RobertB
03 December 2004, 03:21 PM
I've spent a lot of time looking at Appendix C (http://www.dart.org/nweis/nwfeistoc.htm) of the EIS for the Pleasant Grove - Carrollton line. The entire route is in current or former freight line ROW. The southeast leg is really pretty simple -- the northern section replaces the freight tracks (if any) entirely, and the southern section parallels the freight spur for Dal-Tile, which has few branches to deal with.
The northwest stretch, from Downtown to Carrollton, is another matter entirely. I was simply amazed at the complexity involved. DART must work LRT around the existing active freight lines to such an extent that I'm surprised some other routing wasn't used. I've attempted to map out the more interesting spots where DART has to bend over backwards to build what looks like such a straight-line route.
A. Since the Victory developers blocked any sensible routing through their complex, DART had to use the existing freight/TRE ROW. I got to watch this first-hand on my way to work: they built a set of temporary rail bridges, relocated the freight to the temporary bridges, built the new bridges, relocated the freight again to the new bridges, and tore out the temporary bridges. All the while, the freight and TRE had to keep moving. That explains why this small segment cost a whopping $150 million, if I remember correctly. That's two miles of subway plus a station, by my estimate.
B. There used to be freight rail along the Houston Street extension north of Victory. The Victory developers took out the rail and replaced it with a four-lane feeder from Harry Hines to the complex. But when the LRT is extended, the two southbound lanes will be taken out again and replaced with rail. Plus ca change, plus c'est la meme chose.
C. Isn't the Harry Hines/Oak Lawn intersection a mess? DART's about to take care of that little problem... by removing access from and to southbound Harry Hines entirely. Those ramps with the "NO TURNS" signs will go away to make room for the LRT lines. Even then, it still looks to be a tight squeeze between Hines, LRT, and Freight all the way to Market Center Station.
D. DART's entire plan between Market Center Station and Mockingbird Lane depends on this little statement on the plan diagram: "This alignment assumes that freight service can be terminated south of the "Coca-Cola" Spur near Denton Drive at Mockingbird Lane. If freight service can not be terminated, additional ROW will be required." I sure hope they've worked out this little detail... otherwise, things will get as hairy here as they are further north.
E. Assuming DART can decommission the freight, it's still going to be an elevated line, including elevated stations at Market Center and Inwood. This allows the cross-streets to connect to Denton Drive without rail crossings through the mixed-use area, and helps prevent student souffle' near the middle school.
F. DART's luck runs out at Mockingbird Lane. Just south of M'bird, there are spurs to the east *and* to the west. DART takes care of this issue, as well as the intersection of M'bird and Denton, by going deep. They dig a tunnel under the whole mess, with top-of-rail 40 feet below Mockingbird. As shown by the tunnel studies, though, this puts the line smack in the middle of the water table, so DART will have to spend extra time and money waterproofing the stretch from STA 163+50 to STA 181+00 (that's 1,750 feet, over a quarter mile, if I understand the terminology). But at least DART has a head start on a future tunnel to Love.
G. The stretch to Brookhollow Station and isn't so bad, except that DART has to build new sidings, relocate freight, close streets and driveways, and rebuild large portions of crumbling Denton Drive.
H. But from Brookhollow Station to Bachman Station, the geometry gets crazy. DART needs to cross an active spur AND move the LRT to the other side of the freight. This is accomplished in another elevated section with a series of intricate bridges that accomodate the oblique angles between the lines. DART also gets the task of turning the 5-way intersection at Webb Chapel Ext and Denton Dr into a 4-way intersection by turning Cullum Dr. into a cul-de-sac.
I. Bachman Station ends Phase 2, but DART's headaches are just beginning. A little ways north of the station is a "storage track" that consists primarily of a bridge over Northwest Highway, parallel to and at a lower elevation than the main line bridge over the road. The wye to the Irving line is in the same area, but doesn't currently appear to connect to the storage track. It's a messy geometry indeed.
J. Hold on to your hats. At ths point, just north of NWHwy, we have LRT on the west, Denton Dr. in the middle, and freight on the east. But up ahead, apparently, we have some immovable objects that DART gets around in a creative way. The LRT crosses Denton Dr. at a very oblique angle, requiring long bridge spans across the road. But that's not all! The elevated LRT continues to climb, with bridges above and surrounding the freight tracks. The freight trains will essentially be in a tunnel under the DART rail! The DART bridges will be so high -- 40 feet up -- they'll actually be above the freight bridge over Joe's Creek. But the zaniness has just begun.
K. North of Lombardy Lane is a bunch of freight storage tracks between the main freight line and Denton Dr. This must be a good place to store a train, because DART has a pocket track (a stretch of track between the main lines) planned for the spot as well. But how they do it is bizarre. The northbound DART track will continue 30-40 feet overhead. But the southbound track and the pocket track descend to ground level! It doesn't look like a constrained ROW condition, because there's still a full 20' between the NB line and the pocket track (and only 15' between the pocket track and the SB line next to it). This bizarre alignment continues almost to Walnut Hill Lane.
