A4198

Thamesdown Drive looking west from the footbridge

The Summer 2014 revision to the online version of the Ordnance Survey 1:250,000 mapping layer has assigned the number A4198 to the previously unclassified dual carriageway of Thamesdown Drive around the northern edge of Swindon. As the mapping shows the A4198 is a Primary Route, given that the western end does not connect with another Primary Route or at the town centre, the reclassification seemed highly dubious.

Whilst there is only the two secondary sources for this route number at present and no primary source, the possibility that it has been classified as a primary A road is by no means unlikely in Swindon. The town seems to have a history of moving, changing, confusing and creating road numbers seemingly at random - see the B4289 part of which has been upgraded to the A4289 and the A4313 (or is it A313?) as other examples.

Thamesdown Drive is a suburban dual carriageway which starts at the 'Motorola' junction on the A4311 a little to the south of the end of that route, where it connects with the northbound carriageway of the A419. The southbound carriageway is accessed via the single carriageway B4534 which is one of the many classified roads around Swindon that has been moved, broken and become generally confused in the past.

From the A4311, the A4198 heads west along Thamesdown Drive, through a series of junctions, including one with the B4534 - a section no longer connected to that mentioned above. It then turns around to head south, forming the western edge of Swindon's urban area, with Mouldon Hill Country Park to the west of the road. It runs alongside an old railway line, which has been reopened as the Swindon and Cricklade Railway to the north, and comes to an end on the B4534 Purton Road junction.

History

The 2013 edition of the OS 1:250k mapping shows the route as unclassified

The 1:250k sheet from 2016 showing the classification

The road was built in three sections between approximately 1995 and 2001. Sections 1 and 2 were initially opened in the 1990s as single carriageway roads with free flowing roundabout intersections, providing access to the Abbey Meads/St. Andrews Ridge and Taw Hill developments respectively. Section 3 provides access to the newer Priory Vale development, links the western end of section 1 to the northern end of section 2, and was opened in November 2001 as a two lane dual carriageway (D2) from the start, consisting of traffic light controlled intersections. Sections 1 and 2 were called Thamesdown Drive from their date of original opening, and there was clear evidence of reserved land to complete the missing link prior to its construction. Old 2002 aerial imagery viewable in Google Earth shows that section 2 was dualled at the same time that section 3 was being constructed, while dualling work for section 1 was still in progress at the time. The original roundabout intersections on the oldest segment were replaced with traffic light controlled junctions identical to those on the newer segment at its time of dualling.

The Priory Vale Bridge, which allows residents easy footpath access to both sides of the Priory Vale development, was installed during July 2002.

Between 2001 and 2014 the route was officially unclassified, which is quite rare for a lengthy stretch of D2 that serves as more of a bypass than access route, although the route was referred to by Swindon Borough Council as the Northern Orbital Road. In 2014 the Ordnance Survey began displaying the road as a primary route with the number A4198. Google and OpenStreetMap, meanwhile, both display the route number but as a secondary A-road. Considering that none of the road's signs have been modified from white to green, the exact status of the A4198 is somewhat ambiguous. Moreover, there are very few (if any) signs along the road or anywhere in Swindon that mention the A4198 number, so even the number of the road is somewhat disputable. As far back as 2010 a Google Street View image was posted in the SABRE Forums which shows a rogue 'A', without a number on signage on the approach to Thamesdown Drive along Purton Road. This image is still online. As of 2021, though, this sign has been replaced, and the new sign makes no mention of either "A4198" or "A". There are however a limited number of Swindon Borough Council documents that appear to make use of the number such as this one. Another source for the road number was found in section 6 of this Haydon Wick Parish Council meeting.

There have been proposals as far back as the mid 2000s for Thamesdown Drive to one day be extended to meet the B4006 Great Western Way (and thence onto the M4 at junction 16 via the A3102 which would then form a northern and western bypass of the town), but so far this is yet to happen.