EventService Disruption

Colfax Marathon to cause temporary detours, delays for RTD bus, light rail routes

Pauline Haberman

Scheduled connections could be affected; customers should allow extra travel time 

DENVER (May 14, 2025) –– Some Regional Transportation District (RTD) bus and train services will experience detours from 6 a.m. until 2 p.m. Sunday, May 18, due to the Colfax Marathon.

This year marks the 19th anniversary for the marathon, which will run through Denver and Lakewood. Race events take place on Saturday and Sunday, May 17-18, and will temporarily affect RTD light rail and bus routes that run along and across Colfax Avenue.

D, H and L light rail (Sunday, May 18, only):

  • D and H lines will not serve Colfax at Auraria Station through the Downtown Loop stations on Stout and California streets
  • D and H lines will continue to serve 10th•Osage Station, and will reroute to serve Auraria West Station, Empower Field at Mile High Station, Ball Arena•Elitch Gardens Station and Union Station
  • The L Line will not be in service, and customers are encouraged to use bus Route 43 as an alternative option
  • No impacts to RTD rail service are expected to occur on Saturday, May 17
  • Customers should expect delays on D, E, H and W lines during the event due to increased rail traffic at Union Station. Plan for extra travel time to/from Downtown

Bus routes:

  • May 17 only: routes 20 and 24 will have a minor detour around the event, 9 a.m.-noon during the Colfax 5K race 
  • May 18 only: the following bus routes will be temporarily detoured in many areas, and will be allowed to cross the marathon route when possible: 0, 1, 6, 8, 9, 10, 12, 15, 15L, 16, 19, 20, 24, 28, 30, 38, 40, 43, 44, 48, 51, 52, 76, 83L, ART, MALL

Customers using routes affected by the marathon should expect delays and detours, which may affect scheduled connecting bus and rail trips. Check the RTD website before traveling for schedules and to plan a trip.

For the May 18 race day, RTD is accepting Colfax Marathon 2025 race bibs, 6 a.m.-2 p.m. as valid fare payment on the following rail lines and bus routes:

  • Rail lines: W Line
  • Bus routes: 15, 15L, 16

Details on the 2025 Denver Colfax Marathon races and events can be found on their website at: https://www.runcolfax.org.

Written by Pauline Haberman
Rail map shows L Line not operating, and D and H lines connecting to Union Station via 10th•Osage, Auraria West, Empower Filed at Mile High, and Ball Arena•Elitch Gardens.