AGENDA ITEM 6B

BOROUGH OF POOLE

NEWTOWN, PARKSTONE AND PENN HILL AREA COMMITTEE

22 OCTOBER 2003

REPORT OF HEAD OF TRANSPORTATION SERVICES
ON
SANDBANKS RAILWAY BRIDGE TRAFFIC STUDY

1.Matter For Consideration

1.1To review the existing layout and consider options that will make the bridge safer for vehicles, pedestrians and cyclists.

2.Recommendation

2.1It is recommended that the report be noted.

3.Information

3.1 Sandbanks Road is a Classified Road leading to the popular beach area and is subject to high traffic flows in the high and mid seasons. The bridge creates a pinch point where wide vehicles have to wait for gaps in the traffic. Cars can pass oncoming vehicles under the bridge along the whole length if driving with due care. There is a footpath along the North side of the bridge but not the South side, the footpath narrows under the bridge.

3.2 The council regularly receives comments from residents about the safety of the bridge and requests for measures that would improve conditions for pedestrians and vehicles. There are already signs in place warning of wide vehicles approaching in the middle of the road. Movements have been restricted at the Tennyson Rd junction and white lining has been laid to encourage drivers into the correct position for the optimum sight line through the tunnel.

3.3 On 22 February 1996 the Traffic Panel recommended that the effects of introducing a shuttle system through the bridge should be investigated. Traffic surveys were taken on a busy summer afternoon and a mid season May weekend. The assessment concluded that a priority system (i.e.based on signs alone similar to the Bourne Valley Bridge) would lead to excessive queues during high and mid season. A positive form of control (i.e. signals) would allow the southbound traffic stream to have some priority and for queue lengths to be controlled but would still be overloaded during busy periods. A signalised system would be more costly and would lead to additional delays during off peak periods – shuttle working will, in any case, increase delays for vehicles using this stretch of road. In the absence of a record of relevant injury accidents it would be difficult to justify the cost of installing a signal system here.

3.4 The signalised system has been modelled again using vehicle flows from 2002. During peak times queues of 43 cars (260m) will be formed, not only are the queues excessive, this would then cause difficulties for vehicles trying to access and exit the side roads.

3.5 The problems for pedestrians using the footway under the bridge have also been identified during preliminary discussions on the School Travel Plans for Buckholme Towers and Baden Powell Schools.

3.6 The lines and lettering on Sandbanks Road at the bridge have been repainted within the last few months.

3.7 A list of options that have been considered are listed in Appendix A.

4. Conclusion

4.1The low cost options considered in this framework do little more than the existing minor measures that have already been introduced here. They do not address the fundamental problem of pedestrians having to use a substandard footpath alongside vehicles in a narrow carriageway.

4.2The medium cost options of raising kerbs or adding guardrail introduce problems of their own by narrowing the effective footpath width. By making the carriageway appear narrower to drivers, there will inevitably be longer delays, and possible collisions under the bridge.

4.3If safety is to be improved here, then some form of shuttle working is the only way of providing a wider footpath for pedestrians. Not only are the various shuttle working options relatively costly but they will all cause significant delays at peak periods.

4.4The Capital Programme has recently been reviewed and it is unlikely that funding could be justified for any significant improvements for several years.

JIM BRIGHT

Head of Transportation Services

Background Papers

None

Name and Telephone Number of Officer Contact

Steve Dean(01202) 262071

NPPH221003T3C

APPENDIX A
OPTION / COST / BENEFITS / DISADVANTAGES
Do Nothing / £0 /
  • No alteration to the current situation which does not have a relevant injury accident record
/
  • Does not improve the current situation for pedestrians and cyclists

Pedestrian Guard Rail 5m from bridge on South East Side / £1500 /
  • Will make pedestrians cross over to the footpath side of the bridge where they have better sight lines to see the oncoming traffic
/
  • Will look unsightly
  • May cause west bound traffic to move away from the kerb which will cause eastbound to slow down or give way, which will reduce the traffic capacity

Pedestrian Guard Rail along whole length under the bridge / £2000 /
  • Protects Pedestrians on the footpath from passing vehicles
/
  • Narrows the footpath to less than 1m making it difficult for wheelchair users and people with prams
  • Will make it more difficult for cyclists to pass under the bridge Southeast bound due to the added restriction of the railing
  • Could be damaged by cars manoeuvring so they can pass oncoming vehicles.

