| A4 road | |
|---|---|
The Portway running through the Avon Gorge |
|
| Route information | |
| Length: | 6.5 mi (10.5 km) |
| History: | Constructed between 1919 and 1926 |
| Major junctions | |
| From: | Hotwells |
| A3029 road A4176 road A4162 road A403 road M5 motorway |
|
| To: | Avonmouth |
| Location | |
| Primary destinations: |
Avonmouth |
| Road network | |
The Portway is a trunk road, approximately 6.5 miles (10.5 km) long, which links central Bristol, England, with its port at Avonmouth. It is part of the A4 road, which was the primary east west highway in Southern England before the construction of the M4 motorway.
The road starts at Hotwells and runs through the Avon Gorge, under the Clifton Suspension Bridge, parallel to the serpentine path of the River Avon. It passes through the suburbs of Sea Mills, where it crosses the River Trym, and Shirehampton, before terminating at a roundabout in Avonmouth at a junction with the M5 motorway.
Construction of the Portway started in 1919,[1] partly on the line of the Bristol Port and Pier Railway. In 1924, approximately 200 yards (180 m) of newly constructed concrete embankment slid into the river, posing a hazard to navigation and adding 12 months to the duration of the work.[1][2] The Portway was the most expensive road in Britain when it was opened by the Minister of Transport, Colonel Wilfrid Ashley, in 1926, costing £800,000.[1]
Electric lighting was provided to illuminate the new road, but for one year after the opening the lights were kept switched off following objections from river pilots who argued that they would make it hard to distinguish the navigation lights of shipping and the signal lights on the shore. Eventually the electric lights were turned on at a reduced brilliance.[3] In 1974 City of Bristol and DTp were advised by the Civil Engineering consultants appointed that the rock wall so favoured by climbers at the car park green recess was impracticable to save and although Bristol Council members and engineers were concerned over services in the Portway road that the precipice needing taking back to relieve the rocking action that had set into the cliff face. The City refused, the prospective engineers resigned the contract as the slab was so unstable and pinning (rock bolt) would have required too great a stress load. Later some cut back had to be enforced with the Portway closed and many net units were rock bolted into the Avon Gorge face. Canopy as described herein was utilized in Austria at that date and adopted for the section below the Suspension Bridge, where the "Brunel" foundations are juxtaposed with highly cavernous solution reduced Cardoniferous Limestone mass blocks at rest (William J. Larnach & Reginald Bradshaw University of Bristol and other reports in Engineering Geology, University of Bristol, aver there is no immediate danger, but the site is less than suited to alteration of high bearing stress dependency if not monitored and for new build). It is likely if the records are read that even with pins the base nature of the riparian edge and types of rock therein do not suit support of block limestone above. The 2010 closure of Portway Bridge Valley Road is just one session in a number of engineering works, including the loss of the basement road river alluvial edge, piled and service pipes. Rockfalls from the limestone cliffs of the Avon Gorge have caused a hazard to motorists on occasion and every year the road is closed to allow for inspection of the cliffs for potentially dangerous cracks and loose rocks, and to allow remedial works.[4] In 1980, a glass fibre reinforced concrete canopy was constructed over the road where it passes under the Clifton Suspension Bridge in order to protect traffic from danger at that point.[5]
In 2001, a 27-inch (690 mm) water main burst near the junction with Bridge Valley Road, causing a major collapse and putting the road out of action for several months. One passer-by was swept into the river but was rescued uninjured.[6]
The Portway Park and Ride is in Shirehampton near the M5 junction.[7] A bus lane on the inbound section of the road from Sea Mills is designed to allow quicker access for buses to the city centre. The railway stations of both Shirehampton and Sea Mills are both very close to the road and there is a proposal to build a new station at the Park and Ride.[8]
The annual Bristol Half Marathon uses the Portway as part of its route and the annual Bristol's Biggest Bike Ride also uses the road which is closed to motor traffic for the day.[9] In June 2009, city councillor John Rogers proposed that the Portway be closed to motor traffic on summer Sundays to allow cycling in a car free environment.[10]
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