Gatwick Airport's Highway improvements (A23/M23/A217)

[Phil]

I believe Gatwick plan to have a development off the north side of the new GSJ.

Gatwick don't - its the borough of Reigate & Banstead that do! They want to link it into the spur road so that it doesn't put any additional traffic onto their own highway network through Horley.

The country boundary between Surrey / West Sussex CC and Reigate & Banstead BC / Crawley BC runs along the northern side of the spur road.

[Phil]

They still planning on removing motorway regulations from the spur... How pointless & stupid, if anything the whole spur should now be under motorway regulations since South terminal would be GSJ'd.

That would be impossible as it would prevent vehicle access to the airports south terminal facilities like car parks and hotel by those banned from driving on motorways like learner drivers.

As such there is zero scope for extending motorway regulations from their current limits.

(Although the A23 passes under the airport there is no way of accessing it from there as all car based facilities were moved over to the eastern side of the railway to co-incide with the M23 opening and the areas redeveloped).

[Phil]

If the spur loses its motorway regulations, will that allow developers to move in via a new rbt between M23 and the new GSJ? The land between M23 and the railway is undeveloped. Thus, a rbt turned into a GSJ will be ruined by a new rbt or complex signalised crossroads close by. Just saying....

That land you highlight is blighted by aircraft noise from planes coming to land or taking off and is thus totally unsuited for residential development. Yes you could put in place some industrial development on it - but to be honest the industrial sector of Crawley new town is hardly short on vacant space and I'm sure West Sussex CC / Crawley BC will want to direct any industrial development there first

[AnOrdinarySABREUser]

A slip from A23 northbound to the flyover would remove the conflicts at the T-junction. The diverge to Airport Way is close, and a signalised merge onto the A23 southbound may or may not be needed. But even if it was, the timings would much much more favourable with A23 northbound traffic bypassing the lights altogether.

In my opinion, the western roundabout should be grade-separated too, with a flyover being provided from the A23 Redhill side onto Airport Way. This would provide better traffic flow than the signalised junction currently planned as four movements are freeflow as opposed to one, or six if segregated left turns between the A23 and Airport Way are included. The roundabout wouldn't be signalised (as all roundabouts should be). It's a good job that the eastern roundabout is planned to be grade-separated!

Additionally, the M23 junction should have the unnecessary U-turn removed too. Think of J19 of the M4. Ideally, the roundabout would be converted for a trumpet. While the Londonbound slips would be tight due to the bridge to the immediate west of the junction, it wouldn't be too much of an issue.

[M19]

I believe Gatwick plan to have a development off the north side of the new GSJ.

Gatwick don't - its the borough of Reigate & Banstead that do! They want to link it into the spur road so that it doesn't put any additional traffic onto their own highway network through Horley.

The country boundary between Surrey / West Sussex CC and Reigate & Banstead BC / Crawley BC runs along the northern side of the spur road.

R&BBC see this as a high quality employment campus. Options study here on page 535: https://reigate-banstead.moderngov.co.u ... e.pdf?T=10

[jervi]

A slip from A23 northbound to the flyover would remove the conflicts at the T-junction. The diverge to Airport Way is close, and a signalised merge onto the A23 southbound may or may not be needed. But even if it was, the timings would much much more favourable with A23 northbound traffic bypassing the lights altogether.

In my opinion, the western roundabout should be grade-separated too, with a flyover being provided from the A23 Redhill side onto Airport Way. This would provide better traffic flow than the signalised junction currently planned as four movements are freeflow as opposed to one, or six if segregated left turns between the A23 and Airport Way are included. The roundabout wouldn't be signalised (as all roundabouts should be). It's a good job that the eastern roundabout is planned to be grade-separated!

Additionally, the M23 junction should have the unnecessary U-turn removed too. Think of J19 of the M4. Ideally, the roundabout would be converted for a trumpet. While the Londonbound slips would be tight due to the bridge to the immediate west of the junction, it wouldn't be too much of an issue.

In the initial 2021 consultation, documents did show options for the North Terminal Roundabout, which did include GSJ interchanges - infact 4 of the 7 options were this, with altering geometry and speed design.

