounts the footway.

4.2            On two occasions whilst the signals were in operation abnormal loads with boats were observed having difficulty getting through due to the queued traffic restricting the available carriageway. In one instance all traffic had to be diverted up High Street.

4.3            Whilst HGVs travelling in opposite directions currently encounter each other on occasions, it is much more straightforward for them to manoeuvre past each other than would be in a situation where one of them is in a stationary queue of traffic waiting for traffic signals.

4.4            In order to avoid such a situation from occurring,  permanent signals would have to be located some distance further back, with the eastern signal heads moved away from the fire station access (as with the temporary signals), beyond the bridge and around the next bend. Not only would this significantly increase the amount of time that traffic would have to wait on a red signal (increasing queue lengths), there are a number of private properties with accesses that would fall between the two signal heads. This would result in drivers emerging from properties without knowing which direction of traffic in Palace Lane has a green signal.

  1.             Animals in the road

4.5            Since animals are free to roam in this part of the New Forest, it is a common occurrence to see them on Palace Lane. Although this can currently hold up traffic, drivers can usually pass them on a give and take basis. The situation would become somewhat problematic with permanent traffic signals in place; there is no inter-visibility between drivers at each stop line due to the bend, therefore if a driver receives a green signal they will proceed without being aware of animals potentially obstructing the road ahead.

4.6            During the period that temporary signals were in use there was an instance of a 10 minute delay caused by ponies in the middle of the road. This prevented traffic on a green signal from passing through, and since opposing traffic cannot see the traffic passing the signals in the opposite direction (due to the bend) it resulted in traffic meeting head on. This situation occurred several times with donkeys and even a goose. Some drivers, apparently frustrated at the delay, were observed going through a red signal.

5.              Conclusion

5.1            Whilst the use of temporary traffic signals provided a good opportunity to observe traffic patterns under signal control it should be noted that this was not a full study into the workings of permanent traffic signals. In addition to this, the signals were not in use during the busy summer holiday period. The observations are therefore only indicative of the potential impact of permanent signals.

5.2            During the four days the temporary signals were in use they largely operated with minimal impact or problems, although there were daily issues with animals blocking the road and HGVs being unable to pass. These issues still occur without traffic signals, but they cause more delays when signals are in use because traffic movements are formalised with signals and drivers have less flexibility to deal with obstacles.

5.3            Permanent signals are likely to be more efficient at assigning green time according to the flow of traffic compared to temporary signals. However, it is still likely that queues for eastbound traffic could end up blocking the junction with Hatchett Lane. This is even more likely to occur should the stop line for westbound traffic need to be moved further back due to HGVs being unable to pass each other. Introducing signals and queuing traffic could also have an impact on vehicle emissions within the village.

5.4            Although using signals is likely to reduce the occurrence of HGVs overrunning the footway at the bend by the Montagu Arms Hotel and reduce the likelihood of Northern Cottages being struck, they increase the likelihood of the footways near the bridge being overrun unless the signals for westbound traffic are moved further back. Signals would make it hazardous for drivers emerging from private accesses located between the two stop lines.

5.5            A detailed study would be required to assess and quantify the full impact of introducing permanent traffic signals, but since the benefits appear to be offset at best, and outweighed at worst, by the drawbacks of signal operations, it is not recommended that further study is carried out.

5.6            “Bell bollards”, which are intended to prevent wheels from HGVs and other vehicles from mounting footways, have recently been installed outside of Northern Cottages. Whilst they are not particularly suited to Beaulieu’s historic village setting, they have less visual impact than traffic signals and to date appear to be preventing HGVs from mounting the footway and are keeping them away from the cottages.

PG/14.08.13

 

Appendix 1

24 hour flows

Site

Direction of travel

Before signals (30/4 - 3/5)

With signals (7/5 - 10/5)*

Tues

Wed

Thurs

Fri

Tues

Weds

Thurs

Fri

1

Palace Lane Eastbound

5345

5442

5571

5431

5110

 (-4%)

4796

(-11%)

4840

(-13%)

4991

(-8%)

2

Palace Lane Westbound

3978

4046

4146

4354

3892

(-2%)

3568

(-12%)

3636

(-12%)

3788

(-13%)

3

High Street Southbound

739

802

689

771

705

(-5%)

774

(-3%)

889

(+29%)

903

(+17%)

4

Palace Lane Northbound

4499

4518

4748

4416

4476

(-0.5%)

4280

(-6%)

4317

(-10%)

4315

(-2%)

Palace Lane Southbound

4663

4773

4923

5085

4587

(-2%)

4236

(-13%)

4321

(-14%)

4480

(-12%)

5

Palace Lane Eastbound

4890

4964

5124

4842

4670

(-4%)

4354

(-14%)

4415

(-16%)

4537

(-7%)

6

Palace Lane Westbound

4617

4766

4868

5000

4626

(+0.2%)

4228

(-13%)

4318

(-13%)

4420

(-13%)

*Figures in brackets relate to percentage change compared to same day in previous week

Table 1: vehicle flows before signals and with signals

 

Appendix 2

 

Queue length in   Passenger Car Units (pcu)

 

Date

Time

Queue length

No. of vehicles through green phase

Waiting time for vehicle at stop line when signal is   red

 
 

7/5/13 (Tuesday)

08:00

9

9

68 secs

 

09:00

10

10

68 secs

 

12:00

16

14

68 secs

 

17:00

28

14

68 secs

 

18:00

17

14

68 secs

 

8/5/13 (Wednesday)

08:00

9

9

68 secs

 

09:00

16

14

68 secs

 

12:00

16

15

68 secs

 

17:00

16

15

68 secs

 

18:00

16

15

68 secs

 

9/5/13 (Thursday)

08:00

10

8

68 secs

 

09:00

14

13

68 secs

 

12:00

13

13

68 secs

 

17:00

31

19

68 secs

 

18:00

11

10

68 secs

 

10/5/13 (Friday)

08:00

16

14

68 secs

 

09:00

11

10

68 secs

 

12:00

10

10

68 secs

 

17:00

-

-

-

 

18:00

-

-

-

 

Table 2: summary of queue lengths