L. By now, an oblique crossing of LRT and freight seems downright ordinary. Just before Walnut Hill, it happens again. By the time we reach Walnut Hill Station just across the road, we have from west to east: Denton Drive (reconstructed), Walnut Hill Station (elevated), and freight (relocated).
M. The freight lines finally give up between Walnut Hill and Royal Ln. The stretch from Walnut Hill to Forest Ln. is still elevated, though, allowing for cross streets and flood prevention. The freight lines are simply removed all the way to Carrollton.
N. Just south of Crosby Rd., a freight line comes in from the west, and is relocated -- all the way to the end of the line. But for some reason, DART is planning to keep the existing rails, between Crosby Rd. and downtown Carrollton, as freight storage tracks. To accomplish this, DART will again build its rail line above the existing rail, stretching the lines apart to form a tunnel over the freight siding. This introduces complexity at both ends of the storage area, where the freight rails must wind through the DART bridge posts to reach the parent freight line.
O. The approach to Carrollton Square Station will use the ROW currently occupied by the narrow connector between Denton Dr. and Carroll St. The elevated station is just north of Belt Line, and its north end is at the Cotton Belt rail line. The drawing notes that the "Future Cotton Belt Station Site" will have its west end here.
P. Several rail lines and spurs cross between Belt Line and Whitlock (aka Sandy Lake aka Keller Springs). This requires several interesting configurations of the DART elevated line's support columns.
Q. The line goes to ground level, but has to go back up again for yet another freight spur that they just couldn't do without. The oblique crossing of Jackson Rd. also poses some interesting geometry.
R. It looks like NTTA did us one small favor. The freight rail bridge they built to go under the PGBT and over Furneaux Creek will work for the northbound LRT line. But DART still has to build another set of bridges for the southbound line and the relocated freight. Oh, and just for good measure: one more essential rail spur that DART has to build a bridge over, just a bit north of the tollway.
S. Finally, at the end of the line, DART does something interesting. They're not running the LRT rails across Frankford Road, but they are building a new bridge for the freight, west of the existing crossing. This allows the DART rails to be extended further north at some point in the future.
In another thread, someone suggested that DART should preserve the freight rails from Lewisville to Dallas for future commuter rail possibilities. I think the complexity detailed above explains why DART chose to get rid of the parallel freight rails wherever possible! Edit: The segments in red are where LRT shares ROW with Freight, blue indicates LRT-only.
Edit 09/08: Restore image
The northwest stretch, from Downtown to Carrollton, is another matter entirely. I was simply amazed at the complexity involved. DART must work LRT around the existing active freight lines to such an extent that I'm surprised some other routing wasn't used. I've attempted to map out the more interesting spots where DART has to bend over backwards to build what looks like such a straight-line route.
A. Since the Victory developers blocked any sensible routing through their complex, DART had to use the existing freight/TRE ROW. I got to watch this first-hand on my way to work: they built a set of temporary rail bridges, relocated the freight to the temporary bridges, built the new bridges, relocated the freight again to the new bridges, and tore out the temporary bridges. All the while, the freight and TRE had to keep moving. That explains why this small segment cost a whopping $150 million, if I remember correctly. That's two miles of subway plus a station, by my estimate.
B. There used to be freight rail along the Houston Street extension north of Victory. The Victory developers took out the rail and replaced it with a four-lane feeder from Harry Hines to the complex. But when the LRT is extended, the two southbound lanes will be taken out again and replaced with rail. Plus ca change, plus c'est la meme chose.
C. Isn't the Harry Hines/Oak Lawn intersection a mess? DART's about to take care of that little problem... by removing access from and to southbound Harry Hines entirely. Those ramps with the "NO TURNS" signs will go away to make room for the LRT lines. Even then, it still looks to be a tight squeeze between Hines, LRT, and Freight all the way to Market Center Station.
D. DART's entire plan between Market Center Station and Mockingbird Lane depends on this little statement on the plan diagram: "This alignment assumes that freight service can be terminated south of the "Coca-Cola" Spur near Denton Drive at Mockingbird Lane. If freight service can not be terminated, additional ROW will be required." I sure hope they've worked out this little detail... otherwise, things will get as hairy here as they are further north.
E. Assuming DART can decommission the freight, it's still going to be an elevated line, including elevated stations at Market Center and Inwood. This allows the cross-streets to connect to Denton Drive without rail crossings through the mixed-use area, and helps prevent student souffle' near the middle school.
