AADT, Figures for NI 2023; Impact of SLC and Effect on Eastern Transport Plan (ETP) 2035

What is AADT?

AADT stands for Annual Average Daily Traffic – it’s the total number of vehicles that pass through a specific location on an average day throughout the year. Think of it as the “typical daily traffic” for any given road.

Key Findings for Northern Ireland 2023

Overall Traffic Picture

  • 97 traffic counting locations monitored across Northern Ireland
  • 65 locations provided valid traffic data (67% coverage)
  • Average daily traffic: 20,278 vehicles per day across all monitored roads
  • Traffic range: From as low as 1,440 vehicles/day on quiet rural roads to as high as 95,230 vehicles/day on major urban routes

Traffic by Road Type

The data shows clear patterns based on road importance:

Motorways (12 locations monitored)

  • Average: 46,270 vehicles per day
  • Range: 19,168 – 91,386 vehicles per day
  • These are the busiest roads, carrying the most traffic

A-Roads (46 locations monitored)

  • Average: 16,074 vehicles per day
  • Range: 2,747 – 95,230 vehicles per day
  • Major trunk roads with significant variation

B-Roads (6 locations monitored)

  • Average: 3,309 vehicles per day
  • Range: 1,440 – 7,926 vehicles per day
  • Quieter local and rural roads

Busiest Roads in Northern Ireland

The top traffic hotspots are all in and around Belfast:

  1. Westlink, Belfast (A12) – 95,230 vehicles/day
  2. M1 Motorway near Belfast – 91,386 vehicles/day
  3. M1 Stockman’s Lane Junction – 73,788 vehicles/day
  4. M1 Blacks Road to Saintfield Road – 54,824 vehicles/day
  5. M2 Motorway sections – 44,000-50,000+ vehicles/day

Heavy Goods Vehicles (Trucks)

  • Average HGV percentage: 9.2% of all traffic
  • Range: 2.1% to 33.4% depending on location
  • Motorways and major A-roads typically have higher truck percentages

Traffic Volume Categories

  • Low traffic (under 5,000/day): 10 locations – mainly rural B-roads
  • Medium traffic (5,000-20,000/day): 35 locations – suburban A-roads
  • High traffic (20,000-50,000/day): 14 locations – major routes
  • Very high traffic (over 50,000/day): 6 locations – motorways and major urban roads

What This Means

This data helps transportation planners understand where Northern Ireland’s roads are busiest, plan for future infrastructure needs, and manage traffic flow. The concentration of very high traffic around Belfast reflects its role as the region’s major population and economic center, while the lower traffic on B-roads shows the quieter nature of rural Northern Ireland.

Based on research and analysis of the Northern Ireland traffic data, here’s what the likely impact would be on AADT figures if a bridge were built between Portaferry and Strangford:

Current Situation

Ferry Service Details:

  • The alternative road journey is 47 miles (76 km), while the ferry crosses the 0.6 nautical miles (0.69 mi; 1.1 km) in 8 minutes
  • Ferries depart each terminal every 30 minutes and convey about 500,000 passengers per annum
  • To travel the distance between Strangford and Portaferry by road is around 46 miles and takes about an hour-and-a-half by car
  • Current ferry operates at a loss of over £1 million per year according to recent reports

Likely AADT Impact of a Bridge

1. Massive Reduction in Alternative Route Traffic

The current 47-mile detour via Newtownards-Comber-Downpatrick would see significant traffic reduction. Based on the 2023 data:

  • A2 routes in the area currently have AADT figures ranging from 6,900-16,500 vehicles/day
  • A substantial portion of this traffic is likely people avoiding the ferry due to time constraints, costs, or schedule limitations
  • Expected reduction: 20-40% decrease in AADT on the alternative route sections

2. New Bridge Traffic Volume

Estimating the bridge’s AADT based on current patterns:

  • Current ferry: ~500,000 passengers annually ≈ 1,370 passengers/day
  • If we assume 2.5 people per vehicle average, that’s ~550 vehicles/day currently using the ferry
  • Induced demand would likely increase this significantly:
    • No waiting times (ferry runs every 30 minutes)
    • No weather delays
    • 24/7 availability vs 16 hours/day ferry service
    • Lower long-term costs (no per-journey fees)

Conservative estimate: 2,000-4,000 vehicles/day AADT on the bridge Optimistic estimate: 5,000-8,000 vehicles/day AADT (considering full induced demand)

3. Regional Traffic Pattern Changes

Positive Impacts:

  • Ards Peninsula accessibility would dramatically improve, potentially increasing tourism and residential traffic
  • Economic development in Portaferry and Strangford areas could generate additional local traffic
  • Emergency services response times would improve significantly

