tfl.gov.uk

Readiness by lane

Green: tfl.gov.uk. Thin bar: Trains & Public Transport peer median.

Priority fixes for tfl.gov.uk

Ordered by impact and by how common each practice is among peers.

1. Priority 1 · Harden

   DMARC policy enforces quarantine or reject

   Observed: The DMARC policy for tfl.gov.uk was p=none, which asks receivers to take no action on failing mail.

   Why it matters: An enforcing DMARC policy helps receiving mail systems reject email that falsely claims to come from your domain, a common route for phishing your customers.

   What to do: Publish DMARC with p=none and a reporting address first, fix any legitimate senders that fail SPF or DKIM alignment, then move to quarantine and finally reject.

   40% of Trains & Public Transport peers do this. Limit: Read from public DNS at the time of the check; records may have changed since.

   Guide: A Practical Website Health Check for Owners

2. Priority 2 · Accelerate

   Static files cached for 30 days or more

   Observed: A same-site stylesheet or script was cacheable for 7 days, short of the 30-day benchmark.

   What to do: Give versioned (fingerprinted) CSS, JavaScript, fonts and images Cache-Control: public, max-age=31536000, immutable, and change the file name whenever the content changes.

   On Cloudflare: Use Cache Rules to set edge and browser TTLs for static file paths.

   38% of Trains & Public Transport peers do this.

   Guide: Browser Caching Guide for Website Owners

3. Priority 3 · Accelerate

   Modern image formats in use

   Observed: The homepage had 6 images and none used WebP or AVIF.

   What to do: Serve WebP or AVIF with a JPEG or PNG fallback, either through an image CDN or by generating both formats at build time.

   On Cloudflare: Cloudflare Polish can convert images to WebP.

   28% of Trains & Public Transport peers do this.

   Guide: AVIF, WebP, JPEG, and PNG: Choose the Right Image Format

4. Priority 4 · Accelerate

   Offscreen images lazy-loaded

   Observed: The homepage had 6 images and none used loading="lazy".

   What to do: Add loading="lazy" to images below the fold. Do not lazy-load the main hero image, because that delays the largest visible element.

   43% of Trains & Public Transport peers do this.

   Guide: Lazy Loading Without Broken Pages

What tfl.gov.uk already does well

Practices fewer than half of Trains & Public Transport peers use.

• HSTS kept for at least a yearHSTS with a 365-day max-age.41% of peers
• No render-blocking scripts in <head>Head scripts load without blocking.43% of peers
• Certificate lifetime of 100 days or lessShort-lived 90-day certificate from Google Trust Services, already inside the 2027 limit.43% of peers

What we saw

Homepage checked

https://tfl.gov.uk/

Homepage response

HTTP 200

TLS

TLSv1.3, HTTP/2

Certificate

Google Trust Services, 90-day validity, expiring 2026-12-30

CDN or edge

Cloudflare

DNS operators

Cloudflare

HSTS

max-age 365 days

DMARC policy

p=none

Homepage HTML

171 KB, gzip

Images on homepage

6 (png 3, jpg 3)

Limits: homepage only, one location, one moment. Header checks reflect the homepage response; other pages may differ.

Stack and providers

Seen in the homepage response, certificate and DNS. Provider pages compare how their customers configure the same checks.

All 31 checks

Select a gap for the method and fix. How each check works

Compare with other Trains & Public Transport sites

• delhimetrorail.com63
• mbta.com64
• oebb.at64
• ouigo.com64
• transportnsw.info64

Trains & Public Transport readiness benchmark