The third Forth bridge

Published on 30 August 2017

Six years in the making, a brand new cable-stayed bridge across the Firth of Forth opens today, extending the M90 for the first time into Lothian.

In the early hours of this morning, a police convoy held back traffic on the A90 while cones were rearranged at North Queensferry and Echline, and then for the first time traffic was permitted to slowly travel across a brand new bridge. The third bridge over the Forth between Queensferry and North Queensferry, the new bridge was commissioned as a replacement for the A90 Forth Road Bridge, a suspension bridge built in 1964 and which is suffering structural problems.

The new bridge will actually close again on Friday 1 September, after just two days' service, and there will then be a game of ping-pong as traffic of various types is diverted one way and another until finishing works are fully complete and both bridges are in their final configuration. At the time of writing the bridge is signposted as part of the M90 but motorway regulations are not fully in force and the new bridge is temporarily open for use by all classes of traffic that were permitted on the old bridge.

In engineering terms, the new bridge is quite remarkable: it's now the tallest bridge in the UK - a third taller than the A15 Humber Bridge - and is the longest triple-span cable stayed bridge in the world. In traffic terms, it may not be quite such a resounding success. The project was to replace the Forth Road Bridge without increasing road capacity, in order to avoid encouraging an increase in private car commuting into Edinburgh. This morning, as dawn broke, news and travel reports were describing long queues in both directions to get onto the bridge.

CBRD's Motorway Database already includes updates to the M90, including the whole of the crossing and its approach roads in the exit list.

Back and Forth

The timetable from this point on looks like this.

Friday 1 September Early in the morning, the new bridge will be closed and all traffic will be directed over the Forth Road Bridge.
Saturday 2 September First day of public walks over the bridge. 50,000 people won tickets to walk the bridge while closed to traffic. (People who do not already have tickets will be turned away.)
Sunday 3 September Second day of public walks over the bridge.
Monday 4 September Official opening ceremony conducted by the Queen and the Duke of Edinburgh.
Tuesday 5 September Another 10,000 people - this time locals and schoolchildren - will walk over the bridge.
Wednesday 6 September No events planned. And on the sixth day, the bridge rested.
Thursday 7 September Bridge re-opens to traffic as M90, with non-motorway traffic and local buses able to use the A90 Forth Road Bridge.

In the normal run of things, any opening ceremonies, public "walkabouts" and other events that take place on a new road will happen before it opens to traffic at all. Opening the bridge for two days and closing it again is both difficult, costly (in terms of traffic management) and entirely avoidable. So why is it being done here? The answer is, sadly, entirely political. An announcement was made in the Scottish Parliament in June 2017 that the bridge would be open to traffic by the end of August, but progress was slightly delayed, and so the promise can only be kept if traffic is allowed on it at the very end of the month and then closed again for all the other activities to take place.

When it re-opens on 7 September, a 40mph speed limit will be in force until finishing works are complete, at which time speed restrictions will be lifted and the limit across the bridge will be 70mph. The whole M90 from the M9 to junction 2A at Dunfermline will also be subject to variable speed limits.

The motorway that isn't

When completed, all the available construction plans showed that the M90 would, rather unexpectedly, remain in two parts instead of being one continuous route across the Forth. Between junction 1 at Echline (where the A90 branches off eastwards into Edinburgh) and 1A (for the A904 west of Queensferry, the junction at the southern end of the bridge) the new road is built to full motorway standard but classified A90, complete with green signs. In both directions, on approach to this section, signs on the M90 indicate that the motorway ends and the road is signposted as "A90 (M90)".

Intriguingly, this morning, A-Z Digital Mapping indicated that they'd been in touch with the Forth Replacement Crossing Delivery Team and had been told that this anomaly would be corrected: the A90 between junctions 1 and 1A will become part of the M90, though it's not yet known when that will happen.

This seems particularly unusual when, for six years, plans have shown that the road there would not be a motorway, and leaves open a question regarding non-motorway traffic approaching from the east on the A90. Presumably the bus-only sliproads that connect the A90 to the old Forth Road Bridge will be opened to all traffic in order to make this possible (something advocated on SABRE for the whole time the bridge has been under construction - such as in this post from 2011). But it's certainly welcome news that the motorway will indeed be made continuous and route numbering will be consistent for the whole road from the M9 to Perth.

CBRD will hopefully be making a visit and bringing you more from the UK's newest motorway, and one of its most impressive bridges, in the autumn. But for now, here's a video of the whole crossing shot and published this morning by JensRoads.


Toby Speight 30 August 2017

Arguably, it's the fifth Forth Bridge, given that Kincardine (1936) and Clackmannanshire (2008) bridges also cross the estuary...

Adam 30 August 2017

In Aberfoyle there's a tiny little stone bridge over the river that brown signs mark as the "Fourth Road Bridge" (pun very much intended).

Robbie Craig 30 August 2017

I think 6th, you have to start with Stirling Bridge. Think the river is still tidal there.

Stirling Bridge and the bridge carrying the A91 a mile or so east of it both cross the river, not the Firth.

Gavin 30 August 2017

The bridge was opened to traffic in august nothing to do with having to open it up in August, it was opened to allow them to complete the tie in roads and get that sorted out for the links to the old bridge. Once done traffic will be back to the old road to allow the Queen to open it officially.

Geoff 6 September 2017

"extending the M90 for the first time into Lothian"

The M90 has existed in Lothian since 2013; the former M9 spur was redesignated M90 – on the ground at least – at the same time as Kirkliston interchange was completed as part of the M9 smart motorway works. (And it's signed as "Perth, Dundee M90", with no mention of any bridge.)

Simon Barber 11 September 2017

On Thursday 7th September the Queensferry Crossing reopened to all traffic with VMS displays on all approaches and additional yellow signs stating that the motorway restrictions aren't in force. The Forth Road Bridge is closed to everything bar pedestrians and cyclists.

Sometime in November the Forth Road Bridge will reopen as the world's most expensive public transport corridor and the Queensferry Crossing will become the M90 proper and the speed limit raised to 70mph.

Drove over the new bridge as I was heading north and it's very impressive. Massive queues from Edinburgh (not helped by a white van breaking down in the middle lane and a shunt on the hardshoulder causing a lot of rubber necking.) Once we got onto the bridge it was free flowing so hopefully that's an indication of how it'll be once the novelty dies down.


Graham Pearson 23 October 2017

Er, the Queensferry Crossing is not intended "to replace the Forth Bridge" - it doesn't even have railway tracks.

Richard 9 June 2022

I have seen a documentary on building the 1964 bridge, and apparently it was the prototype for the 1966 Severn bridge. I suppose the question should be asked just why has the 64 bridge had these problems, and how much life is left in the bridge and will the buses have to move over eventually?

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