Suffolk CountyMassachusetts
Boston, Massachusetts
Bedrock sits a median 92 ft down across 1,636 logs, deeper than the Massachusetts median of 24 ft. 41 of its 404 inventoried bridges are rated poor (10%, against 9% statewide).
- Live · as of Sep 11, 2026
- 9 public sources · method
- ← All towns
Median depth to bedrock
92 ft
middle half 65–124 ft · 1,636 logs
Bridges rated poor
41
of 404 inventoried · 3 closed
State resilience grants
$1.5M
1 award on file
Construction projects
490
median $8.0M · public bid results
01 · Ground
Deep ground: 86% of logs go past 50 ft before rock
From 1,636 depth-to-rock records inside Boston (MassGIS / MGS borings & well logs). Logs cluster where people drill wells and bore for roads, so treat this as the town’s pattern, not a site answer.
Half of Boston's logs reach rock between 65 and 124 ft
Depth to bedrock: 10th–90th percentile whisker, middle-half box, median tick; dashed line = Massachusetts median.
median 92 ftMA 24 ft
050100150 ft
n = 1,636 logsSource: MassGIS / MGS borings & well logs
▸ Show the numbers▾ Hide the numbers
| Depth to rock (ft) | Logs |
|---|---|
| 0–5 | 21 |
| 5–10 | 23 |
| 10–20 | 53 |
| 20–50 | 131 |
| 50–100 | 688 |
| 100+ | 720 |
Rock within 10 ft
3%
of logs (23% across Massachusetts). Shallow rock means ledge in excavations, refusal for driven piles and rock anchors rather than soil nails; deep ground means taller shoring and more groundwater. 86% of logs here go past 50 ft.
02 · Bridges
41 of 404 bridges are rated poor — about the same as the Massachusetts rate of 9%
Every highway bridge and large culvert in the 2025 National Bridge Inventory that stands inside Boston. Median age 56 years; 16 posted for weight; 3 closed.
22% good, 10% poor
FHWA good / fair / poor rating — the lowest of deck, superstructure, substructure or culvert.
- Good89 · 22%
- Fair274 · 68%
- Poor41 · 10%
Structures by decade built
n = 404 structuresSource: FHWA National Bridge Inventory 2025
▸ Show the numbers▾ Hide the numbers
| Built | Structures |
|---|---|
| pre-1910 | 46 |
| 1910s | 15 |
| 1920s | 12 |
| 1930s | 9 |
| 1940s | 1 |
| 1950s | 56 |
| 1960s | 52 |
| 1970s | 22 |
| 1980s | 26 |
| 1990s | 41 |
| 2000s | 119 |
| 2010s | 5 |
The poor-rated bridges, busiest 12
| Carries | Over | Built | Daily traffic |
|---|---|---|---|
| MORRSSEY BLV | DORCHESTER BAY | 1927 | 78,900 |
| I 90 EB | MBTA | 1965 | 76,373 |
| I 90 WB | MBTA | 1965 | 74,344 |
| STORRW DR WB | STORROW DR EB | 1951 | 57,770 |
| BOWKER INT | I 90 & MBTA | 1965 | 55,075 |
| BLUE HILL AV | MBTA | 1902 | 41,250 |
| US 1 SB | US 1 NB | 1994 | 34,040 |
| CAMBRIDGE ST | CHARLES RIVER | 1925 | 33,400 |
| STORRW DR EBposted | BOWKR ON & OFF RPS | 1954 | 32,000 |
| CAMBRIDGE ST | I 90 & MBTA/CSX | 1964 | 31,600 |
| TRMNT-ARLNGT | AMTRAK/MBTA | 1979 | 30,400 |
| CAMBRIDGE ST | I90 E RPS BDL & CS | 1965 | 27,500 |
03 · Money & permits
490 construction projects on file, median $8.0M — above the state's $1.5M
| Project | Year | Award |
|---|---|---|
| Moakley Park- Resilience Preliminary Design, Technical Analysis, and Pre-Permitting | FY2019 | $1.5M |
Public construction projects
490
Median estimated value $8.0M, middle half $1.5M–$38.4M, against $1.5M across Massachusetts. Capped total $12.2B (each project counted at no more than $100M). Public bid records compiled June 2026, heavy on 2021–22 — a sample, not an annual market.
Ground-related permits in open data
714
Permits in the city’s open-data portal that mention retaining walls, excavation or foundations. Only a handful of portals are read, so this counts what is published, not everything built.
04 · Dams & disasters
Suffolk County has drawn $567M in federal disaster repair since 2010
FEMA Public Assistance is reported by county, so the figure below is Suffolk County-wide context, not a Boston number.
FEMA Public Assistance, Suffolk County
$567M
Federal share obligated across 881 projects in 15 declared disasters since 2010. The largest category is emergency protective measures (97%); roads & bridges took $394K.