F. DART's luck runs out at Mockingbird Lane. Just south of M'bird, there are spurs to the east *and* to the west. DART takes care of this issue, as well as the intersection of M'bird and Denton, by going deep. They dig a tunnel under the whole mess, with top-of-rail 40 feet below Mockingbird. As shown by the tunnel studies, though, this puts the line smack in the middle of the water table, so DART will have to spend extra time and money waterproofing the stretch from STA 163+50 to STA 181+00 (that's 1,750 feet, over a quarter mile, if I understand the terminology). But at least DART has a head start on a future tunnel to Love.
G. The stretch to Brookhollow Station and isn't so bad, except that DART has to build new sidings, relocate freight, close streets and driveways, and rebuild large portions of crumbling Denton Drive.
H. But from Brookhollow Station to Bachman Station, the geometry gets crazy. DART needs to cross an active spur AND move the LRT to the other side of the freight. This is accomplished in another elevated section with a series of intricate bridges that accomodate the oblique angles between the lines. DART also gets the task of turning the 5-way intersection at Webb Chapel Ext and Denton Dr into a 4-way intersection by turning Cullum Dr. into a cul-de-sac.
I. Bachman Station ends Phase 2, but DART's headaches are just beginning. A little ways north of the station is a "storage track" that consists primarily of a bridge over Northwest Highway, parallel to and at a lower elevation than the main line bridge over the road. The wye to the Irving line is in the same area, but doesn't currently appear to connect to the storage track. It's a messy geometry indeed.
J. Hold on to your hats. At ths point, just north of NWHwy, we have LRT on the west, Denton Dr. in the middle, and freight on the east. But up ahead, apparently, we have some immovable objects that DART gets around in a creative way. The LRT crosses Denton Dr. at a very oblique angle, requiring long bridge spans across the road. But that's not all! The elevated LRT continues to climb, with bridges above and surrounding the freight tracks. The freight trains will essentially be in a tunnel under the DART rail! The DART bridges will be so high -- 40 feet up -- they'll actually be above the freight bridge over Joe's Creek. But the zaniness has just begun.
K. North of Lombardy Lane is a bunch of freight storage tracks between the main freight line and Denton Dr. This must be a good place to store a train, because DART has a pocket track (a stretch of track between the main lines) planned for the spot as well. But how they do it is bizarre. The northbound DART track will continue 30-40 feet overhead. But the southbound track and the pocket track descend to ground level! It doesn't look like a constrained ROW condition, because there's still a full 20' between the NB line and the pocket track (and only 15' between the pocket track and the SB line next to it). This bizarre alignment continues almost to Walnut Hill Lane.
L. By now, an oblique crossing of LRT and freight seems downright ordinary. Just before Walnut Hill, it happens again. By the time we reach Walnut Hill Station just across the road, we have from west to east: Denton Drive (reconstructed), Walnut Hill Station (elevated), and freight (relocated).
M. The freight lines finally give up between Walnut Hill and Royal Ln. The stretch from Walnut Hill to Forest Ln. is still elevated, though, allowing for cross streets and flood prevention. The freight lines are simply removed all the way to Carrollton.
N. Just south of Crosby Rd., a freight line comes in from the west, and is relocated -- all the way to the end of the line. But for some reason, DART is planning to keep the existing rails, between Crosby Rd. and downtown Carrollton, as freight storage tracks. To accomplish this, DART will again build its rail line above the existing rail, stretching the lines apart to form a tunnel over the freight siding. This introduces complexity at both ends of the storage area, where the freight rails must wind through the DART bridge posts to reach the parent freight line.
O. The approach to Carrollton Square Station will use the ROW currently occupied by the narrow connector between Denton Dr. and Carroll St. The elevated station is just north of Belt Line, and its north end is at the Cotton Belt rail line. The drawing notes that the "Future Cotton Belt Station Site" will have its west end here.
P. Several rail lines and spurs cross between Belt Line and Whitlock (aka Sandy Lake aka Keller Springs). This requires several interesting configurations of the DART elevated line's support columns.
Q. The line goes to ground level, but has to go back up again for yet another freight spur that they just couldn't do without. The oblique crossing of Jackson Rd. also poses some interesting geometry.
R. It looks like NTTA did us one small favor. The freight rail bridge they built to go under the PGBT and over Furneaux Creek will work for the northbound LRT line. But DART still has to build another set of bridges for the southbound line and the relocated freight. Oh, and just for good measure: one more essential rail spur that DART has to build a bridge over, just a bit north of the tollway.
S. Finally, at the end of the line, DART does something interesting. They're not running the LRT rails across Frankford Road, but they are building a new bridge for the freight, west of the existing crossing. This allows the DART rails to be extended further north at some point in the future.
In another thread, someone suggested that DART should preserve the freight rails from Lewisville to Dallas for future commuter rail possibilities. I think the complexity detailed above explains why DART chose to get rid of the parallel freight rails wherever possible! Edit: The segments in red are where LRT shares ROW with Freight, blue indicates LRT-only.
Edit 09/08: Restore image