Ghost Island on Northwest approach / £2000 /
  • Will encourage lane discipline from the north with improved sight line and road positioning when travelling under the bridge
  • Increased lane discipline will increase the safety of pedestrians and cyclists
/
  • Would have little effect on large vehicles

Red Surfacing under the bridge and in advance for 5m on each approach / £5000 /
  • Will increase driver awareness of the narrowing and encourage slower approach speeds
  • Increases pedestrian and cyclist safety through slower vehicle speeds
/
  • Has to be maintained
  • The impact of red surfacing on drivers decreases over time.
  • The difficult road layout is already obvious to drivers

1.5m wide green surfaced cyclelane northbound under the bridge and for 10m on each approach / £3500 /
  • Provides an advisory visual marking for drivers to avoid
  • Increased cyclist safety when travelling under bridge
  • May reduced the number of cyclists using the pedestrian footpath
/
  • May reduce the capacity of the bridge as vehicles would straddle across the bridge width which would cause more vehicles to give way than as present

Raise the Kerbs along the Footpath under the bridge / £6,000 /
  • Stops vehicles mounting the kerb easily
  • Will encourage cyclists away from kerb which will then make the cars travel behind them instead of trying to pass them
/
  • Will make the road look narrower
  • Cyclists may need more room
  • Pedestrians might find the high kerb a trip hazard

Pedestrianise Bridge, no access by vehicles / £8,000 /
  • Is safe for Cyclists and Pedestrians
/
  • Vehicles will have to take a diverted route. None of the local routes would be suitable to carry such a large volume of traffic
  • Would need to provide a turning head

One way restriction under the bridge and widen footpath / £10,000 /
  • Is safer for pedestrians and cyclists
  • Constant flow of cars in one direction
/
  • Finding a suitable diversion route for diverted traffic None of the local routes would be suitable to carry such a large volume increase in traffic
  • Enforcement
  • Would need a turning head
  • Traffic speeds would increase

Shuttle System – Priority Signs / £15,000 /
  • Is safer for pedestrians, as this would allow a widened footpath
  • Reduces vehicle conflict under the bridge
/
  • Can cause a conflict with Cyclists
  • Drivers need to be courteous and obey priority
  • May cause an increase in congestion to unacceptable levels during the mid-high season
  • When there is a tidal flow in one direction the opposing direction would not be able to progress

Shuttle System – Part Signalised / £40,000 /
  • Is safer for pedestrians, as this would allow a widened footpath
  • Reduces vehicle conflict under the bridge
  • Signals would start to work if unacceptable queues formed (to alternate priority)
/
  • Can cause a conflict with Cyclists
  • Drivers need to be courteous and obey priority
  • Would cause an increase in congestion to unacceptable levels during the mid-high season
  • Experience shows that drivers can find part time signals confusing.

Shuttle System – Signalised / £40,000 /
  • Is safer for pedestrians, as this would allow a widened footpath
  • Reduces vehicle conflict under the bridge
  • Improves safety situation for cyclists
/
  • Would increase congestion to unacceptable levels during the mid-high season

Build a new Tunnel / £1million+ /
  • Improves the situation for vehicles, pedestrians and cyclists
  • Solution does not cause congestion
/
  • The cost is not justifiable
  • Maintenance of an extra highway structure

The cost for a new tunnel:

There would be costs in the feasibility study and the geotechnical analysis of the existing tunnel and railway embankment. Railtrack would need to be thoroughly reassured before they would allow work on their embankment. The tunnel would have to be designed to the current standards, and the existing tunnel may need strengthening because of the alteration in the stresses/loading that it would be subject to while the new tunnel is constructed.

There may need to be temporary support to the bridge and railway line, as there is a live railway line above. There may need to be long periods when the railway will not be operational. There would also need to be a vehicular diversion route.

There may be the need for land purchase. The existing footpath under the tunnel would have to be removed and the carriageway reinstated, and any services/covers lowered. The footpath leading to the tunnel would have to be realigned to lead into the new pedestrian tunnel.

The use of heavy plant will require reinstatement of the contractors site and areas where they have moved heavy plant and there would probably need to be special protective measures to prevent structural damage to neighbouring properties.

The tunnel would need to be well lit and drained.