This provides Free flow connectivity between A23 Redhill to both the A23/M23 spur & A23 towards Crawley. This is clearly the best design for the junction when compared to what is currently proposed, but think it was discounted due to engineering impact on structures.

[AnOrdinarySABREUser]

A slip from A23 northbound to the flyover would remove the conflicts at the T-junction. The diverge to Airport Way is close, and a signalised merge onto the A23 southbound may or may not be needed. But even if it was, the timings would much much more favourable with A23 northbound traffic bypassing the lights altogether.

In my opinion, the western roundabout should be grade-separated too, with a flyover being provided from the A23 Redhill side onto Airport Way. This would provide better traffic flow than the signalised junction currently planned as four movements are freeflow as opposed to one, or six if segregated left turns between the A23 and Airport Way are included. The roundabout wouldn't be signalised (as all roundabouts should be). It's a good job that the eastern roundabout is planned to be grade-separated!

Additionally, the M23 junction should have the unnecessary U-turn removed too. Think of J19 of the M4. Ideally, the roundabout would be converted for a trumpet. While the Londonbound slips would be tight due to the bridge to the immediate west of the junction, it wouldn't be too much of an issue.

In the initial 2021 consultation, documents did show options for the North Terminal Roundabout, which did include GSJ interchanges - infact 4 of the 7 options were this, with altering geometry and speed design.
alt north term-min.PNG
This provides Free flow connectivity between A23 Redhill to both the A23/M23 spur & A23 towards Crawley. This is clearly the best design for the junction when compared to what is currently proposed, but think it was discounted due to engineering impact on structures.

Right. If you're going to build a bridge to make one of the movements freeflow, you might as well go one step further and make 2 more movements freeflow.

[jervi]

In the initial 2021 consultation, documents did show options for the North Terminal Roundabout, which did include GSJ interchanges - infact 4 of the 7 options were this, with altering geometry and speed design.
alt north term-min.PNG
This provides Free flow connectivity between A23 Redhill to both the A23/M23 spur & A23 towards Crawley. This is clearly the best design for the junction when compared to what is currently proposed, but think it was discounted due to engineering impact on structures.

Right. If you're going to build a bridge to make one of the movements freeflow, you might as well go one step further and make 2 more movements freeflow.

That design would have had 4 free flow movements.
A23 Redhill -> A23/M23 Spur by bypassing roundabout to North.
A23 Redhill -> A23 Crawley via flyover
A23/M23 Spur -> A23 Redhill via flyover
A23 Crawley -> A23 Redhill via flyover

[jackal]

In the initial 2021 consultation, documents did show options for the North Terminal Roundabout, which did include GSJ interchanges - infact 4 of the 7 options were this, with altering geometry and speed design.
alt north term-min.PNG
This provides Free flow connectivity between A23 Redhill to both the A23/M23 spur & A23 towards Crawley. This is clearly the best design for the junction when compared to what is currently proposed, but think it was discounted due to engineering impact on structures.

Right. If you're going to build a bridge to make one of the movements freeflow, you might as well go one step further and make 2 more movements freeflow.

That design would have had 4 free flow movements.
A23 Redhill -> A23/M23 Spur by bypassing roundabout to North.
A23 Redhill -> A23 Crawley via flyover
A23/M23 Spur -> A23 Redhill via flyover
A23 Crawley -> A23 Redhill via flyover

This rather highlights the flaw with this proposal, namely, that all the freeflow traffic is coming to or from Longbridge Roundabout. It's a fancy way of speeding traffic to a random suburban roundabout. It would make slightly more sense if that were GSJed too, but then you'd have to wonder why this suburban S2 (A23 Brighton Rd or more likely A217) was getting grade separation when many more important roads aren't.

IMO it makes more sense to focus on the connection between the airport and the M23.

[jervi]

The latest revised drawings.
https://infrastructure.planninginspecto ... utline.pdf

Some minor changes:
New cycle/footway from Southern Terminal to A217/A23 roundabout shown, with link to North Terminal.
A23 spur bridge over railway will gain a footway on Northern Side, which appears to connect onto Balcombe Road.
New path connecting the NCN21 North of the A23 spur to the Southern side via railway bridge.

Seems like they still want to kill the M23 spur.