05 · Next door
Boston and the 14 towns that border it
A dash means no data for that layer, not zero.
| Town | Poor bridges | Rock depth |
|---|---|---|
| Boston, MA | 41 / 404 | 92 ft |
| Newton, MA | 10 / 49 | 30 ft |
| Somerville, MA | 5 / 42 | 27 ft |
| Cambridge, MA | 7 / 37 | 57 ft |
| Quincy, MA | 1 / 34 | 24 ft |
| Revere, MA | 3 / 30 | 40 ft |
| Dedham, MA | 2 / 23 | 14 ft |
| Canton, MA | 3 / 20 | 22 ft |
| Chelsea, MA | 3 / 14 | 80 ft |
| Needham, MA | 2 / 14 | 15 ft |
| Milton, MA | 1 / 13 | 40 ft |
| Brookline, MA | 0 / 10 | 11 ft |
| Everett, MA | 0 / 8 | 75 ft |
| Watertown, MA | 0 / 4 | 51 ft |
| Winthrop Town, MA | 0 / 1 | 79 ft |
Where these numbers come from
Method, sources & caveats
Boston is the Census county subdivision 2502507000 (Suffolk County). Every record is placed here by its coordinates, not by the place name the source uses. Construction-project figures come from Massachusetts public bid results, published as town-level counts, medians and capped totals (n ≥ 10).
- Towns are Census county subdivisions: cities, towns, plantations, and Maine/New Hampshire unorganized territories and townships. Every record is placed in a town by its coordinates (point-in-polygon), not by the source's own place label — so a bridge in Roxbury counts for Boston and a well in 'North Waltham' counts for Waltham.
- Bridges: FHWA NBI 2025, highway structures ≥ 20 ft including large culverts. 'Poor' is FHWA's good/fair/poor rating (lowest of deck, superstructure, substructure or culvert ≤ 4). Percent-poor is shown only for towns with at least 5 structures.
- Depth to bedrock is the median of driller- and boring-reported depths in the town, shown only where at least 10 logs exist. Water-well logs over-sample rural lots and hilltops; one town median never describes a particular site.
- Bedrock depths use the same state databases and filters as the Bedrock & soils module (bedrock wells and borings that reached rock, 0 < depth ≤ 400 ft, exact re-filings dropped), but every log is placed in a town by its coordinates rather than the driller's town field, so town counts can differ slightly between the two pages. Connecticut and Rhode Island have no statewide public well-log database with depths.
- Dams: only high-hazard-potential dams whose latest condition assessment is Poor or Unsatisfactory are counted (live NID). Connecticut and Rhode Island assessments may lag.
- FEMA Public Assistance dollars are federal share obligated for disasters declared since 2010, reported by county — they are county context, not a town figure.
- Grant awards are Massachusetts only (EEA Dam & Seawall program, MVP Action grants, CZM Coastal Resilience). Other states' programs are not yet included.
- Ground-related permit counts cover only the municipal portals the pipeline reads (Boston, Cambridge, Somerville, Worcester, Framingham, Providence, Portsmouth, Hartford and a few others) — an absent count means 'not covered', not zero.
- Data as of
- Sep 11, 2026
- Generated
- Sep 11, 2026
- Records
- 367,748
- Refresh
- Live pull · weekly
- U.S. Census Bureau cartographic boundary files — county subdivisions (2024, 1:500k)Public domain
- FHWA National Bridge Inventory (2025 delimited files)Public domain
- USACE National Inventory of DamsPublic domainHigh-hazard dams rated Poor or Unsatisfactory (live NID).
- USGS U.S. Landslide InventoryPublic domain
- MassGIS / Massachusetts Geological Survey — Bedrock Data PointsPublic recordBorings and well logs that reached rock (MassDEP well drillers, USGS, MWRA, MassDOT…); seismic/HVSR and map-derived shallow-bedrock/outcrop points excluded.
- NH DES Water Well Inventory, Maine Geological Survey Wells Database, Vermont DEC well recordsPublic recordBedrock wells only; driller-reported depth to bedrock / overburden thickness.
- OpenFEMA Public Assistance Funded Projects Details (v2)Public domain
- MA EEA / CZM grant awards — Dam & Seawall, MVP Action, CZM Coastal ResiliencePublic record
- Municipal open-data permit portals (Boston, Cambridge, Somerville, Providence, Portsmouth, others)Public recordOnly permits flagged as ground-related (retaining walls, excavation, foundations) are counted.
Published by Earth Support Corp as a public resource. Regional statistics for planning and curiosity. They are not an engineering report, a bid recommendation or a statement about any particular site, firm or project. Spot an error? Tell us and we will correct it. Full method: methodology.