Network Effects:

  • Traffic would be redistributed from the longer A2 coastal route
  • Downpatrick area (A25/A7 routes) might see reduced through-traffic
  • Newtownards area traffic might decrease as people take the more direct bridge route

4. Comparison with Other Routes

Looking at the 2023 AADT data:

  • B-roads average: 3,309 vehicles/day
  • Minor A-roads: 6,000-10,000 vehicles/day
  • Busy A-roads: 15,000-20,000 vehicles/day

A Portaferry-Strangford bridge would likely fall into the “busy B-road to minor A-road” category initially, but could grow to major A-road levels if it spurred significant development.

Bottom Line

Expected Bridge AADT: 3,000-6,000 vehicles/day initially, potentially growing to 8,000-12,000 vehicles/day over time

This would make it one of the busier routes in rural County Down, comparable to routes like the A31 Magherafelt (6,970 AADT) or A6 Castledawson-Dungiven (16,520 AADT) depending on induced demand and regional development effects.

The bridge would fundamentally reshape traffic patterns in the region, reducing pressure on the longer alternative routes while creating a new significant traffic corridor across Strangford Lough.

Based on my research, here’s my assessment of whether the Portaferry-Strangford bridge should be included in the Eastern Transport Plan 2035:

Current Status of Eastern Transport Plan 2035

The Eastern Transport Plan (ETP) 2035 covers five council areas including Ards and North Down Borough Council (where Portaferry is located) and aims to ensure that the transport network meets the needs of the people and businesses living, working and visiting the ETP area, both now and into the future.

The initial consultation phase ran from September 4 to October 30, 2023, focusing on draft vision and objectives. The plan appears to still be in development as of 2025.

And, Yes, the Portaferry-Strangford bridge should absolutely be included for several compelling reasons:

1. Geographic Coverage

Ards and North Down Borough Council is specifically one of the five council areas covered by ETP 2035, making Portaferry and the broader Ards Peninsula directly within the plan’s scope.

2. Alignment with ETP 2035 Objectives

The plan’s focus on addressing issues arising from the environmental emergency and reducing over-reliance on cars actually supports a bridge proposal:

  • Carbon Reduction: Eliminating the diesel ferry service would reduce emissions
  • Network Efficiency: A bridge would reduce the 47-mile alternative route, cutting overall vehicle miles
  • Sustainable Connectivity: Better access could support sustainable tourism and economic development

3. Strategic Transport Importance

The ferry route represents a critical gap in the transport network where the alternative road journey is 47 miles (76 km) compared to the 0.6 nautical mile ferry crossing. This is exactly the type of network inefficiency that strategic transport planning should address.

4. Economic and Social Case

  • Annual ferry losses of over £1 million represent poor value for public money
  • The ferry conveys about 500,000 passengers per annum, demonstrating substantial demand
  • Improved connectivity would support the plan’s objectives around economic development and social inclusion

5. Future-Proofing Considerations

  • Ferry service faces ongoing operational challenges (recent 15-month closure, vessel reliability issues)
  • Bridge would provide 24/7 reliable connectivity vs current 16-hour ferry operation
  • Climate resilience – bridges are less weather-dependent than ferry services

How It Should Be Included

Short-term (2025-2030)

  • Commission detailed feasibility study including environmental impact assessment
  • Conduct economic appraisal comparing long-term bridge costs vs ongoing ferry subsidies
  • Stakeholder engagement with environmental groups given Strangford Lough’s protected status

Medium-term (2030-2035)

  • Subject to feasibility outcomes, include bridge as a strategic infrastructure project
  • Plan supporting transport measures (approach roads, traffic management)
  • Consider tolling mechanisms to fund construction and maintenance

Strategic Integration

  • Link to broader Ards Peninsula development strategy
  • Coordinate with tourism development plans
  • Consider freight and emergency services benefits
  • Align with Northern Ireland’s Net Zero objectives

Conclusion

The Portaferry-Strangford bridge represents exactly the type of strategic infrastructure that the Eastern Transport Plan 2035 should be considering. Given the substantial traffic analysis showing potential AADT of 3,000-8,000 vehicles/day, the economic case for replacing an expensive, unreliable ferry service, and the plan’s coverage of the relevant geographic area, the bridge should definitely be included as a strategic proposal requiring detailed feasibility assessment within the ETP 2035 framework.

This would ensure the option is properly evaluated against the plan’s sustainability and connectivity objectives, rather than being left to ad-hoc political campaigns or dismissed without proper strategic consideration.