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The A737 (Howwood Bypass)

The A737 is one of the main routes to Aryshire from the M8 motorway. While not a motorway, the road has origins in the historic plans proposed in The Greater Glasgow Transport Study, published in 1967. The main focus of this article is on the section of the road between Howwood and St. James Interchange on the M8.


The A737 number was initially allocated to a different route (to Glasgow via Paisley’s one way system). It wasn’t until 1993 when the Johnstone – Howwood Bypass opened that the A737 route number was assigned to this new trunk road. The number A740 which had been used on the Linclive Link was abandoned at this time.


Key Facts & Figures

LOCATION:   Renfrewshire

LENGTH: 6 Miles



OPENING DATE:   November 29th 1968

DESIGNER:   Crouch & Hogg

CONTRACTOR:   Peter Lind & Marples Ridgeway

SCHEME COST:   £500,000



OPENING DATE:   March 1992

DESIGNER:   Strathclyde Region/Bullen




Last Updated: 13th February 2016

Route History & Breakdown

A737 Header


OPENING DATE:   May 28th 1993

DESIGNER:   Strathclyde Region/Bullen

CONTRACTOR:  Balfour Beatty

Plans for the construction of a dual carrigeway route between the M8 and Howwood were first considered with the publication of the Greater Glasgow Transportation Study in 1967. The plans recommended the construction of  a "Johnstone Motorway” along the line of the present route. The first section (to Linwood) was built as the Linclive Link Road. With the shelving of many of the GGTS proposals it remained incomplete until 1993.


The need for this route was re-emphasised in traffic studies carried out in the 1980s by Stathclyde Regional Council. The scheme was eventually given the go ahead and construction commenced in 1989 on a grade-seperated high speed dual carriageway bypass for Linwood, Johnstone, Kilbarchan and Howwood following roughly the same line as the proposed “Johnstone Motorway”.



The A740 Linclive Link Road was the first section of the current A737 to open to traffic. It was built as an exntension of the M8 Renfrew Bypass. When it was completed on the 29th of November 1968 it provided a connection between the new motorway and Linwood. It was built as all purpose dual two lane carriageway. The route was initially envisaged as being built to motorway standards.



The Johnstone – Howwood bypass is a relatively modern section of road that starts at the Linwood Interchange and ends west of Howwood. At 8.7km long in, the main section between Linwood and Kilbarchan is all purpose dual carriageway complete with grade separated junctions at Kilbarchan, Barrochan and Linwood.  The road carries the A737 number and is a primary route that is maintained by Transport Scotland as a trunk road.


The Bypass was constructed between 1989 and 1993 and was opened to traffic on Friday 28th May by Councillor Malcolm Waugh of Strathclyde Regional Council. The main works were carried out in two phases. The first phase (between Linwood and Kilbarchan) was awarded to R.J. Lavack in October 1989 and completed in March 1992. The second phase (the single carriageway section between Kilbarchan and Elliston) commenced in July 1992 and was constructed by Balfour Beatty.


The junctions on the bypass are grade separated to allow for uninterrupted traffic flow. The first is Linwood interchange. This junction was previously an at-grade roundabout where the A740 Linclive spur ended; however it was designed to allow for future connections to the south west. The junction is now a roundabout interchange with the A737 passing over on a fixed beam viaduct with the non-trunk A761 underneath. It provides a connection to Linwood and the busy Phoenix Retail Park. The interchange also serves a large industrial estate and logistics depot resulting in high numbers of HGV's travelling to and from the M8.


The building of the bypass occurred during an environmentally sensitive time in history and much was undertaken to reduce the road’s impact on the local communities to which it served. The road was landscaped accordingly and many trees were planted along it’s corridor with pedestrian/cycle overbridges provided to reduce severance. Funding for the A737 Johnstone – Howwood Bypass was provided by the Regional Council with grant assistance from the European Regional Development fund through the Strathclyde Integrated Development Operation. The final cost for the 8.6km bypass by the end of the contract was £34 million.



Barrochan junction is a full access signalised diamond-style junction that connects with the B789. Traffic going to and from the town of Johnstone use this junction which also serves Bridge of Weir. This junction caters for high amounts of turning traffic and as a result can suffer from congestion.


Its original layout was a non-signalised dumb-bell interchange which was revised to allow greater capacity in 2009. This involved removing the small roundabouts and installing traffic signals, allowing timed-allocations of priority for traffic entering and exiting the junction.



Less than one mile to the southwest is Kilbarchan junction. At this point the road narrows from dual to single carriageway. The junction is a half-dumbell with east facing slips only. It connects the communities of Milliken Park to Kilbarchan via the B789 that bridges over the narrowing A737. This was the boundary between the first and second stages of the bypass.


One of the more interesting features of this section of bypass is the section that divides Killbarchan. This was completed in 1993 and carries the single carriageway A737 in a deep cutting with masonry retaining walls. It is not known for certain why this design was chosen, however it was most likely to minimise visual impact and the effects of community severance. It makes any future dualling of the road an expensive prospect.


White hatching along this section prevents traffic from overtaking. To the southwest the bypass continues along a high standard single-carriageway alignment. The contractor (Balfour Beatty) encountered a major engineering challenge along this section as they were forced to slightly alter the course of the Black Cart water to allow for a safe alignment of the carriageway.


The junction with the B787 marks the end of the 1993 bypass and the A737 continues on it’s original alignment south from this point.


Southward Extension

The image above shows the route of Phases 1 and 2 of the Johnstone to Howwood Bypass. It runs to 8.6km and cost over £34 million to complete.


The images below show the route as it appears today.


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